Future Biorefinery Joint Research 2 Programme Report 2011-2014 by Fibic

Ohjelmatunnukset

Future Biorefinery Joint Research 2 Programme Report 2011-2014

13 Ohjelmatunnukset

Future Biorefinery Joint Research 2 Programme Report 2011-2014

CONTENT Foreword .........................................................................................................................................................5 World-leading knowledge platforms for wood-based biorefineries...........................................6 Introduction...................................................................................................................................................10 Modelling and techno-economic evaluation of biorefinery concepts.....................................14 New solutions for biomass fractionation ......................................................................................... 32 Ionic liquids for wood fractionation..................................................................................................... 52 Hydroxy acids (and other acids) from black liquor ........................................................................ 72 Biological effects of wood-based extracts and compounds in models of human disease............................................................................................................................................88 Thermoplastic lignin and reinforcing cellulose fiber composites for advanced biocomposite applications.................................................................................................................... 104 Biorefinery products ...............................................................................................................................122

Copyright Finnish Bioeconomy Cluster FIBIC 2014. All rights reserved. This publication includes materials protected under copyright law, the copyright for which is held by FIBIC or a third party. The materials appearing in publications may not be used for commercial purposes. The contents of publications are the opinion of the writers and do not represent the official position of FIBIC. FIBIC bears no responsibility for any possible damages arising from their use. The original source must be mentioned when quoting from the materials. ISBN 978-952-67969-6-3 (paperback) ISBN 978-952-67969-7-0 (PDF) Layout: Brand United Ltd Printing: Kirjapaino LĂśnnberg

Coverpage: TOC graphic image from Parviainen, A., King, A. W. T., Mutikainen, I., Hummel, M., Selg, C., Hauru, L. K. J., Sixta, H., KilpelĂ¤inen, I.: Predicting cellulose solvating capabilities of acid base conjugate ionic liquids. ChemSusChem. 2013. 6. 2161-2169. Copyright Wiley-VCH Verlag GmbH & Co. KGaA. Reproduced with permission. Page 32: Photo by Metla / Erkki Oksanen

FUBIO JR2 PROGRAMME REPORT

FOREWORD The bioeconomy has fast developed as one of the most relevant platforms for business and environmental sustainability today. In parallel, Finland’s centuries-rich forest industry is undergoing radical renewal. Coupling leading-edge wood and paper products expertise with milestone advances in technology, research competence and knowledge, the industry is unlocking vast potential for new products and new integrated processes – and turning its most ambitious targets and concepts into realistic business opportunities. Along with the renaissance of wood use in construction, design and mechanical industry, environmentally friendly wood-derived chemicals are increasingly replacing conventional oil-based materials. The wood raw material for chemical pulping contains numerous components in addition to cellulose that are currently burned for energy recovery. Intelligent process solutions drawing on new knowledge and Finland’s common logistics, energy and technology platform are now enabling the separation and generation of highly value-added products from this valuable bioresource. These new products can be used to enhance existing paper and board products or applied in new alternative business areas. The forest industry has been the backbone of the Finnish economy throughout its history. Today, the urgent need to find innovative applications for new forest-based products is two-fold: the decline in the printing and writing paper sector and the fight to find new sustainable business based on Finland’s staple renewable resource – wood. The work done in the FuBio JR2 programme brings these efforts a significant step forward by opening exciting development opportunities and lighting the path towards innovative and sustainable industry renewal. The five-year EUR 50 million FuBio JR2 programme, a continuation of FuBio 1, represents a dedicated effort and investment by the Finnish Bioeconomy Cluster – joint research company FIBIC Ltd. The programme lays a solid foundation for building competence in bioeconomy research and for business creation. It also significantly enhances networking between industry and the research community as well as joint understanding of the research challenges and needs of the future.

Mika Hyrylä UPM-Kymmene Oyj Chairperson, FuBio Joint Research 2 Programme Management Group

FUBIO JR2 PROGRAMME REPORT

WORLD-LEADING KNOWLEDGE PLATFORMS FOR WOOD-BASED BIOREFINERIES The renewal of the forest industry and creation of new businesses are essential prerequisites for the future success of the Finnish pulp and paper industry as part of a sustainable, bio-based economy. In the second FuBio Joint Research programme,

have participated in the FuBio JR2 programme

companies

organizations

regard ionic liquids as extremely attractive

have jointly developed globally competitive

and promising, they admit that some aspects

knowledge platforms within the field of wood-

need more study and development before

based biorefinery research and development,

industrial-scale utilization.

and

research

by creating new value chains for refining novel materials and chemicals.

The

FuBio

programmes

have

built

competence platform on ionic liquids and led to

A wide range of Finnish forest cluster

the creation of key research teams. However,

companies have actively participated in FuBio

new skills are still needed, and consequently

JR2. In the following chapters the companies

different consortia will launch more focused

highlight the results achieved in the programme.

programmes and projects in the near future, to devise industrial applications.

Great new potential in ionic liquids

The development of new ionic liquids has created great potential for new production

In the FuBio Joint Research programmes 1 and

processes in wood-based value chains. The

2 over 100 new ionic liquids were synthesized.

same knowledge is applicable to other areas

The best ones show great potential for

as well.

certain applications studied in another FIBIC programme, FuBio Cellulose. The FuBio JR 2 research work on ionic liquids is expected to be invaluable for the future of the Finnish forest industry and will probably have a major impact for the renewal of the

Mikael Hannus, Stora Enso: â&#x20AC;&#x153;Before we have industrial applications in use, a lot of development work is needed. In general, breakthrough technologies are not created overnight and are developed at high risk.

biorefinery sector. Ionic liquids may even be a

The Fibic framework is a functional environment

game changer for future biorefineries.

for this kind of research and development.â&#x20AC;?

Although the majority of the companies that

FUBIO JR2 PROGRAMME REPORT

Lignin and hemicellulose – raw materials for future bio-based business

Several alternatives for bio-based barrier materials

The research has given strong indications

The Fubio JR2 programme evaluated the

that residues from pulp and paper production,

applicability of several bio-based alternatives

such as lignin and hemicellulose, will have the

greatest impact in the production of novel bio-

xylan has been identified as one of the new

based products.

barrier materials with the greatest potential,

The Fubio JR2 programme has created new insight into wood chemistry and promoted

barrier

applications.

Alkali-extracted

and its performance has been successfully demonstrated at pilot scale.

broad competence in hemicellulose separation

As a barrier material xylan has many

technologies. Specifically it has improved

advantages: its bio-content is quite high, its

understanding of the phenomena of hot water

availability is good because the pulp and paper

extraction of hemicelluloses.

industry is the main supplier of the raw material,

The applications foreseen are now more realistic

and the production process is workable. The

than at the beginning of the programme.

end product has also been shown to have

However, the separation processes will become

promising converting properties.

more feasible when methods have been

The issues that still need to be solved are the

developed for the utilization of all possible

barrier capability against oxygen, and deeper

fractions.

cost calculations of the production process, as

One of the main research interests in the FuBio JR2 programme was lignin and

well as detailed study on implementation in industrial applications.

its potential as a component in bio-based

The programme helped in understanding

composites. The properties and production

the possibilities, but also the challenges, in

technologies of kraft lignin fibre composites

the use of biopolymers. At the same time, it

were studied, and the teams were capable of

created a framework for performing analyses.

developing and producing prototype products. The demo trials performed by composite manufacturers gave excellent feedback that

Pirkko Liias, Metsä Fibre:

can be utilized in further development.

“The bio-barrier study has generated knowhow about the possibilities of different derivatives, helping to decide which ones ought to be ruled

Kari Saari, Kemira:

out and which should be taken for further

“We regard new sustainable polymeric raw

development.”

materials, such as hemicellulose, as potential future raw materials that can be substitutes for fossil-based ones in use today.”

FUBIO JR2 PROGRAMME REPORT

Networking created more value

The work goes on

In the work that studied ionic liquids, lignin

The research of the FuBio JR2 programme

composites,

was

bio-barriers,

mouldable

fibre

precommercial.

order

achieve

products, new filters or medicinal products,

industrial applications, further development

networking created more value than if the

work is needed. Many companies have already

research teams had been working alone. All

launched internal projects to continue the work.

in all, networking is a key attribute of all Fibic programmes. One of the participants noted that the best outcomes were achieved in the teams that worked openly and dynamically. Dialogue

The techno-commercial models created in the programme broadened the scope of the work with commercial viewpoints, and will act as an excellent tool in further research. Apart from pulp and paper companies,

between representatives of the research

several

and industrial partners has been extremely

in the programme. Through the FuBio JR2

technology

suppliers

participated

important for the successful results of the

knowledge platforms they have been able to

programme.

find suitable partners.

The programme was divided into work packages, each with an industrial partner

Jussi Piira, Andritz:

represented in the steering group and in the

“The programme has provided us with an

technical meetings. This structure ensured that

outlook for future processes. The new processes

the programme was immediately focused in the

require intensive development of technologies,

right direction. In setting the study, important

which is why it is essential for a technology

issues such as regulatory compliance and

supplier to be part of the work as early as

scale-up of the processes were raised at an

possible.”

early stage. Mika Hyrylä, UPM-Kymmene: “The wide international and competent network also made it possible to test end-products, such as composites.”

FUBIO JR2 PROGRAMME REPORT

INTRODUCTION

FuBio research was initiated in March 2009 with the launch of the first two-year joint

The Finnish forest industry has evolved

research programme. In 2011 FuBio was further

over

key

split into two separate programmes: ‘Products

phases, spanning from early tar production

from Dissolved Cellulose’ (FuBio Cellulose) and,

and sawmilling to modern pulp and paper

the focus of this programme report, ‘Future

making. Today, the production of wood-based

Biorefinery Joint Research 2’ (FuBio JR2).

the

centuries

through

several

chemicals – once a focal point of the industry until its eclipse by low-cost, high-performing

At the time of planning the FuBio programme,

chemicals and materials of the petrochemical

national and international attention within the

boom – is seeing a resurgence. Biorefinery

field was almost exclusively focused on biofuels.

has now emerged as the next branch in the

It was therefore decided after careful analysis

evolution of end uses for Finland’s abundant

to exclude biofuels from the FuBio theme. The

forest biomass.

largest Finnish research efforts in biorefinery at the time included the BioRefine programme

Future Biorefinery (FuBio) is one of the strategic

of the Finnish Funding Agency for Innovation

focus areas of the Finnish Bioeconomy Cluster

(Tekes) and various Technical Research Centre

FIBIC (formerly Forestcluster Ltd). The main

of Finland (VTT) programmes. These were also

objective of FuBio research is to establish

taken into account and relevant programme

in Finland globally competitive knowledge

interfaces were established.

platforms for the renewal of the existing forest industry and the creation of new business. The

Creating new biorefinery value chains requires

FuBio research path is expected to create new

deep understanding of biomass structures. New

value chains in which biomass-based materials

processing technologies must be developed

and chemicals are used in substantial, global

hand-in-hand with the design of new biorefinery

markets. The potential markets of focus are

concepts, including their respective value chains.

both well-known to the forest industry (e.g.

Understanding the markets and having the

fibre-based packaging) as well as essentially

freedom to-operate in them are essential. The

new, such as textiles, nonwovens, polymers,

first steps towards future industrial partnerships

resins and thermo-formable composites.

must also be taken.

"The main objective of FuBio research is to establish in Finland globally competitive knowledge platforms for the renewal of the existing forest industry and the creation of new business."

FUBIO JR2 PROGRAMME REPORT

In addition to the main objectives defined

The globally competitive knowledge platforms

above, FuBio also aimed at achieving a broader

targeted by the programme, as mentioned

national impact by:

above, specifically include:

• Improving industry awareness of new wood

• New biomass fractionation methods,

biorefinery opportunities. • Establishing new ways and levels of cooperation within R&D in Finland. • Shortening the time from idea to innovation through effective collaboration. • Establishing strategic, international R&D partnerships. • Maintaining and improving Finnish biorefinery R&D facilities through lab and early-stage piloting/initial material demos. • Educating a new generation of researchers (M.Sc. and D.Sc./PhD) for the biorefinery field.

especially based on ionic liquids and hot water extraction, • Advanced separation technologies suitable for separation of biomass fractions as well as hydroxy acids from black liquor, • Chemical and biotechnical modification/ up-grading of biomass fractions to natural polymers, extractives, hydroxy acids, etc., • Application of wood fractions as structural composites, hydroxy acid products, new board packaging concepts, reactive/active filter materials and health applications, • Modelling, especially techno-economical

The scientific publication output of the FuBio

evaluation of immature biorefinery concepts,

programme has increased as a result of

• Biomass characterization and analysis, and

FuBio JR2, bringing greater global visibility

• Initial process piloting and/or material

for the programme and promoting the open

prototype production

innovation strategy chosen for FuBio. As a summary, Figure 1 shows the key application areas of the FuBio research theme.

Figure 1. The six target markets of FuBio. Regenerated fibre and chemicals was targeted by the FuBio Cellulose programme, the remaining markets by FuBio JR2.

FUBIO JR2 PROGRAMME REPORT

Programme portfolio

groups together with the industrial tutors assisted the WP leaders in focussing the work

FuBio JR2 was divided into eight Work Packages

as needed.

(WPs). The use of wood fractionation alongside a pulp mill (WP1 Hot water extraction) or even to replace a pulp mill (WP2 Novel biomass

The Management Group had the following

fractionation) was examined. Possible future

members:

products were identified in the area of advanced biocomposites (WP3), packaging (WP4), filters (WP4) and health applications (WP5) as well as

• Mika Hyrylä, UPM, Chairman (Eeva Jernström until December 2012)

for hydroxy acids separated from black liquor

• Mikael Hannus, Stora Enso

(WP6). In modelling and piloting (WP7) the focus

• Johannes Heiskanen, Novoplastik

was targeted at improving models for new

• Seppo Hiljanen, Valmet

processes and techno-economical evaluation

• Annaleena Kokko, VTT (Niklas von Weymarn

of selected FuBio product cases. The main goals and results of the work packages are presented in the following chapters.

until August 2012), Programme Manager • Markku Leskelä, FIBIC (Lars Gädda until April 2012) • Pirkko Liias, Metsä Fibre • Risto Lilleberg, Metsäliitto Group

Management of the programme

• Erkki Peltonen, Myllykoski (until September 2011)

The a

FuBio

JR2

Management

programme Group

was

(MG)

led

including

• Jussi Piira, Andritz (Paterson McKeough until May 2013)

representatives from industry and academia.

• Kari Saari, Kemira

The main responsibility for day-to-day execution

• Lauri Verkasalo, Metsä Board (Ari Kiviranta

was with the Programme Manager (PM). Each work package had a WP Leader and one or

until September 2011) • Stefan Willför, Åbo Akademi University,

several Industrial Tutors. The industrial tutors’

Scientific Coordinator

role was to bring an industrial perspective to

• Erja Ämmälahti, Tekes

the work packages, while the WP leaders were responsible for day-to-day management of

Dissemination of the FuBio JR2 programme

the WP. The work packages were divided into

results has been achieved through a variety of

tasks and subtasks, and some of the tasks were

channels. The main channel for the distribution

assigned specific Task Leaders. The PM and WP

of results, reports and meeting minutes has

leaders formed the execution Core Team.

been the FIBIC research portal, accessible to FuBio JR2 programme partners, and the FIBIC

The main task of the management group was to

website (http://fibic.fi/programmes/fubio-jr2-2).

supervise the progress of the programme with

Additionally, results have been extensively

respect to the objectives and the programme

shared in both external (public) and internal

plan. The management group followed the

seminars, and demonstration samples and

work progress of specified issues through a

related posters have been displayed at SHOK

gate system and WP results and achievements

(Finnish strategic centres for science, technology

through WP presentations in management

and innovation) summits and Tekes events, as

meetings and through Programme Milestones

well as in programme overviews presented at

and Deliverable reports. The WP steering

FIBIC seminars and international conferences.

FUBIO JR2 PROGRAMME REPORT

Participants and international cooperation

The

programme

participants

have

also

actively presented the programme results in international conferences, COST action

The three-year joint research programme on

meetings

future biorefinery had a total of 22 industrial

seminars have also been arranged by the

and

workshops.

International

and research partners, bringing multi-faceted

programme, especially in WP2 in the area of

knowledge and competence to the programme.

ionic liquids, which attracted high international interest and was highly commended by the programme partners. In order to demonstrate

Industrial partners:

the increased competence resulting from the programme the main results have been

• Andritz

published in peer-reviewed journals, with

• FIBIC

over 80 publications to date and close to 40

• Kemira

currently submitted for publication. Over 20

• Metsäliitto Group

Master’s theses and five PhD thesis have been

• Metsä Fibre

written by students fully or partly financed

• Metsä Board

by FuBio programmes, with a further 10 PhD

• Myllykoski

students expected to defend their thesis

• Novoplastik

within the coming year.

• Stora Enso • UPM-Kymmene • Valmet

Research partners:

• Aalto University • Lappeenranta University of Technology • Finnish Forest Research Institute, Metla • Tampere University of Technology • University of Helsinki • University of Jyväskylä • University of Tampere • University of Turku • University of Oulu • VTT Technical Research Centre of Finland • Åbo Akademi University International cooperation in Future Biorefinery Joint Research 2 was achieved through researcher exchange, with more than 15 researchers visiting over a dozen universities and research institutes in Portugal, Venezuela, Sweden, Spain, France, Germany and Austria for more than 40 person-months.

FUBIO JR2 PROGRAMME REPORT

MODELLING AND TECHNO-ECONOMIC EVALUATION OF BIOREFINERY CONCEPTS CONTACT PERSON – Work Package 7 leader Eemeli Hytönen, eemeli.hytonen@vtt.fi Aalto University: Moshood Abdulwahab, Waqar Ahmad, Ville Alopaeus, Kaj Jakobsson, Susanna Kuitunen, Zheng Liu, Kaarlo Nieminen, Juha Visuri Andritz: Paterson McKeough GloCell: Jari Aittakari, Hanna Kalanne, Juhani Lehtonen, Pirita Mikkanen, Jukka Seppänen Kemira: Marcus Lillandt, Anna-Maija Saariaho Lappeenranta University of Technology: Mari Kallioinen, Elsi Koivula, Jarno Kohonen, Maaret Paakkunainen, Satu-Pia Reinikainen Metsä Fibre: Esko Turunen Pöyry Management Consulting: Carina Björnström, Henna Jääskeläinen, Jesse Kautto, Anna Saarentaus, Katja Salmenkivi, Juulia Rouhiainen, Petri Vasara Stora Enso: Kalle Ekman University of Oulu: Eva Pongracz, Paula Saavalainen UPM-Kymmene: Mika Hyrylä, Seppo Virtanen Valmet: Seppo Hiljanen, Päivi Uusitalo VTT Technical Research Centre of Finland: Tuomas Helin, Catharina Hohenthal, Timo Kaljunen, Marjo Kauppi, Marjatta Kleen, Vesa Kunnari, Juha Leppävuori, Marja Nappa, Lotta Sorsamäki

FUBIO JR2 PROGRAMME REPORT

ABSTRACT

In Future Biorefinery Joint Research 2 (FuBio JR2), modelling was used at different levels of biorefinery technology development to support research and to indicate the industrial feasibility of the novel technologies developed in the programme. The focus was on i) phenomena-based modelling and statistical experimental design of hot water extraction of hemicelluloses from wood, ii) early-stage techno-economic modelling of future biorefinery concepts based on the wood fractionation technologies and novel biorefinery products developed in the programme, and iii) process modelling and simulation, and quantitative economic and qualitative opportunity analysis of selected promising future biorefinery concepts. Two new models were developed for pressurized hot water extraction (PHWE). The new models are more advanced and comprehensive than the previous PHWE models presented in the literature, enabling more detailed analysis of the phenomena involved and optimization of the process. Several process concepts were designed and evaluated. Conceptual-level technoeconomic screening of some 100 concepts as well as more detailed modelling of five process and product development ideas, including hot water extraction, ionic liquids wood fractionation, black liquor hydroxy acids separation, bio-barriers and biocomposites, were conducted. New methods for process integration, market entry and comprehensive risk assessment were also developed and successfully demonstrated along with the evaluation of several selected concepts in detail. The work was done in close collaboration with research and industry partners.

Keywords: biorefinery concepts, modelling, physico-chemical modelling, techno-economic modelling

FUBIO JR2 PROGRAMME REPORT

1. Background

2. Objective

Different knowledge and data are needed at

The overall objective of the modelling work was

different

stages.

to provide more knowledge and data on the

For example, initial concept analysis requires

technologies developed in the programme in

a systematic approach and modelling of

order to support decision making.

technology

development

overall production systems, but no detailed data is needed on the process conditions or

The specific goals set for physico-chemical

phenomena involved in the different processing

modelling were: 1) develop chip and reactor scale

steps. In contrast, when scaling up a process

models for pressurized hot water extraction

step and designing its process and process

(PHWE), and 2) develop a comprehensive

equipment, understanding of the specific

model for PHWE chemistry (especially model

phenomena involved in that step in the process

the evolution of the hemicellulosesâ&#x20AC;&#x2122; molecular

is needed, whereas modelling of the overall

weight distribution).

production system is not necessarily required. Therefore the problem statement and scope

The specific goals set for techno-economic

of modelling varies significantly during the

modelling were: 1) to create new biorefinery

technology development.

concepts and evaluate their sustainability, and 2) to develop modelling tools and apply them

Many modelling methods and tools related to

to support the technology development work.

the fields of research of the Future Biorefinery Joint Research 2 programme have been previously developed. For example, a number

3. Research Approach

of existing chemical process design methods and simulation tools are applicable to the FuBio JR2 context and these have been combined

3.1 Physico-chemical modelling of hot water extraction

in earlier FIBIC programmes as a toolbox for quantitative and qualitative concept evaluation

Chip and reactor scale modelling of PHWE

for

addition,

For the modelling of simplified PHWE chemistry

simulation tools for modelling pulping and

for chip and reactor model development,

bleaching physico-chemical phenomena have

experimental data from PHWE of coarse birch

also been developed. These state-of-the-art

(Betula pendula) sawdust in a batch reactor

tools required further modifications to meet the

was collected. A high liquid-to-wood ratio

targets of the current programme.

was selected to minimize limitations on the

aiding

decision

making.

solubility of the extracted wood components. Various process and product ideas were

Experiments were conducted at different

studied and developed in FuBio JR2. To steer

temperatures and with different durations.

future research efforts and estimate the future

After each experiment the wood residue was

business potential of these pre-commercial

collected from the reactor and the yield of

stage R&D ideas, production concepts were

the components was measured. Based on

designed, screened and evaluated and tools

this data the appropriate stoichiometry and

for modelling the phenomena taking place in

kinetic parameters of the reactions leading

the studied wood fractionation processes were

to delignification and condensation of lignin

developed.

as well as carbohydrate degradation were estimated. A model combining the reaction

FUBIO JR2 PROGRAMME REPORT

kinetics with the diffusion in a wood particle

A high-order numerical method capable of

was constructed in Matlab. The differential

extremely accurate prediction of integral

equation associated with the model was solved

properties of the distribution is applied. Other

numerically using the finite difference method

parameters

and the PDE tools available in Matlab. The

parameters of the components included in

model enables a simulation of the reaction

the modelling of hot water extraction are then

product evolution at chip level during PHWE.

estimated and gathered from public sources.

physico-chemical

Comsol Multiphysics was chosen for simulating the progress of PHWE at the reactor level, as

The aim was to collect as many as possible

the software includes tools for describing flow

models and parameters from the literature.

and heat transfer in porous media and enables

Some of the model parameters were regressed

equations for the reaction kinetics to be added.

using literature and experimental results of the programme research.

Comprehensive modelling of PHWE chemistry

In order to be able to build the physico-

3.2 Techno-economic modelling

chemical model, understanding was needed of which properties and chemical constituents

The overall techno-economic modelling approach

of wood are relevant to the modelling of hot

used in the programme is illustrated in Figure 1.

water extraction as well as how the chemical constituents react and dissolve from wood into

To support R&D and to provide preliminary

the extract in hot water extraction conditions.

techno-economic performance information for

Both lignin and carbohydrate reactions are

industry regarding the processes and products

considered and, since several reactions are

developed in the programme, various process

catalysed by hydrogen ions, special attention is

concepts were created, designed, and evaluated

paid to accurate modelling of pH evolution.

in the screening phase. A method for this earlystage concept screening was developed. The

In the modelling, changes in the molecular

method exploits early-stage process design

weight

hemicellulose

methods to obtain comparable results for the

polymers are considered by describing chain

different overall production systems that are

lengths as discrete size categories where the

possible for a given concept. The method is

rate of change of number concentrations for

illustrated in Figure 2. Prices of all raw materials,

various polymer chain lengths is calculated.

chemicals, utilities, and the different factors

distribution

the

Figure 1. Overall techno-economic analysis approach.

FUBIO JR2 PROGRAMME REPORT

Figure 2. Light techno-economic analysis method developed for concept screening.

used for fixed cost assessment were agreed,

recycling of the reaction media and catalysts. If

and the concepts were created together with

enough data was not available, short-cut models

the project partners. For capital cost estimation,

and assumptions were used. Preliminary variable

methods developed by Bridgewater and Zevnik

production costs were assessed for sensitivity

& Buchananâ&#x20AC;&#x201A; 1 were used.

analysis

purposes.

The

resulting

process

descriptions and balances were further used in In screening, concepts were developed from

quantitative economic analysis and qualitative

R&D ideas by specifying targeted end products,

modelling of the cases.

feedstocks,

design

capacities,

process

integration opportunities and main process

Net Present Value (NPV) and Return on

parameters. Variable and fixed production

Investment (ROI) were the main quantitative

costs were calculated using parametric models

feasibility analysis instruments used to evaluate

and input-output material and energy balances.

the economic feasibility of the cases. An enhanced probability simulation tool was used

Based on the results of the screening and the

in the analysis to forecast the probabilities

progress of the research, together with project

of achieving positive outcomes for NPV and

partners conceptual designs for five cases were

ROI. This method was chosen because the

developed. Process modelling was then conducted

probability of a given outcome can often be more

for these designs: block-flow diagrams were

informative than the actual figures themselves,

designed or further refined from those designed

especially at the early development stage.

in the screening phase, and mass and energy balances were modelled using process simulation.

In the qualitative opportunity assessment

The simulation models were parameterized using

many variables were assessed. The variables

experimental research results, partnersâ&#x20AC;&#x2122; expertise

were divided into two categories: internal and

and literature. If pulp mill integration was part of

external. The variables were evaluated on a

the concept, the interface between the processes

scale from 2 (high) to low (0) opportunity. In

was defined and pulp mill impacts were simulated

addition, different weight factors were given

using a steady-state process simulation model of

to the variables, reflecting their relative

the entire system. A pulp mill model developed in

importance. External variables in the analysis

the EffFibre programme was used. The technical

mainly included market-related factors such as

analysis focused on the main process (production

market size and growth. Economic feasibility

and purification of the main product), and

was also a key external variable. Internal variables, in turn, mainly included technical

1 e.g. Holland, F.A. & Wilkinson, J.K. Perry's Chemical Engineers'

variables such as technical feasibility, product

Handbook, section 9 (Process Economics), McGraw-Hill, 1999

quality feasibility and technical availability.

FUBIO JR2 PROGRAMME REPORT

4. Results

level and reactor level, respectively. The Matlab program calculates the time development of

4.1 Physico-chemical modelling of hot water extraction

the 3D distribution over the wood chip of the various reaction products of lignin, xylan and glucan. It is possible to alter the size of the

Chip and reactor scale modelling of PHWE

chip, the cooking time and the temperature in

As an example reaction definition, Figure 3

the simulation. Likewise, the Comsol program

shows the reaction scheme for xylan. The data

simulates the product distributions in the

from the experimental treatments indicate that

reactor. The geometry and heating circulation

there are two sub-components of xylan (XN1

of the simulated reactor can be changed, as can

and XN2) with different reaction rate constants

the porosity and permeability of the chip bed.

for degradation into oligosaccharides (XOS). The main results of the modelling of hot water The temperature dependency of the reaction

extraction were increased knowledge of the

rates is assumed to follow the Arrhenius equation.

phenomena taking place in the system, and the

Table 1 shows the related pre-exponential

simulation tool that can be used in further hot

(frequency) factors and activation energies.

water extraction research.

A similar reaction scheme was developed

Comprehensive modelling of PHWE chemistry

for

that

The comprehensive PHWE chemistry modelling

degrades

into

work provides interesting insights into the phe-

hydroxymethylfurfural (HMF). A Matlab program

nomena taking place during PHWE. A schematic

and a Comsol multiphysics program, based

illustration of the various phenomena and reac-

on estimated reaction rates and values for

tions included in the model is shown in Figure 4.

case,

the

degradation

the

glucan.

monosaccharide

physical parameters describing diffusion in the wood particle and flow in the porous medium,

Considering the onset of the PHWE reactions,

were constructed to simulate PHWE at chip

the uronic acids seem to be responsible for

Figure 3. Reaction pathways for xylan in PHWE. Notation: XN1 – fast-degrading xylan, XN2 – slowly degrading xylan, XOS – xylo-oligosaccharides, X – xylose, F – furfural, DP1,DP2 – unspecified low molecular weight degradation products, ki – reaction rate constant. Table 1. Pre-exponential factors (A) and activation energies (Ea) for xylan reactions.

k1 A (min )

3.12 ∙ 10

Ea (kJ mol-1)

161.04

-1

k2 17

FUBIO JR2 PROGRAMME REPORT

7.28 ∙ 10 179.54

k3 17

6.58 ∙ 10 127.94

k4 12

3.08 ∙ 10 129.91

k5 12

5.13 ∙ 1016 168.52

introducing hydrogen ions into the fibre-bound

bre wall, the uronic acids also dissolve. Dissolv-

liquid, which, when the temperature is raised,

ing uronic acids weaken the ion exchange phe-

begin catalysing various reactions such as

nomena, and metal ions are also able to move

deacetylation and hemicellulose degradation.

to the external liquid phase as they are no long-

Metal ions, naturally present in the fibre

er held in the fibre-bound liquid as counter ions

wall, neutralize part of the acidity. In order to

for the dissociated uronic acids. Besides acetic

accurately estimate the initial hydrogen ion

acid, uronic acids and metal ions seem to have

concentration in the fibre wall liquid, it is crucial

a significant influence on the evolution of pH in

to know the amounts of all chemical compounds

the external liquid phase.

influencing pH. According to our current understanding, it seems that uronic acids and

Understanding the behaviour of pH during hot

metal ions are the most relevant compounds.

water extraction is essential because hydrogen

Although, based on our modelling results and

ions catalyse cleavage of the glycosidic bonds,

some evidence provided in the literature, the

thus shortening the hemicellulose polymers.

fibre-bound liquid is acidic, the water external

Besides predicting the evolution of pH, another

to the wood particles is close to neutral pH.

novelty of the model is its capability to predict

The ion exchange, i.e. the unevenness of the

the evolution of the hemicellulosesâ&#x20AC;&#x2122; molecular

electrolyte composition, in these two liquid

weight distribution during hot water extraction.

phases (fibre-bound and external liquid phase)

Furthermore, monomer and other oligomer

was modelled using Donnan theory, which is

concentrations

widely used and acknowledged in the context

feature facilitates the optimization of hot water

of pulp bleaching and, for example, in studying

extraction performance with respect to various

semipermeable membranes.

end products. The amounts of dissolved lignin

are

also

reproduced.

This

and furfural, which are potentially problematic As hemicelluloses start to dissolve from the fi-

for the process, are also predicted by the model.

Figure 4. Schematic of the phenomena included in the comprehensive hot water extraction model.

FUBIO JR2 PROGRAMME REPORT

The chemistry model for PHWE can be used together with the chip and continuous

4.2 Early-stage techno-economic modelling of concepts based on research ideas

digester models developed in the EffFibre/VIC project. Furthermore, a flow-through reactor

Over 100 ideas were evaluated using the method

model using a simplified chemistry model

illustrated in Figure 2 (see Table 2 for aspects

was also developed. In the chemistry model,

varied and combined). The concepts and overall

only the cleavage of the glycosidic bonds in

systems were defined based on discussions

hemicelluloses was considered. The chemistry

with researchers and industry representatives.

model also reproduces the molecular weight distributions of the extracted hemicelluloses.

Based on the early-stage techno-economic modelling of all of the process and overall system

The developed model enables a priori simulations

ideas, the most promising future biorefinery

of the effect of different buffers and additives on

concepts were selected by the industrial

pH evolution. Thus, screening work concerning

partners for further detailed modelling.

optimal

conditions,

such

particle

size,

additives, liquid-to-wood ratio, temperature and duration, can be done with the simulation model.

4.3 Quantitative and qualitative modelling of selected Future Biorefinery concepts

From the academic point-of-view, this kind of phenomena-based modelling enables testing

Five promising overall production systems based

of different theories in a quantitative manner

on the programmeâ&#x20AC;&#x2122;s technology development

and reveals shortcomings in the present

ideas were identified and evaluated:

theories. For industry, the model can be used in process optimization and development.

1) Hot water extraction of high molecular

Table 2. Evaluated concepts from FuBio JR2 process and product development.

Research topic

Examples of concepts

Pressurized hot water extraction (PHWE)

PHWE at a sawmill, kraft pulp mill, TMP plant, or CTMP/soda plant. Extraction of high or low molecular weight hemicelluloses. Extraction of sawdust or chips.

Ionic liquids

Kraft pulp to acetate-grade dissolving pulp. Wood to TMP-like pulp. Wood to kraft-like pulp.

Composites

Internally, externally or unmodified (using internal plasticization, chemicals, enzymes). Different lignin-fibre-plasticizer ratios.

Barriers

PHWE-xylan, modification of GGM, TOFA hybrid polymers, fatty acid cellulose esters, reactive milling, cellulose-polymer blends.

Hydroxy acids (HA)

HA separation technologies (separate & combined): a) Electrodialysis, b) Ion-exchange, c) Chromatography, d) Acidification, e) Cooling crystallization. Products: a) Hot glues, b) Chelating agents.

Future biorefineries

Combinations of the above-listed concepts integrated into the forest industry supply chain.

FUBIO JR2 PROGRAMME REPORT

weight (MW) hemicellulose from sawdust, 2)

Two scenarios were evaluated, in which the

Separation of hydroxy acids from kraft black

extraction yield and extract dry content were

liquor, 3) Biocomposites, 4) Biobarriers, and 5)

varied (Table 3).

Future sawdust biorefinery based on hot water extraction.

The mass and energy balances and the preliminary dimensioning data for the equipment

Case 1 â&#x20AC;&#x201C; Hot water extraction of high MW

were used in quantitative economic analysis, in

hemicellulose from sawdust

which it was clearly seen that the production

Figure 5 illustrates the process concept and

costs for the material were high, more than

the main process parameters and balances for

double the price of competing materials. One

extracting high molecular weight hemicelluloses

major reason for the high costs is the small

from spruce sawdust. The production scale was

design capacity which results in high fixed costs

defined based on sawdust availability in Finnish

(e.g. personnel and capital costs)

sawmills. The process conditions (temperature, pressure, solid:liquid ratio, flux) and efficiencies

The process is considered to be relatively mature

(extraction yield, separation and purification

(suitable process equipment exists); however, the

efficiencies) were based on experimental

overall concept would require further refinement.

results. The balances were simulated using the

For example, the yield based on the experimental

BalasÂŽ process simulator.

work of the programme at the time of conducting the study was very low. Moreover, the end product (extract) is not pure high-MW hemicellulose and might not be suitable for high-value applications without further processing.

Figure 5. Block-flow diagram of Case 1: High MW hemicellulose extraction from sawdust. Table 3. Scenario definition for high MW hemicellulose extraction.

Raw extract yield (= dissolved sawdust

Base case

Optimistic case

Unit

% on dry

1.1

5.0

fraction led to membrane) Dry content of extract

sawdust %

FUBIO JR2 PROGRAMME REPORT

Case 2 – Separation of hydroxy acids from

The results of modelling the four scenarios

kraft black liquor

were used in quantitative and qualitative

From the 12 alternative hydroxy acid separation

evaluation of the case. The economics seem

process

systems

highly promising if acids production is targeted

(alternatives listed in Table 2), two were chosen

exclusively at glue production, compared to the

by the industrial partners for detailed analysis.

option of using part of the acids production as

In these two overall systems, the product

chelating agent. However, although the product

would be either a mixture of all hydroxy acids,

price is quite low, the product quality currently

or two mixtures, a high and a low molecular

remains somewhat uncertain.

concepts

and

overall

weight mixture targeted at hot glue or hot glue and chelating agent applications, respectively.

As process technologies, all of the considered

The process concept included two alternatives,

process steps are mature in different contexts.

which utilized different technology for liberation

However, processing of kraft black liquor using

of acids from their salt form: ion exchange (IEX)

these

or electrodialysis (ED). The process concept is

graphic separation, ion exchange, electrodialysis)

illustrated in Figure 6.

has been done only at laboratory scale and

separation

technologies

(chromato-

therefore further technology development is The main assumptions for the case evaluation

needed. Furthermore, impacts on the pulp mill

were:

chemical recovery cycle (Na/S balance) should be minimized and products’ applicability further

• Pulp mill production capacity 700 000 adt/a

evaluated. Thus, the overall concept still needs

• Hydroxy acids production rate

development.

- 1/3rd of pulp mill black liquor processed and 15% yield of HA -> production 35 000t/a - Volatile (formic and acetic) acids yield 7% of pulping raw material • H2S handling and volatile acids recovery excluded

Case 3 – Biocomposites

A total of 26 overall biocomposite production systems were analysed using light technoeconomic analysis. Of these, two were selected for

detailed

evaluation:

lignin-fibre

• Pulp mill integration

composite without (Figure 7 a) and with internal

- Evaluated using WinGems pulp mill model

lignin plasticization (Figure 7 b).

developed in the EffFibre programme - Cooking variables (effective alkali and

The recipes were based on experimental results

sulfidity) kept constant by NaOH makeup

and optimization for targeted end product

and fly ash purge

properties (composite mechanical properties):

Figure 6. Block-flow diagram of Case 2: Hydroxy acids separation from kraft black liquor.

FUBIO JR2 PROGRAMME REPORT

lignin content 36% and 41%, and fibre

Case 4 â&#x20AC;&#x201C; Biobarriers

content 30% and 20% for the two concepts

Two alternative concepts were also selected

respectively; the remainder of the composite

for detailed analysis of biobarrier production

pellet was plasticizer. Internal plasticization

based on light techno-economic analysis

was assumed to be done using purchased

and technology development. The two very

acetic acid anhydride, and the excess acetic

different

acid that is recovered after plasticization was

production of hydroxypropylated xylan based

assumed to be sold.

and cellulose co-polymer based barriers in

concepts

considered

were

the

fast-food packaging. The process block flow Process

equipment

for

the

composite

diagrams are illustrated in Figure 8.

production exists, and the composite properties can be further developed/targeted and the

In the hydroxypropylated xylan (HPX) case,

most suitable applications found to develop the

xylan extraction from kraft pulp is included in

overall concept.

the concept to enable efficient alkali recycling. Separation and purification process parameters

The process without internal plasticization is

were based on literature and partner input.

simpler and showed better feasibility, but as the composite price range used in the analysis is

The cellulose co-polymer case was based on

wide, product quality will ultimately determine

the research partnerâ&#x20AC;&#x2122;s definition and literature

the price. Therefore, if internal plasticization

process parameters.

enhances the properties, the economics can absorb the cost of internal plasticization. Acetic

The cellulose co-polymer product consists

acid as a side-product also has a significant

mainly of inorganic compounds (sodium and

impact on the overall feasibility.

zinc) and its suitability for food packaging

Figure 7. Block-flow diagram of Case 3: Composite concepts: a) no modification of raw materials, b) internal plasticization of lignin.

FUBIO JR2 PROGRAMME REPORT

applications thus needs careful examination. On

Case 5 – Future sawdust biorefinery based on

the other hand, in the hydroxypropylated xylan

hot water extraction

case the impacts on kraft pulp properties should

The fifth case was constructed around several

be evaluated and possible further valorisation

project focus areas:

of the pulp after xylan extraction to dissolving pulp considered instead of selling it as kraft pulp.

• Hot water extraction of hemicelluloses from

Therefore, in both cases, further technology and

sawdust to produce high and lower MW

concept development is needed.

fractions; use of the high MW fraction for barrier production.

As the economic feasibility of both cases is

• Kraft cooking of the extraction residue to

dependent on coating layer costs, cost per

obtain black liquor and pulp; separation

area is more critical than cost per tonne. Figure

of lignin from the black liquor, e.g., for

9 shows how the probability of a positive ROI

composite production; use of the pulp as

changes as a function of layer cost (c/m2) with

fibre for composites, or oxygen delignified

different layer amounts.

and bleached as pulp.

Figure 8. Block-flow diagram of Case 4: Barrier concepts: a) hydroxypropylated xylan, b) cellulose polymer blend.

FUBIO JR2 PROGRAMME REPORT

Figure 9. Probability of a positive ROI in the studied barrier cases with different coating amounts as a function of coating layer material costs (cent/m2). Cepe: cellulose co-polymer; HPX: hydroxypropylated xylan. Reference material cost illustrated on x-axis: PE&PP – polyethylene & polypropylene, PET – polyethylene terephthalate, PA – polyamide.

The concept is illustrated in Figure 10.

The concept was modelled using the Balas® process simulator and the integration impacts

The main assumptions of the case were:

were simulated using the WinGems pulp mill model developed in the EffFibre programme.

• 100 000 or 20 000bdt/a sawdust

The main integration impacts for 20 000bdt

• Process integrated into a kraft pulp mill

sawdust/a capacity would be:

(600 000 t/a) • Washed pulp to oxygen delignification stage of the kraft pulp mill

• Pulp from sawdust cooking increases pulp production by 1.5%

Figure 10. Block-flow diagram of Case 5: FuBio concept with hypothetical production capacity.

FUBIO JR2 PROGRAMME REPORT

• 1.5% higher fibre line capacity required downstream from oxygen delignification • 1.4% increased white liquor demand

Summary

The cost breakdown of the evaluated cases varies somewhat, as illustrated in Figure 11.

• 2.2% increased evaporation requirement at evaporation plant

The difference in cost distribution results partly

• Decreased net electricity production

from the selected modelling scope (e.g. whether

• Increased fly ash purge

the feedstock has a purchase cost or not), the scale of production, and the processing type

Four products are generated: two streams of

(e.g. whether chemicals are needed or not).

extracted hemicellulose, sawdust-based pulp,

These results should not be used to compare

and lignin separated from the black liquor. The

economic feasibility between cases, as they

raw material for the process is sawdust. In

only indicate the relative cost distribution.

this case, the sawdust cost is essential to the

A preliminary cross-case comparison can,

economic feasibility of the case.

however, be made between cases 1 and 5 where PHWE was considered to be one of the main

The overall system requires further development

technologies: with higher hemicellulose yield

and, due to its small design capacity, process

the share of fixed costs decreases (feedstock

simplifications may be needed, e.g., related

flow nearly the same in these cases) while, on

to lignin separation. The clearly improved

the other hand, the added lignin separation

extraction yields and better selectivity in

process requires chemicals.

purification compared to Case 1 obtained at the laboratory scale indicate good potential, but the final use of the other fractions requires further development.

Figure 11. Operating cost breakdown of the analysed cases

FUBIO JR2 PROGRAMME REPORT

Figure 12 shows the qualitative analysis results based on the present economic evaluation

5. Exploitation and impact of results

and assessment of other qualitative analysis variables. Based on their total scores, the

The

studied cases were plotted (x-axis: sum of

knowledge developed focusing on hot water

internal variables; y-axis: sum of external

extraction phenomena, purification of the hot

variables)

with

the

level

modelling

methods

and

tools

and

opportunity

water extract, and the sustainability of the

increasing from left to right (x-axis) and

different process concepts and value chains

upwards (y-axis).

provides crucial new information for industry decision

Comparing the cases, the level of opportunity

making

and

for

steering

future

research.

was found to be highest in external (marketrelated) terms for the separation of hydroxy

The thorough modelling of PHWE was based

acids

on combined knowledge of aqueous phase

from

black

liquor

and

for

lignin

composites. In these two cases, technical

thermodynamics,

challenges related to operation and product

kinetics, and mass transfer. The resulting

quality were, however, found. Technically, the

model can be used in optimization of PHWE

most promising cases were found to be two

conditions to produce either sugars or high

cases based on hemicellulose fractionation:

molecular

weight

ion

exchange,

hemicelluloses,

reaction

and

for

barrier films based on extraction of xylan from bleached pulp, and hot water extraction of hemicelluloses from sawdust and subsequent sawdust cooking. However, these cases scored relatively low in market-related terms. Conclusions, risks and suggestions for each of the five cases are listed in Table 4.

Fubio Opportunity Evaluation High

Case 1 – Hot water extraction of high MW hemicellulose from sawdust Case 2 – Separation of hydroxy acids from Kraft black liqour

External

Case 3 – Biocomposites Case 4 – Biobarriers Case 5 – Future sawdust biorefinery based on hot water extraction

Low Low

Internal

High

Figure 12. Qualitative opportunity assessment of the studied Fubio JR2 cases.

FUBIO JR2 PROGRAMME REPORT

Table 4. Summary of case evaluations. Case Conclusion

Highest risks

Suggestions

• Technical and economic feasibility

• Target concepts where the cellulose/

• New concept that could generate additional revenue for a sawmill. • Very small production rates and poor

(ROI negative in all cases; labour and

lignin fraction has an end-use of

capital costs significant).

higher added value (compared to

economic potential.

energy use) and hot water extraction is needed to achieve this. • Step-wise extraction with multiple end products could be another interesting concept (poly-, oligo- and mono-based).

• Target product markets are expected to grow annually 4-6%

• Look for alternative ion-exchange

work has been carried out with

system cleaning (organic acid based,

soda black liquor, the separation

or circulation based) to replace the

concept could have >10% IRR with a

processes have not been piloted

high H2SO4 demand (and to remove

product value of 1000 €/bdt.

using black liquor long enough to get

high cost of chemicals and fly ash

• Electrodialysis-based production

• Both production routes and product alternatives seem to have positive as

data, e.g., on fouling & cleaning. • Product quality – application

well as negative environmental and

testing has not been carried out

social impacts based on preliminary

using obtained acid mixtures as

analyses. 3

• Technical feasibility – experimental

• Target market is ~2Mt/a with

of both composite types should be

prices are high on average.

tested in the application to verify

have very good economic return

melt and chelating agent).

feedstocks. • Product quality – strength properties

expected growth of over 5% CAGR; • Unmodified lignin case seems to

disposal). • Conduct further product testing (hot

their performance. • Technical aspect – relatively large

and internal plasticization case

share of the product is plasticizer,

has potential assuming the quality

which is potentially produced from

improvement obtained from

food-grade feedstock.

• Conduct further product testing in target application. • Investigate other possible plasticizers and/or the possibility to decrease its share in the composite.

plasticization is worth over 500 €/t. 4

• The target market is ~ 1Mt/a (Global)

• Product quality – Cellulose co-

• Study the compatibility of the barrier

and 0.4Mt/a (Europe), considering

polymer product consists mainly

in combinations of different barrier

large fast-food chains. Annual volume

of inorganic compounds (sodium

materials (oxygen, water vapour

growth expected to be about 5%.

and zinc) and the suitability in food

• Cellulose co-polymer case seems to

packaging application needs careful

have good economic return due to very good properties with thin layer and relatively simple process. • Hydroxypropylated xylan case

inspection. • Technical aspect – in hydroxypropylated xylan case the

barriers). • In hydroxypropylated xylan case, integrated concept with added value cellulose product should be considered.

xylan extraction system integration

requires thinner layer thickness with

impacts on pulp mill process and

same properties to become more

cellulose product quality.

attractive. 5

• Combined system shows promising economic performance compared to

• Many products and technologies may be challenging.

Case 1 because of improved yield and

• Sawdust has other competing uses.

integration into pulp mill.

• Compatibility of the hot water

• Lignin separation system is very

extraction based high molecular

• Further analysis of the compatibility of the products in the end applications (barriers, animal feed, lignin in composite). • Evaluate which product combination

small compared to e.g. announced

weight hemicelluloses for barrier

generates most value from the

Lignoboost projects and requires

application.

feedstock.

significant investment.

FUBIO JR2 PROGRAMME REPORT

obtaining information that could be difficult to

techniques

measure experimentally. The new models were

technologies, or the costs of modifying the

implemented on a digester modelling platform,

lignin for biocomposite production. The results

which can be used for simulation of industrial-

of the sustainability analysis on the other

scale continuous hot water extraction units.

hand highlighted the opportunities offered

Simulation of a hot water extraction and

by the selected concepts to different players

alkaline pulping sequence for the production

in the value chain. This new information

of dissolving pulp could be one possible case

on business potential can be exploited by

study. Furthermore, the models for hot water

companies using the concept and companies

extraction phenomena (incl. xylan degradation

developing enabling technologies for the value

kinetics, chain scission and diffusion in a chip,

chain. Moreover, the refined overall techno-

and digester flow) can supplement concept

economic analysis approach can be utilized for

modelling

evaluating other new technologies than those

processes

using

hot

water

extraction.

compared

mature

developed in FuBioJR2.

The light techno-economic analysis revealed the potential of the technologies developed

6. Networking

in FuBio JR2. For example, the potential of integrating the PHWE system into different

host processes, the preliminary economic

contributions in this context is presented in

performance of new hydroxy acids separation

Table 5.

summary

the

partners

and

their

Table 5. Partner organizations and their research roles.

Work package partners

Role of the participating organization

Aalto University

Physico-chemical modelling of hot water extraction and implementation of the model into a process simulator, kinetic modelling of hot water extraction at chip and reactor level

Andritz

Work Package Coordinator

GloCell

Quantitative analysis in the techno-economic modelling, market entry evaluation method development

Kemira

Industrial tutor

Lappeenranta University of Technology

Multivariate analysis

MetsĂ¤ Fibre

Industrial tutor

PĂśyry Management Consulting

Techno-economic assessment through investment and production costs and qualitative opportunity assessments

Stora Enso

Industrial tutor

University of Oulu

Social impact assessment

UPM-Kymmene

Industrial tutor

Valmet

Industrial tutor

VTT

WP leader. Early-stage techno-economic modelling and method development, new biorefinery process integration method development, process concept design and process modelling, life cycle assessment

FUBIO JR2 PROGRAMME REPORT

7. Publications and reports Abdulwahab, M. Modelling of ionic liquids' ther-

Liu, Z., Ahmad, W., Kuitunen, S. and Alopaeus,

mal separation and recycling in biomass frac-

V. Modeling of mass transfer and degradation

tionation, M.Sc. Thesis, Aalto University, 2013.

of hemicelluloses in flow-through hot water extraction, Submitted to Industrial & Engineering

Borrega, M., Nieminen K. and Sixta, H. Deg-

Chemistry Research.

radation kinetics of the main carbohydrates in birch wood during hot water extraction in a

Liu, Z., Suntio, V., Kuitunen, S., Roininen, J.

batch reactor at elevated temperatures, Biore-

and Alopaeus, V. Modeling of mass transfer

source Technology, 102, 2011, 10724-10732.

and reactions in anisotropic biomass particles with reduced computational load, Industrial

Hytönen, E. and Leppävuori, J. Future Biore-

& Engineering Chemistry Research, 53, 2014,

finery (FuBio) research into process concepts –

4096 - 4103.

early stage process evaluation and screening, Nordic Wood Biorefinery Conference NWBC

Visuri, J., Song, T., Kuitunen, S., and Alopaeus,

2014, Stockholm, Sweden, March 25-17, 2014.

V. Model for Degradation of Galactoglucomannan in Hot Water Extraction Conditions, Indus-

Kleen, M. Statistical modelling of pressurized

trial & Engineering Chemistry Research, 51,

hot water flow-through extraction process, VTT

2012, 10338-10344.

Research Report, VTT-R-2688-14, May 2014. Kleen, M. Statistical modelling of pressurized hot water batch extraction process, VTT Research Report, VTT-R-2637-14, May 2014. Kleen, M., Pranovich, A. and Willför, S. Statistical modeling of pressurized hot water extraction process to produce hemicellulose with desired properties, 4th International Conference on Biorefinery—towards Bioenergy (ICBB2013), Xiamen, China, December 3-5, 2013. Kuitunen, S. Phase and reaction equilibria in the modelling of hot water extraction,

pulping

and

bleaching

(http://urn.fi/

URN:ISBN:978-952-60-5618-0), Doctoral dissertation, Aalto University, 2014. Kuitunen, S., Vuorinen, T. and Alopaeus, V. The role of Donnan effect in kraft liquor impregnation and hot water extraction of wood, Holzforschung, 67, 2013, 511-521.

FUBIO JR2 PROGRAMME REPORT

NEW SOLUTIONS FOR BIOMASS FRACTIONATION BY PRESSURIZED HOT WATER EXTRACTION, SUPERCRITICAL WATER TREATMENT AND DELIGNIFICATION

CONTACT PERSON – Work Package 1 leader Risto Korpinen, risto.korpinen@abo.fi Aalto University: Fanny Bardot, Marc Borrega, Herbert Sixta, Lasse Tolonen, Yuying Zhang. Andritz: Christian Järnefelt, Tiina Rauhala Finnish Forest Research Institute: Olli Byman, Sanna Hautala, Hannu Ilvesniemi, Petri Kilpeläinen, Veikko Kitunen, Kaisu Leppänen, Zhiqiang Li, Johanna Tanner, Teemu Tikkanen Kemira: Marcus Lillandt, Anna-Maija Saariaho Lappeenranta University of Technology: Mohammed Al-Manasrah, Mari Kallioinen, Elsi Koivula, Mika Mänttäri, Minna Nevalainen, Tuomas Nevalainen, Liis Retsja Metsä Fibre: Ismo Reilama Stora Enso: Kalle Ekman University of Helsinki: Maija Tenkanen University of Jyväskylä: Raimo Álen, Jarkko Kuivanen, Joni Lehto, Mika Leppäaho UPM-Kymmene: Ulf Hotanen, Mika Hyrylä VTT Technical Research Centre of Finland: Anne Kallioinen, Marjatta Kleen, Hanna Kyllönen, Tiina Liitiä, Marjo Määttänen, Tarja Tamminen Åbo Akademi University: Ricardo Garcia de Castro Insua, Henrik Grénman, Jarl Hemming, Jens Krogell, Zhiqiang Li, Andrey Pranovich, Jan-Erik Raitanen, Jussi Rissanen, Tapio Salmi, Annika Smeds, Maunu Toivari, Stefan Willför, Chunlin Xu

FUBIO JR2 PROGRAMME REPORT

ABSTRACT

Pressurized hot water extraction (PHWE) and subsequent delignification processes were examined for their ability to separate hemicelluloses, lignin and cellulose from wood biomass. In addition, the separation and purification of PHWE extracts and hightemperature hydrothermal treatment of microcrystalline cellulose were also studied. PHW extraction parameters were successfully tailored to enable the extraction of relatively large amounts of hemicellulose of relatively high molar mass from wood. If molar mass is not considered a critical factor, nearly all hemicelluloses â&#x20AC;&#x201C; constituting approximately up to one third of wood biomass â&#x20AC;&#x201C; were extractable. Additionally, the pH of the PHWE process was monitored and adjusted as desired by the addition of dilute alkali. The hemicellulose-rich extracts obtained by PHWE contain mixtures of hemicelluloses of varying chain length. A variety of impurities, such as wood extractives and lignin-derived compounds, are also present. In addition, the dry solids content of the extracts is usually relatively low. It was possible to concentrate, purify and fractionate the extracts according to molecular size by combining appropriate pre- and/or post-treatments with membrane filtration, while maintaining sufficient filtration capacity. Crystalline cellulose residues were successfully hydrolyzed and dissolved by rapid nearand supercritical water treatments to produce narrowly distributed, low-molar-mass celluloses and cello-oligosaccharides. The fibrous fraction after PHWE was further isolated as a cellulose-rich fraction by sulfurfree delignification processes. Hardwoods defibrated more readily than softwoods due to differences in lignin structure. The cellulose-rich fraction can be further processed into various products, such as regenerated cellulose.

Keywords: analytical methods, cellulose, delignification, hemicelluloses, lignin, pressurized hot water extraction, pulp, purification, separation, super critical water, wood biomass

FUBIO JR2 PROGRAMME REPORT

1. Background

2. Objectives

The structural building blocks of wood –

I) Investigation of the use of pressurized hot

hemicelluloses, lignin and cellulose – account

water

for the vast majority of all woody biomass.

treatment for the fractionation of wood. II)

Pressurized hot water extraction (PHWE) offers

Concentration and purification of the obtained

an environmentally sound water-based means

hemicellulose- and lignin-containing fractions

of separating out these valuable components.

to enable their utilization in various applications.

The extracted hemicellulose and lignin fractions

III) Further delignification of the extracted

offer a source of valuable biochemicals and

residues to produce novel pulps. IV) Transfer

other bioproducts, thus contributing to reduced

of knowledge obtained from laboratory scale

reliance on petrochemicals, while the cellulose-

experiments to the pilot scale.

extraction

and

supercritical

water

rich fibre fraction can be used in composites or further processed into new fibre products or regenerated cellulose.

3. Research approach

In the PHWE process, wood is treated with

Spruce and birch wood were pressurized hot

water at elevated pressure and temperature,

water extracted using different reactor setups

up to 220 °C, to separate the hemicellulose-

(batch, flow-through and cascade). The reactor

rich fraction from the wood matrix. No organic

volumes varied from 33 ml to 300 l. An example

solvents or toxic chemicals are needed. The

of a batch mode setup, accelerated solvent

attained fibre fraction subsequent to PHWE is

extraction (ASE) system, used in the PHWE

further fractionated into lignin and cellulose

experiments can be seen in Figure 1. Different

by sulfur-free delignification processes and

extraction parameters were studied, such as

possible additives.

temperature, pressure, time and particle size.

Pressurized hot water treatment in near- and

The aim of the extractions was to produce as

supercritical

distinct

high-molar-mass hemicelluloses as possible

liquid and gas phases are absent, can be used

at high yield. The extracted residues were

to achieve rapid hydrolysis and dissolution

delignified using sulfur-free processes. The

of crystalline cellulose residue to produce

aim was to produce pulps suitable for the

low molar mass polymer without addition of

production of regenerated cellulose and other

cellulose solvent.

products. The hemicellulose-rich extracts were

conditions,

which

fractionated, concentrated and purified using Isolation of hemicellulose, lignin and cellulose

membrane filtration and different purification

from each other by PHWE is, however, not

techniques.

complete and the obtained fractions thus

were hydrolyzed and dissolved by rapid near-

contain a variety of impurities. In addition,

and supercritical water treatments in order to

the fractionation processes are relatively

produce narrowly distributed, low molecular

water intensive. Therefore, purification and

weight celluloses and cello-oligosaccharides at

dewatering processes are needed to enable

high purity. Analytical methods needed in the

utilization

wood fractionation processes were mapped

applications.

these

fractions

various

Crystalline

cellulose

residues

and method comparisons were carried out.

FUBIO JR2 PROGRAMME REPORT

4. Results 4.1 Key results of PHWE Particle size and temperature had a significant effect on the extraction of hemicelluloses, as illustrated in Figures 2 and 3. Norway spruce sapwood of different particle sizes (0.25â&#x20AC;&#x201C;1.0 mm vs. 8â&#x20AC;&#x201C;12 mm) was pressurized hot water extracted using different extraction times and temperatures. The smaller particle sizes resulted in a considerably higher amount of total dissolved solids in the extracts. Furthermore, higher

extraction

temperature

resulted

higher hemicellulose yield, but the average Figure 1. Accelerated solvent extractor ASE 350.

molar mass of the hemicelluloses decreased. At

Figure 2. Amount of dissolved wood substances in extract as a function of extraction temperature and time, a) sawdust and b) blocks.

Figure 3. Average molar mass of ethanol precipitated hemicelluloses from extracts as a function of extraction temperature and time, a) sawdust and b) blocks.

FUBIO JR2 PROGRAMME REPORT

higher temperature and prolonged extraction

4.2 Up-scaling experiences of PHWE

time, more intense hydrolytic degradation of

place.

Two pilot scale PHWE appliances were used to

Additionally, larger wood particles cause mass

carbohydrates

and

lignin

takes

demonstrate the extraction results obtained

transfer limitations, preventing molecules from

from laboratory experiments. Figure 5 shows

migrating out from the wood matrix.

the 300-litre reactor (flow-through mode)

â&#x20AC;&#x192;

and the 30-litre reactor (both batch and flow-

Monitoring and controlling pH is essential.

through modes). Due to the large size of

If the pH drops too low during extraction the

these reactors compared to laboratory scale

hemicellulose chains start to degrade and

reactors, they were also used to produce

lower molar mass is obtained. The pH values of

sufficient amounts of extracts and PHWE-

the extracts were typically measured at room

treated fibres for further processing.

temperature after removing the samples from the reactor. This resulted in a delay in the data.

It was shown that the laboratory scale

To avoid this, high-temperature pH electrodes

extractions could be up-scaled by a factor of

were installed and tested. As Figure 4 shows,

300 and 6000. The results of birch wood flow-

the pH measured inside the reactor during

through pressurized hot water extraction at the

PHWE was approximately 0.5 units higher

laboratory scale and pilot scale using the same

than that measured at room temperature. A

extraction conditions and reactor dimensions

difference of 0.5 pH units corresponds to a 3.2

are shown in Table 1.

times lower H+ concentration. It can also be seen that by adding dilute alkali and using high-

The

temperature pH electrodes it was possible to

hemicelluloses extracted from birch wood were

amounts

and

extraction

rates

adjust and maintain the pH at the desired level.

similar for both the laboratory and pilot scale, as shown in Figure 6. In addition, the pH profile of the extracts was identical.

Figure 4. In-line pH control during PHWE at 170 Â°C.

FUBIO JR2 PROGRAMME REPORT

Figure 5. Pilot scale PHWE reactors, 300 l flow-through (a) and 30 l batch and flow-through (b). Table 1. Laboratory- and pilot scale extraction conditions.

Laboratory scale (0.05 l)

Pilot scale (300 l)

Temperature

160 째C

Diameter / length, ratio

34 mm / 59 mm, 0.6

590 mm / 1040 mm, 0.6

Flow rate

3.3 ml/min

20 l/min

Residence time

12 min

Extraction time

60 min

Based on the modelling work done in the

in batch mode. The obtained model values and

laboratory using a 100 ml reactor, pilot scale

the pilot scale results were comparable (Table 2)

extractions of spruce wood were carried out

although the pilot- and laboratory scale PHWE

using a 30-litre reactor (scale-up factor 300)

setups had slightly different configurations.

Figure 6. a) pH of the extracts, b) hemicellulose yield and average molar mass, c) cumulative yield of hemicellulose, d) chemical composition of extracts after 60 min extraction. Error bars represent the relative standard deviations of three parallel extractions.

FUBIO JR2 PROGRAMME REPORT

Table 2. Comparison of values from a statistical model based on laboratory- and pilot scale results. Model values (100 ml) 155 °C, 25 min, W:W 5

Pilot results (30 l) 155 °C, 25 min, W:W 5

Model values (100 ml) 170 °C, 20 min, W:W 10

Pilot results (30 l) 170 °C, 20 min, W:W 10

pH of extract

4.2

3.9

3.7

3.6

Extraction residue yield, % of orig.

94.7

93.2

86.1

82.8

Total dissolved solids (TDS), mg/g wood

67.0

56.5

138.0

161.4

17800

13936

9600

8346

23.8

27.2

67.2

90.5

Average Mw, Da GGM content of extract, mg/g wood

Spruce extractions using batch mode and

in the extract was 63 mg/g after PHWE and 118

30-litre reactor were performed either at 160

mg/g after PHWE, washing and compression,

°C for 40 min or at 170 °C for 60 min, both

representing an 87% increase in TDS. Furthermore,

with a water-to-wood (W:W) ratio of 5 or 10.

the molar masses of the different washing and

After PHWE and removal of the extract, the

compression fractions were maintained.

extracted residue was washed at 50 °C for 30 min using the same W:W as in the extraction.

The pilot scale PHWE experiments showed that it

The amount of dissolved material was doubled

was possible to obtain relatively high-molar-mass

by using a W:W ratio of 10 instead of 5 in the

hemicelluloses at relatively high yield by using:

milder extraction conditions, as seen in Figure 7. In the harsher conditions, about 70% more

• Moderate extraction temperature range

TDS was obtained when using a W:W ratio of

(155–165 °C)

10. Slightly lower molar mass hemicellulose was

• Relatively short extraction time (25–35 min)

obtained when a higher W:W ratio was used.

• High packing degree of wood in the reactor • Moderate water-to-wood ratio (5–10:1)

The amount of dissolved material in the extract

• Washing and compression of the wood after

could be further increased by compressing the wood material after the extraction and washing

extraction • Secondary wall exposed wood by means of

stages, as seen in Figure 8. The dissolved material

mechanical treatment

Figure 7. Total dissolved solids (a) and average molar mass (b) of PHW extracts and wash water from spruce wood.

FUBIO JR2 PROGRAMME REPORT

Figure 8. Total dissolved solids (a) and average molar mass (b) of PHW extract, wash water and compression water from spruce wood.

4.3 Near- and supercritical water treatment

shares of the reaction products depended on the treatment time and temperature for the

Near- and supercritical water treatment rapidly

two different microcrystalline celluloses, as

hydrolyzed and dissolved the recalcitrant

seen in Figure 10.

crystalline cellulose and produced a mixture of cellulose polymers of varying molar mass. The

Dissolution as a precipitating polymer was

used reactor setup can be seen in Figure 9.

promoted by increasing the temperature, in particular to above 320 °C, providing that the

After the treatment, the dissolved products

treatment time was kept sufficiently short

slowly precipitated as low molar mass and highly

to prevent extensive depolymerization of

crystalline cellulose with a narrow molar mass

the dissolved products. It was observed that

distribution. The rest of the dissolved material

wood-derived

remained in solution as oligo- and monosugars

(MCCs)

and

mixture

various

microcrystalline

exhibited

higher

celluloses velocity

degradation

dissolution than those derived from cotton,

products formed via concomitantly occurring

possibly due to the dimensional differences

dehydration and retro-aldol reactions. The

of the cellulose crystallites.

Figure 9. “MIKKI” reactor system for near- and supercritical water treatment of microcrystalline cellulose using short reaction times below one second (a). The short treatment time is achieved by rapid heating with preheated supercritical water and quenching with cold water (b).

FUBIO JR2 PROGRAMME REPORT

100 %

80 %

40 %

40 % 20 % 0%

250 260 270 280 290 300 310 320 330 340 350 360 370 380

20 % 0%

60 %

Other Water-soluble sugars Precipitate MCC from Residue prehydrolysis Kraft pulp Temperature (°C)

MCC from Cotton linter

250 260 270 280 290 300 310 320 330 340 350 360 370 380

60 %

Temperature (°C)

Figure 10. Mass balances of two microcrystalline celluloses prepared by acid hydrolysis from prehydrolysis kraft pulp (a) and cotton linter (b). Microcrystalline celluloses were treated in sub- and supercritical water with varying temperature. Treatment time 0.20 s and pressure 250 bar.

Supercritical water treatment has potential

and part of the lignin prior to pulping. The

for

with

intensity of PHWE was described by a modified

the advantage that cellulose dissolution and

cello-oligosaccharide

production

P-factor (here Log Pxs). Soda-AQ pulping

hydrolysis can be carried out in a single stage. Other

experiments were then conducted at 150 °C,

techniques require the use of a cellulose solvent to

with 22% NaOH and 1% AQ, based on initial

dissolve cellulose crystallites and heterogeneous

dry wood. The yield of main wood components

hydrolysis, e.g. by acid hydrolysis processes,

from birch wood after hot water extraction and

mainly produces only monosaccharides. Cello-

soda-AQ pulping are shown in Figure 12.

oligosaccharide production was demonstrated by treating commercially available MCC powder

The cellulose content of the pulp remained

in supercritical water at 380 °C for reaction

unaffected up to a hot water extraction

times of 0.2, 0.4 and 0.6 s (Table 3 and Figure

intensity (Log Pxs) of about 4.5 (Figure 12 b),

11). Up to 42% yield of cello-oligosaccharides

but higher intensities led to extensive cleavage

was reached with the 0.4 s treatment.

of glycosidic bonds, thus facilitating the occurrence of peeling reactions and resulting

4.4 Delignification of PHWE-treated fibres

in a cellulosic pulp with low yield. Nonetheless, unbleached pulps with an acceptable yield (over

Pressurized hot water extractions of birch wood

30% based on initial dry wood), and containing

chips at temperatures between 180 °C and 220

over 90% cellulose, less than 5% xylan, and

°C were conducted to extract hemicelluloses

about 2–3% lignin, were produced.

Table 3. Yield of undissolved residue, precipitate, cello-oligosaccharides and monosaccharides after a supercritical water treatment at 380 °C and 250 bar for 0.2–0.6 s.

Treatment time (s)

Residue (%)

Precipitate (%)

DP2–9 Cellooligosaccharides (%)

Monosaccharides (%)

0.2

3.0

0.4

6.1

0.6

9.1

FUBIO JR2 PROGRAMME REPORT

Figure 11. (a): Oligomer concentrations in water solution after supercritical water treatment, analyzed by HPAEC-PAD in aqueous solution (PA100 column). (b): Molar mass distributions of the solid precipitate fraction. Analyzed by GPC-RI system (4 x PL-mixed A columns) after dissolution in anhydrous 90 g/L LiCl/DMAc.

Figure 12. Cumulative yields of main birch components in wood residue after hot water extraction (a) and in the pulp after soda-AQ pulping (b), plotted as a function of hot water extraction intensity (Log Pxs).

Selected wood residues after the pressurized

similar to the viscosity of pulp produced from

hot water extractions were subjected to

untreated wood. At higher extraction intensities

SAQ pulping (0.1% AQ) with the addition of

the viscosity rapidly decreased, reaching a

carbohydrate

sodium

minimum slightly above 100 ml/g. The addition

borohydride (BH) and anthraquinone-2-sulfonic

of stabilizing agents against peeling had little

acid sodium salt (AQS). The addition of 1% AQS

effect on pulp viscosity.

stabilization

agents

had no clear effect on the yield of carbohydrates, whereas the addition of 1% BH resulted in an

The soda-AQ cooks of untreated and PHWE-

average yield increase of about 3%, similar to

treated birch sawdust were conducted under

the yield obtained by increasing the AQ charge

varying conditions: i.e., alkali charge 18, 20, and

from 0.1 to 1%. The yield increase was mostly

22% on o.d. feedstock, AQ charge 0.1% on o.d.

due to stabilization of cellulose, although xylan

feedstock, cooking time 90, 120, and 150 min,

was also preserved to some extent. The intrinsic

temperature 170 째C, and liquor-to-feedstock

viscosity of unbleached pulps derived from low-

ratio 5 l/kg. Pulp yields of the soda-AQ-cooks

intensity autohydrolysis (log Pxs < 4.25) was

are presented in Table 4.

FUBIO JR2 PROGRAMME REPORT

Table 4. Birch soda-AQ cooking yield.

Soda-AQ cooks of birch wood 18% NaOH Time,

20% NaOH

22% NaOH

Ref

PHWE*

PHWE**

Ref

PHWE*

PHWE**

Ref

PHWE*

PHWE**

min 90

51.6

53.5

38.5

50.4

54.0

38.8

49.1

52.8

38.0

120

50.9

53.1

38.1

49.7

53.5

38.5

47.6

51.4

37.0

150

51.1

52.9

38.0

49.1

51.6

37.1

47.8

50.7

36.5

*Cooking yield (% of material charged into the reactors). **Total cooking yield (% of oven-dry feedstock before pre-treatment).

Clearly higher yields were achieved with the

170 °C, and liquor-to-wood (L:W) ratio 5 l/

reference material (untreated birch sawdust)

kg. The cooking liquor was first bubbled

compared to the pressurized hot water extracted

with oxygen (for 5 minutes) and an oxygen

materials. On the other hand, the colour of the

atmosphere was then created in the reactors

pulp produced from PHW extracted feedstocks

by an oxygen flow. The oxygen-alkali cooking

was clearly lighter (visible difference). Clearly

yields for both feedstocks are presented in

lower kappa numbers were achieved with pulps

Table 6.

produced from the PHW extracted materials, as seen in Table 5. As the table shows, the kappa

Again, clearly higher cooking yields were

numbers were very low, especially when pulping

achieved with the reference material (untreated

was conducted with pressurized hot water

sawdust) when compared to the pressurized

extracted feedstocks (T, “treated”).

hot water extracted materials. In general, PHWE-treatment conducted before oxygen-

Cooking experiments were also conducted

alkali

using oxygen-enhanced alkali cooking with

especially with birch sawdust. However, only

cooking

facilitated

the

defibration,

untreated and PHW extracted birch and spruce

very slight improvement could be observed

sawdust. The same cooking equipment was

in the case of spruce. Overall, spruce sawdust

used for the oxygen-alkali cooks as for soda-

was very poorly defibrated during oxygen-

AQ cooks. The cooking conditions were: alkali

alkali cooking experiments. Pulp reject after

charge 19% on o.d. feedstock, cooking time

screening (material not passing a 0.2-µm sieve,

30, 60, 90, 120, and 150 minutes, temperature

% of cooking yield) is presented in Table 7.

Table 5. Kappa numbers of the birch soda-AQ pulp samples.

Time, min

18 % NaOH

20 % NaOH

22 % NaOH

90 (NT*)

14.9

11.8

10.2

90 (T*)

6.4

5.5

120 (NT)

13.3

11.1

9.8

120 (T)

5.8

5.4

5.5

150 (NT)

12.2

11.0

9.3

150 (T)

5.4

4.6

5.6

*NT= not treated (i.e., no PHWE), T= treated

FUBIO JR2 PROGRAMME REPORT

Table 6. Spruce and birch oxygen-alkali cooking yields.

Oxygen-alkali cooks Birch

Spruce

19% NaOH

Time, min

Ref

PHWE*

PHWE**

Ref

PHWE*

PHWE**

59.5

59.7

42.9

67.9

74.4

56.2

56.8

54.7

39.3

63.5

70.3

53.1

55.4

52.4

37.9

60.3

66.2

50.0

120

54.1

52.3

37.6

58.3

63.8

47.7

150

51.2

50.0

36.0

57.4

61.3

46.3

*Cooking yield (% of material charged into the reactor). **Total cooking yield (% of oven-dry feedstock before pre-treatment). Table 7. Pulp reject (% of cooking yield) after oxygen-alkali cooking.

Time (min)

Birch (Ref)

Birch (PHWE)

Spruce (Ref)

Spruce (PHWE)

70.2

29.9

86.0

82.6

68.9

11.5

85.4

79.9

64.6

3.8

81.5

76.6

120

57.9

1.7

81.0

75.8

150

47.2

80.7

73.4

4.5 Separation and purification of hemicellulose-rich extracts

ultrafiltration (10 kDa) regenerated cellulose membrane is used and filtration is performed using a high shear rate filter. High volumes of

Hemicellulose-rich wood extracts after PHWE

water and small compounds can be removed

contain relatively large amounts of water

from the extract with a reasonable filtration

and impurities which need to be removed before further utilization. Membrane filtration is a convenient method for simultaneously concentrating and fractionating the extract. Pilot scale membrane filtration equipment (Figure 13) was used to separate high-molarmass hemicelluloses from the PHWE extracts. The

results

from

several

concentration

filtration experiments performed at the pilot scale revealed that concentration of wood extracts

produce

high-molar-mass

hemicellulose fraction can be done using a relatively high filtration capacity (flux) without any pre-treatment when a hydrophilic

FUBIO JR2 PROGRAMME REPORT

Figure 13. Cross-rotational (CR)-350 ultrafiltration equipment, membrane area 1 m2.

capacity (> 100 kg/(m2 h)) (Figure 14). The flux

2.5 bar (60 °C, circumferential velocity of rotors

gradually decreased as the feed concentration

8.6 m/s), indicating that the decrease in filtration

increased, which could be expected. However,

capacity occurring at the end of concentration

at a certain point the flux suddenly collapsed

filtration can be compensated by increased

(Figure 14). Changes in the feed composition

filtration pressure. Despite the significant flux

due to increasing concentration, i.e. increased

decline seen at the end of the concentrate

total solids content and average molar mass of

filtrations, the membranes were not significantly

compounds present in the feed, may have led

fouled and filtration capacity was easy to restore

to an increase in osmotic pressure difference

with simple alkaline cleaning.

across the membrane and increased viscosity. In addition, the rheological properties of

Several pre-treatments for improving the

the feed may have changed as a result of

filtration capacity and increasing the purity

concentration. These combined factors may

of the resulting hemicellulose fractions were

have led to the considerable and rapid flux

investigated. For instance, a combination

reduction. It was found that the filtration

of pre-treatment, ultrafiltration and post-

capacity (flux) can be maintained at a good level

treatment was studied at laboratory scale

(about 95 kg/(m h)) if the pressure is increased

using a 40 cm2 RC70PP membrane with a 10

in line with the reduction in feed volume (i.e.

kDa cut-off. Spruce extract was first oxidized

increase in concentration) at least until the TDS

and then ultrafiltered and diafiltered at 60 °C

of the concentrated fraction is about 8% (Figure

and 2 bar. As Figure 15 shows, the combined

14). This was demonstrated in the experiments

purification and separation steps removed

in which spruce extract (TDS content 0.86%)

significant amounts of impurities from the

was fractionated in constant flux mode, where

extract, although some hemicellulose losses

the filtration pressure increased from 1.3 bar to

occurred in the process.

Constant pressure (2 bar)

200

Constant flux

Pressure at constant flux mode

Constant flux mode TDS 3.79% at 4.8 h

Constant pressure mode TDS 3.85% at 2.7 h

TDS(feed) 0.86%

3.0

180 2.5

Flux (60°C), kg/(m2h)

160 140

2.0

120 100

1.5

80 1.0

60 40

0.5

20 0

Pressure (constant flux mode), bar

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

Time, h Figure 14. Filtration capacity in the treatment of spruce extract with the RC70PP membrane and the CR-350 filter using constant pressure and constant flux filtration modes. Both experiments were conducted at 60 °C with a rotor circumferential velocity of 8.6 m/s.

FUBIO JR2 PROGRAMME REPORT

Figure 15. Chemical composition of original spruce extract before separation and purification (a) and chemical composition of the concentrate after oxidative pre-treatment, ultrafiltration and diafiltration (b).

4.6 Analytical methods for compositional and structural analyses

composition, the structural features of the biomass fractions must also be examined in order to evaluate the applicability and value of

In order to evaluate the efficiency of the

the material. The choice of analytical techniques

developed processes, the composition of the

depends on the sample matrix. In addition,

obtained fractions must be analysed. This

appropriate

is important for determining the purity and

applied. The most important analytical methods

mass balance of the fractions. In addition to

for the research challenges described above are

pre-treatments

must

also

Table 8. Analysis methods for solid wood and fibrous samples.

Solid wood and fibrous samples

Obtained information

Pre-treatment: grinding and sieving Carbohydrate content and composition - Acid methanolysis/GC

Hemicelluloses and uronic acids

- Acid hydrolysis (two-stage)-HPAEC/PAD

Cellulose and hemicelluloses

Extractives content and composition - Extraction by ASE, Soxtec, Soxhlet with aceto- Total amount of (acetone soluble) extractives ne, gravimetric detection - Group analysis with short GC column

Quantitation of compound groups

- Analysis by GC-FID/GC-MSD

Identification of individual components

Lignin amount (after extraction) - Acid hydrolysis, gravimetric analysis of residue

Total lignin as Klason lignin + acid soluble lignin

+ UV detection of the hydrolysate Molar mass - Dissolution (multi-step) in DMAc/LiCl - HPSEC

Molar mass distribution of cellulose (+hemicelluloses), calculated average values

ASE: Accelerated Solvent Extraction, FID: Flame Ionisation Detector, GC: Gas Chromatography, HPAEC: High Performance Anion Exchange Chromatography, HPSEC: High Performance Size Exclusion Chromatography, MSD: Mass Spectroscopic Detector, PAD: Pulse Amperometric Detector, UV: Ultraviolet.

FUBIO JR2 PROGRAMME REPORT

listed in Tables 8, 9 and 10 for different sample

techniques, it was possible to follow the

matrices, including a brief description of the

formation

method and the information obtained. The

cellulose under supercritical water treatment

methods suggested for solid wood and fibrous

conditions (Tolonen et al. 2014). The other

samples are based on either standard methods

methods mentioned in Table 9 are based on

or literature.

literature.

Molar mass is one of the most crucial criteria

Lignin was partly extracted in the PHWE

for determining hemicellulose quality. Lignin is

treatments along with hemicelluloses as

always present in the hemicellulose fractions

an impurity. However, lignin is a valuable

either as such or linked to carbohydrates. This

component in itself with a range of potential

causes problems in molar mass analysis using

applications. The structure and properties

universal calibration with light scattering-

of lignin depend on its origin (raw material

based detection due to autofluorescence.

and process). The methods listed in Table 10

Because of the challenges related to this critical

provide useful information for evaluating the

measurement, a comparison between several

quality and properties of isolated lignins.

cello-oligosaccharides

from

methodologies was performed using hotwater extracted spruce galactoglucomannans (GGM) and birch glucuronoxylans as substrates (Xu et al. 2013). Four different size exclusion

5. Exploitation plan and impact of results

chromatography (SEC) configurations used by different partners were compared. Ethanol

The main objective was to generate a concept

precipitations were carried out on the birch

based on pressurized hot water extraction

and spruce extracts to explore the effect of

(PHWE)

lignin content on molar mass.

hemicelluloses at high yield from wood of

for

producing

high-molar-mass

varying particle size. Another goal was to The difference in Mw values of the birch samples

utilize the remaining fibre fraction after PHWE

was found to be relatively larger than that of

for the production of new fibre products and

the spruce samples, presumably because

regenerated cellulose. Because no entirely

the birch extracts contained more lignin than

pure fractions can be separated from wood,

spruce. The difference in Mw values before

comprehensive studies of separation and

and after ethanol precipitation was similarly

purification technologies required for these

ascribed to differences in lignin content of the

processes were also carried out. Furthermore,

birch and spruce samples. In addition, the Mw

fundamental understanding of the factors

values determined by RI increased during the

affecting PHWE and subsequent delignification

precipitation窶電issolution cycle, probably due

processes is needed for developing industrial-

to aggregation. It was therefore not possible to

scale processes. These general objectives

identify an optimal method for all sample types.

were met and the processes and knowledge generated can be implemented, at least in

Another

analytical

part, in industry. As a result, increased use

and

of biomass instead of oil for materials and

quantitation of individual oligosaccharides,

products will have a positive impact on society

either in their native form or in altered form

and contribute towards a sustainable future.

hemicelluloses

challenge the

identification

during processing. By combining several chromatographic and mass spectroscopic

FUBIO JR2 PROGRAMME REPORT

Table 9. Analysis methods for PHWE extracts and isolated hemicelluloses. PHWE extracts and isolated hemicelluloses

Obtained information

Solids content, gravimetric

Total amount of dissolved material

Carbohydrate content and composition - Freeze-drying-acid methanolysis/GC

Hemicelluloses and uronic acids

- Weak acid hydrolysis-HPAEC/PAD

Hemicelluloses

Lignin amount - Acidic solutions: direct UV detection or freeze-drying - acetyl bromide or Klason lignin

Content of dissolved lignin

Acetic acid / formic acid, degree of acetylation - HPLC, CE or benzylation-GC/MS

Content of volatile acids

- Alkaline hydrolysis + analysis of acetic acid

Degree of acetylation

Furfural-type degradation products - HPLC or CE

Content of furfural and hydroxymethylfurfural (HMF)

Other degradation products - Silylation-GC/MS

(Hydroxy)acids

Molar mass distribution of dissolved hemi and lignin - HPSEC-various detectors*

Molar mass distribution and calculated average values

Oligosaccharides - HPAEC-PAD/MSQ**

Quantitative analysis of oligosaccharides if standards available, otherwise tentative identification by MSQ (as deacetylated analogues)

- MALDI-TOF-MS, AP-MALDI-MS/MS, ESI-MS/MS**

Identification including native acetylation

AP: Atmospheric Pressure, CE: Capillary Electrophoresis, ESI: Electron Spray Ionisation, HPLC: High Performance Liquid Chromatography, MALDI: Matrix Assisted Laser Desorption Ionisation, MS: Mass Spectrometry, MSQ: Quadrupole Mass Spectrometry, TOF: Time of Flight, other abbreviations as in Table 8. * For method comparison, see text above and ref. Xu et al. 2013. ** For application example and details, see text above and ref. Tolonen et al. 2014. Table 10. Analysis methods for isolated lignin. Isolated lignin

Obtained information

Composition - Ash content (metals) by incineration

Organic content

- Carbohydrate content: hydrolysis and HPAEC/PAD

Lignin-Carbohydrate Complexes (LCC)

Structure - Derivatisation-31P NMR

Frequency of hydroxyl functionalities

- 1D and 2D NMR techniques

Substructures and inter-unit linkages

- Pyrolysis-GC/MS

Fingerprint, mainly for sample comparison

Molar mass - HPSEC-UV in NaOH

Molar mass distribution

Elemental analysis (CHONS)

Elemental composition

Thermal properties - Glass transition temperature by DSC, degradation

Transitions and degradation as a function of tempe-

by TGA

rature

CHONS: Carbon, Hydrogen, Oxygen, Nitrogen and Sulfur, DSC: Differential Scanning Calorimetry, NMR: Nuclear Magnetic Resonance, TGA: Thermogravimetric Analysis, other abbreviations as in Tables 8 and 9.

FUBIO JR2 PROGRAMME REPORT

6. Networking The research was carried out jointly by Aalto University, the Finnish Forest Research Institute, Lappeenranta University of Technology, University of Helsinki, University of Jyväskylä, VTT Technical Research Centre of Finland, Åbo Akademi University and Finnish Bioeconomy Cluster companies. Table 11 presents the research partners and their roles. Table 11. Partner organizations and their research roles.

Work package partners

Role of the participating organization

Aalto University

Pressurized hot water extraction, near- and supercritical water treatment, delignification

Andritz

Industrial tutor

Finnish Forest Research Institute

Pressurized hot water extraction, purification, delignification

Kemira

Work Package Coordinator

Lappeenranta University of Technology

Membrane filtration, separation, purification

Metsä Fibre

Industrial tutor

Stora Enso

Industrial tutor

University of Helsinki

Enzymatic hydrolysis, analytical methods

University of Jyväskylä

Delignification, characterization of black liquor

UPM-Kymmene

Industrial tutor

VTT

Pressurized hot water extraction, analytical methods, enzymatic hydrolysis, modelling, delignification, green liquor extraction

Åbo Akademi University

WP leader. Pressurized hot water extraction, analytical methods, purification, reaction kinetics, hydrolysis by heterogeneous catalysis, chemical characterization, delignification

FUBIO JR2 PROGRAMME REPORT

7. Publications and reports Bardot, F. Cellulose stabilization during alkaline

Kilpeläinen, P., Kitunen, V., Pranovich, A., Il-

pulping for the production of high‐purity dis-

vesniemi, H. and Willför, S. Pressurized hot

solving‐grade pulp, Master’s thesis, Aalto Uni-

water flow-through extraction of birch saw-

versity, 2012.

dust with acetate pH buffer, BioRes., 8, 2013, 4, 5202–5218.

Borrega, M., Tolonen, L.K., Bardot, F., Testova, L. and Sixta, H. Potential of hot water extrac-

Kilpeläinen, P., Hautala, S. Byman, O., Tan-

tion of birch wood to produce high‐purity dis-

ner, J., Korpinen, R., Lillandt, M., Pranovich,

solving pulp after alkaline pulping, Bioresource

A., Kitunen, V., Willför, S. and Ilvesniemi, H.

Technology, 135, 2012, 665–671, DOI: 10.1016/j.

Pressurized hot water flow-through extraction

biortech.2012.11.107.

system scale up from laboratory to pilot scale, Green Chem., 2014, DOI: 10.1039/C4GC00274A.

Borrega, M., Niemelä, K. and Sixta, H. Effect of hydrothermal treatment intensity on the for-

Koivula, E., Kallioinen, M., Sainio, T., Antón,

mation of degradation products from birch-

F.E., Luque, S. and Mänttäri, M. Enhanced

wood, Holzforschung, 67, 2013, 8, 871–879, DOI:

membrane filtration of wood hydrolysates for

10.1515/hf-2013-0019.

hemicelluloses recovery by pretreatment with polymeric adsorbents, Biores. Tech., 143, 2013,

Borrega, M. and Sixta, H. Purification of cel-

275-281.

lulosic pulp by hot water extraction, Cellulose, 20, 2013, 2803–2812, DOI 10.1007/s10570-013-

Korpinen, R., Kallioinen, M., Hemming, J.,

0086-1.

Pranovich, A., Mänttäri, M. and Willför, S. Comparative evaluation of various lignin deter-

Garcia de Castro Insua, R. Acid hydrolysis of

mination methods on hemicellulose-rich frac-

birch and spruce hemicelluloses by heteroge-

tions of spruce and birch obtained by pres-

neous catalysis, Master’s thesis, Åbo Akademi

surized

University, 2013.

subsequent ultrafiltration (UF), Holzforschung,

hot-water

extraction

(PHWE)

and

2014, DOI: 10.1515/hf-2013-0233. Grénman, H., Eränen, K., Krogell, J., Willför, S., Salmi, T. and Murzin, D. Kinetics of Aqueous

Krogell,

Extraction of Hemicelluloses from Spruce in

Pranovich, A. and Willför, S. High-temperature

an Intensified Reactor System, Ind. Eng. Chem.

pH measuring during hot-water extraction of

Res., 50, 2011, 7, 3818–3828.

hemicelluloses from wood, Industrial Crops and

J.,

Eränen,

K.,

Granholm,

K.,

Products, 61, 2014, 9–15. Kilpeläinen, P., Leppänen, K., Spetz, P., Kitunen, V., Ilvesniemi, H., Pranovich, A. and

Krogell,

Willför, S. Pressurised hot water extraction

Pranovich, A., Salmi, T., Murzin, D. and Willför,

J.,

Korotkova,

E.,

Eränen,

K.,

of acetylated xylan from birch sawdust, Nord.

S. Intensification of hemicellulose hot-water

Pulp Pap. Res. J., 27, 2012, 4, 680–688.

extraction from spruce wood in a batch extractor - Effects of wood particle size, Bioresource Technology, 143, 2013, 212–220.

FUBIO JR2 PROGRAMME REPORT

Kuivanen, J. Kuusen ja koivun jatkuvavirtauk-

Retsja, L. Puuperäisten biomassahydrolysaat-

sellinen paineistettu kuumavesiuutto, Master’s

tien likaamien membraanien pesu, Master’s the-

thesis, University of Jyväskylä, 2012.

sis, Lappeenranta University of Technology, 2013.

Lehto, J. and Alén, R. Purification of hardwood-

Rissanen, J., Grénman, H., Willför, S., Mur-

derived autohydrolysates, BioResources, 7,

zin, D. and Salmi, T. Spruce Hemicellulose for

2012, 1813–1823.

Chemicals Using Aqueous Extraction: Kinetics, Mass Transfer, and Modeling, Industrial &

Lehto, J., Alén, R. and Malkavaara, P. Multivar-

Engineering Chemistry Research, 53, 2014, 15,

iate correlation between analysis data on dis-

6341–6350.

solved organic material from Scots pine (Pinus sylvestris) chips and their autohydrolysis pre-

Song, T. Extraction of polymeric galacto-glu-

treatment conditions, BioResources, 9, 2014,

comannans from spruce wood by pressurised

93–104.

hot water, Doctoral thesis, Åbo Akademi University, 2013.

Lehto, J., Alén, R., and Malkavaara, P. Multivariate correlation between analytical data for

Testova, L., Borrega, M., Tolonen, L.K., Pent-

various organics dissolved during autohydrol-

tilä, P.A., Serimaa, R., Larsson, P.T. and Sixta,

ysis of silver birch (Betula pendula) chips and

H. Dissolving-grade birch pulps produced un-

treatment conditions, BioResources, 9, 2014,

der various prehydrolysis intensities: quality,

4958–4970.

structure and applications, Cellulose, 2014, DOI 10.1007/s10570-014-0182-x.

Leppäaho, M. Kuumavesiuutetun kuusisahanpurun sooda-antrakinonikeitto, Master’s thesis,

Tikkanen, T. Paineistetulla kuumavesiuutolla

University of Jyväskylä, 2013.

tuotetun hemiselluloosarikkaan jakeen entsymaattinen puhdistaminen, Master’s thesis, Uni-

Li, Z. Optimisation of alkaline flow-through ex-

versity of Oulu, 2013.

traction of spruce wood for lignin recovery, Master’s thesis, Åbo Akademi University, 2013.

Tolonen, L.K., Penttilä, P.A., Serimaa, R., Kruse, A. and Sixta, H. The swelling and disso-

Nevalainen, M. Ultrasuodatusmembraanin mo-

lution of cellulose crystallites in subcritical and

difiointi entsyymeillä suodatusominaisuuksien

supercritical water, Cellulose, 20, 2013, 6, 2731-

parantamiseksi, Master’s thesis, Lappeenranta

2744. doi:10.1007/s10570-013-0072-7.

University of Technology, 2013. Tolonen, L.K., Juvonen, M., Mikkelson, A., NiePenttilä, P.A., Kilpeläinen, P., Tolonen, L., Su-

melä, K., Tenkanen, M. and Sixta, H. Super-

uronen, J.-P., Sixta, H., Willför, S. and Serimaa,

critical water treatment for cello-oligosaccha-

R. Effects of pressurized hot water extraction

ride production from microcrystalline cellulose,

on the nanoscale structure of birch sawdust,

Manuscript submitted to ChemSusChem 2014.

Cellulose, 20, 2013, 5, 2335–2347. Xu, C., Korpinen, R., Hirsilä, P., Liitiä, T., Tuomainen, P., Tamminen, T., Willför, S. and Tenkanen, M. Effect of lignin on the molar mass analysis of hot water extracted hemicelluloses, FuBio Seminar, 27.8.2013, Helsinki, Finland.

FUBIO JR2 PROGRAMME REPORT

IONIC LIQUIDS FOR WOOD FRACTIONATION

CONTACT PERSON – Work Package 2 leader Alistair W. T. King, alistair.king@helsinki.fi Aalto University: Ville Alopaeus, Lauri Hauru, Michael Hummel, Yibo Ma, Alexandr Ostonen, Annariikka Roselli, Erlin Sapei, Herbert Sixta, Petri Uusi-Kyyny Andritz: Christian Järnefelt, Tiina Rauhala Lappeenranta University of Technology: Mika Mänttäri, Olli Nakari, Arto Pihlajamäki Metsä Fibre: Pirkko Liias Stora Enso: Paula Rantamäki, Heidi Saxell University of Helsinki: Jussi Helminen, Ashley Holding, Uula Hyväkkö, Tia Kakko, Ilkka Kilpeläinen, Arno Parviainen UPM-Kymmene: Ulf Hotanen, Mika Hyrylä VTT Technical Research Centre of Finland: Anna Suurnäkki, Ronny Wahlström Åbo Akademi University: Ikenna Anugwom, Valeri Eta, Jyri-Pekka Mikkola, Päivi Mäki-Arvela, Pasi Virtanen

FUBIO JR2 PROGRAMME REPORT

ABSTRACT

During FuBio 1, new concepts in wood processing with novel ionic liquids as potentially environmentally benign reaction media were presented. These include a refinement in our understanding about the effects that these unique solvators have on woody material and examples of the new structures under development, which offer increased process sustainability over the initial generations of ionic liquids. Herein we present the updated results from these fractionation concepts, including switchable ionic liquid (SIL, selective extraction of components) fractionation and ionic liquid-aided fractionation (ILAF, homogeneous dissolution and selective precipitation of components). One new concept is presented, called the IONCELL-P process, which is a process for fractionation of kraft pulp into its higher-value pure components (cellulose and hemicellulose). As ionic liquids must be recovered in all processes, we also present the most up-to-date recyclable ionic liquid structures that have been developed during the FuBio project (switchable: SIL; distillable: DIL; phase-separable: PSIL) and the methods that are being used to assess ionic liquid purification (thermodynamics of distillation in ionic liquids and membrane purification methods). Overall, we have developed understanding that makes us highly competitive on the international scale in the area of bioprocessing with ionic liquids.

Keywords: fractionation, dissolution, biomass, distillable, switchable, sustainable, IONCELL

FUBIO JR2 PROGRAMME REPORT

1. Background 1.1 Ionic Liquid Bioprocess Sustainability

ionic liquids (SILs), distillable ionic liquids (DILs) and phase-separable ionic liquids (PSILs).

one

The results from fractionation of wood and

sustainable resource to replace fossil fuels.

subsequent recycling, using all classes of ILs

However, challenges exist in the incorporation

described above, are presented in this chapter.

Wood

regarded

the

number

of wood-based feedstocks and processes into traditionally fossil-based value chains. Therefore, new ‘tuneable’ methods offering

2. Objectives

more varied and improved selectivities for the fractionation and processing of wood

The main application objectives of this work

biopolymers into materials, chemicals and

package were focussed on the development

energy are necessitated. The reported high

of processes that utilize ionic liquids, namely:

efficiency in the solvation of cellulose, as a major wood component, by ionic liquids (ILs)

• Develop recyclable, cheap and low toxicity ionic liquids that are capable of dissolving

has thus afforded new processing opportunities whereby wood itself can be effectively solvated

cellulose, wood or extracting wood.

and processed accordingly. In addition, room

• Assess their potential for fractionation

temperature ionic liquids (RTILs), such as

of wood into its components of specified

1-ethyl-3-methylimidazolium acetate ([emim]

quality for novel processes or to fit into existing value chains.

[OAc], m.p. -45°C), offer so effective cellulose solvation

capabilities

that

they

are

now

• Assess the recyclability and purification

considered to be industrially viable media

of these ionic liquids before and after

for existing and novel cellulose processing

fractionation steps.

applications. An important example is in the replacement of N-methylmorpholine-N-oxide

On the whole, the objectives called for the

hydrate (NMMO·H2O) in a ‘Lyocell’ process,

assessment of existing structures for their

circumventing

stability

efficiency in the fractionation of woody

issues. [emim][OAc] has been so successful in

material and for the development of new

cellulose solvation that BASF is now producing

ionic liquids. This was necessary due to the

it on a ton-scale. Publications are appearing,

poor stability and recyclability of existing

however, that highlight the instability of

structures. A general pre-requisite for new

[emim][OAc] in the presence of lignocellulosic

ionic liquids for the above application was

solutes, although this may be beneficial for

that they be effective at dissolving both lignin

homogeneous dissolution of wood as certain

and wood polysaccharides, such as cellulose

[emim][OAc]

hazardous

thermal

decomposition

products

are

hemicelluloses.

Determining

which

known to catalyse certain chemistries. In

biopolymers these ionic liquids dissolve or

regard to process sustainability, basic ILs such

extract from the substrate will dictate which

as [emim][OAc] are also known to have reduced

fractionation schemes can be applied.

thermal stabilities. This effectively prevents the recovery of the IL on an industrial-scale by distillation. As such, other methods of recycling or more recyclable structures/systems were sought during FuBio 1 & 2, e.g., switchable

FUBIO JR2 PROGRAMME REPORT

3. Research approach Due to the infancy of ionic liquids research

• Develop structure property relationships

and the structural complexity of ionic liquids

in regard to the physical properties of the

in comparison to molecular solvents, this

ionic liquids (e.g. thermal stabilities) and the

work package demanded a more academic

observed effects and phenomena (mainly

approach. This was conducted alongside

biopolymer solubilities). This was achieved

assessment of ionic liquids for their efficacy

through a process of parameterization of

for the processing of lignocellulosics. Three

effective and non-effective ionic liquids.

main areas were focused on (Scheme 1).

Computational methods were also used to predict physiochemical properties of

The research strategy outlined in Scheme 1 can be summarized as follows:

structures. • Through this understanding of effects, parameters and the generation of new

• The starting point was the synthesis of existing imidazolium-based ionic liquids • Next was to further our understanding of different effects and phenomena that occur when lignocellulosics are contacted with ionic liquids (e.g. dissolution capabilities,

structures, it was possible to develop hypotheses about which structural features would enable more advantageous effects (e.g. lower viscosities or more recyclable structures) • New series of structures were synthesized

fractionation efficiency, fibrillation,

bringing an improved understanding of

chemical reaction).

physical properties and recycling issues, in particular • This was finalized by assessment of their potential in fractionation processes

Scheme 1. Strategy for academic development of novel and effective ionic liquids.

FUBIO JR2 PROGRAMME REPORT

4. Results 4.1 Switchable Ionic Liquid Fractionation

current kraft process, in which they are burnt for energy recovery.

The main objective of the work was to develop a process to fractionate the main biomass

The SILs were synthesized by bubbling CO2 or

components to enable their utilization in the

SO2 through the liquid mixture with the ratio

production of materials, chemicals and fuels

of amidine/guanidine to hydroxyl-containing

for the future bioeconomy.

compound calculated based on the number of hydroxyl groups in the alcohol or alkanol. Here

Several Switchable Ionic Liquids (SIL) were

a sample case is presented as an example

synthesized and characterized. The prepared

procedure. DBU-MEA-SO2-SIL was prepared

SILs were used in a novel process involving the

by passing SO2 through the mixture containing

fractionation of Nordic woody biomass by se-

1:1 molar amounts of 1,8-diazabicyclo-[5.4.0]-

lective dissolution. The process was discov-

undec-7-ene (DBU) and monoethanolamine

ered and extensively developed during the

(MEA). The weight increase with the SIL

FuBio programme, with the duration of frac-

corresponds to a molar ratio of 1:1:1 of all

tionation successfully reduced from five days

components. These results indicate that all

to just two hours. In addition, relatively high

OH groups of the MEA react upon formation

purity of the resulting fractions was achieved;

of the ionic liquid according to Scheme 2. This

for example, cellulose-rich material contain-

observation is supported by NMR and FTIR

ing 79 wt-% cellulose, 11 wt-% hemicelluloses

studies.

and 5 wt-% lignin was obtained from spruce chips. All of the produced fractions were char-

In previous studies it has been demonstrated

acterized in detail using several methods.

that SILs are potential novel solvents for the

The SIL treatment enables the fractionation

fractionation of lignocellulosic material into

of biomass into relatively pure fractions un-

suitable fractions. However, the fractionation

der milder conditions than in current industri-

efficiency has not been comparable to those

al processes, thus consuming less energy. The

obtained with conventional ILs mainly due to

process could be utilized where the production

the low treatment temperature. Therefore,

of hemicelluloses and lignin together with cel-

the fractionation of lignocellulosic material

lulose fibres is targeted. Hemicelluloses and

was investigated based on new types of

lignin fractions could be processed further as

SILs. These were based on glycerol or alkanol

bio-based chemical and materials, thus adding

amine, CO2 or SO2 and an amidine (DBU).

value to these raw materials compared to the

The new SILs have one major advantage

Scheme 2. Proposed reaction scheme for the formation of DBU-MEA-SO2-SIL (adapted from Anugwom et.al. 2014. ChemSusChem 7, 1170).

FUBIO JR2 PROGRAMME REPORT

compared to previously presented SILs: their

filtration. The undissolved wood material

decomposition temperatures are significantly

was washed several times with isopropanol

higher,

at about 40°C until all the SIL was visually

thus

allowing

higher

treatment

temperatures, which leads to more efficient

removed.

fractionation. Wood was fractionated without

of wood, the undissolved residues as well

any

normal

as precipitated materials from the SIL were

pressure and at 100-120°C. However, the

analysed by various methods. Weight losses

treatment time was found to be too long

were recorded and the materials were analysed

and too cost-intensive to implement at an

in order to determine their composition. The

industrial scale. Furthermore, the use of large

latest results showed that the STHT method

amounts of SILs and the need for drying

can be used to remove almost all lignin and

of the wood raw material would also add to

the majority of hemicelluloses from wood

the process cost. However, addition of water

in just two hours. For example, DBU/MEA/

to the wood/SIL mixture or/and use of fresh

CO2-water treated spruce contained 79 wt-%

non-dried wood was found to be effective in

cellulose, and only 11 wt-% hemicelluloses and

reducing SIL consumption. The optimization

5 wt-% lignin. In addition, the resulting fibres

of conditions for the selective fractionation

are very light in colour (Figure 1).

mechanical

agitation

under

After

the

dissolution/extraction

of woody biomass was investigated via a novel and economically feasible fractionation

Significant further improvements to the process

method using an alkanol amine (MEA) and

can be made. Firstly, the recovery of dissolved

an organic superbase (DBU) derived SIL with

hemicelluloses and lignin from the spent SIL

water. The Short Time High Temperature

should be improved. In addition, the process is still

(STHT) approach was used, where the wood

far from optimized, thus, substantially improved

was immersed in the SILs and water added

results could be achieved through optimization.

to achieve a 1:3:5 weight ratio. The mixture

Furthermore, the number of new SIL designs is

was kept at 160°C under normal atmospheric

considerable and remains so far unexplored.

pressure for 2 hours without stirring. While

Most importantly, SILs ‘triggered’ with acid gases

the mixture was still hot, the undissolved

other than those studied here could give rise to a

wood fraction was separated using vacuum

rich family of yet unknown potential.

Figure 1. Undissolved fluffy material recovered from A) birch and B) spruce after SIL treatment applying the STHT method. The SIL applied was DBU-MEA-SO2 with water at 160°C for 2 h.

FUBIO JR2 PROGRAMME REPORT

4.2 Recyclable Ionic Liquid Design

[P8881][OAc], which was demonstrated to be phase-separable upon addition of water or

Throughout FuBio 1 & JR2, emphasis was placed

kosmotropic electrolyte solutions (e.g. sodium

on the development of recyclable systems

acetate solution), was also found to be an excellent

for biomass processing at the University of

solvent for cellulose as the DMSO electrolyte. Its

Helsinki. The motivation for this was that no

ability to form isotropic solutions was so strong

workable strategies were available for recycling

that it was possible to obtain 1H-13C heteronuclear

ionic liquids after a fractionation step. Typically,

single-quantum correlation (HSQC) NMR spectra

oligomeric

are

where the cellulose backbone was free from any

present that are very difficult to remove due

ionic liquid resonances (Figure 4). To the best of

to the non-volatility of traditional ionic liquids.

our knowledge, this was the first time that this

Therefore, we sought to introduce recyclability

has been achieved with high DP cellulose (MCC).

to the ionic liquid in the form of the classical

Moreover, we were able to assign the terminal

purification methods of distillation and phase

glycosidic C1 and anomeric C1 signals from the

separation (Figure 2). In this case the distillation

chain ends in the 1H NMR spectra (Figure 5).

of [TMGH][CO2Et] required 130Â°C and 5 mbar in

Cellulose regenerated from this solution mainly

a Kugelrohr. In the case of recycling by phase-

as the more thermodynamically stable cellulose

separation, dissolved cellulose and [P8881][OAc]

II crystalline polymorph, together with some

could be recovered by addition of pure water

residual cellulose I and amorphous cellulose

or kosmotropic salts. [P8881][OAc] could then be

(Figure 4). Therefore, these are highly suitable

reused in the dissolution of cellulose.

media for further biomass pre-treatments,

materials

and

inorganics

fractionations or chemical modification. This After

continued

optimization

different

will be thoroughly investigated in the future.

distillable acid-base conjugate ionic liquids for biomass processing, it was found that [DBNH] [OAc] was a highly effective ionic liquid for cellulose dissolution. This was a result of the very low viscosity achieved by the combination of

1,5-diazabicyclo(4.3.0)non-5-ene

(DBN,

superbase) and acetic acid (organoacid), which was similar to that of the benchmark ionic liquid [emim][OAc] (Figure 3). When combining different bases with acetic and propionic acid, a clear trend developed concerning cellulose solubility. Combinations of these acids with the superbase range proved effective at dissolving cellulose, whereas their combination with normal organic bases was ineffective. This was rationalized by the fact that the basicity of the unconjugated base is also a measure of the ionic liquidsâ&#x20AC;&#x2122; cation acidity. It was concluded that if the cations are too acidic they stabilize the anion to such an extent that solvation of cellulose, with significant enthalpy of dissolution gain through cellulose hydrogen bond breakage, is inhibited.

FUBIO JR2 PROGRAMME REPORT

Figure 2. Distillation of the cellulose-dissolving [TMGH][CO2Et] (a) and the recycling strategy for phaseseparable ionic liquids, such as [P8881][OAc] (b), which dissolve cellulose as their DMSO electrolytes (Adapted from King et al. 2011, Angew. Chem. Int. Ed. 50, 6301 and Holding et al. 2014. ChemSusChem 9, 1565).

FUBIO JR2 PROGRAMME REPORT

Figure 3. Viscosities vs. temp. of a range of acid-base conjugate ionic liquids (a), with [DBNH][OAc] having the same viscosities as the benchmark [emim][OAc]. X-ray crystal structure of [DBNH][OAc] (b) indicating strong hydrogen bonding between anion and cation. Proposed model for how cation acidity influences the enthalpy gain for Gibbs free energy of dissolution (c). (Adapted from Parviainen et al. 2013 ChemSusChem 6, 2161).

Figure 4. (a) Solution-state HSQC NMR of MCC dissolved in [P8881][OAc]:d6-DMSO. (b) XRD of untreated and regenerated MCC (adapted from Holding et al. 2014. ChemSusChem 9, 1565).

Figure 5. Assigned 1H NMR of MCC dissolved in [P8881][OAc]:d6-DMSO showing polymeric and terminal C1 peaks.

FUBIO JR2 PROGRAMME REPORT

4.3 Homogeneous Ionic Liquid-Aided Fractionation

Without autohydrolysis, 7% of birch was insoluble. Thus, after autohydrolysis (P-factor 500) the purity of precipitate 1 increased sig-

The objectives of this task were to define ad-

nificantly (LIG/CH = 0.27 to 0.16) without loss

equate pretreatments to enhance IL frac-

of cellulose yield or molar mass.

tionation of wood components and to define quantitative measures of ILâ&#x20AC;&#x2122;s wood polymer

The process was repeated with different

solvation capability. We employed a standard

particle sizes and P-factors. Compared to <125

process, explained in Figure 6, to investigate

Âľm Wiley meal, more insolubles were produced

the effects of pretreatments.

with commercial sawdust, but this could be compensated by increasing the autohydrolysis

Comparing native and autohydrolyzed birch,

P-factor from 500 to 1500. In order to fragment

the latter produced better results (Figure 7).

the remaining lignin, ozonation was applied on

Figure 6. Standard fractionation scheme for optimization of processing conditions.

Figure 7. (a) ILAF of wood; (b) ILAF of autohydrolyzed wood.

FUBIO JR2 PROGRAMME REPORT

autohydrolyzed wood. However, no increased

hemicellulose selective dissolution window,

selectivity in terms of molar mass or solubility

as illustrated in Figure 8. Maximum removal

was gained.

of xylan is at the border line between the selective and unselective areas of the chart.

A final cellulose II pulp with a lignin content of

When the molar fraction of water exceeds a

13% was thus produced. On centrifugation, the

certain threshold value, hemicelluloses are no

pulp compacted into a form containing 96%

longer soluble in the system. This means that

water, which oven-dried to a black, hard sol-

the water can also be used to regenerate the

id. As is, the pulp could be blended with card-

dissolved material.

board pulp to potentially reduce porosity. With further conventional delignification, dissolving

As a result of testing several ionic liquid systems

pulp could be produced.

and different sources of pulps for optimizing IONCELL-P fractionation, it can be reported

4.4 IONCELL-P Process

that fractions separated in optimal conditions (3h, at 60˚C, water content dependent on used

The objective of this research task was to define

ionic liquid system) have no molecular weight

the optimal conditions for the quantitative

degradation, have high recovery yields of

fractionation of paper grade pulps using the

fractionated polysaccharides, and maintain the

IONCELL-P(ulp) process in order to upgrade

cellulose I crystallinity of the cellulose fraction.

them to acetate grade or dissolving pulps. The study was based on the differences in solubility

The

behaviour of cellulose and xylan in ionic liquid

concluded to be successful, since it has

systems. Different co-solvents mixed with the

been shown that high yields and high purity

ionic liquid alter the ionic liquid’s dissolution

polymeric components can be retrieved from

abilities to different levels. Water addition

the IONCELL-P fractionation processes, with

deteriorates

the

ionic

liquid’s

dissolution

pulp

extraction

cellulose

fractions

processes

having

can

promising

abilities. When a sufficient amount of water is

properties to enter the market for value-added

added, the solvent system enters a so-called

acetate grade pulps.

Figure 8. Selective hemicellulose dissolution window of [emim][OAc] as a function of ionic liquid, water and pulp content as weight %. The selective dissolution window is highlighted dark blue (a). Molar mass distributions (b): of the initial birch kraft pulp, the separated cellulose fraction (blue), the precipitated hemicellulose fraction (red), and the calculated sum of the fractions (treatment, 15 wt % water, 60°C, 3 h; consistency, 10.5 wt %).

FUBIO JR2 PROGRAMME REPORT

4.5 Cellulase Modification of Cellulose in Ionic Liquid

DMP and [EMIM]AcO, two cellulose-dissolving ILs, were very basic in aqueous solution and, thus, the medium basicity appeared a plausible

Ionic liquids (ILs) dissolve cellulose. This

reason for the observed enzyme inactivity.

opens up new interesting opportunities for

Studies on enzymatic cellulose hydrolysis in

modifying

chemically

different basic solutions without IL, as well as

and

cellulose

enzymatically.

physically,

cellulose

studies with alkaline cellulases, did not, however,

modifications in IL solutions have so far

Enzymatic

support the theory of IL basicity being a major

not been studied significantly. The benefits

contributor to enzyme inactivation. On the other

of using enzyme catalysis include, e.g.,

hand, cellulase thermostability appeared to

mild reaction conditions leading to energy

correlate with higher hydrolytic performance in

savings and less product degradation, and

IL solutions. In the programme, novel cellulose-

highly specific reactions meaning fewer by-

dissolving and distillable ILs based on the TMG

products as compared to chemical reactions.

and DBN superbases were developed. The

With different enzymes it could be possible to

cellulase-compatibility of these ILs was tested,

catalyse oxidation, hydrolysis, acylation and

but thee ILs were found not to offer any increased

other cellulose modifications in ILs. In FuBio

cellulase activity compared to other IL types.

JR2 WP2, enzyme work was concentrated on

Analysis of saccharide content in IL solutions

studying the action of glycosyl hydrolases,

was found to be difficult when developing a

mainly endoglucanases, in cellulose hydrolysis

capillary electrophoresis method for the analysis

in aqueous ILs. By designing functional

of oligosaccharides tolerating the presence of IL.

combinations of glycosyl hydrolases and ILs, new concepts can be considered for tailoring

Radiolabeled

pulp properties (e.g. controlling DP and

study their cellulose-binding capability in

cellulases

were

used

removing hemicelluloses) and for the total

IL solutions (Figure 9). The binding studies

hydrolysis of plant cell wall polysaccharides to

were done pairwise with intact cellulases

monosaccharides in the production of biofuels

and their core domains, i.e. cellulases lacking

and biochemicals.

a carbohydrate-binding module (CBM). The results clearly show the cellulose binding

Cellulases are severely inactivated by cellulose-

to be sensitive to IL presence. CBM binding

dissolving ILs. In this study, the reasons for

was found to be highly IL-sensitive, whereas

cellulase inactivation were studied in detail. At the

cellulose binding through the active site tunnel

beginning of the study, it was noticed that [DMIM]

in cellobiohydrolases was much less affected

Figure 9. Binding isotherms for Trichoderma reesei endoglucanase Cel5A (A), cellobiohydrolase Cel7A (B) and the core domain of Cel7A (C) in five different ionic liquid media.

FUBIO JR2 PROGRAMME REPORT

by ILs. Endoglucanases were found to be very

glycerol switchable ionic liquid (SIL) systems.

dependent on their CBM for cellulose-binding,

In addition to the experimental work, thermal

which translated into a high IL sensitivity.

separation processes for ionic liquid (IL) recycling in biomass fractionation processes

Although cellulases were generally inactivated

using ionic liquids as fractionating agents

in IL solutions, the IL [DMIM]DMP was found to

were modelled.

be stabilizing for cellulases during prolonged incubation

were

The Knudsen effusion apparatus is depicted

found to reduce the DP of partially dissolved

periods.

Endoglucanases

in Figure 10. Initial tests were carried out.

microcrystalline cellulose in 90% [DMIM]

The apparatus is effective for measuring

DMP, representing a new cellulase activity on

compounds with very low vapour pressures

dissolved, non-derivatized cellulose.

(e.g. aprotic ionic liquids).

4.6 Thermodynamics and Modelling of Ionic Liquid Distillation

The measurement results indicate that DILs can be distilled at pressures below 45 mbar without significant decomposition. Distillation at lower

The work done consisted of Knudsen effusion

pressures and temperatures decreased the

apparatus

pressure

decomposition of DILs. In addition, pure DBN

[DBNH]

was regenerated, possibly from hydrolysis

[CO2Et] and [DBNH][OAc] distillable ionic liquids

products of DBN, which may have an important

(DILs), distillation experiments of [DBNH]

role in improving process feasibility. In the

[OAc] + water mixture and phase equilibrium

distillation experiments, the DIL was purified

measurements and modelling of CO2 + DBU +

to 90 m-% purity, without further optimization.

construction,

measurements

vapour

[TMGH][CO2Et],

The structure of CO2 + DBU + glycerol SILs was highly dependent on the DBU:glycerol ratio. SIL systems were stable in the 30-80째C temperature range. Addition of water into the system caused formation of competing CO2 + DBU + H2O SIL.

Figure 10. Schematic of the Knudsen effusion apparatus: a) wide range gauge; b) turbo pump Edwards STPA 1303C; c) scroll pump XD510; d) gate valve; e) cold finger for liquid nitrogen; f) ball valve; g) air admittance valve; h) gas admittance valve; i) vacuum chamber; j) aluminium blocks (ovens); k) temperature panel Nokeval; l) PID temperature controllers; m) computer.

FUBIO JR2 PROGRAMME REPORT

For modelling the recovery processes of

were examined. Membrane filtration of these

ILs, three promising ILs having water as

ILs is challenging, mainly due to their high

the

[emim]

viscosity. This can be overcome either by using

[OAc]; 2) a distillable ionic liquid formed from

low-viscosity co-solvents, such as molecular

1,1,3,3-tetramethylguanidine

solvents

antisolvent

were

chosen: and

propanoic

(methanol,

ethanol,

isopropanol,

acid; 3) a switchable ionic liquid formed from

etc.), or by performing filtrations at elevated

1,8-diazabicyclo[5.4.0]undec-7-ene and butanol.

temperatures. As very high temperatures

The modelling of the chemical systems relied

cannot be used with polymeric membranes,

on various estimation methods for modelling

ceramic

physical property, VLE and energy variables. The

However, ceramic membranes offer restricted

simulated pressure levels and the presence of

cut-off options at the nanofiltration scale. After

reactions in the chemical systems indicate short-

identifying suitable membranes and proving

path distillation in the technical implementation

their usability with the ILs, the final step

of the recovery processes of ILs.

involved trials with real residue solutions of the

membranes

were

also

tested.

ILs. The NF270 nanofiltration membrane and

4.7 Membrane Purification of Ionic Liquids

TiO2 ceramic nanofiltration membranes were tested with real residues and the results were very positive: good retentions for sugar-like

The focus of this study was on the recovery

organics were gained with these membranes for

and recycling of Ionic Liquids (ILs) by pressure-

both ILs in the studied conditions (see Figure 11

driven membrane separation processes. ILs

below for [emim][DMP] residue). The separation

were used for processing whole wood. First,

processes can also be optimized for better

the filterability and tolerance of selected

performance through optimal combinations of

membranes towards [emim][DMP] (IL) and

parameters such as temperature, cross-flow

DBU-MEA-SO2 (Switchable Ionic Liquid, SIL)

velocity and pressure.

b) Figure 11. a) Flux of [emim][DMP]-Isopropanol (1:4) solution through the ceramic InoporÂŽultra TiO2 membrane (mean pore size 5 nm, cut-off 8500 g/mol) showing the retention of saccharides at different times during the test. Batch 2 L, Î&#x201D;p 3 bar, temperature 30Â°C, cross-flow velocity 0.8 m/s, filtration area 1040 cm2 and VRF = 2.0. b) The filter unit for high-pressure cross-flow filtrations showing the module for polymeric flat sheet membranes. Inset: module with ceramic membrane.

FUBIO JR2 PROGRAMME REPORT

5. Exploitation plan and impact of results Our academic understanding of the area

due to their relative novelty. Therefore, much

has developed to a very high level, and is

effort has been targeted at understanding

reflected in the quality of the publications

these enigmatic structures and the phenomena

produced.

have

that they present. To achieve future success in

been presented, with both SIL fractionation

this area, work should be focused on selected

and the IONCELL-P process representing

target processes and sufficient resources

highly promising methods of wood and pulp

for continued research should be continued

fractionation (respectively). Three new classes

as new unique effects and phenomena are

of recyclable ionic liquids, switchable (SILs),

constantly

distillable (DILs) and phase-separable (PSILs),

media that are not present or achievable with

are being developed, which should be placed

molecular solvents.

Several

new

processes

being

discovered

with

these

in their appropriate applications in future work. All three are known to dissolve cellulose.

Switchable ionic liquid (SIL) fractionation

SILs are best understood in regard to wood

and the IONCELL-P process offer interesting

fractionation to produce high-purity cellulose

avenues

through extraction of lignin and hemicellulose.

fractionation clearly needs further work to

DILs and PSILs are known superb solvents for

demonstrate full recyclability of the system,

cellulose, although their ability to fractionate

as this was only partly touched upon during

wood is less studied. Cellulase enzyme activity

the

is reduced in ionic liquids but not destroyed.

pulp quality will also likely emerge as a

Mechanistic understanding of this process

result of this development. The IONCELL-P

is being developed and further studies are

process, as the simplest process studied,

planned. Methodologies and equipment for

studying and modelling the thermodynamics of

techno-economic studies would be useful

ionic liquid recycling are also being developed,

to refine these processes further. To reduce

as are those for membrane purification of the

research costs and enable up-scaling, future

used ionic liquid. For those membranes that

programmes should establish protocols for

are stable in ionic liquids, unoptimized cross-

the recycling and reuse of ionic liquids under

flow nanofiltration of the used ionic liquid

study. Investment in equipment judiciously

demonstrated reasonable fluxes and good

located

saccharide retention. Important progress by

would facilitate this and the development of

international standards has been made in

competence in this area.

for

project.

already

future

development.

Improvements

quite

the

mature.

appropriate

SIL

recovered

detailed

departments

the area of the processing of lignocellulosics using ionic liquids, and the potential of this area of research is clear. Further academic understanding and process optimization are clearly needed to prove the use of ionic liquids for wood fractionation. In contrast to our understanding of molecular solvents, the area of ionic liquids is a highly demanding area with more complex chemistry

FUBIO JR2 PROGRAMME REPORT

6. Networking Close

different

work. These included Tom Welton and Jason

partners and international research groups

collaboration

between

the

Hallet from Imperial College, Seema Singh from

was encouraged during the project. Two

the Joint Bioenergy Institute, Roberto Rinaldi

international symposia were organized on the

from the Max Planck Institute for Coal Research,

topic of the work package. One was held in May

Joern Viell from AVT-Aachen and Martin Lawoko

2012 at Haikko Manor, Porvoo, and one in August

from the Wallenberg Wood Science Centre.

2013 at the University of Helsinki. Respected international researchers in the area of ionic

Table 1 shows both the partners and their role

liquids and biomass processing presented their

in the work package.

Table 1: Work package partners and their roles

Work package partners

Role of the participating organisation

Aalto University

(FPT) IONCELL-P Process, Homogeneous IL-aided

• Forest Products Technology (FPT)

fractionation,

• Biotechnology and Chemical

(BCT) Thermodynamics and Modelling of Ionic Liquid

Technology (BCT)

Distillation

Andritz

Industrial tutor

Lappeenranta University of

Membrane Purification of Ionic Liquids

Technology Metsä Fibre

Work Package Coordinator

Stora Enso

Industrial tutor

University of Helsinki

WP leader. Recyclable Ionic Liquid Design

UPM-Kymmene

Industrial tutor

VTT

Cellulase Modification of Cellulose in Ionic Liquids

Åbo Akademi University

Switchable Ionic Liquid Fractionation

FUBIO JR2 PROGRAMME REPORT

7. Publications Anugwom, I., Eta V., Mäki-Arvela, P., Virtanen,

Ebner, G., Vejdovszky, P., Wahlström, R., Su-

P., Hedenström, M., Hummel, M., Sixta, H. and

urnäkki, A., Schrems, M., Kosma, P., Rosenau,

Mikkola, J.-P. 2014. Switchable Ionic Liquids as

T. and Potthast, A. 2014. The effect of 1-ethyl-

Delignification Solvents for Lignocellulosic Ma-

3-methylimidazolium acetate on the enzymat-

terials. ChemSusChem 7, 1170-1176.

ic degradation of cellulose. Journal of Molecular Catalysis B: Enzymatic 99, 121-129.

Anugwom, I., Eta, V., Mäki-Arvela, P., Virtanen, P., Hedenström, M., Ma, Y., Hummel,

Eta, V., Anugwom, I., Virtanen, P., Eränen, K.,

M., Sixta, H. and Mikkola, J.-P. 2014. Towards

Mäki-Arvela, P. and Mikkola, J.-P. 2014. Loop

optimal selective fractionation for Nordic

vs. batch reactor setups in the fractionation

woody biomass using Novel Amine–Organ-

of birch chips using switchable ionic liquids.

ic Superbase derived Switchable Ionic Liquid

Chemical Engineering Science 238, 242-248.

(SIL). Manuscript Submitted. Eta, V., Anugwom, I., Virtanen, P., Mäki-Arvela, Anugwom, I., Eta, V., Mäki-Arvela, P., Vir-

P. and Mikkola, J.-P. 2014. Enhanced mass trans-

tanen, P., Lahtinen, M. and Mikkola, J.-P. 2014.

fer upon switchable ionic liquid mediated wood

The composition and crystallinity of birch

fractionation. Industrial Crops & Products 55,

chips (Betula pendula) upon 'DBU-DEA-CO2-

109-115.

SIL' alkanol amine - organic super base - derived Switchable Ionic Liquid (SIL) treatment.

Froschauer, C., Hummel, M., Iakovlev, M., Ro-

Green Processing & Synthesis 3, 147-154.

selli, A., Schottenberger, H. and Sixta, H. 2013. Separation of Hemicellulose and Cellulose from

Anugwom, I., Mäki-Arvela, P., Virtanen, P.,

Wood Pulp by Means of Ionic Liquid/Cosolvent

Damlin, P., Sjöholm, R. and Mikkola, J.-P. 2011.

Systems. Biomacromolecules 14, 1741-1750.

Switchable Ionic liquids (SILs) based on glycerol and acid gases. RSC Advances 1, 452-457.

García, V., Valkama, H., Sliz, R., King, A. W. T., Myllylä, R., Kilpeläinen, I. and Keiski, R. L.

Anugwom,

I.,

Mäki-Arvela,

P.,

Virtanen,

2013. Pervaporation recovery of [amim]Cl dur-

P., Willför, S., Sjöholm, R. and Mikkola, J.-

ing wood dissolution; effect of [amim]Cl prop-

P. 2011. Treating birch wood with a switchable

erties on the membrane performance. Journal

1,8-diazabicyclo[5.4.0]-undec-7-ene-glycerol car-

of Membrane Science 444, 9-15.

bonate ionic liquid. Holzforschung 66, 809-815. Hauru, L. K. J., Hummel, M., King, A. W. T., Anugwom, I., Mäki-Arvela, P., Virtanen, P.,

Kilpeläinen, I. and Sixta, H. 2012. New insights

Willför, S., Sjöholm, R. and Mikkola, J.-P. 2012.

into the requirements for dissolution of cellu-

Selective extraction of hemicellulose from

lose into ionic liquids. Biomacromolecules 13,

spruce with Switchable Ionic liquids. Carbohy-

2896−2905.

drate Polymers 87, 2005-2011.

FUBIO JR2 PROGRAMME REPORT

Hauru, L. K. J., Ma, Y., Hummel, M., Alekhi-

King, A. W. T., Parviainen, A., Karhunen, P.,

na, M., King, A. W. T., Kilpeläinen, I. A., Pent-

Matikainen, J., Hauru, L. K. J., Sixta, H. and

tilä, P. A., Serimaa, R. and Sixta, H. 2013. En-

Kilpeläinen, I. 2012. Relative and inherent nu-

hancement of ionic liquid-aided fractionation

cleophilicity/basicity/diffusivity of imidazoli-

of birchwood. Part 1: Autohydrolysis pretreat-

um-based ionic liquids – the implications for

ment. RSC Advances 16365-16373.

lignocellulose processing applications. RSC Advances 2, 8020-8026.

Holding, A. J., Heikkilä, M., Kilpeläinen, I. and King, A. W. T. 2014. Phase-separable ionic liq-

King, A. W. T., Xie, H., Fiskari, J. and Kilpeläin-

uids and electrolytes for biomass processing.

en, I. Reduction of biomass recalcitrance via bi-

ChemSusChem 9, 1565-1577.

omass pre-treatments, Chapter 7; Materials for Biofuels, World Scientific Publishing, Ed. Arthur

Hummel, M., Froschauer, C., Laus, G., Röder,

Ragauskas, 2013. (ISBN: 978-981-4513-27-2).

T., Kopacka, H., Hauru, L. K. J., Weber, H. K., Sixta H. and Schottenberger H. 2011. Dimethyl

Kyllönen, L., Parviainen, A., Deb, S., Lawoko,

phosphorothioate and phosphoroselenoate

M., Gorlov, M., Kilpeläinen, I. and King, A. W. T.

ionic liquids as solvent media for cellulosic ma-

2013. On the solubility of wood in ionic liquids.

terials. Green Chemistry 13, 2507-2517.

Green Chemistry 15, 2374-2378.

Hyväkkö, U., King, A. W. T. and Kilpeläinen, I.

Leskinen, T., King, A. W. T. and Argyropou-

2014. Extraction of wheat straw with aqueous

los, D. S. Fractionation of lignocellulosic ma-

tetra-n-butylphosphonium hydroxide. BioRe-

terials with ionic liquids; Production of biofuels

sources 9, 1565-1577.

and chemicals with ionic liquids, Springer Book Series - Biofuels and Biorefineries, Ed. Zhen

Hyvärinen, S., Mikkola, J.-P., Murzin, D. Yu.,

Fang, 2013. (ISBN 978-94-007-7710-1).

Vaher, M., Kaljurand, M. and Koel, M. 2014. Sugars and sugar derivatives in ionic liquid

Leskinen, T., King, A. W. T., Kilpeläinen, I. and

media obtained from lignocellulosic biomass:

Argyropoulos, D. S. 2013. Fractionation of lig-

Comparison of capillary electrophoresis and

nocellulosic materials using ionic liquids: Part

chromatographic analysis. Catalysis Today

2. Effect of particle size on mechanisms of

223, 18-24.

fractionation. Industrial & Engineering Chemistry Research 52, 3958-3966.

King, A. W. T., Asikkala, J., Mutikainen, I. and Kilpeläinen, I. 2011. Distillable Acid-Base Con-

Mikkola, S-K, Robciuc, A., Lokajova, J., Hold-

jugate Ionic Liquids for Cellulose Dissolution

ing, A. J., Lämmerhofer, M., Kilpeläinen, I.,

and Processing. Angewandte Chemie Interna-

Holopainen, J. M., King, A. W. T. and Wied-

tional Edition 50, 6301-6305.

mer, S. K. 2014. Impact of amidinium, imidazolium and phosphonium based ionic liquids on biological cells and liposomes. Submitted to Green Chemistry.

FUBIO JR2 PROGRAMME REPORT

Ostonen, A., Sapei, E., Uusi-Kyyny, P., Kle-

Wahlström, R., Rovio, S. and Suurnäkki, A.

melä, A. and Alopaeus, V. 2014. Measure-

2012. Partial Enzymatic Hydrolysis of Micro-

ments and modeling of CO2 solubility in 1,8

crystalline Cellulose in Ionic Liquids by Tricho-

diazabicyclo-[5.4.0]-undec-7-ene

derma reesei Endoglucanases RSC Advances

glycerol

solutions. Fluid Phase Equilibria 347, 25-36.

2, 4472-4480.

Parviainen, A., King, A. W. T., Mutikainen, I.,

Wahlström, R., Rovio, S. and Suurnäkki, A.

Hummel, M., Selg, C., Hauru, L. K. J., Sixta, H.

2013. Analysis of Mono- and Oligo-saccharides

and Kilpeläinen, I. 2013. Predicting cellulose

in Ionic Liquid Containing Matrices. Carbohy-

solvating capabilities of acid-base conjugate

drate Research 373, 42-51.

ionic liquids. ChemSusChem 6, 2161-2169. Rauhala, T., King, A. W. T., Zuckerstatter, G., Suuronen, S. and Sixta, H. 2011. Effect of autohydrolysis on the lignin structure and the kinetics of delignification of birch wood, Nordic Pulp & Paper Research Journal 26, 386-391. Roselli, A., Hummel, M., Monshizadeh, A., Maloney, T. and Sixta, H. 2014. Ionic liquid extraction method for upgrading eucalyptus kraft pulp to high purity dissolving pulp. Submitted to Cellulose. Stépán, A. M., King, A. W. T., Kakko, T., Toriz, G., Kilpeläinen, I. and Gatenholm, P. 2013. Fast and highly efficient acetylation of xylans in ionic liquid systems. Cellulose 20, 2813-2824. Wahlström, R., King, A. W. T., Parviainen, A., Kruus, K. and Suurnäkki, A. 2013. Cellulose hydrolysis with thermo- and alkali-tolerant cellulases in cellulose-dissolving superbase ionic liquids. RSC Advances 3, 20001-20009. Wahlström, R., Rahikainen, J., Kruus, K. and Suurnäkki, A. 2014. Cellulose hydrolysis and binding with Trichoderma reesei Cel5A and Cel7A and their core domains in ionic liquid solutions, Biotechnology & Bioengineering 111, 726-733.

FUBIO JR2 PROGRAMME REPORT

HYDROXY ACIDS (AND OTHER ACIDS) FROM BLACK LIQUOR ADVANCED SEPARATION TECHNOLOGIES POLYMERIZATION OF HYDROXY ACIDS BIOTECHNICAL PRODUCTION OF GLYCOLIC ACID

CONTACT PERSON – Work Package 6 leader Jarmo Ropponen, jarmo.ropponen@vtt.fi Hycail: Svante Wahlbeck Kemira: Jukka Hietala Metsä Fibre: Ismo Reilama Lappeenranta University of Technology: Sanna Hellstén, Mari Kallioinen, Jussi Lahti, Mika Mänttäri, Tuomo Sainio University of Helsinki: Sari Rautiainen, Timo Repo University of Jyväskylä: Raimo Álen, Pauli Moilanen UPM-Kymmene: Päivi Varvemaa VTT Technical Research Centre of Finland: Thomas Gädda, Sakari Kaijaluoto, Katariina Kemppainen, Outi Koivistoinen, Klaus Niemelä, Minni Pirttimaa, Peter Richard

FUBIO JR2 PROGRAMME REPORT

ABSTRACT

The purpose of this study was to develop technologies and competences to recover hydroxy acids from black liquor and produce glycolic acid biotechnically from sugars. A novel multistep separation process for recovering hydroxy acids from black liquor, combining membrane filtration, chromatographic separation and electrodialysis, was developed. Further polymerization of the hydroxy acids was also conducted to evaluate their properties as value-added products. The results suggest that in the demonstrated process the neutralization of black liquor is not required, and that the purity of the end product is suitable for polymerization. In addition, the study demonstrates for the first time the conversion of purified hydroxy acid mixtures obtained from black liquor to polymeric material. Furthermore, production of 17 g/l of glycolic acid was achieved by fermentation of the engineered Kluyveromyces lactis strain. Development of bioreactor cultures and the selection of a suitable yeast host led to improvements in production levels that demonstrate technical feasibility. The results identify black liquor as an untapped source of hydroxy acids which can be further developed into value-added products.

Keywords: hydroxy acids, separation, polymerization, biotechnical production

FUBIO JR2 PROGRAMME REPORT

1. Background

chromatography, membrane

and

processes steps.

combination

with

precipitation-

Globally, more than 140 million tonnes of wood

crystallization

kraft pulp and 20 million tonnes of non-wood

was made in each of these areas, resulting

kraft and soda pulps are produced each year.

in a number of potential process concepts

Only a fraction of the dissolved organic matter

for further optimization and development.

originating from this production – including

In order to achieve reasonable amounts of

tall oil (1.4 million tonnes), turpentine (200 000

hydroxy acids to enable practical application

tonnes) and kraft and soda lignin (100 000

evaluations, efforts were focused on developing

tonnes) – is currently isolated as pulping by-

a multistep separation and purification process

products for chemical or material applications.

encompassing

The spent cooking liquor from kraft pulping, or

purification methods.

all

Significant

the

progress

abovementioned

‘black liquor’, consists mainly of lignin and wood extractives, but also contains salts of hydroxy carboxylic acids, which are formed from wood

2. Objectives

carbohydrates in alkaline conditions during pulping. All black liquors contain varying

The main objective was to design a novel

amounts of glycolic, lactic, 2-hydroxybutanoic,

value chain based on hydroxy acids separated

2,5-di-hydroxypentanoic, xyloisosaccharinic,

from black liquor or biotechnically produced

and glucoisosaccharinic acids as the main

from sugars. These hydroxy acids would

hydroxy acids, in addition to numerous minor

be converted into novel biopolymers and

ones. The formation of hydroxy acids may

developed and tested for the technologies

account for up to 10–15% of wood raw material

needed to enable such a value chain in reality.

consumption in pulping. Their isolation as new

The specific aims were to develop:

pulping by-products has not been realized at the mill scale to date due to a number of technical challenges as well as limited markets for many compounds. The annual production of these hydroxy acids in kraft pulping is approximately 6 million tonnes in Europe

• Concept for the separation of organic acids from black liquor • Fermentation-based technology for the production of glycolic acid • Potential applications for these organic acids

alone, representing a vast underutilized raw material source. Hydroxy acids are building block chemicals which could be widely utilized

3. Research approaches

in the synthesis of a range of chemicals and polymeric materials as replacements for

As there were no existing feasible separation

fossil-derived materials. Potential spearhead

processes for the recovery and purification

applications include biodegradable plastics,

of hydroxy carboxylic acids from black liquor

packaging films, adhesives and cosmetics.

to serve as a starting point, the research approach in process development was strongly

Most previous studies addressing the isolation

experimental in nature. It was concluded early

of hydroxy acids from black liquors deal

on that a multistage separation process will be

with isolation in small volumes for analytical

needed due to the complexity of the feedstock

purposes. In the FuBio programme, three

and the high purity requirements of the final

approaches for larger-scale isolation of hydroxy

product. The majority of process development

acids

was conducted using authentic soda black

were

investigated:

electrodialysis,

FUBIO JR2 PROGRAMME REPORT

liquor instead of kraft black liquor mainly for

4. Results

safety reasons. The selection of ultrafiltration modules

and

membranes,

however,

was

carried out with kraft black liquor. Experiments with synthetic solutions were also carried out

4.1 Separation process for recovery and purification of organic acids from black liquor

to investigate the most relevant separation mechanisms in more detail.

A process sequence consisting of ultrafiltration, size-exclusion chromatography, ion exchange,

Both hardwood (HW) and softwood (SW) soda

adsorption, and evaporation was successfully

black liquors were used. The main differences

implemented at laboratory scale (Figure 1) to

in the acid compositions of HW and SW

recover and purify a mixture of hydroxy acids

soda black liquors are the larger amount of

from black liquor. The purpose of the ultrafiltration

glucoisosaccharinic acid (GISA) in SW black liquor

stage was to remove the majority of lignin and

and the higher concentrations of 2-hydroxy

thus facilitate the subsequent chromatographic

butanoic acid and acetic acid in HW black liquor.

step, in which the carboxylic acids and NaOH were separated from each other. The acids

These hydroxy acids offer many potential

were liberated using an ion exchange resin and

applications, e.g., as polymer precursors. As

concentrated by evaporation. Evaporation also

the separated hydroxy acids were obtained in

effectively eliminated volatile acids from the

acid form, polymerisations were carried out

hydroxy acid fraction. Finally, residual lignin was

using condensation polymerisation to obtain

removed by adsorption. Mixtures of hydroxy acids

polymeric materials. In addition, ring-opening

were obtained in high purity both from softwood

polymerisations were used to polymerize

and hardwood soda black liquors. An example of

glycolide produced from glycolic acid and

concentrations of individual acids and lignin after

benchmarked against commercial glycolide-

each process step is displayed in Figure 2.

based

polyglycolic

acid.

Moreover,

the

development of glycolic acid production based on yeast fermentation was continued from the first phase of the programme.

Figure 1. Separation process for recovering hydroxy carboxylic acids, volatile acids, and NaOH from black liquor.

FUBIO JR2 PROGRAMME REPORT

Figure 2. Typical average compositions of the hydroxy acid containing streams after each process step.

Removal of lignin and recovery of hydroxy acid

that the permeate of UP010 requires excessive

salts from soda black liquor

washing of the chromatographic column, and

Based on preliminary experiments, UP010 and

therefore the 1 kDa NP010 is recommended for

NP010 membranes with cut-off values of 10 kDa

ultrafiltration.

and 1 kDa, respectively, were chosen for more detailed studies. Filtration experiments were

The concentrations of acids in the ultrafiltration

carried out with a rectangular cross-flow module

permeates are shown in Table 1. It was found

at a constant permeate flux of 70 kg/(m2h) and 40

that the hydroxy acids were well recovered in

kg/(m2h) until the pressure needed for constant

the permeate. For instance, more than 90%

flux increased to a predefined upper limiting value

of the isosaccharinic acids (softwood soda

(10 bar with UP010, 20 bar with NP010). With both

cooking liquor) were in the permeate stream (1

membranes, lower pressures were needed for

kDa, NP010 membrane) at a volume reduction

constant flux with softwood soda cooking liquor

of about 80%. Generally, acids retention was

than with hardwood cooking liquor.

very low or even negative. Due to the analytical uncertainties,

In the filtration of hardwood soda black liquor,

small

differences

acid

concentrations are not meaningful.

lignin concentration decreased from 79.5 g/L to 16.2 g/L when NP010 membrane was used

A significant purification of acids was achieved.

and to 32.6 g/L when using UP010 membrane.

For instance, the purity (based on total organic

The dry solids content decreased from 14.1

matter) of isosaccharinic acids increased from

wt-% to 9.0 wt-% using NP010 and to 10.4

20% to 40% when the softwood soda cooking

wt-% using UP010. For the softwood soda

liquor was filtered (1 kDa membrane). Purity

black liquor, the amount of lignin decreased

increase was caused by removal of lignin and

from 72 g/L to 14.6 g/L using NP010 membrane

probably also hemicelluloses. Only about 10%

and to 22.5 g/L using UP010. The amount of

of inorganic compounds (NaOH) were retained

dry solids decreased from 14.0 wt-% to 10.8

by the membrane.

wt-% with NP010 and 10.3 wt-% with UP010. Subsequent chromatographic tests confirmed

FUBIO JR2 PROGRAMME REPORT

Table 1. Concentrations of carboxylic acids based on CE analysis in the feed and in the ultrafiltration permeates of NP010 and UP010 membranes in ultrafiltration of hardwood (HW) and softwood (SW) soda black liquors. XISA, g/L

GISA, g/L

2,5DHPA g/L

2-OHLactic butanoic acid, acid, g/L g/L

Glycolic acid, g/L

Oxalic acid, g/L

Acetic acid, g/L

Formic acid, g/L

Total, g/L

HW Feed

3.2

7.3

1.1

4.0

2.8

1.2

0.5

13.7

5.4

39.2

NP010

2.8

6.8

0.9

4.4

1.8

1.2

0.3

13.6

4.7

36.6

UP010

4.5

6.0

0.8

4.0

2.5

1.4

0.5

16.0

6.0

41.7

SW Feed

3.7

15.7

1.3

4.2

1.9

0.5

4.4

5.4

38.4

NP010

4.4

18.3

1.1

1.3

0.0

1.7

0.7

1.6

5.9

35.1

UP010

4.9

18.7

1.3

1.4

4.8

1.9

0.7

5.2

5.9

44.6

Chromatographic separation of hydroxy acids

overlaid on a photograph of the sample bottles

and sodium hydroxide

in Figure 3. NaOH elutes between approximately

The key step in the multistep separation

0.8 and 1.0 bed volume (fractions 7 and 8),

process developed here is chromatographic

whereas the hydroxy acids elute between 0.5

separation of hydroxy acids from the inorganic

and 0.8 bed volume (fractions 3 to 6).

compounds in black liquor. As no method was available to conduct such a separation in

Some fractionation of the acids by size-

alkaline conditions, considerable efforts were

exclusion occurred in the Sephadex column,

invested in finding a suitable chromatographic

although this was not the main objective of

separation material for this purpose.

this separation step. Isosaccharinic acids elute rapidly due to their large molecular size, and

After testing six different types of separation

therefore the largest concentrations were

media and several ionic forms of various ion

observed in fractions 3 and 4 obtained from

exchange resins, Sephadex Gâ&#x20AC;&#x201C;10 size-exclusion

hardwood soda black liquor. Interestingly,

gel was found to be suitable for separating

dicarboxylic acids were also enriched in

hydroxy acids in the form of sodium salts from

fractions 3 and 4. Smaller 2-hydroxy butanoic

sodium hydroxide. A typical chromatogram, i.e.

acid was accumulated in fractions 5 and 6.

concentration history at the column outlet, from

GC/MS analysis also revealed the presence of

the separation of hardwood soda black liquor is

polar aromatic acids in fraction 6. Highest acid

Figure 3. Chromatographic separation of hydroxy acids and sodium hydroxide from ultrafiltration permeate (NP010) of hardwood soda black liquor using Sephadex Gâ&#x20AC;&#x201C;10.

FUBIO JR2 PROGRAMME REPORT

concentrations were found in fractions 4 and

of hydroxy acids present. Injection volumes

5, while the concentration of acids in fraction

up to 24% were found to provide satisfactory

6 was very low. The total recovery yield of

purity of the hydroxy acids with respect to

hydroxy acids was 95% with the fractionation

sodium hydroxide. However, the concentration

scheme chosen. Similar results were also

of lignin in the hydroxy acid fraction increases

obtained for softwood soda black liquors.

with increasing injection volume.

It was further found that the recovery of

A series of 44 separation runs with hardwood

hydroxy acids from soda black liquor is possible

soda black liquor were conducted in the

also when the feed is concentrated to 25

Sephadex Gâ&#x20AC;&#x201C;10 column to determine whether

wt-% dry solids. This is attractive, as a higher

the material is fouled by lignin. No shifts in

feed concentration markedly increases the

the retention times or concentration profiles

productivity of the process. Moreover, good

of the hydroxy acids and sodium hydroxide

separation was achieved with injection volumes

were observed in the conductivity and RI-

significantly larger than 8% of bed volume

signals, indicating that fouling does not affect

(Figure 4). This is because the elution of sodium

the separation of hydroxy acids and NaOH.

hydroxide slows down with increasing amount

On the other hand, the amount of lignin in the

Figure 4. Effect of injection volume on the separation of hydroxy acids from hardwood soda black liquor using Sephadex Gâ&#x20AC;&#x201C;10.

FUBIO JR2 PROGRAMME REPORT

hydroxy acid fraction doubled during the 44

the pulp mill, this stream must be treated

consecutive cycles. This does not necessarily

separately, e.g. by electrodialysis.

pose major problems, as the residual lignin can be effectively removed in the subsequent

Removal of residual lignin by adsorption

process steps.

Most of the lignin was precipitated from the hydroxy acid fraction in the ion-exchange

The

the

stage. For example, from the hardwood

manufacturer for Sephadex G–10 is 2 to 13.

range

recommended

soda black liquor the average lignin content

Therefore, its long-term stability in highly

decreased from approximately 3 g/L to less

alkaline conditions and elevated temperature

than 1 g/L. Removal of residual lignin was done

was investigated. Moisture retention capacity

by adsorption on a neutral hydrophobic polymer

is often used as a measure of effective cross-

resin (XAD–16). After adsorption treatment, the

link density in polymer gels. The changes in

lignin contents of the hardwood and softwood

the moisture retention capacity of Sephadex

soda black liquors were approximately 0.2 g/L

G–10 during 4 weeks exposure to 1 M NaOH at

and 0.1 g/L.

60 oC were below the experimental accuracy, which suggests that its cross-link density was

No significant losses of hydroxy acids were

not significantly reduced. Nevertheless, two

observed during adsorptive lignin removal. The

unidentified compounds were observed in

yield of acids in the lignin removal step was

HPLC analyses of liquid phase samples after

96%. XAD–16 was thus concluded to be quite

aging of Sephadex G–10 in 1 M NaOH.

selective towards lignin over hydroxy acids.

Liberation of acids by ion exchange

Concentration by evaporation

Ion exchange with strong acid cation exchange

The hydroxy acid fractions were concentrated

resins was found to be suitable for liberation

by evaporation at reduced pressure after

of the acids (i.e. replacement of Na+ with H+).

the adsorption treatment step. The relative

The fractions obtained in the chromatographic

amount of volatile acids was reduced by

separation step were fed through an ion

40–70%. The final purity of hydroxy acids

exchange column packed with CS11GC resin in

was 38–91%. If higher purity is required

H+ form. The pH of the solutions collected at the

the product can be purified, for example by

column outlet after ion exchange ranged from 1.6

crystallization or chromatographic separation.

to 2.9. The conversion of sodium salts to acid form

The concentrations of the main components in

was 95–100% for all fractions. No loss of acids

the final products are presented in Table 2. In

due to adsorption to the stationary phase was

addition, GC/MS analysis revealed the presence

observed. The acid composition was unchanged,

of some glycerol and sugars (not shown).

with the exception that GISA is converted to its lactone form due to the decrease in pH.

The final concentration could also be performed using membrane filtration, provided that the

An aspect that deserves attention when

membrane can withstand acidic conditions

applying ion exchange for liberation of the

(initial pH 2, final pH approximately 1). Using

acids is the formation of sodium salts during

a suitable membrane, small volatile acids

regeneration of the resin. For example, if

could be separated in the concentration step.

sulphuric acid is used for regeneration, a

Concentration by membrane filtration is most

sodium sulphate stream is produced. To avoid

probably not feasible before liberation of the

disturbing the sodium–sulphur balance of

acids due to high lignin solubility at alkaline pH.

FUBIO JR2 PROGRAMME REPORT

Further results on recovery and purification of

Recovery and liberation of carboxylic acids

hydroxy acids

by electrodialysis. Electrodialysis (ED) was

Further findings regarding the recovery and

investigated as an alternative method for

purification of hydroxy acids from black liquor

recovery and purification of hydroxy acids from

are described briefly below.

black liquor. It was noted that electrodialysis membranes were chemically not very durable

Recommended ultrafiltration module. In order

against black liquor at any concentration,

to select an appropriate type of membrane

even when the solution pH was decreased

module for further studies, low shear rate (DSS)

by carbonation. This was mainly due to the

and high shear rate (CR, VSEP) membrane

precipitation of lignin (and partly extractives)

filtration modules were tested. 10 wt-% kraft

on the membrane surface, which rapidly led to

black liquor (UPM Kaukas mill) was successfully

permanent losses in ion exchange efficiency of

concentrated to about 90% volume reduction

the membrane. In a typical case, the efficiency

with both low and high shear rate modules

for the first 4 hours was 0.25 kWh/mol and

using NP010 (1 kDa) membrane. The flux of the

during 4-9 hours 0.42 kWh/mol.

CR-filter was significantly higher than that of the VSEP-filter or the DSS-filter. In the CR-filter,

Electrodialysis was also tested as an alternative

the average flux was over 130 kg/(m2h) up to

for ion exchange in liberation of the acids.

a volume reduction of 80%. When the volume

A fraction of hydroxy acids obtained by

reduction exceeded 75% the flux started to

ultrafiltration and chromatography was used as

decrease very rapidly from 100 kg/(m2h) to 5 kg/

the feed. The fraction used as feed contained

(m2h) at a volume reduction of 90%. It was thus

approximately 3.3 g/L of lignin.

concluded that the CR-filters with a rotating blade near the membrane surface were the

In the first phase, the fraction was processed

best choice for ultrafiltration of black liquor.

by ED. After this experiment the membranes

Table 2. Concentrations of lignin and carboxylic acids in the concentrated product fractions recovered and purified from hardwood (HW) and softwood (SW) soda black liquors. Fraction

Mass

Lignin,

XISA,

GISA,

2,5-

2-OH-

Lactic

Glycolic

Oxalic

Acetic

Formic

reducti-

g/L

DHPA,

butanoic

acid,

g/L

acid,

g/L

on, wt-%

g/L

HW black liquor 3

1.21

6.2

7.4

0.00

0.4

1.0

3.0

2.5

0.0

1.41

46.2

22.9

0.00

10.2

7.9

9.7

1.5

23.3

3.9

2.13

5.0

2.2

0.00

16.3

4.9

3.5

0.0

20.9

10.6

1.92

0.00

4.1

0.6

0.3

0.5

2.8

1.03

5.2

45.8

0.00

1.7

2.9

3.8

3.6

0.7

SW black liquor 1

53.4

148

4.38

7.9

34.1

24.0

0.0

13.0

9.2

2.49

8.4

2.0

2.20

5.6

8.5

5.0

0.0

7.0

15.2

FUBIO JR2 PROGRAMME REPORT

were kept in the initial fraction and, after two

of pH on the retention of acid compounds was

weeks, the same membranes were used again

investigated by increasing the pH of the feed

for ED. The same procedure was repeated

liquor stepwise from pH 2.3 to 12 with NaOH.

after six weeks. As can be seen from Table 3, efficiency clearly dropped already after 2 weeks

It was found that pH had a marked effect

from 0.23 kWh/mol to 0.29 kWh/mol. After six

on permeate flux and retention, and thus

weeks, the efficiency was 0.28 kWh/mol. This

on hydroxy acid separation. Higher pH can

efficiency deterioration was probably due to

either increase retention, as with sulphate and

the conditions used in the durability tests, i.e.,

xyloisosaccharinic acid XISA, or decrease it, as

when bipolar membranes were soaked in the

with formic acid (Figure 5). Nanofiltration can

hydroxy acid fraction also its anionic side was

thus be used to fractionate organic acids into

influenced, which would not be the case under

two fractions that are rich in different hydroxy

normal operating conditions.

(or volatile) acids. Acetic and formic acids permeated the NF membrane especially at high

Membranes were visually estimated after 2 and

pH, and isosaccharinic acids and sulphate ions

6 weeks of soaking and no visual changes were

were concentrated in the retentate stream.

observed. After ED runs a thin layer of lignin

Nanofiltration at pH 2.3 led to a concentrated

was precipitated on the surface of the bipolar

stream with an acids content of about 80% of

membraneâ&#x20AC;&#x2122;s cationic side. This layer could be

total organic matter. Furthermore, GISA purity

rinsed off with water. The results indicate that

in the concentrate was almost 40% based on

at least 90% of initial lignin is removable from

total organic matter.

the black liquor by ED treatment. Fractionation

hydroxy

acids

4.2 Polymeric materials from fractionated black liquor

nanofiltration. The use of nanofiltration to separate carboxylic acids from each other was

Fractionated black liquor samples for the

demonstrated using Desal-5 DK membranes.

polymerization

A kraft black liquor that was pre-treated by

partners in the project. One fraction (HW1) from

cooling crystallization and acid precipitation to

hardwood black liquor and three fractions (SW1,

remove lignin was used as the feed. The effect

SW2, and SW3) from softwood black liquor

were

obtained

from

the

Table 3. Results obtained from the Lappeenranta fraction (as such and after the ED experiments with varying treatment time).

Parameter

Fresh

2 weeks

6 weeks

Hydroxy acids (g/L)

19.6

20.1

Efficiency after 1 h

0.23

0.29

0.28

2.37

2.23

2.07

Lignin (at 280 nm; alkali so- 0.36

0.26

0.24

1.09

1.11

0.19

0.01

(kWh/mol) pH after ED luble) (g/L) Lignin (at 205 nm; acid so- 1.36 luble) (g/L) Residual sodium (g/L)

0.30

FUBIO JR2 PROGRAMME REPORT

Figure 5. Effect of pH on the retention of various organic acids during nanofiltration with Desal-5 DK membrane (70 °C, 25 bar).

were used. The fractions were purified by the

a catalyst. Temperature of the reaction was

abovementioned combination of ultrafiltration

increased gradually from 130 °C to 160 °C while

and

Two

maintaining a pressure of 500 mbar. Pressure

samples of black liquor were purified by

was then gradually decreased to 30 mbar. Once

electrodialysis (ED). The black liquors originated

the target pressure was achieved, the reaction

from soda-AQ pulping. The compositions of the

was allowed to continue for 24 h. Polymeric

various fractions were calculated from results

materials were successfully obtained from all of

obtained by capillary electrophoresis (Table 4).

the fractions by condensation polymerization.

size-exclusion

chromatography.

The distillate obtained from the dilute hydroxy The dilute aqueous fractions of black liquor were

acid mixtures was analysed to determine how

polymerized by condensation polymerization.

the polymerization proceeds. The distillates

A predetermined reaction volume was placed

analysed were shown to contain in all cases

into a suitable round-bottomed flask equipped

formic and acetic acid. Glycolic, lactic and

with a Teflon® covered magnetic stirring bar

2-hydroxybutyric acids were also detected in

and a distillation head. Sn(Oct)2 (0.1 wt-%

some cases.

based on analysed acid content) was used as Table 4. Compositions [g/L] and molar ratios (χ) of black liquor fractions analysed by capillary electrophoresis.

2HBA

2,5-DHPA

XISA

g/L

GISA g/L

(χOA)

(χFA)

(χAA)

(χGA)

(χLA)

(χ2HBA)

(χDHPA)

(χXISA)

(χGISA)

HW1

1.5 (1.0)

3.9 (5.2)

23.3 (23.9)

9.7 (7.8)

7.9 (5.4)

10.2 (6.1)

SW1

3.8 (2.8)

0.7 (1.0)

3.6 (4.0)

2.9 (2.5)

1.7 (1.2)

46.2 (18.9)

22.9 (8.5)

5.2 (2.3)

45.8 (18.4) 148.1 (27.8)

SW2

9.2 (6.2)

13.0 (6.8)

24.0 (9.8)

34.1 (11.8)

7.9 (2.4)

4.4 (1.0)

53.4 (11.1)

SW3

15.2 (27.7)

7.0 (9.8)

5.0 (5.5)

8.5 (7.9)

5.6 (4.5)

2.20 (1.4)

8.4 (4.7)

2.0 (1.0)

SODAAQ1

0.4 (3.2)

0.9 (6.1)

0.3 (1.8)

0.5 (2.2)

0.2 (1.0)

1.2 (3.5)

3.0 (6.7)

SODAAQ2

2.0 (14.8)

1.9 (10.5)

0.9 (4.1)

1.1 (4.3)

0.6 (1.8)

1.6 (1.0)

5.0 (10.1)

0.4 (1.0)

FUBIO JR2 PROGRAMME REPORT

All products had the physical appearance of

Glycolide production and ring-opening

solid materials or highly viscous fluids. This is

polymerization of glycolide

taken as primary evidence for the formation

In addition, a method for glycolide production

of polymers. Similarly, the thermal properties

by polycondensation of glycolic acid using

of the samples suggest that polymers were

a catalyst under reduced pressure suitable

obtained. The Tgs varied between -1 and 49

for large-scale production was successfully

째C, depending on the sample. The reason for

developed. The production of glycolide using

this variance is not understood and further

the chosen distillation method produced a yield

experiments should be done with larger

of only 20% glycolide from the polycondensate

amounts of polymer formed. The properties

of glycolic acid. Using a catalyst, glycolide

reaction

formation reached 100 g/kg polycondensate/

volumes, yields, theoretical yields calculated,

hour. However, the simultaneous formation

thermal properties and molecular weights are

of insoluble residue was a main concern for

presented in Table 5.

the development of an industrial continuous

the

characterized

products,

production process based on the studied The obtained polymer yields were generally

method. The purity of the produced glycolide was

higher than the calculated yield based on

comparable to commercial polymerization grade

the amount of acids. This indicates that the

glycolide. Collecting the distillate of glycolide in a

condensation is incomplete and there is still

nonpolar solvent and re-crystallization yields a

unreacted

result

purity of 99%, which is suitable for production of

was expected as the OH/COOH ratios are not

high molecular weight polymers. Polymerization

even. The polymers obtained were found to

of high molecular weight polyglycolic acid

be relatively poorly soluble in most common

(PGA) was demonstrated using ring-opening

organic solvents. The polymers were insoluble in

polymerization in the melt (0.1 wt-% SnOct,

chlorinated solvents, hydrocarbons and alcohols.

250째C, 4h). The glycolide samples along with

The solubilities varied from poor to good when

a commercial reference were polymerized

dissolved into polar aprotic solvents such as

successfully (Table 6). The polymers obtained

DMSO and THF. The solubility of the materials

showed some differences in structural analysis

depended on the material composition, although

(Figure 6). The additional peaks seen with the

thorough analysis of this was not possible due to

polymers prepared from glycolide samples 53

the limited amounts of material available.

and 102 are due to the polymer end groups. The

material

remaining.

This

minor peaks observed at ~69 ppm and ~66 ppm are due to residual glycolide. Table 5. Reaction volumes, obtained and theoretical yields, obtained and theoretical glass transition temperatures and obtained molecular weights of the polymers obtained from black liquor fractions. Volume

Acid

Yield

Tg,calc.

Mn,theor

[mL]

content

[g]

[%]

[째C]

[g/mol]

[g/L] HW1

125.5

-1

770

734

1010

SW1

63.6

1.38

128

1740

1030

1420

SW2

294.0

0.56

112

620

540

750

SW3

53.8

0.82

3560

1600

2400

SODAAQ1

200

6.5

1.27

117

670

1330

1900

SODAAQ2

200

13.6

1.72

1010

1030

1410

FUBIO JR2 PROGRAMME REPORT

Table 6. Results from glycolide polymerizations. Glycolide

Yield

GPC

Mw/Mn

(째C)

PURAC

99%

5,890 / 3,400

217

Hycail 1

98%

25,700 / 13,400

210, 221

Hycail 53

99%

22,100 / 11,500

209, 222

Hycail 102

99%

36,600 / 17,400

221

4.3 Glycolic acid by fermentation

cycle and directs the metabolic flux towards the cycle, thus allowing the yeast to produce

Biotechnical

production

glycolic

acid

glycolic acid (Figure 7). Development of

was demonstrated using host organisms

bioreactor cultures and the selection of a

Saccharomyces cerevisiae, Aspergillus niger,

suitable yeast host led to improved production

and Kluyveromyces lactis. Glycolic acid was

levels that demonstrate technical feasibility.

produced in the glyoxylate cycle of the cell.

Production of glycolic acid was shown to be

Expression of the glyoxylate reductase gene

possible also at low pH, which is an advantage

and deletion of the malate synthase gene are

for the purification process and a clear benefit

the minimum requirements for glycolic acid

when compared to Escherichia coli, which has

production.

also been reported to be used as a host for glycolic acid production. At low pH there is

Yeast codon optimized glyoxylate reductase

less need for neutralization and the separation

gene, GLYR1, from the plant Arabidopsis

process is thus easier because less gypsum is

thaliana was introduced to the production

formed and the glycolic acid is in acid form.

host. Overexpression of this gene combined

Low pH also decreases the risk of bioreactor

with other modifications boosts the glyoxylate

contamination.

Figure 6. 13C NMR comparison showing only minute differences in polymer structures.

FUBIO JR2 PROGRAMME REPORT

Figure 7. Modified glyoxylate cycle in S. cerevisiae. Overexpressed genes are presented in green, deleted genes in red.

The best result (17.2 g/l) in the production of

After five days, about 3 g l-1 of glycolic acid was

glycolic acid was achieved by fermentation

produced in flask cultivations. The modified

strain

the

engineered

Kluyveromyces

lactis

was

grown

unbuffered

media

strain. The benefit of K. lactis compared to

containing 20 g l-1 xylose and 20 g l-1 ethanol

S. cerevisiae is that it is a Crabtree negative

and fed daily with additional 10 g l-1 ethanol.

yeast which favours respiratory metabolism,

Further work is needed to increase the

meaning that the organism does not catabolize

production rate and also to bypass the ethanol

sugars to ethanol as efficiently as S. cerevisiae.

step, as it has been shown that only ethanol is converted to glycolic acid, whereas xylose

The first step in constructing the glycolic acid

and other sugar substrates are either used

production strain in K. lactis was to delete

solely for cell growth or are first converted to

malate synthase in order to prevent the

ethanol before converting to glycolic acid. The

conversion of glyoxylate to malate. In addition,

result shows that K. lactis is a promising host

the cytosolic isocitrate dehydrogenase was

for glycolic acid production as it is producing

deleted and, finally, the S. cerevisiae codon-

more glycolic acid with fewer modifications

optimized glyoxylate reductase, GLYR1, was

than S. cerevisiae strains.

overexpressed from a multicopy plasmid.

FUBIO JR2 PROGRAMME REPORT

Kluyveromyces lactis bioreactor cultivations

K. lactis strain H3986 was grown in a Biostat

5. Exploitation plan and impact of results

CT-DCU bioreactor at pH 5.0, at 30째C, 1 volume air [volume culture]-1 min-1 (vvm) and 500 rpm

The work focuses on separation of hydroxy acids

agitation. Xylose (20 g l-1) and ethanol (20 g l-1)

from black liquor and their further upgrading,

were provided as carbon source at the beginning

e.g. as hot melts or reactive monomers. From

of the fermentation. Xylose and ethanol were

the industry point of view, if the separation

fed to the bioreactor as separate feeds based

concept proves economically feasible, hydroxy

on their consumption. The fermentation was

acid based products recovered from black

monitored for 12 days (Figure 8).

liquor would offer opportunities for pulp and papermaking companies to utilize this

Extracellular metabolites in cell-free spent

side-stream as a valuable raw material for

culture medium were analysed by capillary

environmentally friendly products.

electrophoresis. H3986 produced extracellularly 17.2 g glycolic acid l-1 after 9 days at pH 5.0 (Table 7). The yield of glycolic acid on xylose-ethanol media was approximately 0.13 g glycolic acid [g ethanol + xylose]-1. Acetate was also produced towards the end of fermentation, but as the

Table 7. Glycolic acid production by strain H3986 at pH 5.0 in a bioreactor.

glycolic acid level was already close to maximum at this stage, it would have been possible to stop the fermentation before acetate accumulation, thus facilitating the separation process.

Glycolic acid production (g l-1) Day 0 Day 2 Day 4 Day 6 Day 8 Day 9 0

9.9

13.8

14.8

16.1

17.2

Figure 8. Xylose, ethanol and oxygen consumption and glycolic acid, acetate and CO2 production.

FUBIO JR2 PROGRAMME REPORT

6. Networking The research was carried out jointly by research organisations and Finnish bioeconomy cluster companies. Table 8 below presents the research partners and their roles. Table 8. Partner organizations and their research roles. Work package partners

Role of the participating organization

Hycail

Preparation of glycolide from glycolic acid

Kemira

Industrial tutor

Lappeenranta University of

Fractionation and purification of hydroxyl acids from black liquor by

Technology

membrane filtration and chromatographic separation

Metsä Fibre

Industrial tutor

University of Helsinki

Expertise in oxidation of sugars to hydroxy acids

University of Jyväskylä

Developing the separation of hydroxy acids from black liquor by electrodialysis

UPM-Kymmene

Work Package Coordinator

VTT

WP leader. Development of a chromatographic separation method for hydroxy acids from black liquor and analysis. Polymerization and copolymerization of hydroxy acids. Development of an enzymatic route to glycolic acid from sugars.

7. Publications and reports Hellstén, S. Recovery of biomass-derived val-

Koivistoinen, O.M., Kuivanen, J., Barth D., Turk-

uable compounds using chromatographic and

ia H., Pitkänen, J-P., Penttilä, M. and Richard,

membrane separations, Doctoral dissertation,

P. Glycolic acid production in the engineered

Lappeenranta University of Technology, 2013.

yeasts Saccharomyces cerevisiae and Kluyveromyces lactis, Microb Cell Fact 12, 2013, 16 pp.

Hellstén, S., Heinonen, J. and Sainio, T. Size-exclusion chromatographic separation of hydroxy

Koivistoinen, O., Kuivanen, J., Penttilä, M. and

acids and sodium hydroxide in spent pulping

Richard, P. Eukaryotic cell and method for pro-

liquor, Sep. Purif. Technol., 118, 2013, 234–241.

ducing glycolic acid, WO13050659A1.

Hellstén, S., Lahti, J., Heinonen, J., Kallioinen,

Pirttimaa, M., Rovio, S., Harlin, A., Ropponen,

M., Mänttäri, M. and Sainio, T. Purification pro-

J. and Gädda, T. Polymers derived from isolat-

cess for recovering hydroxy acids from soda

ed hydroxy acids obtained from hardwood and

black liquor, Chem. Eng. Res. Des., 91, 2013,

softwood black liquor, submitted.

2765-2774. Koivistoinen, O. Catabolism of biomass-derived sugars in fungi and metabolic engineering as a tool for organic acid production, Doctoral dissertation, University of Helsinki, 2013.

FUBIO JR2 PROGRAMME REPORT

BIOLOGICAL EFFECTS OF WOOD-BASED EXTRACTS AND COMPOUNDS IN MODELS OF HUMAN DISEASE

CONTACT PERSON - Work Package 5 leader Niina Saarinen-Aaltonen, niina.saarinen@utu.fi Stora Enso: Jukka Kahelin University of Helsinki: Raisa Haavikko, Vânia Moreira, Jari Yli-Kauhaluoma University of Tampere: Heikki Eräsalo, Mirka Laavola, Tiina Leppänen, Eeva Moilanen University of Turku: Sari Mäkelä,Lauri Polari, Niina Saarinen-Aaltonen, Emrah Yatkin UPM-Kymmene: Mika Hyrylä, Suvi Pietarinen VTT Technical Research Centre of Finland: Kirsi Bromann, Tiina Nakari-Setälä, Mervi Toivari Åbo Akademi University: Annika Smeds, Stefan Willför

FUBIO JR2 PROGRAMME REPORT

ABSTRACT

The project aimed at building a Finnish knowledge platform on the health-promoting potential of wood-derived compounds. The focus was on obesity-associated disorders, inflammatory diseases â&#x20AC;&#x201C; especially (osteo)arthritis and allergy, and cancer, i.e. diseases that are common and increasingly prevalent in Finland and other Western countries. The work demonstrated through various cell-based assays in vitro and in animal models in vivo that pine knot extract and its components have anticarcinogenic and immunomodulatory / anti-inflammatory properties and alleviate obesity-associated disorders. Mechanisms of action relevant to several diseases in the focus areas were identified, along with signalling mechanisms relevant to specific diseases. The results contribute greatly to our general understanding of the effects of wood-derived compounds on human health. A unique, interdisciplinary research environment was created, providing an innovative knowledge platform enabling identification of novel applications for wood-derived compounds. The focus of the research on bioactive compounds derived from raw material sources available for large-scale production is also unique and increases Finnish competence for further exploitation of innovations in this field. The work paves the way for the development of high-value products from unexploited raw material sources as an integral part of the Finnish forest industry renewal process.

Keywords: pine knot extract, stilbenoids, obesity, adipose tissue, aromatase, breast cancer, prostate cancer, inflammation, arthritis, cartilage, allergy

FUBIO JR2 PROGRAMME REPORT

1. Background

2. Objectives

Nature is a rich source of bioactive compounds

The project was designed to contribute to

with therapeutic potential. It is estimated that

building a globally competitive and unique

about half of all drugs used in current medical

Finnish knowledge platform on wood-derived

treatment originate from plants and other

compounds and their potential use as health-

natural sources. Nordic wood, especially conifer

promoting agents.

knotwood, is a rich source of compounds with health-promoting potential, such as polyphenols.

The main objective was to identify and

Some of these compounds are similar to those

biologically

found in other sources, such as edible plants.

wood knot and bark components with the

However, unlike in many other plants, the majority

aim of providing preclinical proof-of-concept

of polyphenolic compounds in wood are present

level evidence in at least one of the focus

in unconjugated form. In addition, polyphenol-

areas: obesity-associated health problems,

rich knot material is available in large quantities

cancer,

as a side product of current industrial processes.

relation to (osteo)arthritis and allergy. Each

Therefore, isolation of polyphenols from knot-

line of research began by recognizing relevant

enriched wood material in high quantities for

target(s) and continued by identifying effective

further exploitation is feasible.

extract(s) and/or compound(s) and further

characterize

and

health-promoting

inflammation,

especially

documenting the efficacy and preliminary In this project, wood materials that are not

safety of the selected materials in cell-based

important for pulp production were investigated.

assays and/or animal experiments (in vivo

The research focused on health problems that

disease models) in comparison with previously

are common and continuously increasing in

known control compounds.

Finnish and other Western populations: obesity, inflammatory diseases, especially osteoarthritis and allergy, and cancer. Obesity is a risk factor for

development

metabolic

3. Research approach

syndrome,

which is associated with type 2 diabetes and

Initially, the project involved three main raw

cardiovascular disease. In Finland, 60% of men

materials: pine knot extract, spruce knot extract,

and 50% of women are overweight or obese and

and birch bark extract, and purified compounds

15% of men and 5% of women have metabolic

of these, respectively. Based on the findings

syndrome. It has been estimated that half a

during the project, the work was further focused

million Finns have symptomatic osteoarthritis

on pine knot extract and its compounds.

and about 30% of Finns suffer from various forms of allergic diseases. In addition, the

3.1 Obesity-associated health problems

incidence of certain cancers, in particular

prostate cancer and breast cancer, is increasing

The work was focused on obesity-induced

in Western countries. By 2020, prostate cancer

endocrine disturbances caused by dysregulation

will constitute almost 50% of diagnosed cancer

of aromatase (CYP19A1) gene expression in white

cases in men. Breast cancer is now, and will

adipose tissue. Aromatase enzyme catalyzes

continue to be, responsible for more than 40%

the final step in oestrogen biosynthesis, i.e.

of cancer cases in women. Clearly, there is an

conversion

urgent need for novel preventive means and

and

treatment options against these diseases.

and oestradiol). White adipose tissue is an

androgens

testosterone)

(androstenedione

estrogens

(oestrone

FUBIO JR2 PROGRAMME REPORT

important site for extragonadal aromatization 3.3 Immunomodulatory / antiand oestrogen production in man. To investigate inflammatory properties of pine knot pine knot extract effects in vivo, a humanized extract and its compounds transgenic hAro-Luc reporter mouse was utilized. These mice express the full-length promoter To screen the anti-inflammatory potential of the region of the human aromatase gene, and can pine knot extract and its known constituents, be used to study, for example, obesity-related a widely used animal model in pharmacology factors that regulate aromatase expression in research,

i.e.

carrageenan-induced

paw

vivo. Obesity was induced by high-fat diet (HFD). inflammation, was used. The advantage of Effect of pine knot extract on weight gain and this model is that the effects can be compared body composition (adiposity) was determined to large background data on the activity of and serum biomarkers of metabolic disturbance various anti-inflammatory compounds and were measured. Obesity-induced adipose tissue series of other natural products. Also, the inflammation was assessed using histological early inclusion of in vivo disease models in parameters in the tissue and by measuring the evaluation of the biological activity of adipose tissue proinflammatory cytokine levels. the extract and compounds of interest also Adipose tissue cultures and bone marrow stromal gave a preliminary understanding of the cell cultures were established as novel tools bioavailability of the investigated materials. to investigate factors that regulate aromatase Furthermore, additional in vivo disease models expression in fat tissue.

were developed.

3.2 Effects on prostate cancer

Cell-based

assays

were

established

investigate the effects of the extract and Anticarcinogenic

potential,

mechanism

of its

constituents

inflammatory

gene

action, and effective concentration range of expression in various inflammatory cells and pine knot extract and its main polyphenols in chondrocytes. The cell culture conditions and their metabolites were evaluated in in were adjusted to mimic the inflammatory vitro assays by using human prostate and milieu in vivo and the cells were stimulated breast cancer cells and in vivo by using accordingly. In addition to appropriate cell human cancer cell derived tumours in mice. lines, also primary human cell cultures were in vitro, the effects of pine knot extract and used

when

possible.

Inflammatory

gene

compounds derived therefrom were tested expression was measured using standard for proliferation and apoptosis in androgen- procedures, e.g. quantitative real-time reverse independent human prostate cancer cells.

transcriptase polymerase chain reaction (RTqPCR) to detect mRNA levels, and Western

The effective dose of pine knot extract in vivo blotting and enzyme-linked immunosorbent was assessed in prostate cancer tumours grown assay (ELISA) to measure protein levels. in mice. Growth of the tumours was followed Also, an array-based approach was used and several biomarkers of tumour development where appropriate. Furthermore, the effects and mechanisms of chemoprevention were on intracellular signalling mechanisms were assessed using morphological and biochemical investigated using, inter alia, phosphoprotein analyses. Statistical multivariate analyses were and reporter gene assays. applied to combine essential tumour growth markers and to identify effective dosing of pine knot extract.

FUBIO JR2 PROGRAMME REPORT

4. Results

Obesity

induces

chronic

low-grade

inflammation in adipose tissue, which causes

4.1 Pine knot extract attenuates obesityinduced metabolic disturbances and aromatase expression in adipose tissue

numerous functional changes that promote the

development

obesity-associated

diseases. Formation of crown-like structures (CLS), i.e. necrotic adipocytes surrounded by

A mouse model of diet-induced obesity

macrophages, and increased levels of tissue

allowed us to study simultaneously multiple

proinflammatory cytokines are typical for

aspects of obesity-associated disorders in

obesity-related adipose tissue inflammation

vivo. The effects of two dietary doses of a pine

and dysfunction. The higher dose of dietary

knot extract were investigated: “low dose”

pine knot extract decreased the number of CLS

and “high dose”, which resulted in 32.5 mg/

in visceral and subcutaneous white adipose

kg and 162.5 mg/kg body weight exposures,

tissues (Figure 1) and reduced the tissue level of

respectively. The “low dose” corresponds

proinflammatory cytokines. In summary, these

roughly to 1g daily intake of phenolics in a 70

data indicate that dietary pine knot extract

kg human, i.e. an intake achievable through

can attenuate obesity-induced adipose tissue

diet, while the “high dose” corresponds

inflammation in vivo.

roughly to a 2g daily intake of pinosylvins in a 70 kg human. As expected, high-fat diet

Functional changes induced by obesity include

(HFD) increased body weight and body fat

induction of aromatase expression in adipose

content in male mice compared to low-fat

tissue, which, in turn is one of the key events

diet (LFD). Administration of pine knot extract

leading

for 8 weeks in HFD diet was well tolerated.

disturbances.

Neither dose of pine knot extract significantly

necessary for the production of oestrogen

affected body weight gain or fat content.

from androgens. Downregulation of oestrogen

However, a higher dose of pine knot extract

biosynthesis in adipose tissue has an impact, for

administered in the HFD diet decreased

example, on the prevention of obesity-related

serum leptin, resistin, insulin, and fasting

hypoandrogenemia in obese men and on the

blood glucose levels, which are hallmarks of

development of oestrogen-responsive breast

metabolic disturbances in humans.

cancer in postmenopausal obese women.

obesity-associated Aromatase

endocrine enzyme

Figure 1. Density of crown-like structures (CLS) in visceral (A) and subcutaneous fat (B). LFD, low-fat diet; HFD, high-fat diet, HFD-PKE pine knot extract containing high-fat diet.

FUBIO JR2 PROGRAMME REPORT

In humans, expression of aromatase is highly

aromatase gene reporter expression was

regulated through untranslated first exons that

modulated by pine knot extract in MSCs. In

are differently utilized in different tissues. In

addition, other more indirect effects of pine

rodents, the regulatory region of the aromatase

knot extract seen in the in vivo setting may, at

gene is much less complex and, unlike in

least in part, account for the downregulation

humans, the expression level in adipose tissue

of Luc expression in subcutaneous fat. In

is very low. Therefore, we used a humanized

summary, these data suggest that pine knot

transgenic hARO-Luc reporter mouse. These

extract affects oestrogen biosynthesis in male

mice express the full-length regulatory region

adipose tissue by modulating aromatase gene

of the human aromatase gene attached to a

expression and may thus have potential to

luciferase (Luc) reporter gene.

attenuate excessive oestrogen production in white adipose tissue of obese men.

In hAro-Luc mice, we showed that HFDinduced

adiposity

was

associated

with

upregulation of Luc expression in adipose tissue. In line with this, adipose tissue Luc

4.2 Pine knot extract shows anticarcinogenic efficacy in prostate cancer

activity correlated positively with adipose tissue

levels.

In this project, we showed that pine knot extract

Importantly, we demonstrated that dietary

pro-inflammatory

cytokine

and its stilbenoids (monomethyl pinosylvin

pine extract down-regulates the expression of

and pinosylvin), and lignans (matairesinol and

human aromatase gene in subcutaneous fat of

nortrachelogenin) have antiproliferative and

obese HFD-fed male mice (Figure 2).

proapoptotic efficacy at ≥40 μM concentration in vitro (Figures 3 and 4). We also showed that

human

adipose

pine extract (≥ 10 mg/L) and its stilbenoids

mainly expressed in mesenchymal stromal

enhance TRAIL-induced apoptosis already at

cells

(MSCs).

≥10 μM concentration in vitro (Figure 4B).

MSC

cells

from

tissue, isolated

hARO-Luc

aromatase and

cultured

mouse

bone

marrow. As expected, Luc expression in

Four

MSCs

B1,

was

stimulated

glucocorticoids

main

compounds

pinosylvin, and

pine

monomethyl

extract

pinosylvin,

and proinflammatory cytokines through the

matairesinol,

aromatase gene promoter I.4. Interestingly,

identified to account for the observed pine

nortrachelogenin,

were

knot extract effects. These compounds, when combined in the same ratio as present in the extract, resulted in similar responses in the cell proliferation and apoptosis assays as the extract and, when tested as single compounds, were effective at ≥ 10μM concentrations (Figures 3C and 4). These data indicate that concentrations of ≥ 10 mg/L of pine extract or ≥ 40μM single pine extract compounds are required for inhibition of proliferation and induction of apoptosis in human prostate Figure 2. Aromatase reporter expression in male subcutaneous white adipose tissue. LFD, lowfat diet; HFD, high-fat diet; HFD-PKE pine knot extract containing high-fat diet.

FUBIO JR2 PROGRAMME REPORT

cancer cells in vitro.

Figure 3. Pine knot extract and its polyphenols inhibit proliferation of PC-3M-luc2 human prostate cancer cells. PKE, pine knot extract; LS, lignan-stilbenoid mixture containing pinosylvin (PS), monomethyl pinosylvin (MEPS), matairesinol (MR), and nortrachelogenin (NTG). Ab, abietic acid; RV, resveratrol. Figure published in PlosOne 2014, 9(4):e93764.

Figure 4. Pine knot extract and its compounds induce apoptosis in PC-3M-luc2 human prostate cancer cells (A) and sensitize these cells to TRAIL-induced apoptosis (B). PKE, pine knot extract; LS, lignanstilbenoid mixture containing pinosylvin (PS), monomethyl pinosylvin (MEPS), matairesinol (MR), and nortrachelogenin (NTG). Ab, abietic acid; RV, resveratrol. Figure published in PlosOne 2014, 9(4):e93764.

Two in vivo studies investigating the effects

(i.e. tumour volume, vascularization, and cell

of pine knot extract on advanced androgen-

proliferation) (Figure 5).

independent prostate cancer in vivo were completed. Two doses of the extract were

Urine and serum analyses of “high dose” pine knot

investigated: “low dose” resulting in 32 mg/kg/

extract fed mice revealed significant absorption

body weight exposure and “high dose” resulting

and metabolism of the extract compounds.

in 162.5 mg/kg/body weight exposure. Three-

In serum, high micromolar concentrations of

week peroral exposure to high-dose pine knot

nortrachelogenin, and monomethyl pinosylvin

extract B1 (52 mg of lignans and stilbenoids

along with resveratrol were measured. Resin

per kg body weight) showed anti-tumorigenic

acids that are present in the pine knot extract

efficacy, demonstrated by multivariate analysis

were not detected in urine or serum samples.

combining essential markers of tumour growth

FUBIO JR2 PROGRAMME REPORT

Figure 5. Relation between tumour vascularization, tumour cell proliferation and tumour volume. The hyperplane indicates that two of the groups (vehicle in black and high dose in green) were linearly separable when the three factors were considered together. Figure published in PlosOne 9(4): e93764.

In summary, these data demonstrate that

if aberrantly activated or regulated, prolonged

orally-administered pine knot extract is well

or inappropriately focused (e.g. against host

tolerated and inhibits the growth of prostate

tissues, as in autoimmune diseases, or against

cancer tumours. The in vitro results indicate

normally harmless allergens, as in allergic

that pine knot extract derived lignans and

diseases) the inflammatory response has

stilbenoids and their metabolites account

considerable potential to cause harm and

for the anticarcinogenic effect. The main

may lead to the development of inflammatory

polyphenol in pine knot extract, monomethyl

diseases, such as allergy, asthma or arthritis.

pinosylvin,

Despite recent successes in the development

was

identified

novel

bioavailable stilbenoid with anticarcinogenic

potential against prostate cancer. In addition,

drugs, there are still considerable unmet needs

especially

biological

ingestion of pine knot extract increased

in the treatment of inflammatory diseases. In

serum resveratrol concentrations markedly,

fact, for most inflammatory diseases, current

indicating that the extract is a novel and cost-

drugs can only offer symptoms relief and no

effective source of resveratrol, monomethyl

curative or disease-modifying treatments are

pinosylvin and other potentially beneficial

available. In the present research programme,

lignans and stilbenoids.

investigated

the

anti-inflammatory

immunomodulatory properties of pine knot

4.3 Pine knot extract and its stilbenoid constituents have anti-inflammatory properties in vivo

extract and its constituents, especially in relation to disease mechanisms of (osteo) arthritis and allergic inflammation. Examples of the results are presented below.

Inflammation is a protective response in the human body that aims to eliminate microbes

To determine whether pine knot extract

and other offending agents as well as cancer

has

cells and injured or necrotic tissue. However,

we utilized a widely-used animal model in

FUBIO JR2 PROGRAMME REPORT

anti-inflammatory

potential

vivo,

pharmacology research, i.e. carrageenaninduced paw inflammation, in the mouse. Interestingly, the standard pine knot extract when given as a single oral dose of 100 mg/kg

4.4. Pine knot extract and its stilbenoid constituents down-regulate inflammatory gene expression in inflammatory cells and in chondrocytes

significantly attenuated carrageenan-induced inflammation, as shown in Figure 6A.

In order to understand the anti-inflammatory properties of the pine knot extract and its

Following this finding, we investigated whether

stilbenoid constituents at the cellular level and

the stilbenoid constituents of the extract

their effects on the mediators of inflammation,

might be responsible for the anti-inflammatory

we investigated their effects on various cells

bioactivity discovered in the pine knot extract.

participating in different types of inflammation.

The extract is known to contain two principal

Selected effects of the pine knot extract and

stilbenoids, i.e. pinosylvin and monomethyl

its stilbenoids pinosylvin and monomethyl

pinosylvin. These compounds had a clear

pinosylvin on macrophages and chondrocytes in

anti-inflammatory effect in the carrageenan-

cell culture conditions mimicking inflammatory

induced paw inflammation model in the mouse,

milieu are presented below.

as can be seen in Figure 6B. Furthermore, they were more potent than resveratrol, an

Macrophages

earlier known natural stilbenoid, which was

Macrophages are key inflammatory cells

used as a control compound. The efficacy of

that are differentiated in tissues from blood

the two pine stilbenoids was comparable to

monocytes.

that of the standard anti-inflammatory drug

functions in the first line of defence against

dexamethasone, although the pine stilbenoids

microbes and in the development of specific

were needed in higher doses to obtain the

lymphocyte-mediated immune response as

efficacy

well as in the regulation of inflammatory and

the

dexamethasone.

anti-inflammatory

steroid

Macrophages

have

various

repair mechanisms through the production of a variety of inflammatory mediators.

Figure 6. Anti-inflammatory properties of pine knot extract and its stilbenoid constituents pinosylvin and monomethyl pinosylvin in carrageenan-induced paw inflammation in the mouse. In (A) the pine knot extract (100mg/kg) was dosed orally and in (B) pinosylvin (100 mg/kg) and monomethyl pinosylvin (100 mg/kg) as well as control compounds resveratrol (100 mg/kg) and dexamethasone (2 mg/kg) were given intraperitoneally 2h prior to the inflammation was induced by injecting carrageenan into the paw. Results are expressed as mean Âą SEM, n=6.

FUBIO JR2 PROGRAMME REPORT

In the present study, we investigated the effects

manner. Interestingly, expression of these

of pine knot extract and its stilbenoids on

inflammatory

inflammatory gene expression in macrophages

by pinosylvin and monomethyl pinosylvin

activated through the TLR4 pathway by

(stilbenoids present in the extract) as well as

adding bacterial endotoxin lipopolysaccharide

by resveratrol, which was used as a control

(LPS) into the culture. As seen in Table 1 below,

stilbenoid.

genes

was

also

inhibited

pine knot extract inhibited the production of inflammatory factors interleukin 6 (IL-6),

Chondrocytes

monocyte chemotactic protein 1 (MCP-1) and

Osteoarthritis (OA) is the most common

inducible nitric oxide synthase (iNOS) and its

joint disease worldwide. The disease affects

product nitric oxide (NO) in a dose-dependent

the entire joint causing disability and pain.

Table 1. The effects of pine knot extract and its components pinosylvin and monomethyl pinosylvin as well as the control stilbenoid resveratrol on nitric oxide (NO), interleukin 6 (IL-6) and monocyte chemotactic protein 1 (MCP-1) production and inducible nitric oxide synthase (iNOS) expression in activated macrophages. The results are expressed as mean Âą SEM; * indicates p<0.05 and ** = p<0.01.

FUBIO JR2 PROGRAMME REPORT

The primary cause of OA remains unknown.

pine knot extract inhibited the production

Degradation of the cartilage matrix is the

of the three MMP enzymes typical of OA

most important feature of OA pathology. The

pathogenesis (i.e. MMP-1, MMP-3 and MMP-

degradation is caused by an imbalance between

13) in a dose-dependent manner. The effect

catabolic and anabolic mediators in the joint,

could be due to the stilbenoids present in the

and by the inflammatory mediators produced

extract, because pinosylvin and monomethyl

by the cells in the cartilage and synovial

pinosylvin, as well as the control compound

membrane. Matrix metalloprotease enzymes,

resveratrol, also had an inhibitory effect on the

especially MMP-1, MMP-3 and MMP-13, are

synthesis of MMP enzymes.

produced by chondrocytes in the OA cartilage and play a significant role in cartilage matrix degradation. (Figure 7) Compounds capable of inhibiting the synthesis of MMP enzymes are being intensively sought and investigated

4.5 Pine knot extract and its stilbenoid constituents attenuate the activity of two major inflammatory signalling pathways

as potential future drugs to alleviate cartilage degradation associated with OA.

The cell culture studies were extended in order to further understand the mechanisms

In the present study, we investigated the

of action of the pine knot extract and its

effects of pine knot extract and its stilbenoid

stilbenoid constituents in inflammatory cells.

constituents on the production of various

Nuclear factor-kB (NF-kB) is an important

catabolic, anabolic and inflammatory factors in

inflammatory

human chondrocytes by using a chondrocyte

known to be activated by various inflammatory

cell line and primary human chondrocytes

stimuli. Once activated and translocated to

isolated from human cartilage tissue from OA

the nucleus, NF-kB is able to augment the

patients removed during joint replacement

transcription of various inflammatory genes,

operations. As can be seen in Table 2, the

including many of those found to be regulated

transcription

factor

that

by the pine knot extract and its constituents. Inhibitors of NF-kB are under development for the treatment of arthritis and asthma, and other inflammatory diseases. To investigate the effects of the pine knot extract and its stilbenoid compounds on NF-kB activation and NF-kB dependent transcription, we generated two different types of reporter gene containing cell lines. The cells were transfected with a reporter gene construct, in which the luciferase gene (which is not normally expressed in human cells) was linked to an NF-kB dependent promoter, as shown in Figure 8A. In those cells, the promoter activity could be enhanced by inflammatory factors which are known to activate NF-kB (e.g. LPS, Figure 7. Pathological changes and mechanisms in osteoarthritis.

IL-1 or TNF), and this in turn could be measured as increased luciferase mRNA levels or as

FUBIO JR2 PROGRAMME REPORT

Table 2. Effects of pine knot extract and its components pinosylvin and monomethyl pinosylvin as well as the control stilbenoid resveratrol on the production of matrix metalloprotease enzymes MMP-1, MMP3 and MMP-13 in a human chondrocyte cell line activated with the inflammatory cytokine interleukin 1. The results are expressed as mean Âą SEM; ** indicates p<0.01.

Figure 8. Effects of pine knot extract and its components pinosylvin and monomethyl pinosylvin on NF-kB mediated transcription. Figure A is a schematic presentation of the cell model generated and used in the studies. Figure B shows the effects of the pine knot extract and its stilbenoid constituents pinosylvin and monomethyl pinosylvin as well as the effects of the control stilbenoid resveratrol and an earlier known NF-kB inhibitor MG132 on NF-kB mediated transcription, which was measured as luciferase activity in the model described in A. The results are expressed as mean + SEM; ** indicates p<0.01.

FUBIO JR2 PROGRAMME REPORT

increased luciferase enzyme activity in the

and anti-inflammatory factor HO-1 in a dose-

cells.

dependent manner. Interestingly, pinosylvin and monomethyl pinosylvin also enhanced

Figure 8B shows an example of the results of

cellular HO-1 levels, at least when used at

the studies in which the effects of the pine knot

100 ÎźM concentrations, while the effects of

extract and its stilbenoid constituents on NF-

resveratrol were minor. The increased HO-1

kB mediated transcription were investigated.

expression may contribute to or mediate

The pine knot extract significantly inhibited

the inhibitory effect on NF-kB mediated

NF-kB mediated transcription, and the effect

transcription caused by the pine knot extract

was shared by pinosylvin and mono-methyl

and its stilbenoid constituents.

pinosylvin as well as by resveratrol, which was used as a control stilbenoid.

PI3K/Akt is another major intracellular signalling pathway involved in inflammation and cancer.

Heme oxygenase 1 (HO-1) is a factor known to

PI3K (phosphoinositide 3 kinase) activation

play a role in cellular defence against oxidative

leads to phosphorylation of Akt, which regulates

stress and to have anti-inflammatory and

the activation of many inflammatory genes.

cytoprotective properties. Those effects are,

Therefore, we were curious to investigate whether

at least partly, mediated through inhibition

the pine knot extract and its bioactive stilbenoid

of NF-kB activation. Therefore, we aimed to

constituents have an effect on the PI3K/Akt

investigate whether the pine knot extract and

pathway in activated inflammatory cells.

its stilbenoid compounds, which were able to inhibit NF-kB mediated transcription, could

As expected, inflammatory stimuli, such as LPS,

also augment the expression of HO-1.

activated the PI3K/Akt pathway in macrophages, measured as Akt phosphorylation. The pine

As shown in Figure 9A, the pine knot extract

knot extract inhibited Akt phosphorylation in

enhanced the expression of the cytoprotective

those conditions, and the effect was shared by

Figure 9. Effects of (A) pine knot extract and (B) its components pinosylvin and monomethyl pinosylvin as well as the control stilbenoid resveratrol on heme oxygenase 1 (HO-1) expression in macrophages activated with the inflammatory stimulus LPS. Hemin was used as an earlier recognized positive control compound to enhance HO-1 expression. The results are expressed as mean + SEM; *indicates p<0.05, ** = p<0.01 and *** = p<0.001.

100

FUBIO JR2 PROGRAMME REPORT

the pine stilbenoids pinosylvin and monomethyl

diseases targeted by the research (obesity,

pinosylvin as well as by resveratrol, which was

osteoarthritis, allergy, and cancer) are major

used as a control stilbenoid. An example of

public health problems of increasing incidence,

the results is shown in Figure 10. These results

the impact of which at the individual and

suggest that stilbenoids are responsible for the

societal level is growing substantially along

inhibitory effect of the pine knot extract on the

with their cost to the health care system. Thus,

PI3K/Akt pathway. Furthermore, the studies

there is a clear need for new preventive means

of NF-kB and the PI3K/Akt pathway strongly

and treatment options for these diseases. In

suggest that those mechanisms may explain,

the present project, several health targets

at least partly, the anti-inflammatory properties

and product applications were identified for

of the pine knot extract and its bioactive

further development.

stilbenoids on inflammatory gene expression and inflammatory responses in vivo.

Finnish wood resources hold vast potential for the development of novel and innovative high-

5. Exploitation plan and impact of results

value products. This project identified wood components that are not yet exploited but have potential to be utilized for the development of health-promoting high-value products, such as

This project contributes to building a globally

functional foods, nutraceuticals, natural drugs

competitive and unique Finnish knowledge

or pharmaceuticals. The focus was on wood

platform on wood components and their

extracts rich in bioactive components and

potential use as health-promoting agents. The

with broad exploitation potential. This opens opportunities for the development of new value chains and business concepts from raw material supply to further product development and commercialization, thus helping drive the renewal of the forest industry.

Figure 10. Effects of pine knot extract and its components pinosylvin and monomethyl pinosylvin as well as the control stilbenoid resveratrol on the PI3K/Akt pathway, measured as Akt phosphorylation. LY294002 was used as a control compound known to inhibit PI3K. The results are expressed as mean + SEM; **indicates p<0.01.

FUBIO JR2 PROGRAMME REPORT

101

6. Networking The research was carried out in cooperation by the partners, see Table 3. the work package partners and their roles. Table 3. Research partner organizations and their research roles.

Work package partner

Role of the participating organization

Stora Enso

Industrial tutor

University of Helsinki

Chemical modification of wood-derived compounds.

University of Tampere

Investigation of bioactivity of wood-derived extracts and compounds in inflammation with special reference to (osteo)arthritis and allergy

University of Turku

WP leader. Investigation of bioactivity of woodderived extracts and compounds in obesity and cancer

UPM-Kymmene

Industrial tutor

VTT

Biotechnological modification of wood-derived compounds.

Ă&#x2026;bo Akademi University

Composition analysis of wood extracts and their metabolites.

102

FUBIO JR2 PROGRAMME REPORT

7. Publications and reports Bromann,

K.,

Toivari,

M.,

Viljanen,

K.,

Vuoristo, A., Ruohonen, L. and Nakari-Setälä, T. Identification and characterization of a novel diterpene gene cluster in Aspergillus nidulans. Plos One, 2012, 7(4):e35450. Eräsalo, H., Laavola, M., Hämälainen, M., Leppänen, T., Nieminen, R. and Moilanen, E. PI3K inhibitors LY294002 and IC87114 reduce inflammation in carrageenan-induced paw edema and down-regulate inflammatory gene expression in activated macrophages. Basic and Clinical Pharmacology and Toxicology, 2014 in press. Laavola, M., Nieminen, R., Leppänen, T., Eckerman, C., Holmbom, B. and Moilanen, E. Pinosylvin and monomethyl pinosylvin, constituents of extract from knots of Pinus sylvestris,

reduce

inflammatory

gene

expression and inflammatory response in vivo. Submitted for publication. Polari,

L.,

Ojansivu,

P.,

Mäkelä,

S.,

Eckerman, C., Holmbom, B. and Salminen, S. Galactoglucomannan extracted from spruce (Picea abies) as a carbohydrate source for probiotic bacteria. Journal of Agricultural and Food Chemistry, 2012, 60(44):11037-43. Qiu, Yaqi. Dietary factors affecting human aromatase gene reporter expression in normal tissues and cancer; Focus on mammary gland and breast cancer. Master’s thesis. Åbo Akademi University, Dept. of Biosciences. 2013. Yatkin, E., Polari, L., Laajala, TD., Smeds, A., Eckerman, C., Holmbom, B., Saarinen, NM., Aittokallio, T. and Mäkelä, S. Novel lignan and stilbenoid mixture shows anticarcinogenic efficacy in preclinical PC-3M-luc2 prostate cancer model. PlosOne 2014, 9(4):e93764.

FUBIO JR2 PROGRAMME REPORT

103

THERMOPLASTIC LIGNIN AND REINFORCING CELLULOSE FIBER COMPOSITES FOR ADVANCED BIOCOMPOSITE APPLICATIONS

CONTACT PERSON – Work Package 3 leader Antti Ojala, antti.ojala@vtt.fi Metsä Fibre: Pirkko Liias Novoplastik: Johannes Heiskanen, Pietari Heiskanen, Merja Lehto Stora Enso: Kalle Ekman, Janne Pynnönen University of Helsinki: Juha Fiskari, Ilkka Kilpeläinen, Maarit Lahtinen University of Jyväskylä: Markku Kataja, Arttu Miettinen UPM-Kymmene: Mika Hyrylä, Eeva Jernström VTT Technical Research Centre of Finland: Stina Grönqvist, Karita Kinnunen-Raudaskoski, Jani Lehmonen, Kalle Nättinen, Lisa Wikström

104

FUBIO JR2 PROGRAMME REPORT

ABSTRACT

The processability and thermomechanical performance of thermoplastic lignin composites were studied. The aim was to develop processes and materials to enable the production of composites with high lignin (>50% of the matrix) and wood-based material content. Processing of the composites was carried out using twin-screw extrusion and injection moulding techniques. The focus was on softwood kraft lignin, but also lignins from alkali and hot water extractions were evaluated. To reduce the high glass transition temperature of kraft lignin and to enhance the ductility of the composites, both external as well as internal plasticization routes were employed. Thermomechanical (TMP) and bleached (Fusellu) softwood pulps were used to improve the processability and mechanical performance of the composites. Materials reinforced with Fusellu demonstrated slightly higher mechanical performance than the TMP-reinforced composites. The best performance was obtained using a mixture of acetylated starch (Ac-starch) and triethyl citrate (TEC) as the external plasticizer and Fusellu reinforcements. Acetylation, hydroxypropylation and palmitic acid grafting methods were used to internally plasticize kraft lignin. Of the internally plasticized materials, composites with the Ac-starch-TEC plasticized acetylated lignin (Acet-L) matrix and Fusellu reinforcement gave the best mechanical properties. The fabricated composites had a tensile strength of 35 MPa and modulus of 6.6 GPa. The overall content of the wood-based materials was 70%. The structure of the composites was characterized using X-ray computed microtomography (X-ÂľCT). The focus of the study was on fibre dispersion and breakage. The fibre dispersion in the thermoplastic lignin matrices was observed to be good. However, the processing conditions had a significant detrimental impact on fibre length.

Keywords: thermoplastic lignin, injection moulding, thermomechanical pulp, bleached pulp, X-ray microtomography

FUBIO JR2 PROGRAMME REPORT

105

1. Background

2. Objectives

Modern biorefineries (e.g. pulping mills and

The aim of the research was to develop

bioethanol plants) using lignocellulosic feedstocks

technologies and competences enabling the

produce as a by-product large amounts of lignin,

production of novel biocomposite materials

which is currently almost exclusively burned

in which wood-derived lignin and cellulose

for energy. For example, it is estimated that

fibre are the main constituents. For best

the annual global production of lignin in kraft

performance, both the fibre and lignin fractions

pulp mills exceeds 50 million tonnes. Lignin is

were modified. Modification of the lignin fraction

therefore a vastly underutilized resource.

included internal and external plasticization for improved ductility and processability. Chemical

Global annual plastics production currently

modifications of the fibres were targeted at

stands at around 250 million tonnes, of which

enhancing bonding with the matrix lignin and

thermoplastic materials account for 65%. By

the subsequent reinforcement effect.

far the largest thermoplastic segments are petroleum-based PE, PP and PVC at 33%,

The target application sectors were construction

21% and 17%, respectively. The share of non-

and furniture.

petroleum based materials remains highly marginal (<1% of all produced thermoplastics). Furthermore, current renewable materials are

3. Research approach

almost exclusively based on starch, and thus compete directly with global food production.

The main task was to evaluate the potential

There is therefore a clear demand for low-

of lignin as a thermoplastic matrix material in

cost non-food based plastics from renewable

wood pulp reinforced composites. The focus

feedstock. One of the most promising candidates

was on the processability of lignin and the

is thermoplastic lignin – the world’s second most

mechanical performance of the composites.

abundant polymer after cellulose.

Softwood

kraft

lignin

(LignoBoost™)

was

used as the main component, in addition Initial trials on kraft lignin were carried out in

to which hot water extracted and alkali

the FuBio programme (2009-2011), in which the

lignins and commercial lignins were also

thermoplastic properties and processability of

tested. The reinforcing wood fibres were

lignin were briefly evaluated. Based on these

chemically bleached softwood pulp (Fusellu)

promising results, it was decided to dedicate a

and thermomechanical softwood pulp (TMP)

separate work package to thermoplastic lignin

supplied by Metsä Fibre and UPM, respectively.

composites under the FuBio Joint Research 2

Additionally, PHWE extracted and ionic liquid

programme launched in 2011.

extracted fibres supplied by Metla were evaluated in the composites. The research was divided into the following four tasks: • Development of lignin modifications (“internal plasticization”) with the goal of reducing glass transition temperature (Tg ) and brittleness.

106

FUBIO JR2 PROGRAMME REPORT

4. Results

• Chemical and enzymatic modification of fibres with the goal of enhanced fibre and

4.1 Structural and thermal characterization of lignins

matrix lignin interaction. • Manufacturing of the composites. Two simultaneous routes were employed: i) selection and development of the actual

The main lignin source was softwood kraft

processes and equipment needed for

lignin LignoBoost (LB, purity 96.7%) supplied by

manufacturing lignin-fibre composite

Metso. Table 1 shows the chemical composition

compounds and ii) iterative development

of LB determined by the 31P NMR method. The

of the lignin-fibre composite compounds at

total amount of hydroxyl groups (mmol/g)

laboratory and pilot scale.

was 5.28, of which 3.39 were phenolic and the

• Structural characterization of the

rest were aliphatic, condensed or carboxylic

composites using X-ray computed

acid. Additionally, the molecular weight (Mw)

microtomography (X-µCT)

distribution for LB as well as for alkali lignin (AL) and pressurized hot water extracted lignin

Figure 1 shows the key processing steps

(PHWE) were determined using GPC methods.

involved

thermoplastic

The results of the GPC analyses are presented

lignin composites. In the first step, the

producing

the

in Table 2. LB has the highest Mw at 4450 Da.

extracted lignin was plasticized to improve its

AL and PHWE have Mws of 2800 and 1700 Da,

processability (i.e. to reduce the glass transition

respectively, clearly lower than that of LB.

temperature, Tg ). Two different approaches, internal and external plasticization, were

Thermal properties of the lignin samples were

used. In the second step, plasticized lignin

analysed using differential scanning calorimetry

was processed with wood pulp to produce

(DSC). Figure 2 and Table 3 present the results

wood fibre reinforced thermoplastic lignin

of the DSC scans. All lignin samples show two

composites. Finally, the composite parts were

glass transition points (Tg) at 60-70 °C (Tg1) and

produced by injection moulding.

at 100-180 °C (Tg2). LB has the highest Tg2 at 152.5

Figure 1. Schematic presentation of the processing of lignin composites. Table 1. Amount of different hydroxyl group species (mmol/g) in lignin samples as detected by NMR . Lignin

Aliphatic OH

Carboxylic acid

Condensed

Phenolic OH

Total OH

1.60

0.29

1.46

0.00

1.89

0.05

3.39

5.28

FUBIO JR2 PROGRAMME REPORT

107

Table 2. Molar mass distributions of the LB, AL and PHWE samples.

Sample

Mn (Daltons)

Mw (Daltons)

Polydispersity

2289

4450

1.94

1800

2800

1.51

PHWE

1200

1700

1.36

Figure 2. Second heating cycle scans for the AL (red), PHWE (green) and LB (blue) samples. The heating ramp was 10 °C/min from -50 °C to 200 °C.

Table 3. Results of the thermal analyses for the LB, AL and PHWE lignins as well as for the internally plasticized PL, HPL and Ace-L lignins.

Lignin

108

Description

Tg1 / °C

Tg2 / °C

Tdeg10% / °C

Softwood kraft lignin

68.5

152.5

328.5

PHWE

Hardwood PHWE lignin

71.8

120.8

282.0

Softwood alkali lignin

61.0

102.4

282.5

Palmitic acid modified LB lignin

n/d

245.1

HPL

Hydroxypropylated LB lignin

63.0

112.4

300.9

Acet-L

Acetylated LB lignin

46.0

101.4

272.6

FUBIO JR2 PROGRAMME REPORT

°C, whereas AL and PHWE have Tg2 at 102.4 and

Together with external plasticization, inter-

120.8 °C, respectively. Note that the Tg2 of the

nally plasticized lignins were evaluated as the

PHWE sample is substantially higher than that

matrix materials in the composites. The aim

for AL, although the Mw of PHWE is clearly lower.

of the internal plasticization was to reduce the high Tg of the native kraft lignin (LB) and,

The thermal stabilities of the lignin samples

successively, to improve the ductility of the

were determined using thermogravimetric

composites. Palmitic acid grafted lignin (PL),

analysis (TGA). The results are presented in

hydroxypropylated lignin (HPL) and acetylat-

Table 3. LB has the highest thermal stability of

ed lignin (Acet-L) were selected as the main

the analysed samples. The point at which 10%

target modifications. The samples were syn-

of the sample weight is lost (Tdeg10) is observed

thesized using LB as the starting material.

at 329 °C. AL and PHWE are, in turn, less sta-

Based on the

ble with Tdeg10 at 283 and 282 °C, respectively.

of substitution (DS) of the aromatic and alkyl

Compared to the DSC analyses, it is clear that

hydroxyl groups for HPL, PL and Acet-L were

the degradation temperatures for the lignin

100, 88, and 97%, respectively.

P NMR analyses the degree

samples are significantly higher than the softening temperatures. The degradation tem-

The results of the TGA analyses for the modified

peratures are also significantly higher than the

lignins are presented in Table 3. Compared to

corresponding temperatures for the employed

native LB, the modified lignins have somewhat

wood pulps (approx. 220 °C). Hence, we can

reduced thermal stabilities. The Tdeg10 was

conclude that the lignins are suitable for melt

observed for the PL, HPL and Acet-L samples

processing with the wood pulps.

at 245, 301 and 273 °C, respectively.

Figure 3. Second heating cycle scans for the HPL (green), PL (red) and Acet-L (blue) samples. The heating ramp was 10 °C/min.

FUBIO JR2 PROGRAMME REPORT

109

The main purpose of the internal plasticization

Based on the preliminary laboratory scale

was to reduce the softening temperatures of

results, the most interesting materials and their

lignin and hence improve the ductility of the

combinations were further evaluated using a

composites. Figure 3 presents the results of

continuous pilot scale process. Figure 5 shows

the DSC scans for the modified lignins. The

the main processing steps in the manufacture

PL sample gives a complex graph with endo-

of thermoplastic lignin composites at the pilot

thermic peaks at 0.4 °C and 47.3 °C and a very

scale. Compacting was used to reduce the large

weak endothermic decline at 78.7 °C. It is un-

volume of the pulps prior to compounding.

clear whether some of these peaks are related

The

to Tg . In the HPL and Acet-L scans, the clear

approximately 15mm x 4mm in size, after which

endothermic declines at 112 and 101 °C, respec-

the fibre pellets, lignin, plasticizers and possible

tively, are attributed to Tg2 . Furthermore, the

additives were thermally mixed to form uniform

two weak endothermic declines at 63 (HPL)

compounds. The compounds were prepared

and 46 (Acet-L) °C are attributed to Tg1 .

by using a twin-screw extruder (ZE25 x 48D,

fibres

were

compacted

into

pellets

Berstorff GmbH). Finally, the compounds were

4.2 Processing of lignin composites

injection moulded as test specimens using an Engel (ES 200/50 HL) and mechanically tested

Thermoplastic lignin composites were processed

using an Instron tensile tester.

at two different size scales. Preliminary testing of the new materials and the material combination

The charpy method was used to measure the

was carried out at the laboratory scale. Lignin,

impact strengths for the un-notched samples.

additives and fibres were thermally mixed in a Brabender Plasticorder batch mixer with a

4.3 Thermoplastic lignin composites

sample size of 44 g. The test specimens (see Figure 4) were then injection moulded using a

Various external plasticizers for LB were

MiniJet (ThermoHaake) and mechanically tested

tested

using a tensile tester (Instron).

Based on the preliminary trials, polyethylene

laboratory

scale

experiments.

a) b) Figure 4. Lignin composite in a Brabender batch mixer (a). Two tensile test specimens prepared at laboratory and pilot scale (b).

Figure 5. Processing steps in the pilot scale manufacture of lignin composites.

110

FUBIO JR2 PROGRAMME REPORT

glycol (PEG) was observed to give the best

water soluble, which significantly reduces

processability and tensile properties. Samples

the weather resistance of the composites.

with TMP and Fusellu reinforcements were

Therefore, a new plasticizer for lignin based

produced. The TMP-reinforced composites had

on a mixture of starch acetate (Ac-starch) and

somewhat higher mechanical performance

triethyl citrate (TEC) was developed. Previous

than that of Fusellu. To further evaluate

studies with flax fibre reinforced Ac-starch-

the processability of kraft lignin, externally

TEC composites have shown that the mixture

plasticized composites based on LB, PEG and

has excellent compatibility with cellulosic

TMP reinforcements were fabricated at the

fibres. In addition, Ac-starch and TEC can be

pilot scale. To determine optimal LB lignin/

obtained from renewable sources, and they

TMP/PEG ratios, a series of composites with

are scarcely soluble in water. Preliminary

different compositions were fabricated. The

evaluation

best performing composites had a composition

ratio was performed at the laboratory scale

(by weight) of 49% LB lignin, 30% TMP and

followed by more comprehensive pilot scale

21% PEG. These composites had a tensile

trials. The optimal Ac-starch/TEC ratio was

strength of 28.8 MPa, Youngâ&#x20AC;&#x2122;s modulus of 5.1

found to be approximately 60/40 (by weight).

the

optimal

Ac-starch/TEC

GPa and impact strength of 4.6 kJ /m . Further 2

increases in TMP content did not improve

After the preliminary evaluations, the effect

the tensile properties. Additionally, higher

of lignin content was studied at the pilot

PEG contents (relative to lignin) resulted in

scale (Figure 6). In all prepared samples, the

improved impact strength but also significant

Ac-starch/TEC ratio was 60/40 and the TMP

reductions in tensile strength and stiffness.

fibre content was 20%. Tensile strength of the composites was found to decrease with

PEG has two major drawbacks as a plasticizer:

increasing lignin content. The composites with

1) it is of non-renewable origin and 2) it is highly

32% lignin demonstrated a tensile strength

Figure 6. Effect of lignin content on the mechanical properties of Ac-starch-TEC plasticized composites. The Ac-starch/TEC ratio was 60/40 and the TMP content was 20% in all cases. The best PEG-plasticized composites (49% LB lignin/30% TMP/21% PEG) are shown as a reference.

FUBIO JR2 PROGRAMME REPORT

111

of 26.6 MPa, whereas increasing the lignin

of the initial dry weight. Furthermore, the

content to 49% decreased the strength to

FTIR analysis revealed that the dissolved solid

19.6 MPa. In turn, stiffness of the composites

was almost exclusively PEG. Thus, the large

improved

content.

water uptake (weight increase) of the PEG-

Compared to the PEG-plasticized composites,

plasticized composites can be explained by

the tensile strength of the Ac-starch-TEC

the dissolution of the highly water soluble PEG

plasticized composites were comparable.

component and the successive formation of a

with

increasing

lignin

hollow structure that readily absorbs water. In Water absorption

turn, the dissolved solid from the Ac-starch-

To study weather stability, a series of water

TEC plasticized samples was only 0.3% of the

absorption trials was performed for the

initial dry weight.

injection moulded PEG (49% LB/21% PEG/30% TMP)

and

Ac-starch-TEC

Ac-starch-TEC/27.5%

(45%

TMP)

LB/27.5%

Effect of lignin type on performance

plasticized

The properties of AL and PHWE lignins

composites. The composites were immersed

supplied by Metla and a commercial alkali

in water and the weight changes were

lignin (GV) from GreenValue in composites

monitored over a period of two weeks. Figure

were evaluated. GV is extracted from plant

7 presents the results of the trials. During the

feedstock by an aqueous sodium hydroxide

first week, the weight of the PEG-plasticized

method.

composites increased rapidly until levelling

reinforcement and PEG plasticization of AL

off at 41% after 1.5 weeks. In turn, Ac-starch-

and GV were fabricated at laboratory scale.

TEC plasticized composites demonstrated

Figure 8 presents the results of the tensile

very slow water uptake with a weight increase

tests. Compared to the composites with

of only 6% after two weeks. To evaluate the

the LB matrix, the samples with GV and AL

dissolved material, the used water bath

show reduced tensile strengths and modulus,

solutions were collected and evaporated. The

whereas the strains at break are significantly

residual solids were weighted and analysed

increased. The notably high ductility of the AL

with FTIR. The amount of dissolved material

composites is attributed to the low Tg2 of the

from the PEG-plasticized samples was 7.5%

material.

Identical

samples

with

TMP

Figure 7. Results of the water absorption tests for PEG (diamonds) and Ac-starch-TEC (circles) plasticized composites.

112

FUBIO JR2 PROGRAMME REPORT

Figure 8. Tensile properties of the PEG and Ac-starch-TEC plasticized composites with different lignin matrices.

Moreover, composites with Ac-starch-TEC

corresponding AL composites. The viscosity

plasticization were fabricated at laboratory

of the LB composites was so high that the

scale using AL and PHWE lignins as the matrix

composites could not be injection moulded.

materials. Compared to PEG plasticization, Ac-starch-TEC

plasticized

composites

Following

the

promising

laboratory

scale

show higher tensile strength and modulus,

tests, AL and PHWE lignins were also tested

whereas the strain at break is lower. In

at the pilot scale. Figure 9 shows the results

turn, the Ac-starch-TEC plasticized PHWE

for the Ac-starch-TEC plasticized composites.

composites

tensile

The properties are highly similar between the

strength and modulus with respect to the

samples. The only exception is observed in

have

notably

higher

Figure 9. Mechanical properties of composites based on the LB, AL and PHWE matrices. In all cases, the composition was 41% lignin/39% Ac-starch-TEC/20% TMP. The composites were fabricated at the pilot scale.

FUBIO JR2 PROGRAMME REPORT

113

impact strength, which was 2.1 and 2.3 kJ/m2 for

plasticizers such as PEG is a significant

the AL, PHWE composites, respectively, and 1.6

limitation on the wider utilization of the

kJ/m2 for the composites with the LB matrix.

material. One possibility for improving the stability is to reduce the content of free PEG.

Composites based on acetylated lignin

However, a simple reduction of PEG content in

In addition to external plasticization, internally

the composites leads to significantly weaker

modified (i.e. internally plasticized) lignins

tensile properties, such as lower ductility

were also tested in composites. The selected

and increased brittleness. To circumvent this

modification

acetylation,

problem and to optimize the compatibility

hydroxypropylation and palmitic acid grafting.

between the fibres and the matrix, TMP was

The aim of internal plasticization was to

chemically cross-linked with PEG diepoxide

replace the external plasticizers or, at least,

[PEGDE, polyethylene glycol (200) diglycidyl

to significantly reduce the need for external

ether, Polysciences, Inc.] to produce PEG-

plasticizers. The composites based on palmitic

grafted TMP.

methods

were

acid grafted lignin (PL) were processable without

external

However,

For the composite trials, several samples

processing of the composites based on the

with different degrees of cross-linking were

acetylated (Acet-L) and the hydroxypropylated

prepared. The results of tensile tests on

(HPL)

possible

two samples with a lower (6%) and a higher

without external plasticizers. Moreover, both

(20%) degree of cross-linking are shown in

modifications required the same amount of

Figure 10. The details of the compounded

Ac-starch-TEC plasticizer as the composites

samples are presented in Table 4. Based on

based on unmodified LB.

these results, the tensile strengths were

lignin

plasticizers.

matrices

was

not

significantly increased when the sample In the preliminary laboratory scale tests, the

had a higher degree of cross-linking (20%).

best performance was obtained with Acet-L

Furthermore, a lower degree of cross-linking

composites.

therefore

(6%) had a positive effect. In comparison

selected for closer evaluation in pilot scale trials

This

material

was

with the reference sample, after PEG grafting

using Ac-starch-TEC as the external plasticizer.

the tensile strength improved by 45%.

Fusellu was employed as the reinforcing fibre

Simultaneously, the amount of free PEG could

as it gave generally better results in Ac-starch-

be reduced by 4 wt% without compromising

TEC plasticized systems compared to TMP.

ductility or stiffness, which improved by 23%.

The composites with the Acet-L matrix had higher improved properties compared to the unmodified LB composites. Composites with 36% Acet-L, 34% Ac-starch-TEC and 30%

4.4 Structural characterization of the composites using X-ray microtomography

Fusellu had the best mechanical properties, and their recorded tensile strength (35 MPa)

The utilized processing techniques (twin-screw

was the highest of all the injection moulded

extrusion and injection moulding) expose

composites. In addition, their impact strength

the fibres to harsh conditions such as high

(3.8 kJ/m2) was the highest of all the Ac-starch-

temperatures and shear forces. The process is

TEC plasticized composites.

particularly harmful to cellulosic fibres, which have been observed to undergo substantial

114

Composites based on chemically modified TMP

decomposition.

The low water stability of typical lignin

especially problematic as this is one of the key

Reduced

fibre

length

FUBIO JR2 PROGRAMME REPORT

Figure 10. The effect of cross-linking with PEG diepoxide on strength properties of the compounded material at laboratory scale. The amounts of different components and the degree of cross-linking are shown in Table 4. Table 4. Composition of the compounded samples cross-linked with PEG diepoxide (strength test results are presented in Fig. 10).

Sample

Lignins

wt-%

Plasticiser

wt-%

Fibre

wt-%

FU88, Ref

PEG

TMP

FU112

PEG

22,8

TMP-g-PEG (6%)

21,2

FU113

PEG

TMP-g-PEG (20%)

factors defining the mechanical performance

visible and some fibre agglomerates (white

of the reinforced composites. Particularly

lumps) can be seen indicating poor dispersion.

challenging is the low impact strength, which limits the utilization of lignin composites in

Before

more demanding applications, such as in

geometrical structure of the samples can be

vehicles. Therefore, the effect of processing

made, the images must be pre-processed to

conditions on the reinforcing fibres in the

remove spurious noise. Different methods for

thermoplastic lignin composites was analysed

noise removal filtering were tested. The best

using

microtomography

of these appear to be simple Gaussian filtering

(X-ÂľCT). Particularly, the focus was on fibre

and variance weighted mean filtering. In the

length and distribution in the matrix.

first method, the final value of a pixel is the

X-ray

computed

quantitative

assessments

the

weighted mean of the surrounding pixel values The characterization study began with an

where the weight function is a Gaussian. In the

initial search of imaging parameters. This

second method, the mean around a pixel is

process, done using thermoplastic lignin

weighted using the inverse of local variance

composite materials, indicated that the image

around the pixel, thus reducing blurring of

contrast between fibre and matrix is sufficient

sharp edges. The method of choice depends

to enable the phases to be differentiated

on the quality of the original image and the

from each other. Figure 11 shows a composite

type of analysis carried out on the sample.

material sample consisting of a PEG-plasticized LB matrix and 25% TMP. The fibres are clearly

FUBIO JR2 PROGRAMME REPORT

The methods of analysis found to be most

115

a) b) c) Figure 11. X-µCT images of a PEG-plasticized lignin/20% TMP sample processed at laboratory scale. Crosssection of the sample (a) shows fibres visible as brighter areas. Two 3D visualizations of the same sample with different, b) low and c) high resolution. Large white areas in the middle image are fibre agglomerates.

useful for the materials include measurement

approximate diameter). All of the methods

yield the distribution of the measured value

fibre

length

using

granulometric

technique, measurement of fibre orientation

(e.g. fibre length distribution).

using the structure tensor method, and measurement of fibre cross-sectional shape

The homogeneity of the fibre volume fraction

parameters using a novel technique where

in the PEG-plasticized LB matrix with 20%

local fibre orientation information is used to

TMP tensile test specimens was analysed

construct 2-dimensional slices of fibres in

(See Figure 12). Depending on the sampling

the direction of their orientation. The slices

position, the measured fibre volume fraction

can then be used to measure e.g. the cross-

was found to increase such that the volume

sectional area of fibres or shape descriptors

fraction is lowest close to the injection cavity

of the fibre cross-sections (e.g. circularity or

and highest at the other end of the specimen.

Figure 12. Volume fraction of fibres in different locations (a) in the thermoplastic lignin test specimen (b). The injection direction was from “broken end” to “non-broken end”.

116

FUBIO JR2 PROGRAMME REPORT

Following these results, further tomographic

To compare the present results with such

analyses were conducted on samples taken

measurements, the mean fibre lengths were

from the middle part of the specimen.

also determined for the L > 500 µm fractions. The results indicate mean fibre lengths in the range

It was observed that the aspect ratio of the fibres

650 µm – 900 µm for the tensile test specimens

decreases significantly when the intact fibres

and 1500 µm and 960 µm for intact chemical

are processed as injection moulded specimens.

and mechanical pulps, respectively (see Figure

A good example of the results is given in Figure

14). It is thus evident that the pelletization,

13, where the aspect ratio distributions and the

compounding and injection moulding processes

corresponding means for pulp fibres, pelletized

significantly increase the fraction of fines,

fibres and the final injection moulded tensile test

possibly decreasing the mechanical properties

specimen are shown. The material in FUMO68

of the composite materials.

consisted of 20% Fusellu, 39% Ac-starch-TEC and 41% lignin. The reduction in mean aspect

ratio is clearly visible both in the distributions

mechanisms of composite materials is whether

key

question

concerning

the

fracture

and in the means.

the reinforcement fibres are mainly broken at the fracture surface, or whether some of them

The mean fibre length of the injection moulded

are pulled out of the matrix at fracture. The latter

specimens was in the range 150 µm–300 µm,

case would be indicative of inadequate bonding

and the mean aspect ratio in the range 10 – 20

between the matrix and the fibres. The fracture

µm (see Figures 14 and 15). The composition

surfaces of two material samples manufactured

of the composites is presented in Table 5. The

in this project, FUMO18 (20% TMP in PEG-

mean fibre length of the raw chemical (Fusellu)

plasticized LB matrix) and FUMO39 (20% TMP

and mechanical (TMP) pulp, measured with the

in Ac-starch-TEC plasticized LB matrix), were

X-µCT technique, was 1100 µm and 600 µm,

studied using X-µCT imaging. Based on visual

respectively. The decrease in fibre length due

inspection of the images, it appears that in both

to processing is thus very large.

of the studied samples only a minor proportion of fibres were pulled out, with most remaining firmly

In some manual methods fibres less than 500 µm

attached to the matrix, see Figure 16. Hence,

in length (typically classified as “fines”) are not

we can conclude that the fibres have a strong

included in the mean fibre length determination.

positive reinforcing effect on the composites.

Figure 13. a) Length/diameter distributions estimated for FUMO68 b) Mean length/diameter distributions for FUMO68. Mean values are calculated based on both major (d1) and minor (d2) diameters of fibres, but the distributions are shown only for L/ d1.

FUBIO JR2 PROGRAMME REPORT

117

Figure 14. Mean fibre length of the selected composites, raw fibres and pellets. Means are calculated from full data (blue bars) and from the >500 Âľm length fraction (red bars).

Figure 15. Mean fibre aspect ratio of the selected composites, raw fibres and fibre pellets. The crosssection of the fibre has been approximated with an ellipse, where d1 refers to the length of the major axis and d2 to the length of the minor axis of the ellipse.

Table 5. Composition of the composites. Fibre weight fraction was 20% in all cases.

Sample

Fibre type

Lignin wt-%

Acetylated

TEC wt-%

starch wt-%

118

FUMO39

TMP

40.8

23.2

16.0

FUMO68

Fusellu

40.8

23.2

16.0

FUBIO JR2 PROGRAMME REPORT

a) b) Figure 16. Cross-sectional X-µCT slices of FUMO18 (a) and FUMO39 (b). Dark, medium grey and light grey colours indicate air, matrix and fibres, respectively. Only a few pulled-out fibres and micro-cracks extending in the bulk material are visible.

4.5 Demonstrators

Fusellu reinforcements). Two different moulds were employed to produce the parts. The

The processability of the thermoplastic lignin

“spacer mould” is a commercial mould used

composites was demonstrated at VTT by

to manufacture complex, thin-walled parts

injection moulding parts using commercial

employed in concrete casting (a). The other

moulds provided by Rinotop (Figure 17). The

mould was a “ball mould” used for producing

demonstrator parts were prepared using

knobs for skipping ropes (b). The ball mould

the best material combinations (PEG as well

has thick walls setting special requirements

as Ac-starch-TEC plasticized LB matrix and

for the heat conductivity of the material.

a) b) Figure 17. Injection moulded demonstrator parts with wood-derived material contents up to 77%.

FUBIO JR2 PROGRAMME REPORT

119

5. Exploitation plan and impact of results In this project, novel thermoplastic lignin

potential is substantial, and furthermore, large

composites

pulp

quantities of lignin are commercially available

after the recent introduction of the LignoBoost

thermoplastic lignin was demonstrated using

technology. The results of this work serve as

typical processing equipment, such as twin-

a platform for further development of high-

screw extruders and injection moulders.

performance composite materials based on

The tensile properties of the lignin composites

thermoplastic lignin.

were

reinforced

developed.

The

with

wood

processability

are close to its main competitors: wood fibre composites

with

petroleum-based

matrix

polymers. Therefore, the potential application

6. Networking

areas for the lignin composites are the same as for the aforementioned polymers and

The research was carried out jointly by

reinforced composites. These areas include

research organizations and Finnish forest

the construction (e.g. decking, fencing, window

cluster companies. Table 6 presents the

frames), furniture (e.g. chairs, tables, cupboards)

partners and their role in the research.

and automotive (e.g. interior parts) industries. Lignin

samples

and

mechanical

The most promising target applications with

performance data were exchanged between

the current material performance profile are

the

foreseen to be found in construction. At present,

(Canada) during the project.

project

partners

and

FPinnovations

the inadequate impact strength of the injection moulded composites limits the utilization of the material in more demanding applications, such as in vehicles or furniture. However, the

Table 6. Partner organizations and their research roles.

Work package partners

Role of the participating organization

Mets채 Fibre

Industrial tutor. Supplier of bleached softwood pulp.

Novoplastik

Testing and evaluation of composite samples.

Stora Enso

Industrial tutor

University of Helsinki

Chemical activation and modification of fibres enabling binding with matrix lignin in composite materials.

University of Jyv채skyl채

Characterization and analysis of composites by X-ray computed microtomography.

UPM-Kymmene

Work Package Coordinator. Supplier of thermomechanical softwood pulp.

VTT

WP leader. Processing and production of thermoplastic lignin composites. Chemical modification of lignin and enzymatic modification of fibres.

120

FUBIO JR2 PROGRAMME REPORT

7. Publications and reports Lahtinen, M., Ojala, A., Wikström, L., Hietala, S., Nättinen, K., Fiskari, J. and Kilpeläinen, I. Injection-molded fiber-reinforced lignin composites from chemically modified thermomechanical pulp (TMP) fibers, in preparation. Miettinen, A., Joffe, R., Madsen, B., Nättinen, K. and Kataja, M. Quantitative analysis of length-diameter distribution and cross-sectional properties of fibers from three-dimensional tomographic images, Proceedings of the 34th Risø International Symposium on Materials Science, 2013. Miettinen, A., Ojala, A., Wikström, L., Joffe, R., Madsen, B., Nättinen, K. and Kataja, M. Nondestructive automatic determination of aspect ratio and cross-sectional properties of fibres, in preparation. Myllymäki, T. Ligniinin rakenne ja kemiallinen muokkaus, Master’s thesis, University of Helsinki, 2014. Nättinen, K., Kouisni, L., Paleologou, M., Wikström, L. von Weymarn, N. and Browne, T. Composites of kraft lignin, Poster presentation together with FPInnovations in NWBC, Helsinki, 2012. Ojala, A., Wikström, L., Lehmonen, J. and Nättinen, K. Foam-laid formed thermo-mouldable nonwovens, Proceedings of Composites Australia and the CRC for Advanced Composite Structures, Newcastle, Australia, 2014.

FUBIO JR2 PROGRAMME REPORT

121

BIOREFINERY PRODUCTS INITIAL PROCESS PILOTING AND MATERIAL PROTOTYPE PRODUCTION IN THE CASE OF BARRIERS, 3D-MOULDABLE PACKAGING AND FILTERS

CONTACT PERSON – Work Package 4 leader Jonas Hartman, jonas.hartman@vtt.fi Aalto University: Ramarao Abburi, Ilari Filpponen, Jiagi Guo, Karoliina Junka, Janne Laine, Alexey Khakalo, Eve Saarikoski, Jukka Seppälä, Ola Sundman, Monika Österberg Kemira: Mari Ojanen, Reetta Strengell, Tarja Turkki Lappeenranta University of Technology: Kaj Backfolk, Henry Lindell, Daria Nevstrueva, Arto Pihlajamäki, Sami-Seppo Ovaska, Esa Saukkonen, Panu Tanninen Metsä Board: Pekka Suokas Metsä Fibre: Pirkko Liias, Raili Koponen Stora Enso: Mari Hiltunen, Outi Kylliäinen, Titta Lammi, Jari Räsänen Tampere University of Technology: Hanna Christophliemk, Johanna Lahti University of Helsinki: Juha Fiskari, Susanna Heikkinen, Pirkko Karhunen, Ilkka Kilpeläinen, Sirkka-Liisa Maunu, Kirsi Mikkonen, Pirita Rämänen, Joonas Siirilä, Maija Tenkanen University of Oulu: Aleksi Kolehmainen, Henrikki Liimatainen, Juho Sirviö, Miikka Visanko UPM-Kymmene: Harri Kosonen, Leena Kunnas, Jutta Nuortila-Jokinen, Irmeli Sinisalo, Heli Viik Valmet: Ismo Mäkinen, Pasi Nurminen, Ari Puurtinen, Peter Rosenberg, Timo Sutela VTT Technical Research Centre of Finland: Martta Asikainen, Marie Gestranius, Antti Grönroos, Minna Hakalahti, Ali Harlin, Pirjo Heikkilä, Juha Heikkinen, Jaakko Hiltunen, Juha Houni, Petri Jetsu, Saila Jämsä, Timo Kaljunen, Kari Kammiovirta, Annaleena Kokko, Hanna Koskela, Vesa Kunnari, Hanna Kyllönen, Christiane Laine, Marjo Määttänen, Heikki Pajari, Jaakko Pere, Pentti Pirkonen, Pauliina Pitkänen, Hille Rautkoski, Elias Retulainen, Erkki Salo, Harri Setälä, Asko Sneck, Riku Talja, Tekla Tammelin, Alexey Vishtal Åbo Akademi University: Pedro Fardim, Jasmina Obradovic, Joanna Narewska, Victor Kisonen, Stefan Willför

122

FUBIO JR2 PROGRAMME REPORT

ABSTRACT Demonstration and piloting under the title â&#x20AC;&#x153;Improving traditional fibre productsâ&#x20AC;? focused on multilayer barrier packaging, 3D-mouldable packaging and new filter materials. Different types of biobarriers were successfully prepared and coated as water dispersions on precoated base board. The biopolymer-coated webs were also extrusion coated and finally converted into tray form. Six different types of bio-based derivatives were developed and tested during the project. The tested materials were modified GGM, modified xylan, TOFA esters and TOFA alkyd acrylates, dialdehyde cellulose and DAC alginates and cellulose-copolymer blends. Good grease barrier properties were obtained in several barrier material groups. Additional studies on the effect of the base substrate fibre composition revealed that the hemicellulose content of the base substrate affects the convertability of the paperboard and indicated changes in the dispersion coating holdout and grease resistance of dispersion-coated paper. In the case of 3D-mouldable packaging, the maximum extensibility obtained for the paper was around 21% when the polymer dosage was 8%. In-plane compaction increased extensibility up to 35% in the machine direction. Gelatin effectively improved the extensibility and tensile strength of the paper and readily adsorbed on the fibres. In order to enhance the effects, a combination of several chemicals is possible. The treatments are compatible with current papermaking environments and can be used for the production of food packaging materials. The convertability of the produced paper materials was demonstrated in all main forming process types. Several different new filter materials and manufacturing methods were tested. The results obtained with some of the demo materials were very promising. Cellulose membrane cast from ionic liquid was produced for industrial trials and for comparison with commercial references. Retentions of the studied sample were similar or slightly lower than those of the commercial references and in general the demo sample showed very stable but somewhat lower flux in all tested effluents compared to the commercial membranes. Dicarboxylic acid cellulose (DCC) nanofibre-coated membranes gave promising results. The vacuum filtration method of producing the samples proved effective at the laboratory scale, indicating that efficient production of larger membranes, for example by roll-to-roll coating, could be achieved. Initial process piloting and material prototype production gained wide interest from the partner companies. Each of the three product groups had an engaged group of industrial tutors whose input focused the research and contributed considerably to successfully improving on conventional fibre products. Keywords: 3D-forming, biobarrier, filter, forging, formability, membrane, moldability, multilayer barrier, packaging

FUBIO JR2 PROGRAMME REPORT

123

1. Background

renewable material that has certain advantages over

plastic-based

materials.

However,

There is a fast-growing need to find replacements

fibre-based packaging materials cannot yet

for oil-based products. Increasing demand

compete with plastic packaging in terms of

for packaging creates opportunities for bio-

convertability or package design â&#x20AC;&#x201C; fibre-based

based barrier materials that can be produced

packaging exists in rather simple geometrical

from industrial sidestreams, such as from

forms, whereas plastics can be formed into a

paper and board production. The replacement

vast variety of shapes. The main limiting factor

of oil-based products with products derived

for the production of advanced 3D shapes from

from natural sources has been the focus of

paperboard is its poor formability, i.e. its limited

intensive research in recent years. Due to their

ability to withstand certain types of plastic

renewability, biocompatibility, biodegradability,

deformation without damage.

wide availability and non-toxicity, natural biobased products offer a sustainable means

Formability is the ability of a material to be

of obtaining chemicals and materials and

formed

replacing non-renewable resources. One such

forming processes such as hot pressing, vacuum

important group of biorenewable products is

forming,

biopolymers, including polysaccharides, among

formability of fibres and paper is primarily limited

which cellulose, hemicellulose and starch have

by poor elongation, which is typically below 5%.

been extensively studied. Due to their positive

Formability determines the maximum depth

properties compared to oil-based materials,

of shapes and, to certain extent, the material

one of the most promising target applications

appearance. The forming process and process

of biopolymers is in environmentally friendly

variables (including moisture and temperature)

food packaging materials.

also play a central role in formability.

The focus of the FuBio Joint Research 2

Membranes

programme was on biomass fractionation and

materials

the development of current and new biorefinery

pass through whilst rejecting others. Natural

products. The work was based on the research

membranes

results of the first FuBio programme targeting

the main fractions of wood (e.g. cellulose,

although the use of artificial membranes has

hemicelluloses), in which several bio-based

become established in recent decades in a

polymers and polymer blends were developed

wide range of separation processes. The first

for a range of interesting applications. These

artificial membranes were made using the

include dialdehyde cellulose, which is a cellulose

cellulose-based

derivate produced by a regioselective oxidation

Today,

of cellulose using periodate as an oxidation agent,

cellulose acetate and nitrate, are widely used

modified hemicelluloses (galactoglucomannan

in microporous membranes for micro- (MF)

and xylan), tall oil including alkyd-acrylate

and ultra-filtration (UF) and haemodialysis.

hybrid polymers and tall-oil modified cellulose

In addition cellulose-based membranes can

as well cellulose-polyethylene copolymer blends

be used in gas separation as dense, non-

(CePE).

porous films. Cellulose membranes can be

into

complex

stamping

many

are

allowing

certain an

material

The

barrier

compounds important

membrane

cellulose-based

through

deep-drawing.

semipermeable

perform

biological

geometries

to role

processes,

cellulose

nitrate.

materials,

mainly

either symmetric or asymmetric, and their

124

From the point of view of 3D-packaging,

physical strength can be improved with the

cellulose is a recyclable, biodegradable, and

use of support layers. Cellulosic materials are

FUBIO JR2 PROGRAMME REPORT

intrinsically highly hydrophilic and therefore

2. Objectives

ideal for water-based membrane processes. Although synthetic polymers have taken over

New types of bio-based materials were tested

some membrane applications, it is believed

in different packaging applications with the

that novel cellulose materials and advanced

aim of improving traditional fibre products. The

processing technologies will open up new

main objectives were:

possibilities for cellulose, thus reclaiming some markets from synthetic polymers.

• To develop multi-layered board packaging structures, including layers made of possible

The pulp and paper industry is a large consumer

sidestreams such as xylan, GGM, TOFA or

of water, the quality of which varies widely, for

dissolved cellulose, with good grease barrier

example in terms of amount and type of solutes,

properties at high relative humidity to create

pH and temperature. As an example, selected

holistic usage of all materials in a mill/

properties of three waters from pulp mill UF

production site

applications are presented in Table 1. Membrane life cycles are typically expected to be several

In 3D-mouldable packaging structures, the ob-

years, and the typical water processing cost is

jectives were:

less than 1 €/m3, a third of which is attributed to membranes. Cost reduction is needed, as

• To improve of the formability of paper webs

increasing requirements for process water

to a qualitatively new level and develop fibre

recycling are expected in the future. Typical

web based materials for producing deep 3D

water consumption of a pulp mill is currently

shapes (2-3 cm) using industrially feasible

around 20-30 m3 per tonne of pulp. With more advanced membrane technology this could be

technology • To demonstrate the convertability of the

reduced to less than 10 m3 / tonne. Filtration

developed paper-based materials in existing

performance, stability in harsh conditions,

and emerging forming processes

long life span, and low price are key factors

• To increase knowledge of the role of

for membranes used in the pulp and paper

mechanical properties and process

industry.

parameters in the formability of paper webs In filter development, the objective was: • To improve the flux, retention, and/ or prolong the lifespan of membranes, especially those used in pulp and paper industry water systems.

Table 1. Typical examples of pulp mill ultrafiltration waters (pH, temperature and chemical oxygen demand (COD) – commonly used as an indirect measure of organic compounds).

Water

Temperature

COD

White water from the pulp drying machine

4–5

50 °C

500-650 mg/l

EOP filtrate from the bleaching plant

9 – 10

60 °C

2000-5000 mg/l

70 °C

> 100000 mg/l

Press washer filtrate after chemical cooking

FUBIO JR2 PROGRAMME REPORT

125

3. Research approach

Figure 1 shows a schematic of the barrier development approach. In the barrier research,

Three product applications were selected for

each of the six material groups developed

initial piloting and demonstration: 1) grease

their products individually (Figure 1: Synthesis).

barrier in multilayer board packaging structures,

Studies

and 2) 3D-mouldable webs and 3) filters.

coating assisted in the evaluation of the film

When the results for the different materials

formation properties and application recipe

developed in the first FuBio programme for

of the materials (Figure 1: Self-standing films,

similar

the

Spin coating). All materials were applied on a

importance of centralized testing environments

selected base board and the resulting barrier

and measurements became clear. Therefore,

properties were tested (Figure 1: Laboratory

in the present programme centralized testing

coating, Pilot coating). After each coating

platforms were designed.

application round (several laboratory rounds

applications

were

compared,

self-standing

films

and

spin

and a pilot trial) feedback was given to the In

packaging

development

barrier was

research,

aimed

material

achieving

material development groups and improvement

targets were agreed (e.g. moving from solvent-

grease barrier by means of dispersion coating,

based system towards water dispersion, aiming

improving the mouldability of conventional

for a less tacky product, etc.). After two years,

fibre webs, and demonstrating and piloting the

the industrial tutors selected the three most

developed materials.

promising derivatives for an additional pilot

â&#x20AC;˘ Comparison between samples that spread well â&#x20AC;˘ Clear effect of substrate and barrier sample chemistry

Synthesis

Self-standing films

Pilot coating

Extrusion

Spin coating

Laboratory coating

Converting

Figure 1. Barrier research approach.

126

FUBIO JR2 PROGRAMME REPORT

scale trial. After pilot coating the biobarrier-

formability was improved via two approaches:

coated webs were extrusion coated and further

1) increasing the extensibility potential of fibres

converted into tray form, representing the final

and paper, and 2) subjecting swelled pulp fibres

product (Figure 1: Extrusion, Converting).

to extremely high pressure loads. Table 2 shows the research approach.

As part of the dispersion barrier development, additional studies with dual-polymer systems

In filter development, the used test waters

with and without high aspect ratio plate-

were kept as constant as possible throughout

like pigment addition were also conducted in

the project and fibres and new technologies

order to increase the grease resistance and

were studied with the aim of producing

convertability of paperboard. The effect of

materials applicable in reactive and active

the base substrate on flexible packaging was

filter and membrane applications. The work

evaluated with special attention to the fibre

included membrane and membrane component

composition. The effect of fibre composition on

development and functionalization as well

convertability was studied by preparing a novel

as study of membrane properties. The main

papermaking fibre with cellulose-rich fibre

approaches

surfaces by enzymatic hemicellulose removal.

included casting of membranes using ionic liquid

membrane

development

(IL) and preparation of nano- and micro-fibrous In the 3D-mouldable web research task,

materials for layered structures using coatings

various approaches were taken to improve

of dicarboxylic acid cellulose (DCC) nanofibres

the formability of paper-based materials. The

and electrospun micron and sub-micron fibres.

Table 2. Mouldable web research approach.

FUBIO JR2 PROGRAMME REPORT

127

4. Results

area with respect to 3a) grease resistance and water vapour barrier or 3b) oxygen and water

4.1 Improving grease resistance in multilayered board packaging structures

vapour barrier. Regarding

the

cellulose-copolymer

blends

In the barrier research, new coating materials

(CePE), grease resistance of over 65 days

for achieving grease resistance of paperboard

was obtained with a dissolved cellulose/

in packaging applications were developed.

poly(ethylene-co-acrylic acid) blend with a

One aim was to obtain the coating materials

95/5 polymer/polymer ratio. After dispersion

as water-based dispersions. Six different types

coating, the best OTR achieved was 130 cc/

of bio-based derivatives were developed and

(m2d bar); however after PE extrusion OTR the

tested during the project. These were modified

value was as low as 2 cc/(m2d bar). The WVTR

GGM (Åbo Akademi University), modified xylan

target was also achieved. In this group, the

(VTT), TOFA esters and TOFA alkyd acrylates

blending capability of commercial co-polymers

(University of Helsinki), dialdehyde cellulose

with alkaline aqueous cellulose solution was

alginates (University of Oulu) and cellulose-

studied and the mixing procedure and blend

copolymer blends (Aalto University). Additionally,

compositions developed. This was done in order

the barrier coatings were up-scaled from lab

to obtain the best morphology of the solutions/

to pilot scale and the multi-layer paperboard

suspensions for the coating trials.

packaging structures with good grease barrier properties were demonstrated. More than 60

TOFA-based

derivatives were tested during the project.

synthesized and applied on paperboard and

hybrid

latexes

(HL)

were

Centralized coating tests were performed at

water and grease barrier properties were

VTT facilities (Figure 2) and pilot coated samples

analysed. Good water and water vapour barrier

were further sent to TUT for extrusion coating

properties were achieved, whereas the grease

and LUT for conversion into tray form.

barrier was moderate. Oxygen barrier property was improved when talc or cellulose was used

Sample characterisation was also conducted

as filler. The materials were also heat-sealable.

in a centralized testing environment, including

However, some process scale-up issues (e.g.

grease, water vapour transmission (WVTR) and

adhesion problems) remained unresolved.

oxygen barrier (OTR) measurements. The

128

xylan

derivatives

–

particular

When considering the grease barrier, the most

hydroxypropylated xylan (HPX) dispersions

promising coatings are cellulose-copolymer

– could be coated as such, cross-linked,

blends (CePE) and hydroxypropylated xylan

plasticized and filled with talc or nanoclay and

coatings. Figure 3 shows the results for the

showed good grease barrier properties in all

best candidate of these two (CePE and xylan)

cases. The barrier-enhancing fillers concept

as well as TOFA hybrid latex (HL) derivative

was demonstrated and WVTR of 46 g/(m2d)

families as normalized to 20 µm thickness. In

and OTR of 72 cc/(m2d bar) were achieved.

grease resistance measurements our target

In addition, the concept of low DS combined

was to attain extended resistance, i.e. high

with external plasticization, enabling a bio

values when measured in days (y-axis) as

content of up to 90%, was tested successfully.

well as low water vapour and oxygen transfer

The colour of the coating material colour was

rates (WVTR and OTR, respectively). The blue

white and remained stable during drying and

circle represents the combined target value

converting. Heat sealability was achieved, and

FUBIO JR2 PROGRAMME REPORT

Figure 2. Pilot trial equipment at VTT.

Figure 3. Best barrier properties of the three most promising derivatives normalized at 20 Âľm thicknesses, measured at 23 oC, 50%RH. The targeted area in Figure a) is in the top left corner and in Figure b) in the bottom left corner.

PE extrusion coating was possible leading to

and multi-layer paperboard structures with

OTR values below 10 cc/(m2d bar). Die-cutting

several beneficial characteristics, especially

and press-forming into trays was successful.

grease barrier properties, were produced. All of the derivatives require further optimization

In conclusion, several potential barrier dispersion

according to the target end use, but can be

coatings were developed and demonstrated

readily utilized at the industrial scale.

FUBIO JR2 PROGRAMME REPORT

129

Improving grease resistance of starch-based

4): a) mechanical treatment of fibres to reduce

coatings

their axial stiffness, create microcompressions

When synthetic polymer was added to

and dislocations (steps 2 & 3); b) improvement

modified

(dual-

of inter-fibre bonding by spray application of

polymer system) at optimized amounts,

polymers (step 4) c) structural modification

efficient grease resistance was achieved. The

of the fibre network by in-plane compaction

addition of synthetic polymer to starch-based

treatment and unrestrained drying of the paper

coatings improved the elastic properties and

to allow free shrinkage (steps 5 & 6). Used in

plasticity and, subsequently, the mechanical

combination, these stages could achieve paper

convertability of the product. Addition of plate-

elongation of 15â&#x20AC;Ś30%. In addition to these

like like pigment to the renewable dispersion

treatments, the forming conditions (mainly

coating increased the grease resistance of

temperature and moisture content of paper) that

the non-converted blanks, whereas micro-

affect the softening of the polymers (cellulose,

scale cracks in the barrier were frequently

hemicelluloses, added polymers) could improve

observed after tray conversion, resulting in

the extensibility by 2â&#x20AC;&#x201C;4 percentage points. It

poor grease resistance.

was found that paper at a moisture content of

starch-based

dispersion

8-11% can soften at 80 Â°C, but further increases in temperature or moisture decrease formability.

Effect of hemicellulose removal on

The combined approach for the improvement of

convertability

The

effect

fibre

composition

formability is shown in Figure 4.

convertability was studied by preparing a novel papermaking fibre with cellulose-rich

The

fibre surfaces by enzymatic hemicellulose

polymers was tested (starch, xyloglucan,

removal. Xylanase treatment of refined never-

hydroxypropylcellulose, CMC, gelatin, agar).

dried bleached birch kraft pulp demonstrated

Spray addition of these biochemicals was found

selective

the

to increase both strength and elongation. The

outermost fibre layers, reducing 14.2 wt% of

most interesting chemicals were agar and

the total amount of xylan in the studied pulp.

gelatin. For example, gelatin improved the

The mechanical properties of paperboard at

extensibility and tensile strength of unrestrained

180 g/m2 grammage were mainly preserved

and restrained dried paper. A 4% gelatin addition

despite a 14.2 wt% reduction in xylan content.

improved the tensile strength from ca. 50 Nm/g

Press-forming of the produced materials

to ca. 80 Nm/g, and extensibility from ca. 9%

revealed differences related to the end

to 13% for unrestrained dried paper. However,

moisture content of the produced paperboard

besides strengthening fibre bonding, chemical

(i.e. drying severity), fibre composition (i.e.

addition also increased drying shrinkage.

hydrolysis

xylan

from

application

several

natural

hemicellulose content), and press-forming parameters. Consequently, the suitability of

Papers prepared using the combined approach

the paperboard could be optimized for flexible

(as shown in Figure 4, excluding the compaction

packaging

stage) were used to produce three sets of demo

tailoring

the

carbohydrate

composition of the base substrate.

materials. The test results clearly demonstrated that different forming processes have different

4.2 Improving formability of paper-based materials

formability requirements. One key difference between the processes is whether the paper blank is allowed to slide into the mould (sliding

130

The approach used for improved formability of

blank) or whether it is strained into the mould

the fibre web included three major stages (Figure

(fixed blank). In the deep-drawing process

FUBIO JR2 PROGRAMME REPORT

Figure 4. Combined approach for improvement of formability.

Figure 5. Classification of the basic forming methods tested and examples of shapes obtained. The hot pressing mould is a VTT Design.

the paper is allowed to slide and the depth of

was obtained at a polymer dosage of 8%.

the shape is almost unlimited, although the

In-plane compaction further increased the

appearance worsens with increased depth.

extensibility up to 35% in the machine direction.

The basic process types tested in the project

Gelatin effectively improved the extensibility

are classified in Figure 5. Detailed photos of

and tensile strength of the paper and readily

samples made in fixed blank processes are

adsorbed on the fibres. For enhanced effects, a

shown in Figures 6-8.

combination of several chemicals can be used. These treatments are compatible with current

Maximum paper extensibility of around 21%

FUBIO JR2 PROGRAMME REPORT

papermaking environments and can be used for

131

Figure 6. Tray-like shapes (underside and top side) obtained by a hot pressing process developed by the Moldable Web project at VTT. The shape depth is around 16 mm.

Figure 7. Double-curved structure produced by hydroforming. Around 20% extensibility is required for this formation. (Hydroforming performed by the Royal Institute of Technology (KTH), Sweden.)

Figure 8. Tray-like shape air-formed by PACCOR (Coveris). Maximum shape depth ~25 mm.

Figure 9. Schematic approach for the improvement of mouldability of cellulose (Ă&#x2026;A): 1) Starting material: softwood dissolving pulp; 2) Swelling of cellulose in DMAc-LiCl; 3) Forging the swelled cellulose at 70MPa pressure; 4) The resulting cup-like form, height ca. 50 mm.

132

FUBIO JR2 PROGRAMME REPORT

the production of food packaging material. The

ture of the obtained material was unique and

convertability of the produced paper materials

the properties of the produced membranes var-

was demonstrated in all main forming process

ied according to the process parameters, such

types.

as coagulation bath temperature and used additives. In lab-scale testing, the prepared mem-

Preparation of three-dimensional cellulose

branes were compared with one of the best

objects from fibres previously swelled in

commercial RC70PP membranes.

DMAc/LiCl solvent system

In this approach, the aim was to take advan-

One membrane sample was produced for in-

tage of the modifications in intermolecular in-

dustrial trials for comparison with commer-

teractions that swelling treatment induces in

cial references. The sample was pure cellulose

cellulose in order to be able to subject the cel-

(8 wt-%) without any additives or any surface

lulose to moulding and high pressure. Cellulose

functionalization supported by PET nonwo-

pulp was swelled with DMAc/LiCl solvent sys-

vens. Industrial trials were carried out by Valmet

tem, washed and dried before further process-

Technologies at the MetsĂ¤ Fibre Rauma mills

ing. In addition, acrylated epoxidized soybean

using a CR250/2 unit (effluents listed in Table

oil was incorporated into the swollen fibres to

3). Retentions of the studied sample were simi-

improve mouldability. The formability of these

lar or slightly lower than the commercial refer-

treated cellulose samples was then evaluated.

ences (see white water example in Table 3), and in general the demo sample showed very sta-

This approach is unique in that the core treat-

ble, but somewhat lower flux in all tested efflu-

ment involves the swelling of the dissolving

ents compared to the commercial membranes.

pulp in non-aqueous salt solution to disrupt the inter- and intramolecular hydrogen bonding

The results obtained are very promising, as

and decrease the crystallinity of the cellulose,

there are currently no commercial cellulose

with subsequent forging under high pressure

membranes fabricated directly from cellulose.

to create a dimensionally stable shape. Swell-

The membrane preparation process however

ing of cellulose in non-aqueous salt solution

requires further development in order to opti-

with consequent forging may be used for the

mise the membrane properties for specific end

production of three-dimensional translucent

uses, to enable the production of larger mem-

shapes from cellulose.

brane pieces for flat membranes, and to transfer the technology to hollow fibre (HF) mem-

4.3 Main results for filter materials

brane production.

IL casting

Functional IL-cast membrane

Casting based on phase inversion by immersion

IL casting was also used to create temperature-

precipitation typically produces an asymmetric

responsive membrane in cooperation with LUT

membrane structure with a thin, tighter skin lay-

and VTT. VTTâ&#x20AC;&#x2122;s allylated cellulose was cast at

er for good separation on one side and an open

LUT and subsequently grafted with poly(N-iso-

pore structure bulk layer providing good flux.

propylacrylamide) (PNIPAAm) at VTT. A non-

Such materials are typical in UF filtration appli-

grafted reference and the PNIPAAm grafted

cations. LUTâ&#x20AC;&#x2122;s casted membranes were based

demo material were tested at the lab scale.

on commercial cellulose dissolved into IL liquid.

Stimuli-responsive behaviour of the grafted

The solution was cast and the resulting wet film

membrane was observed in pure water flux

was soaked in a non-solvent bath. The struc-

testing as well as anti-fouling and easy-clean-

FUBIO JR2 PROGRAMME REPORT

133

Figure 10. a) Pure water flux at different temperatures; and b) at different stages of wood hydrolyzate filtration; and c) appearance of non-grafted and PNIPAM grafted allylated cellulose membrane. In (c) nongrafted sample on left, grafted on right. Table 3. Analyzed compounds in the feed and the permeate samples of white water using the LUT demo sample and commercial RC 30 kDa membrane.

Sample

COD total mg/l

COD soluble mg/l

Conductivity mS/m

Charge Âľekv/l

TSS GF/A mg/l

Turbidity NTU

White water feed

610

520

4.5

230

-40

167

128

LUT demo sample

470

460

4.8

220

-32

0.4

Reduction

23%

12%

20%

100%

RC 30 kDa

500

490

220

-15

0.3

Reduction

18%

63%

100%

4.8

ing properties during wood hydrolyzate filtra-

on top of a commercial support material using

tion, see Figure 10. The cycle was repeated

DCC-nanofibrils (see Figure 11). The properties

twice and the properties of the grafted mem-

of the produced membranes depended on the

brane restored fully after each cycle.

various process parameters, such as the layer thickness and used cross-linking agent.

DCC nanofibre coating

134

Layered structures are characteristic of fibrous

These cellulose-based membranes are best

materials. Whereas an asymmetric pore size

suited to neutral conditions with a pH range of

distribution is obtained inherently in casting,

1-11, preferably 5-9. The membranes can puri-

a similar effect can be obtained by combining

fy clear water from feed solutions where the

layers of different pore size. Support materi-

largest contaminant particles have been re-

al layers provide mechanical strength without

moved and the temperature is below 70Ë&#x161;C. The

significantly affecting flux, while layer(s) with

functionality of the fabricated membranes was

smaller fibres and pore sizes provide effective

demonstrated with real industrial process wa-

depth filtration. University of Oulu prepared a

ter with a high level of purification achieved

new type of membrane barrier layer structure

with paper machine disc filter fractions (cloudy

FUBIO JR2 PROGRAMME REPORT

Figure 11. DCC barrier layer (a) surface structure and (b) cross-sectional structure.

and clear filtrate). The filtration efficiency in

materials was demonstrated in all main forming

terms of fouling, flux and purification degree

process types. Here the exploitation potential

was as good as the commercial reference

of the results depends on the raw material pric-

UH030 when CaCl2 was used as a cross-linking

es of addition chemicals and costs for new unit

agent in membrane preparation.

operations. The development of new filter materials shows promising results, however this

The results obtained with this demo materi-

area needs a lot of research before industrial

al were very promising. The vacuum filtration

products can be talked about.

method of producing samples proved effective at the laboratory scale, indicating that efficient

This work will have itâ&#x20AC;&#x2122;s largest impact on im-

production of larger membranes by roll-to-roll

proving conventional fibre products through

coating can be achieved.

increased knowledge among researchers and industry in the areas of biobarriers, mouldable

5. Exploitation plan and impact of results

packaging and filter.

6. Networking

Initial process piloting and material prototype production tasks focused on improving con-

Several research partners were involved this

ventional fibre products. Whilst different types

study. In addition, industry partners actively

of biobarriers were successfully prepared and

participated in steering and guiding the work

coated as water dispersions on precoated base

and in conducting measurements and trials,

board many process and product issues still

see Table 4. Partner organizations and their re-

need to be solved before any of the materials

search roles.

can be taken to products. In the case of 3Dmouldable packaging, on the other hand, the studied treatments are compatible with current papermaking environments and can be used for the production of food packaging materials. Also the convertability of the produced paper

FUBIO JR2 PROGRAMME REPORT

135

Table 4. Partner organizations and their research roles. Work package partners

136

Role of the participating organization

Aalto University • Polymer Technology (P) • Forest Products Technology (FP)

(P) Blending capability of commercial co-polymers with alkaline aqueous cellulose solution, mixing procedure to obtain best morphology in the solutions and to function well as barrier coatings. (FP) Preparation of model surfaces, analysis of model surfaces and spin coating. Investigation of the effect of different polysaccharides and their properties on web mouldability. Membrane functionalization by click chemistry.

Kemira

Assisted partners with dispersion knowledge, Industrial tutor.

Lappeenranta University of Technology • Packaging Technology (PT) • Fiber and Paper (FP) • Separation Technology (ST)

(PT) Production and collection of commercial samples for the coating testing platform. (FP) Studies on coating hold-out, infiltration with an aim to identify the effect of substrate properties on paper-coating interaction. (ST) Preparation of Cellulose Membranes.

Metsä Board

Industrial tutor

Metsä Fibre

Industrial tutor

Stora Enso

Task 2 Coordinator, study on microwavable packaging materials, barrier measurements, converting trials.

Tampere University of Technology • Paper Converting and Packaging Technology

Provided the dissolved cellulose for Aalto Polymer Technology Extrusion coatings, measurement of barrier properties

University of Helsinki • Organic Chemistry (OC) • Polymer Chemistry (PC) • Food and Environmental Sciences (FES)

(OC) prepared materials with good grease barrier properties for coating experiments using dissolving pulp as starting material. (PC) Preparation of alkyd-acrylate copolymers. Structural characterization of products. (FES) studies of free films, mechanical and barrier properties.

University of Oulu • Fibre and Particle Engineering (FPE) • Organic chemistry (OC)

(FPE) Mechanical activation, production of micronized cellulose and application testing. Membrane structures based on DAC/DCC microfibers. (OC) Chemical derivatization and functionalization of fibre material, production of new modified carbohydrates.

UPM-Kymmene

Task 1 Coordinator

Valmet

Task 3 Coordinator, industrial testing of developed membrane material.

VTT

WP leader. Chemical modification of xylan, development of TOFAbased alkyds, model surface studies, barrier testing, laboratory and pilot coating. Chemical modification of pulp, grafting of thermoplastic polymers and impregnation of webs with polymers. Verification of the testing platform for formability. Functionalization of fibres for membranes and commercial cellulose-based membranes, especially stimuli-responsive materials. Electrospun membranes. Membrane testing, lab-scale preparation of (demo) membrane materials.

Åbo Akademi University • Wood and paper chemistry (WPC) • Fibre and cellulose technology (FCT)

(WPC) Chemical modification of GGM, optical method for grease barrier determination. (FCT) Preparation of cellulose 3D objects using physicochemical pretreatments of pulp fibres in combination with mechanical treatment or forging.

FUBIO JR2 PROGRAMME REPORT

7. Publications and reports Heikkinen, S.L., Mikkonen, K.S., Koivisto, P.,

Rämänen, P., Penttilä, P.A., Svedström, K.,

Heikkilä, M., Pirkkalainen, K., Liljeström, V.,

Maunu, S.L. and Serimaa, R. The effect of dry-

Serimaa, R. and Tenkanen, M. Long-term phys-

ing method on the properties and nanoscale

ical stability of plasticized hemicellulose films,

structure of cellulose whiskers, Cellulose, 2012,

BioResources, 2014, 9, 906-921.

19, 901-912.

Laine, C., Harlin, A., Hartman, J., Hyvärinen,

Rämänen, P. Pitkänen, P., Jämsä, S. and

S., Kammiovirta, K., Krogerus, B., Pajari, H.,

Maunu, S.L. Natural oil-based alkyd-acrylic co-

Rautkoski, H., Setälä, H., Sievänen, J., Uoti-

polymers: New candidates for barrier materials,

la, J. and Vähä-Nissi, M. Hydroxyalkylated xy-

J. Polym. Env., 2012, 20, 950-958.

lans - their synthesis and application in coatings of packaging and paper, Industrial Crops

Saarikoski, E., Rautkoski, H., Rissanen, M.,

and Products, 2013, 44, 692–704. http://dx.doi.

Hartman, J. and Seppälä, J. Cellulose/acrylic

org/10.1016/j.indcrop.2012.08.033

acid copolymer blends for films and coating applications, Journal of Applied Polymer Science,

Mikkonen, K.S., Schmidt, J., Vesterinen, A.-

2014, 131, 402864. DOI 10.1002/app.40286

H. and Tenkanen, M. Crosslinking with ammonium zirconium carbonate improves the

Schmidt, J. Ristisidotut kuusen galaktoglu-

formation and properties of spruce galactoglu-

komannaanikalvot, Master’s thesis, EKT Series

comannan films, Journal of Materials Science,

1581, 2012, University of Helsinki.

2013, 48, 4205-4213. Sirviö, J. A., Kolehmainen, A., Liimatainen, H., Matikainen, J., Karhunen, P., Kulomaa, T., Fis-

Niinimäki, J. and Hormi, O. E. O. Biocomposite

kari, J., Mikkonen, K.S., Tenkanen, M. and Kil-

cellulose-alginate films: Promising packaging

peläinen, I. Films from dissolving pulp modified

materials, Food Chemistry, 2014, 151, 343.

with fatty acids, EWLP Helsinki August 27–30, 2012, Proceedings, 338–341.

Sirviö, J. A., Liimatainen, H., Niinimäki, J. and Hormi, O. Sustainable packaging materials

Mikkonen, K.S. and Tenkanen, M. Sustaina-

based on wood cellulose, RSC Advances, 2013,

ble food-packaging materials based on future

3, 16590 – 16596.

biorefinery products: xylans and mannans, Trends in Food Science & Technology, 2012, 28,

Tanninen, P., Lindell, H., Saukkonen, E. and

90-102.

Backfolk, K. Thermal and mechanical stability of biopolymer barrier coatings in press forming

Narewska J., Lassila L. and Fardim P. Prepa-

of paperboard, Packaging Technology and Sci-

ration and characterization of new mouldable

ence, 2014, 27, 5, 353-363.

cellulose-AESO biocomposites, Cellulose Journal, DOI 10.1007/s10570-013-0157-3

Vishtal, A., Hauptmann, M., Zelm, R., Majschak, J.-P. and Retulainen, E. 3D Forming of

Rämänen, P. and Maunu, S.L. Structure of tall

Paperboard: The Influence of Paperboard Prop-

oil fatty acid-based alkyd resins and alkyd-

erties on Formability, Packag. Technol. Sci.,

acrylic copolymers studied by NMR spectros-

2013, doi: 10.1002/pts.2056.

copy, Prog. Org. Coat., 2014, 77, 361–368.

FUBIO JR2 PROGRAMME REPORT

137

Vishtal A. and Retulainen E. Deep-drawing of paper and paperboard: the role of material properties, BioResources, 2013, 7, 3, 424-450. Vishtal, A. and Retulainen, E. Improving the extensibility, wet web and dry strength of paper by addition of agar, Nordic Pulp and Paper Research Journal. 29 (3): in press (2014). Zeng X., Retulainen, E., Heinemann, S. and Fu, S. Fibre Deformations Induced by Different Mechanical Treatments and Their Effect on ZeroSpan Strength, Nord. Pulp Pap. Res. J., 2012, 27, 2, 335-342. Zeng, X., Vishtal, A., Retulainen, E, Sivonen, E. and Fu S. The Elongation of Paper â&#x20AC;&#x201C; How fibres should be deformed to make paper extensible?, BioRes, 2013, 8, 1, 472-486.

138

FUBIO JR2 PROGRAMME REPORT

139

The main objective of FuBio is to establish, in Finland, globally competitive knowledge platforms within the field of wood biorefinery R&D for the renewal of the forest industry and creation of new business. FuBio is focused on development of novel value chains, in which wood is refined into especially materials and chemicals.