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Materials News
The growing global problem of microplastics is prompting industry experts and companies to develop novel ways to banish microplastics from the environment, says Angelica Buan in this report.
Health-hazard particles up in the air
It is not a typical Hollywood film effect but microplastics falling from the sky are real – and should be taken seriously. Recent studies have shown that microplastics are no longer concentrated only in the oceans. Mismanaged wastes that are either landfilled or entering the oceans break down into tiny pieces, and are circulated in the atmosphere.
One recent study by researchers at Cornell and Utah State Universities says that microplastics from the oceans, roads and agricultural soils are purged into the atmosphere via mechanical processes. The airborne 2.5 micron or less in size microplastic wafts from urban areas to remote areas. The study, published in the Proceedings of the National Academy of Sciences (PNAS), found this plastic cycle to be similar to the biogeochemical cycles of water or nitrogen.
Inhaling contaminants is certainly bad for health, adds a study done by researchers from the Florida State University (FSU). Published in Chemical Research in Toxicology, the study says that exposure to microplastics, even only for a few days, may disrupt the lung’s cellular function. The team led by FSU Professor of Chemistry and Biochemistry Amy Sang, research specialist Joan Hare, doctoral students Kerestin Goodman and Timothy Hua, and former FSU graduate student Zahraa Khamis, exposed lung cells in a petri dish to small amounts of PS, used in common disposable items.
The experiment showed that microplastics can slow down the lung cells’ metabolism and growth; as well as alter the shapes. Declustering also occurred so that gaps existed in what is typically a solid sheet of cells. Additionally, the rapid migration of the plastics towards the nucleus resulted in the microplastic particles forming a ring around the cell’s nucleus, raising concerns that will be a focus of succeeding studies.
The findings may be helpful to understand the effect of microplastics, particularly for individuals
A new study says that mismanaged plastic wastes break down into fragments, and circulate in the atmosphere
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with respiratory disorders like lung cancer, asthma, emphysema, pneumonia, fibrosis or chronic obstructive pulmonary disease (COPD), they said.
The team also added that while the experiment exposed the lung cells to common environmental levels of microplastics, they were directly exposed to the cells in a liquid solution. “The process of breathing in and out could not be mimicked and could potentially affect the amount that an individual inhales and ingests,” the researchers said.
Eliminating microplastics with microbes
Researchers have found various routes in removing microplastics from the environment, from deploying microbes to seize plastic particles to filtering microplastics at source, especially from wastewater that has been found to be highly loaded with microplastics .
Amid the growing ecological threat of microplastics, a team of researchers from the Hong Kong Polytechnic University developed a solution to trap microplastics using biofilms engineered with the Pseudomonas aeruginosa bacteria, which has been found to colonise microplastics in the environment. The sticky exopolymeric substances (EPS) biofilms aggregate the microplastics in a bioreactor, thus facilitating microplastic collection and recycling. The findings demonstrate the biofilms’ potential for use in wastewater treatment plants to prevent microplastics leaking into the oceans. The researchers also observed that the engineered biofilm showed potential application in curbing microplastics pollution in seawater samples collected from sewage pipes.
Canada's INRS developed an electro-analytical system for identifying appropriate electrodes for anodic oxidation processes
Along the same vein, experts from the Canadian Institut National de la Recherche Scientifique (INRS) have developed an electrolytic treatment of wastewater that degrades microplastics at source. The research is published in the Environmental Pollution journal.
Led by Professor Patrick Drogui, the study, which tested sample water that is artificially contaminated with PS using electrolytic oxidation, found that this process can have a degradation efficiency of 89%. Importantly, the technique does not require chemicals or involve physical isolation of contaminants.
The electrodes generate hydroxyl radicals that attack microplastics, they said, adding that the technique enables degrading the particles in CO2 and water molecules. The next step for the team is to test the process on real water, which according to them contains other materials such as carbons and phosphates that can impede oxidation and affect the degradation process.
HKPU developed a solution to trap microplastics using biofilms engineered with the Pseudomonas aeruginosa bacteria, which has been found to colonise microplastics in the environment Breakthrough processes to improve plastics biodegradabilty
Compostable and biodegradable plastics have been touted as plausible solutions to plastic waste pollution. But these eco-friendly materials differ in their degradation processes. Some biodegrade slowly, while others break down into plastic fragments, or not disintegrate at all. There are also plastics under these categories that require industrial composting. According to experts, biodegradable plastics can still be improved so that they will not generate microplastics.
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remelting plastic to recycle it into new plastic. Additionally, programmed degradation could be the key to recycling many objects. For example, computer circuits or electronics held together with biodegradable glue can be dissolved so that the devices fall apart and all the pieces can be reused or repurposed.
Plastic components with longer lifespan to curb microplastics
Almost 23% of global energy consumption can be attributed to friction losses. Components with reduced friction therefore represent an important contribution to conserving resources and achieving climate protection UC Berkeley and the UM Amherst collaborated in an Army-funded project to develop targets. In the case of plastics, an enzyme-activated compostable plastic that can break down by up to 98%, with just reduced friction can also heat and water, and within a few weeks reduce microplastics in the environment.
Scientists at the University of California (UC), With the development of microcapsules filled with Berkeley and the University of Massachusetts Amherst, liquid lubricants for plastics, the Potsdam Fraunhofer in a project funded by the Department of Defence’s Institute for Applied Polymer Research IAP and the Army Research Office, developed an enzyme-activated Plastics Center SKZ in Würzburg are supporting these compostable plastic that can break down by up to 98%, goals. Their self-lubricating plastics achieve up to 85% with just heat and water and within a few weeks. The less wear. Since March 2021, the successful research novel process involves embedding polyester-eating project has been continued for two years. enzymes in the plastic during its production. Whether it is sliding doors, laminate, plastic gears
Ting Xu, UC Berkeley Professor of Materials or other moving components – there is a variety of Science and Engineering and senior author of the applications where materials are subject to friction. study published in Nature journal, explains that these Plastics manufacturers are therefore sometimes enzymes are protected by a simple polymer wrapping incorporating solid lubricants into plastics to reduce consisting of molecules called random heteropolymers component wear. However, there are only a relatively or RHPs that prevent the enzyme from untangling and small number of solid lubricants suitable for plastics becoming useless. processing. In contrast, there is a much wider range of
When exposed to heat and water, the enzyme liquid lubricants, some of which are more effective. In discards its polymer shroud and starts gnawing the a cooperative effort, the two research institutes have plastic polymer, reducing it to its building blocks. In succeeded in encapsulating liquid lubricants in such the case of renewable material-derived polylactic acid a way that they can be incorporated into polymers (PLA), it is reduced to lactic acid, which can feed the as functional substances and later develop all the soil microbes in compost. The polymer wrapping also advantages of a liquid lubricant in the component. degrades. The process, thus, eliminates microplastics. "We managed to incorporate Fraunhofer IAP‘s The new technology should theoretically be applicable microcapsules filled with liquid lubricant into to other types of polyester plastics, potentially allowing thermoplastics using a twin-screw extruder. The the creation of compostable plastic containers, Xu said. challenging task was to mix the microcapsules with The team is developing RHP-wrapped enzymes that thermoplastics under high temperatures without can degrade other types of polyester plastic. Xu is damaging the capsules. Only when friction occurs in the also modifying the RHPs so that the degradation can final component the capsules should break and release be programmed to stop at a specified point and not the lubricant. This allows the component to lubricate itself completely destroy the material, a useful technique for automatically,” explains Moritz Grünewald, researcher
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in the Materials Development Group at SKZ. "Our friction and wear tests showed a reduction in wear of up to 85% on plastic-steel pairings. Thus, components last significantly longer and generate less microplastic."
Based on these results, the material system is being optimised further for potential applications. The development is now focusing on improved mechanical and thermal properties of the selflubricating plastics.
The additional use of reinforcing materials such as fibres is intended to make the self-lubricating plastics more mechanically stable. In the project, the researchers investigate, which type of fibre is best suited for this purpose and how the microcapsules can be optimally bonded to the plastic matrix. In addition, the capsules are also to be incorporated into higher-melting Self-lubricating plastics are expected to drastically reduce component wear in the future, and thus microplastics from the environment plastics to further widen the technical application for companies in this regard: the wide range of liquid possibilities. To this end, even more stable capsule wall and advanced lubricants can now be used as internal materials are being developed in close cooperation lubricants with on-demand release properties. between the project partners. The project is accompanied by a committee
The researchers say that numerous inquiries that includes companies from all sectors of the from the industry highlight the need for novel plastics industry, lubricant manufacturers and plastics with optimised friction and wear properties. microencapsulators and is also open to further Microencapsulation technology has major advantages partners.
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