International Journal of Modern Research in Engineering & Management (IJMREM) ||Volume|| 2 ||Issue|| 9 ||Pages|| 39-47 || September 2019 || ISSN: 2581-4540
Rapid Adsorption of Methylene Blue from an Aqueous Medium via various Bio-sorbents Impregnated with Iron Chloride 1,
Mian Jawaduddin, 2,Zubeda Butt, 3,M. Faizer Panhwar, 4,Ali Akbar
1
Institute of Environmental Engineering and Management Mehran University of Engineering and Technology Jamshoro Sindh Pakistan 2 Department of Zoology University of Sindh Jamshoro Sindh Pakistan 3 Institute of Environmental Engineering and Management Mehran University of Engineering and Technology Jamshoro Sindh Pakistan 4 Institute of Environmental Engineering and Management Mehran University of Engineering and Technology Jamshoro Sindh Pakistan
-----------------------------------------------------ABSTRACT----------------------------------------------------Activated carbon (AC) is an adsorbent commonly used in the separation and purification industries. Activated carbon (AC) relay porosity and its external structure adsorption capacity. The aim of this study was to prepare activated carbons (ACs) from various agriculture wastes including cotton ginning trash (CGT), cotton stalk (CS) and rice straw (RS) using two-step physio-chemical activation method. The carbonization process was carried out at 550 C0 for 1 hour in a sealed nitrogen atmosphere. The char products were impregnated with iron chloride (FeCl3) at impregnation ratio of 1:4 (gm FeCl3: gm Charcoal). The chemically treated chars then proceeded to the oven for 24 hours at 110 C0. In last dried chemically treated charcoals were active at an activation temperature of 400 C0, with iron chloride. The methylene blue adsorption results for CGT, CS, and RS were 330.25 mg/gm, 156 mg/gm, and 183.25 mg/gm. Furthermore, scanning electron microscopy (SEM) method used to analyze the porous structures formed on the surfaces of ACs after the carbonization and activation process, while through X-ray diffractometer (XRD) graphs the crystalline arrangements of ACs were also examined. The presences of various functional groups which are key factors in an adsorption process were identified with the help Fourier transform infrared spectra (FTIR) method.
KEYWORDS: Activated Carbon, Biomass, Methylene Blue, XRD, SEM, FTIR ----------------------------------------------------------------------------------------------------------------------------- ---------Date of Submission: Date, 11 August 2019 Date of Publication: 30 September 2019 ----------------------------------------------------------------------------------------------------------------------------- ----------
I.
INTRODUCTION:
Activated carbon is a very important porous material because it is widely used to adsorb contaminants in gas or liquid phases, and to store gases. Most activated carbon is produced by a two-step carbonation process followed by activation [1]. The first step is to enrich the carbon content and produce an initial porosity, which helps to improve the pore structure. Activation can be done through two different processes - physical and chemical [2]. Chemical activation has two important advantages over physical activation. One of them is the lower temperature at which the process ends. Another reason is that the global production of chemical activation is often large because it does not require burning coal [3]. The use of inexpensive waste and agricultural by-products to produce activated carbon has proven to provide an economical solution. Many precursors have been successfully used to produce activated carbon, including almond [4] guava seeds [5] black cherry seeds [6], peach kernels [7-8], orange peel [9], and peanut shells [10] for the production of activated carbon. Some examples of low raw materials. Methylene blue (MB) is a cationic thiazine dye widely used as a chemical indicator, dye, bio-dye, and drug [1113]. However, due to its toxicity to nerve tissue, reproductive system, and skin, the unbridled discharge of methylene blue into the surface and groundwater can cause harm to humans and other organisms [14]. Therefore, the removal of methylene blue from wastewater is important for the environment and human health. In particular, the purpose of this study was to prepare air conditioners based on various agricultural wastes by thermal carbonization using FeCl 3 activation. The feasibility of FeCl3-AC adsorption on MB was tested. In this work, a biosorbent impregnated with ferric iron (Fe III) was prepared from CGT, CS, and RS and then used to study the adsorption of methylene blue from an aqueous solution. The experimental data were analyzed using kinetic equations and equilibrium isotherms.
II.
MATERIAL AND METHODS
Bio-sorbents Preparation and Characterization: Cotton stalk (CS), Cotton ginning trash (CGT), and Rice straw (RS) were used as precursors for the preparation of activated carbons. The precursors were collected from localities near Hyderabad, Pakistan. Each raw material (CS, RS, and CGT) were washed separately before the
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Rapid Adsorption of Methylene Blue from an Aqueous‌ carbonization to remove dirt and other impurities. After washing each biomass weight 48 gm of were put into an iron made reactor separately having length 20 cm and 8 cm diameter. The reactor had two ends inlet to nitrogen gas and outlet for oxygen, was filled with nitrogen gas and both ends were tightly closed to create a total inert atmosphere. The agro wastes were carbonized at 550 0C for 1 hour in a furnace, after carbonization the weight of each charcoal obtained was 20 gm. In the next stage, 5 gm activating agent (FeCl3) diluted in 100 ml distilled water was mixed up with the charcoal for 2 hours and later oven dried at 110 C0 for 24 hours to remove moisture. On the last stage, each materials containing activating agents were again put into the reactor separately with an inert nitrogen atmosphere and pyrolyzed at 400 0C for 1 hour in a furnace. The weight after activation of each AC was 23.8 gm [15]. Characteristics of Surface Functional Groups: The presence of various functional groups on the surface of the FeCl3-based air conditioner was measured using Fourier transform infrared spectroscopy (FTIR). The device model is Thermo Nicolet 5700 and includes KBR active needle and deuterated triglycine sulfate (DTGS) sensor. The software used to analyze the functional groups is a commercially available OMNIC IR spectrum analyzer. The recorded spectral range is 500 to 4000 cm-1 with a resolution of 4 cm-1 [16]. Scanning Electron Microscope (SEM) Micrographs: The change of surface area and the distribution of pore AC distribution at high temperature were studied by scanning electron microscopy. The sample AC for SEM classification was mounted on a carbon ribbon, and images were obtained using various magnifications of 500 to 3500 resolution. The SEM equipment used for this test was (SEM, JEOL TOKYO JAPAN) [17]. X-ray Diffractometry: X-ray diffraction is a method for qualitatively characterizing the crystal structure of a solid material. The FeCL3-AC diffraction pattern was obtained using a Phillippe X-ray diffractometer. The input speed of the recorder graphics is 2cm-1. Radiographs 2'2θ - 20'2θ2θ were given to the sample AC to observe their reflection behavior [18]. Adsorption Experiments Methylene Blue (MB): To determine the amount of activated carbon in methylene blue, 0.05 g of activated carbon was mixed with 100 ml of 100 ppm of MB at 200 rpm for 1 hour. The solution was then filtered through Whatman 41 filter paper and the remaining methylene blue concentration was determined by measuring the optical density at 661 nm using a UV/visible spectrophotometer (CECIL-CE-100). The amount of methylene blue is calculated by the following equation [19]. đ?’Žđ?’ˆ đ?‘˝ đ?‘¸đ?’† ( ) = (đ?‘Şđ?’Š − đ?‘Şđ?’‡) (1) đ?’ˆđ?’Ž
đ?’Ž
When Qe is the adsorbed MB, Ci is the initial concentration MB, Cf is the equilibrium concentration MB, V is the volume of the solution liter, and m is the mass AC. đ?‘Şđ?’Šâˆ’đ?‘Şđ?’‡ % đ?‘¨đ?’…đ?’”đ?’?đ?’“đ?’ƒđ?’†đ?’… = đ?&#x;?đ?&#x;Žđ?&#x;Ž (2) đ?‘Şđ?’Š The MB number is determined by plotting Qe as a function of Ci according to the Langmuir model, and the parameters Qm and KL of Langmuir are estimated using the least squares method. Qm is methylene blue. Iodine Number (IN): The iodine value is the number of milligrams of iodine adsorbed on 1 gram of carbon 20. The iodine value was determined according to the method of ASTM D4607-9422. 0.1 g of dry activated carbon was placed in several Erlenmeyer flasks, 5 ml of 5% HCl was added, boiled and cooled. 10 ml of 0.1 N was added to the cold solution. Iodine solution. The contents were shaken vigorously for about 4 minutes and filtered. Then, using starch as an indicator, 10 ml of the filtrate was titrated with a standard (0.1 N) Hypo solution. Calculate the concentration of iodine adsorbed in milligrams [20]. đ?‘°đ?‘ľ = đ?‘Ş Ă— đ?‘Şđ?’?đ?’?đ?’—đ?’†đ?’“đ?’”đ?’Šđ?’?đ?’? đ?‘đ?’‚đ?’„đ?’•đ?’?đ?’“ (đ?’‡) (3) Where, đ?‘Ş = đ?‘Šđ?’?đ?’‚đ?’?đ?’Œ đ?‘šđ?’†đ?’‚đ?’…đ?’Šđ?’?đ?’ˆ – đ?’—đ?’?đ?’?đ?’–đ?’Žđ?’† đ?’?đ?’‡ đ?’‰đ?’šđ?’‘đ?’? đ?’„đ?’?đ?’?đ?’”đ?’–đ?’Žđ?’†đ?’… đ?’‚đ?’‡đ?’•đ?’†đ?’“ đ?’„đ?’?đ?’?đ?’”đ?’–đ?’Žđ?’‘đ?’•đ?’Šđ?’?đ?’? đ?’?đ?’‡ đ?‘¨đ?‘Şđ?’” The conversion factor (f) is calculated as: đ?‘´đ?’?đ?’?đ?’†đ?’„đ?’–đ?’?đ?’‚đ?’“ đ?’Žđ?’‚đ?’”đ?’”Ă—đ?‘ľđ?’?đ?’“đ?’Žđ?’‚đ?’?đ?’Šđ?’•đ?’š đ?’?đ?’‡ đ?’Šđ?’?đ?’…đ?’Šđ?’?đ?’†Ă—đ?&#x;?đ?&#x;Ž đ?‘Şđ?’?đ?’?đ?’—đ?’†đ?’“đ?’”đ?’Šđ?’?đ?’? đ?‘đ?’‚đ?’„đ?’•đ?’?đ?’“ = (4) đ?‘´đ?’‚đ?’”đ?’” đ?’?đ?’‡ đ?’‚đ?’„đ?’•đ?’Šđ?’—đ?’‚đ?’•đ?’†đ?’… đ?’„đ?’‚đ?’“đ?’ƒđ?’?đ?’?Ă—đ?‘Šđ?’?đ?’‚đ?’?đ?’Œ đ?’“đ?’†đ?’‚đ?’…đ?’Šđ?’?đ?’ˆ
III.
RESULTS
Adsorption of Iodine and Methylene Blue: Adsorption of methylene blue and iodine by activated carbon are simple and generally used techniques for its characterization. The methylene blue provides the information about the number of macro size pores present in one gram of activated carbon, while iodine adsorption clarifies the number of mesopores present in one gram of activated carbon. The results of MB adsorption were 156.25 mg/gm,
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Rapid Adsorption of Methylene Blue from an Aqueous‌ 183 mg/gm and 330 mg/gm for CS-AC, RS-AC and CGT-AC respectively. While the iodine numbers were 224 mg/gm, 287 mg/gm and 478 mg/gm for CS-AC, RS-AC and CGT-AC respectively [21]. The removal efficiency of all the prepared activated carbons were also analyzed on the methylene blue solution having a concentration of 50 ppm. The percentage of removal of MB solution from 50 ppm were 74 % for CSAC, 83 % for RS-AC and 91 % for the CGT-AC [22]. Table 1: Iodine number, Removal % of Methylene Blue and Methylene Blue number S.No 1 2 3
FeCl3-ACs CS-AC RS-AC CGT-AC
Iodine Number 224 287 478
Removal % from 50 ppm MB solution 74 83 91
MB Number 156 183 330
Removal % of MB solution from 50 ppm 120 91
100 83 80
74
60 40 20 0
CS-AC
RS-AC
CGT-AC
Figure 1: Removal percentage of methylene blue through CS, RS and CGT based-ACs Characteristics of Surface Functional Groups: Studies of FTIR spectral characteristics were performed to identify functional groups in activated carbon based on FeCl 3. The adsorption capacity of the alternating current mainly depends on its pore distribution and the reactivity of the functional groups. The presence of many functional groups on the surface of activated carbon exhibits better adsorption capacity than molecules other than carbon. FTIR analysis of FeCl3 saturated activated carbons displayed several absorption bands. CGT-AC showed initial peaks at 693 cm-1, and 762 cm-1 having monosubstance and 1, 2, 3-trisubstance structure respectively, while their assignment was C-H of aromatic class. The next peak was observed at 946 cm-1, having structure RCO-OH and assignment C-H of carboxylic group. The peak at 1980 cm -1 was identified as aromatics having structure RN=C=S and assignment RCOOH. The final peak was found at 2165 cm -1 shows miscellaneous class with R-C-N structure and isocyanides structure. Furthermore, RS-AC showed initial two peaks at 711 cm-1 and 873 cm-1 with a 1,2,3-trisubstance structure having C-H assignment of aromatics class. While the peak at 1062 cm-1 has Si-OR structure with Si-OR assignment of miscellaneous class. The last two peaks at 2351 cm -1 and 2365 cm-1 have PH phosphine structure with P-H phosphine assignment of miscellaneous class. During the CS-AC FTIR analysis, the first peak was detected at 877 cm -1 indicating the presence of an aromatic hydrocarbon, and then at 1156 cm -1, the alkali metal halide may be associated with the decomposition of chlorine present in FeCl 3. The evidence for the C-O carboxylic acid bond of 1557 cm-1 is due to the decomposition of the amino acids present in the cotton stalk. 1568 cm-1 is an olefin having a C=C bond and a 4-ring structure. Four main peaks were observed during the FTIR study: aldehydes, carboxylic acids, hetero and alkyne of 1683 cm -1, 1695 cm -1, 1991 cm -1 and 2112 cm -1, respectively. In addition, 2358 different bonds were found, and 3323 cm-1 having an RC≥CH structure was identified as an alkyne. 3592-3582 cm-1 is an alcohol having the O-H name and the structure RCH2OH. After 3592 cm -1, a continuous peak was observed up to 3889, probably due to the presence of various forms of OH and moisture in the activated carbon.
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Rapid Adsorption of Methylene Blue from an Aqueous… Table 2: Fourier Transforms Infrared spectroscopy analysis of CGT-AC Wave Number (cm-1) 693 762 946 1980 2165
S.No. 1. 2. 3. 4. 5.
Structure Monosubstance 1,2,3-Trisubstance RCO-OH R-N=C=S R-C-N
Assignment C-H
Class Aromatics
C-H RCOOH Isocyanides
Carboxylic Group Aromatics Misc.
FTIR of CGT-AC 3000
% Transmittance
2500 Aromatics
Misc.
2000 1500 1000
Aromatics
Aromatics
1
2
Carboxylic Group
500 0 3
4
5
Wave Number cm-1
Figure 2: Fourier Transforms Infrared spectroscopy analysis of CGT-AC Table 3: Fourier Transforms Infrared spectroscopy analysis of RS-AC Wave Number (cm-1) 711 873 1062 2351 2365
S.No. 1. 2. 3. 4. 5.
Structure 1,2,3-Trisubstance
Assignment C-H
Class Aromatics
Si-OR P-H phosphine
Si-OR P-H phosphine
Misc. Misc.
FTIR of RS-AC
% Transmittance
3000 2500
MIsc.
MIsc.
4
5
2000 1500 1000
Aromatics
Aromatics
MIsc.
500 0 1
2
3
Wave Number cm-1
Figure 3: Fourier Transforms Infrared spectroscopy analysis of RS-AC
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Rapid Adsorption of Methylene Blue from an Aqueous… Table 4: Fourier Transforms Infrared spectroscopy analysis of CS-AC Wave Number (cm-1) 877
S.No. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Structure 1,2,4-trisub
1156 1557 1568 1683 1695 1916 1991 2112 2358 3323 3585 3592 3889
Assignment C-H out of the plane C-H wag C-O C=C C=O
CH2X RCO-O 4-rings C=CCHO C=C-CO-OH R-N=C=S RC≡CH Si-H silane RC≡CH RCH2OH
Class Aromatic
N=C
Alkali halides carboxylic acid Alkenes Aldehydes carboxylic acid Misc.
C≡C Si-H silane C≡H O-H
Alkynes Misc. Alkynes Alcohols Various
FTIR of CS-AC 4500
% Transmittance
Various
Various Alcohols
4000 3500 3000
Carboxylic Acid
2500
ALdehydes Carboxylic acid
2000
1500 Aromatics 1000 ALkenes Alkali Halides 500
Various
Alkynes Alkynes Misc
Misc.
0 1
2
3
4
5
6
7
8
9
10
11
12
13
14
Wave Number cm-1
Figure 4: Fourier Transforms Infrared spectroscopy analysis of CS-AC Scanning Electron Microscope (SEM) Micrographs: The surface morphology of FeCl3-AC was investigated by scanning electron microscopy (SEM). The analysis revealed that the outer casing of the CGT-AC was well organized and had a corrugated structure, as well as the inner shell of the CGT-AC having a sheet structure. This indicates that the outer and inner surfaces of the CGT-AC are different in shape. Silica is mainly located in the strong intermediate layer (skin) of CGT-AC and is also filled in the space between epidermal cells. SEM micrographs show regular spherical sheets of nearly identical size (40-50 μm) arranged in parallel. In addition, many residual pores were distributed in the CGT-AC sample, indicating that CGT-AC is a highly porous material with a large internal surface area. CGT fibers are destroyed by thermal decomposition of organic matter, leaving a highly porous structure. In addition, as the heating temperature increases, the loss of volatile materials also increases, which provides a more active porous structure. Photomicrographs of the RS-AC SEM nanocomposites indicate non-homogeneous morphology due to the presence of charcoal. The optimistic region in the image labeled 10 μm indicates the presence of FeCl3 and the black portion indicates the presence of charcoal from the straw. The pore structure was not clearly seen on the electrogram, which shows an SEM image of the carbon/FeCl3 nanocomposite. The SEM results of the CS-AC image show the formation of a uniform structure, such as a cell or a series of tunnels, during carbonization. At high magnification, up to 3,000 subsequence sequences can be observed. This demonstrates that the activator (FeCl3) has a large effect on agricultural residues (cotton stalks) and produces a very porous adsorbent after the pyrolysis process.
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Rapid Adsorption of Methylene Blue from an Aqueous…
Figure 2: Scanning Electron Microscope images of CGT-AC
Figure 3: Scanning Electron Microscope images of RS-AC
Figure 4: Scanning Electron Microscope images of CS-AC
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Rapid Adsorption of Methylene Blue from an Aqueous… X-ray Diffractometry: The XRD result of AC-CGT is shown in Figure 5. The peak 270 at 2 theta known as graphite peak. Same time it performed noise of the powdered X-Ray Diffraction which revealed that the structure of carbon is amorphous. Furthermore, it indicated that chemical bonds of organic-compounds were broken down by the pyrolysis process with temperature and converted into active compounds. Standard graphite layers and stacks of planes were produced during carbonization by these compounds. The peak at 29 o at 2 theta confirms that produced CGT-AC is amorphous in nature. Both the peaks at 21o and 29o authenticate that the prepared CGT-AC was crystallized and layered structure without the formation of any spinel structure of activated carbon. The crystal structure of RS-AC was studied using XRD features as shown in (Figure). The initial broad peak appears in the range 2θ = 100, the next appears in 2θ = 150, and the second appearance at 2θ = 400 confirms the modification of samples with amorphous structures, such as Filson, Dawson, and Schwegler (As described in 2009), in a similar manner, as studied by Lu and Hsieh (2010), the pattern to the last peak indicates the presence of residual ash and amorphous metal traces. X-ray diffraction analysis of AC based on FeCl3 showed the presence of significant amounts of FeCl3 in the adsorbent. Three of the ten peaks are coordinated with the XRD link, which explains that the adsorbent extracted from the straw does not completely fall into the crystal group, and the main part is carbongraphite, as discussed by Yan et al. (2018). The XRD diffraction pattern shows that the size of the adsorbent can be in the range of 8-20 nm. Activated carbon FeCl3 obtained from cotton stalk showed several radiographs, as shown in Figure. The results show that the coal is essentially an amorphous solid. Amorphous phenomena can be described as the presence of several C-C starches (due to aromatic rings), the development of various groups and their effects on the surface throughout the process. In addition, checking all the strips can more easily explain the characteristics of the cotton stalk. XRD explains the characteristics of the precursors extracted from wood and their elemental chemical composition. At the same time, the amount of lignin, cellulose, and hemicellulose is different in all parts of the cotton stalk. In the production of activated carbon FeCl3, various types of gases and water vapor are released, which indicates that the soft portion contains hemicellulose and cellulose, which have a polymer residue of a glucose structure. Furthermore, lignin is only found in its more robust part, which has the form of a rigid covalent bond of several phenolic groups. This is responsible for the formation of porous volumes, texture structures, specific surface areas and surface reactivity in activated carbon.
Figure 5: X-Ray Diffractometry Graph of CGT-AC
Figure 6: X-Ray Diffractometry Graph of RS-AC
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Rapid Adsorption of Methylene Blue from an Aqueous…
Figure 7: X-Ray Diffractometry Graph of CS-AC Conclusion: The effect of activators on the properties of activated carbon obtained by chemical activation of ginning chips (CGT), straw (RS) and cotton stalks was investigated. Activators have a significant impact on the properties of surface functional groups. The FTIR results show that all of the activated carbons obtained contain aromatic, carbonic acid, alcohol, aldehyde, etc. as oxidized surface functional groups. Using SEM micrographs, activated carbon impregnated with ferric chloride showed a good pore structure. Iodine and methylene blue adsorption also indicated that CGT-AC was the efficient activated carbon of the other activated carbons tested. Therefore, this study shows that a cotton gin (CGT) can be used as a source of lignocellulosic material for the manufacture of inexpensive activated carbon having a large surface area and using FeCl 3 as an activator with good porosity.
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