Iranian journal of chemistry & chemical engineering, 2019
Acetic acid was separated from a dilute mixture using a commercial polyvinyl alcohol (PVA) membra... more Acetic acid was separated from a dilute mixture using a commercial polyvinyl alcohol (PVA) membrane. Intrinsic separation characteristics of the membrane were studied as a function of temperature. The degree of membrane swelling decreased marginally with increase in feed temperature. At 25oC the maximum degree of swelling was found out to be 46.3%, which reduced to 39.5% at 65oC. Although the pervaporation flux increased with increasing temperature of the liquid feed mixture, the separation factor decreased. From the temperature dependence of diffusion and permeation values, the Arrhenius apparent activation parameters for water permeation were estimated. Diffusion and partition coefficient for water and acid were found to increase with temperature, but the diffusion coefficient of water was substantially higher than that of acetic acid at a constant feed concentration. The membrane used in the present study could tolerate highly concentrated corrosive acetic acid, thus may be use...
Dehydration of dilute acetic acid solution was carried out in a pervaporation pilot plant unit us... more Dehydration of dilute acetic acid solution was carried out in a pervaporation pilot plant unit using commercial polyvinyl alcohol-polyethersulfone composite membrane. Membrane swelling coefficients obtained by dynamic swelling study were found to increase with increasing water concentration in the feed. For 10% (by volume) feed water concentration swelling coefficient of the membrane was 0.3053 which increased to 0.4919 at 90% feed water concentration. Pervaporation separation index (PSI) was found to decrease with increasing feed concentration whereas enrichment factor increased. For 10% feed water concentration acetic acid and water diffusion coefficients were estimated to be 1.8963 × 10 −12 and 11.843× 10 −12 m 2 /s respectively, which rose to 6.8732 × 10 −12 and 40.973 × 10 −12 m 2 /s respectively at 90% feed water concentration. The study indicates that in addition to the effect of differences in diffusivity for the permeating components, preferential sorption contributes to a ...
Iranian Journal of Chemistry & Chemical Engineering-international English Edition, 2019
Acetic acid was separated from a dilute mixture using a commercial polyvinyl alcohol (PVA) membra... more Acetic acid was separated from a dilute mixture using a commercial polyvinyl alcohol (PVA) membrane. Intrinsic separation characteristics of the membrane were studied as a function of temperature. The degree of membrane swelling decreased marginally with increase in feed temperature. At 25oC the maximum degree of swelling was found out to be 46.3%, which reduced to 39.5% at 65oC. Although the pervaporation flux increased with increasing temperature of the liquid feed mixture, the separation factor decreased. From the temperature dependence of diffusion and permeation values, the Arrhenius apparent activation parameters for water permeation were estimated. Diffusion and partition coefficient for water and acid were found to increase with temperature, but the diffusion coefficient of water was substantially higher than that of acetic acid at a constant feed concentration. The membrane used in the present study could tolerate highly concentrated corrosive acetic acid, thus may be use...
Abstract: The potential of activated carbon prepared from the seeds of Manilkara zapota, an agric... more Abstract: The potential of activated carbon prepared from the seeds of Manilkara zapota, an agricultural waste, was assessed for adsorptive dephenolation from aqueous solution. ZnCl2 was used as the activating agent. Batch adsorption experiments were conducted to ...
Dehydration of acetic acid was carried out in a small scale pervaporation pilot plant unit using ... more Dehydration of acetic acid was carried out in a small scale pervaporation pilot plant unit using commercial polyvinyl alcohol (PVA) membrane supported on polyether sulfone (PES). The hydrophilic membrane was able to selectively transport water molecules from the acetic-acid water mixture. It was observed that PVA membrane swelled significantly when the acetic acid concentration was increased in the feed solution. With increase in feed temperature degree of swelling decreased marginally. At 25C the maximum degree of swelling was found out to be 46.3%, which reduced to 39.5% at 65C. Although the pervaporation flux increased with increasing temperature of the liquid feed mixture, the separation factor decreased. From the temperature dependence of diffusion and permeation values, the Arrhenius apparent activation parameters have been estimated. The resulting activation energy values, obtained for water permeation being lower than those of acetic acid permeation values, suggest that the ...
Abstract Present work explored the effect of current density and applied voltage along with the p... more Abstract Present work explored the effect of current density and applied voltage along with the performance of graphite and SS 316 L as electrodes in the electrodialytic separation of sulfuric acid from model spent acidic solution. The study established that applied voltage in the range of 2–12 V was most suitable for maintaining current densities in the range 2–50 mA/cm2 for different initial catholyte concentration. Around 90% acid separation could be achieved with more than 70% current efficiency. The electrical energy (kJ/l) required for the concentration enhancement of sulfuric acid by electrodialysis (ED) was estimated and was compared with the thermal energy required for the same by evaporation (EV). ED was found to be less energy intensive process. An economic evaluation of the integrated ED and EV was also carried out under present experimental conditions and the likelihood of which was found to be 21% and 24% more economical than standalone ED or EV respectively.
The potential of activated fly ash has been investigated for the adsorption of copper (II) dissol... more The potential of activated fly ash has been investigated for the adsorption of copper (II) dissolved in wastewater. Physico-chemical parameters such as adsorbate concentration, pH, adsorbent dose, temperature, presence of interfering ions etc were optimized by employing batch adsorption technique. Adsorption was endothermic and followed Langmuir and Freundlich isotherms, however, the latter fitted well. Isotherms were used to estimate thermodynamic parameters for the adsorption process. Kinetic data were fitted to the models of intraparticle diffusion, pseudo second order and Lagergren model which followed more closely to the pseudo second order chemisorption model. The regeneration and reusability of the adsorbents were also assessed. Maximum removal of copper (II) was obtained at pH 4 and temperature 50°C (about 98% for adsorbent dose of 20 g/l and 50 mg/l initial feed concentration).
Chopped stems of Prosopis juliflora, an invasive xerophyte, were digested in a laboratory digeste... more Chopped stems of Prosopis juliflora, an invasive xerophyte, were digested in a laboratory digester following alkaline sulfite pulping process to generate spent liquor whereby lignin underwent sulfonation to produce sodium lignosulfonate (SLS). SLS was concentrated from the spent liquor by ultrafiltration. Raw wood was featured by high lignin (23.5%), low extractives (1.0%), low wax (0.41), and low ash (2.25%) content thus making it an ideal feedstock to produce lignosulfonates with appreciable physico-chemical property and relatively high mechanical strength. Attempts were made to provide basic information on SLS structure and structural changes that might occur during pulping of P. juliflora under the present experimental conditions. Spectral and X-ray diffraction studies on as-produced SLS revealed substantial depolymerization and structural modification of lignin during sulfite pulping. The derived SLS had higher crystallinity index than the feedstock wood. Effect of average size...
Cascaded electrodialysis system has been developed for increasing the concentration of sulfuric a... more Cascaded electrodialysis system has been developed for increasing the concentration of sulfuric acid from aqueous solution using an interpolymer anion exchange (IPA) membrane. Enrichment process was carried out in a cascade of six electrodialyzers at 20.2 mA/cm2 current density. The performance of the process was evaluated rigorously in terms of current efficiency, voltage requirements and processability to enrich the acid concentration. The bench-scale experimental results exhibited the ability of membrane to perform as a low proton leakage membrane and to enrich the sulfuric acid concentration up to 27.93 wt. %. The higher values of current efficiencies were reported to be in the range of 50 to 60 %. Proton leakage through the membrane, acid back diffusion, concentration polarization and solution conductivity were considered to be the limiting factors for acid enrichment and their effects were found significant on current efficiency and voltage requirement.
The present study deals with the decolourization of synthetic Reactive Turquoise Blue 21 (RTB21) ... more The present study deals with the decolourization of synthetic Reactive Turquoise Blue 21 (RTB21) dye-based model wastewater using an indirect electro-oxidation process and enhanced by modified graphite electrodes. Graphene oxide (GO) was successfully synthesized and deposited on the surface of pre-treated graphite electrodes. It was further reduced to form reduced graphene oxide (rGO). The resultant newly developed anode electrodes were designated as (Gr) 0 , (rGO/ Gr) 1 , and (rGO/Gr) 2 and used for the treatment of wastewater. Electrodes, thus developed, were characterized using Fourier-transform infrared spectroscopy, X-ray diffractions, Field emission scanning electron microscopy, and Contact angle (CA). The effect of process parameters such as initial pH, current density, electrolyte concentration, and temperature on the performance of novel anode electrodes was investigated. The colour removal efficiency was increased significantly almost 25.80% in the presence of a modified electrode with the highest efficiencies of about 96.69% in a natural pH environment, 200 A/m 2 , 2 g/L NaCl concentration, 30 °C temperature, and 15 min process time for 50 ppm RTB21 dye concentration for (rGO/Gr) 2 electrode. The RTB21 decolourization by indirect electro-oxidation process follows the pseudo-first-order kinetics, and the activation energy was estimated to be 23.42 kJ/mol. The stability of (rGO/ Gr) 2 electrode was also examined. The rGO coated electrode was a superior electrode for the indirect electro-oxidation process, giving enhanced colour removal (%).
Barring a selected few as beneficial trace elements, majority of them have no established biologi... more Barring a selected few as beneficial trace elements, majority of them have no established biological functions and are considered as nonessential metals. Because of their high degree of toxicity, lead (Pb), arsenic (As), cadmium (Cd), chromium (Cr), selenium (Se), and nickel (Ni) rank among the priority metals that are of great public health significance. [2] These are all systemic toxicants inducing multiple organ damage, even at lower levels of exposure. According to the United States Environmental Protection Agency and the International Agency for Research on Cancer, these metals are also classified as either "known" or "probable" human carcinogens based on epidemiological and experimental studies, depicting an association between exposure and cancer incidence in humans and animals. [3] Heavy metal exposure, in particular, affects all organ systems including the nervous, dermatologic, cardiovascular, gastrointestinal, and respiratory systems. [3-5] Mostly, the waters of highly metalcontaminated sites and abandoned mines are in acidic range due to the higher concentration of sulphates, metals, and metalloids. White rot fungal communities may play crucial role in removal of heavy metals as they grow in acidic medium and survive with higher concentration of heavy metals. [6] Additionally, white rot fungi accumulate organic acids, carboxylic, and thiol ligands and other polymeric substances extracellularly, which reduce the toxicity of heavy metals. [7,8] Phanerochaete chrysosporium, a representative white rot fungus, has been used extensively for environmental engineering fields as its favorable metal absorption ability. [8-10] In the present study, free cells of P. chrysosporium are used for metal absorption, which offers several advantages over living cell study: i) wide range of operating conditions (pH and temperature), ii) no nutrition requirement, iii) comparative fast metal removal (in terms of time), and iv) resistant to initial higher metal concentration. [6] In biosorption studies, biosorbent concentration, pH, temperature, and metal concentration are the most important parameters, which directly affect the biosorption efficacy of metals. Previously, various researchers studied the biosorption efficiency of fungal biomass, optimized using either OFAT (one factor at a time) method or multivariate optimization Efficient degradation of hazardous contaminants from contaminated water is the major challenge for researchers, wherein heavy metals are the prominent contaminants. Consequently, the assessment of multimetal removal is necessary using efficient biosorbant. In this work, the capability of Phanerochaete chrysosporium is evaluated for the individual and simultaneous removal of heavy metals. Individual and simultaneous removal of As, Cd, and Cr is optimized using response surface methodology based on the central composite design by changing the variables, i.e., pH, fungal biomass, and metal concentration. Optimization of the individual metal removal study reveals that fungus effectively absorbs As (29.95 mg L −1), Cd (18.1 mg L −1), and Cr (26.34 mg L −1) at 6.1, 5.64, and 4.15 of pH, respectively. Similarly, As (14.18 mg L −1), Cd (4.53 mg L −1), and Cr (9.28 mg L −1) are absorbed by fungal hyphae simultaneously within 1 h. Changes in the morphology of fungal hyphae are detected in metal absorbed samples as compared to the control hyphae. Interaction of metal-absorbed fungal hyphae is analyzed using FTIR spectroscopy, revealing that the proteins, carbohydrates, and fatty acids present in the fungal cell are interacted with metals. The model white rot fungi used in the present study can be applied efficiently for the multimetal removal in effluent treatment plants. Metal Removal
Applied Microbiology and Biotechnology, Jul 31, 2004
Fermentation of biomass or carbohydrate-based substrates presents a promising route of biological... more Fermentation of biomass or carbohydrate-based substrates presents a promising route of biological hydrogen production compared with photosynthetic or chemical routes. Pure substrates, including glucose, starch and cellulose, as well as different organic waste materials can be used for hydrogen fermentation. Among a large number of microbial species, strict anaerobes and facultative anaerobic chemoheterotrophs, such as clostridia and enteric bacteria, are efficient producers of hydrogen. Despite having a higher evolution rate of hydrogen, the yield of hydrogen [mol H 2 (mol substrate −1)] from fermentative processes is lower than that achieved using other methods; thus, the process is not economically viable in its present form. The pathways and experimental evidence cited in the literature reveal that a maximum of four mol of hydrogen can be obtained from substrates such as glucose. Modifications of the fermentation process, by redirection of metabolic pathways, gas sparging and maintaining a low partial pressure of hydrogen to make the reaction thermodynamically favorable, efficient product removal, optimum bioreactor design and integrating fermentative process with that of photosynthesis, are some of the ways that have been attempted to improve hydrogen productivity. This review briefly describes recent advances in these approaches towards improvement of hydrogen yield by fermentation.
In the present study the esterification of palm fatty acid distillate (PFAD), a by-product from p... more In the present study the esterification of palm fatty acid distillate (PFAD), a by-product from palm oil industry, in the presence of super phosphoric acid (SPA) catalyst was studied. The effects of various physico-chemical parameters such as temperature, PFAD to methanol molar ratio and amount of catalyst on the conversion of biodiesel were investigated. The percent conversion of FFA and properties of the biodiesel were determined following standard methodologies. Percent conversion of biodiesel was found to increase with the increase in PFAD to methanol molar ratio and at 1:12 molar ratio and 70°C temperature 95% conversion was achieved. Thermodynamic parameters were also evaluated in terms of Gibbs free energy, enthalpy and entropy at different molar ratio and temperatures. Both pseudo first and second order irreversible kinetics were applied to a wide range of experimental data. However, according to regression coefficient (R2) the second order described better experimental beha...
The potential of activated fly ash has been investigated for the adsorption of copper (II) dissol... more The potential of activated fly ash has been investigated for the adsorption of copper (II) dissolved in wastewater. Physico-chemical parameters such as adsorbate concentration, pH, adsorbent dose, temperature, presence of interfering ions etc were optimized by employing batch adsorption technique. Adsorption was endothermic and followed Langmuir and Freundlich isotherms, however, the latter fitted well. Isotherms were used to estimate thermodynamic parameters for the adsorption process. Kinetic data were fitted to the models of intraparticle diffusion, pseudo second order and Lagergren model which followed more closely to the pseudo second order chemisorption model. The regeneration and reusability of the adsorbents were also assessed. Maximum removal of copper (II) was obtained at pH 4 and temperature 50°C (about 98% for adsorbent dose of 20 g/l and 50 mg/l initial feed concentration).
Iranian journal of chemistry & chemical engineering, 2019
Acetic acid was separated from a dilute mixture using a commercial polyvinyl alcohol (PVA) membra... more Acetic acid was separated from a dilute mixture using a commercial polyvinyl alcohol (PVA) membrane. Intrinsic separation characteristics of the membrane were studied as a function of temperature. The degree of membrane swelling decreased marginally with increase in feed temperature. At 25oC the maximum degree of swelling was found out to be 46.3%, which reduced to 39.5% at 65oC. Although the pervaporation flux increased with increasing temperature of the liquid feed mixture, the separation factor decreased. From the temperature dependence of diffusion and permeation values, the Arrhenius apparent activation parameters for water permeation were estimated. Diffusion and partition coefficient for water and acid were found to increase with temperature, but the diffusion coefficient of water was substantially higher than that of acetic acid at a constant feed concentration. The membrane used in the present study could tolerate highly concentrated corrosive acetic acid, thus may be use...
Dehydration of dilute acetic acid solution was carried out in a pervaporation pilot plant unit us... more Dehydration of dilute acetic acid solution was carried out in a pervaporation pilot plant unit using commercial polyvinyl alcohol-polyethersulfone composite membrane. Membrane swelling coefficients obtained by dynamic swelling study were found to increase with increasing water concentration in the feed. For 10% (by volume) feed water concentration swelling coefficient of the membrane was 0.3053 which increased to 0.4919 at 90% feed water concentration. Pervaporation separation index (PSI) was found to decrease with increasing feed concentration whereas enrichment factor increased. For 10% feed water concentration acetic acid and water diffusion coefficients were estimated to be 1.8963 × 10 −12 and 11.843× 10 −12 m 2 /s respectively, which rose to 6.8732 × 10 −12 and 40.973 × 10 −12 m 2 /s respectively at 90% feed water concentration. The study indicates that in addition to the effect of differences in diffusivity for the permeating components, preferential sorption contributes to a ...
Iranian Journal of Chemistry & Chemical Engineering-international English Edition, 2019
Acetic acid was separated from a dilute mixture using a commercial polyvinyl alcohol (PVA) membra... more Acetic acid was separated from a dilute mixture using a commercial polyvinyl alcohol (PVA) membrane. Intrinsic separation characteristics of the membrane were studied as a function of temperature. The degree of membrane swelling decreased marginally with increase in feed temperature. At 25oC the maximum degree of swelling was found out to be 46.3%, which reduced to 39.5% at 65oC. Although the pervaporation flux increased with increasing temperature of the liquid feed mixture, the separation factor decreased. From the temperature dependence of diffusion and permeation values, the Arrhenius apparent activation parameters for water permeation were estimated. Diffusion and partition coefficient for water and acid were found to increase with temperature, but the diffusion coefficient of water was substantially higher than that of acetic acid at a constant feed concentration. The membrane used in the present study could tolerate highly concentrated corrosive acetic acid, thus may be use...
Abstract: The potential of activated carbon prepared from the seeds of Manilkara zapota, an agric... more Abstract: The potential of activated carbon prepared from the seeds of Manilkara zapota, an agricultural waste, was assessed for adsorptive dephenolation from aqueous solution. ZnCl2 was used as the activating agent. Batch adsorption experiments were conducted to ...
Dehydration of acetic acid was carried out in a small scale pervaporation pilot plant unit using ... more Dehydration of acetic acid was carried out in a small scale pervaporation pilot plant unit using commercial polyvinyl alcohol (PVA) membrane supported on polyether sulfone (PES). The hydrophilic membrane was able to selectively transport water molecules from the acetic-acid water mixture. It was observed that PVA membrane swelled significantly when the acetic acid concentration was increased in the feed solution. With increase in feed temperature degree of swelling decreased marginally. At 25C the maximum degree of swelling was found out to be 46.3%, which reduced to 39.5% at 65C. Although the pervaporation flux increased with increasing temperature of the liquid feed mixture, the separation factor decreased. From the temperature dependence of diffusion and permeation values, the Arrhenius apparent activation parameters have been estimated. The resulting activation energy values, obtained for water permeation being lower than those of acetic acid permeation values, suggest that the ...
Abstract Present work explored the effect of current density and applied voltage along with the p... more Abstract Present work explored the effect of current density and applied voltage along with the performance of graphite and SS 316 L as electrodes in the electrodialytic separation of sulfuric acid from model spent acidic solution. The study established that applied voltage in the range of 2–12 V was most suitable for maintaining current densities in the range 2–50 mA/cm2 for different initial catholyte concentration. Around 90% acid separation could be achieved with more than 70% current efficiency. The electrical energy (kJ/l) required for the concentration enhancement of sulfuric acid by electrodialysis (ED) was estimated and was compared with the thermal energy required for the same by evaporation (EV). ED was found to be less energy intensive process. An economic evaluation of the integrated ED and EV was also carried out under present experimental conditions and the likelihood of which was found to be 21% and 24% more economical than standalone ED or EV respectively.
The potential of activated fly ash has been investigated for the adsorption of copper (II) dissol... more The potential of activated fly ash has been investigated for the adsorption of copper (II) dissolved in wastewater. Physico-chemical parameters such as adsorbate concentration, pH, adsorbent dose, temperature, presence of interfering ions etc were optimized by employing batch adsorption technique. Adsorption was endothermic and followed Langmuir and Freundlich isotherms, however, the latter fitted well. Isotherms were used to estimate thermodynamic parameters for the adsorption process. Kinetic data were fitted to the models of intraparticle diffusion, pseudo second order and Lagergren model which followed more closely to the pseudo second order chemisorption model. The regeneration and reusability of the adsorbents were also assessed. Maximum removal of copper (II) was obtained at pH 4 and temperature 50°C (about 98% for adsorbent dose of 20 g/l and 50 mg/l initial feed concentration).
Chopped stems of Prosopis juliflora, an invasive xerophyte, were digested in a laboratory digeste... more Chopped stems of Prosopis juliflora, an invasive xerophyte, were digested in a laboratory digester following alkaline sulfite pulping process to generate spent liquor whereby lignin underwent sulfonation to produce sodium lignosulfonate (SLS). SLS was concentrated from the spent liquor by ultrafiltration. Raw wood was featured by high lignin (23.5%), low extractives (1.0%), low wax (0.41), and low ash (2.25%) content thus making it an ideal feedstock to produce lignosulfonates with appreciable physico-chemical property and relatively high mechanical strength. Attempts were made to provide basic information on SLS structure and structural changes that might occur during pulping of P. juliflora under the present experimental conditions. Spectral and X-ray diffraction studies on as-produced SLS revealed substantial depolymerization and structural modification of lignin during sulfite pulping. The derived SLS had higher crystallinity index than the feedstock wood. Effect of average size...
Cascaded electrodialysis system has been developed for increasing the concentration of sulfuric a... more Cascaded electrodialysis system has been developed for increasing the concentration of sulfuric acid from aqueous solution using an interpolymer anion exchange (IPA) membrane. Enrichment process was carried out in a cascade of six electrodialyzers at 20.2 mA/cm2 current density. The performance of the process was evaluated rigorously in terms of current efficiency, voltage requirements and processability to enrich the acid concentration. The bench-scale experimental results exhibited the ability of membrane to perform as a low proton leakage membrane and to enrich the sulfuric acid concentration up to 27.93 wt. %. The higher values of current efficiencies were reported to be in the range of 50 to 60 %. Proton leakage through the membrane, acid back diffusion, concentration polarization and solution conductivity were considered to be the limiting factors for acid enrichment and their effects were found significant on current efficiency and voltage requirement.
The present study deals with the decolourization of synthetic Reactive Turquoise Blue 21 (RTB21) ... more The present study deals with the decolourization of synthetic Reactive Turquoise Blue 21 (RTB21) dye-based model wastewater using an indirect electro-oxidation process and enhanced by modified graphite electrodes. Graphene oxide (GO) was successfully synthesized and deposited on the surface of pre-treated graphite electrodes. It was further reduced to form reduced graphene oxide (rGO). The resultant newly developed anode electrodes were designated as (Gr) 0 , (rGO/ Gr) 1 , and (rGO/Gr) 2 and used for the treatment of wastewater. Electrodes, thus developed, were characterized using Fourier-transform infrared spectroscopy, X-ray diffractions, Field emission scanning electron microscopy, and Contact angle (CA). The effect of process parameters such as initial pH, current density, electrolyte concentration, and temperature on the performance of novel anode electrodes was investigated. The colour removal efficiency was increased significantly almost 25.80% in the presence of a modified electrode with the highest efficiencies of about 96.69% in a natural pH environment, 200 A/m 2 , 2 g/L NaCl concentration, 30 °C temperature, and 15 min process time for 50 ppm RTB21 dye concentration for (rGO/Gr) 2 electrode. The RTB21 decolourization by indirect electro-oxidation process follows the pseudo-first-order kinetics, and the activation energy was estimated to be 23.42 kJ/mol. The stability of (rGO/ Gr) 2 electrode was also examined. The rGO coated electrode was a superior electrode for the indirect electro-oxidation process, giving enhanced colour removal (%).
Barring a selected few as beneficial trace elements, majority of them have no established biologi... more Barring a selected few as beneficial trace elements, majority of them have no established biological functions and are considered as nonessential metals. Because of their high degree of toxicity, lead (Pb), arsenic (As), cadmium (Cd), chromium (Cr), selenium (Se), and nickel (Ni) rank among the priority metals that are of great public health significance. [2] These are all systemic toxicants inducing multiple organ damage, even at lower levels of exposure. According to the United States Environmental Protection Agency and the International Agency for Research on Cancer, these metals are also classified as either "known" or "probable" human carcinogens based on epidemiological and experimental studies, depicting an association between exposure and cancer incidence in humans and animals. [3] Heavy metal exposure, in particular, affects all organ systems including the nervous, dermatologic, cardiovascular, gastrointestinal, and respiratory systems. [3-5] Mostly, the waters of highly metalcontaminated sites and abandoned mines are in acidic range due to the higher concentration of sulphates, metals, and metalloids. White rot fungal communities may play crucial role in removal of heavy metals as they grow in acidic medium and survive with higher concentration of heavy metals. [6] Additionally, white rot fungi accumulate organic acids, carboxylic, and thiol ligands and other polymeric substances extracellularly, which reduce the toxicity of heavy metals. [7,8] Phanerochaete chrysosporium, a representative white rot fungus, has been used extensively for environmental engineering fields as its favorable metal absorption ability. [8-10] In the present study, free cells of P. chrysosporium are used for metal absorption, which offers several advantages over living cell study: i) wide range of operating conditions (pH and temperature), ii) no nutrition requirement, iii) comparative fast metal removal (in terms of time), and iv) resistant to initial higher metal concentration. [6] In biosorption studies, biosorbent concentration, pH, temperature, and metal concentration are the most important parameters, which directly affect the biosorption efficacy of metals. Previously, various researchers studied the biosorption efficiency of fungal biomass, optimized using either OFAT (one factor at a time) method or multivariate optimization Efficient degradation of hazardous contaminants from contaminated water is the major challenge for researchers, wherein heavy metals are the prominent contaminants. Consequently, the assessment of multimetal removal is necessary using efficient biosorbant. In this work, the capability of Phanerochaete chrysosporium is evaluated for the individual and simultaneous removal of heavy metals. Individual and simultaneous removal of As, Cd, and Cr is optimized using response surface methodology based on the central composite design by changing the variables, i.e., pH, fungal biomass, and metal concentration. Optimization of the individual metal removal study reveals that fungus effectively absorbs As (29.95 mg L −1), Cd (18.1 mg L −1), and Cr (26.34 mg L −1) at 6.1, 5.64, and 4.15 of pH, respectively. Similarly, As (14.18 mg L −1), Cd (4.53 mg L −1), and Cr (9.28 mg L −1) are absorbed by fungal hyphae simultaneously within 1 h. Changes in the morphology of fungal hyphae are detected in metal absorbed samples as compared to the control hyphae. Interaction of metal-absorbed fungal hyphae is analyzed using FTIR spectroscopy, revealing that the proteins, carbohydrates, and fatty acids present in the fungal cell are interacted with metals. The model white rot fungi used in the present study can be applied efficiently for the multimetal removal in effluent treatment plants. Metal Removal
Applied Microbiology and Biotechnology, Jul 31, 2004
Fermentation of biomass or carbohydrate-based substrates presents a promising route of biological... more Fermentation of biomass or carbohydrate-based substrates presents a promising route of biological hydrogen production compared with photosynthetic or chemical routes. Pure substrates, including glucose, starch and cellulose, as well as different organic waste materials can be used for hydrogen fermentation. Among a large number of microbial species, strict anaerobes and facultative anaerobic chemoheterotrophs, such as clostridia and enteric bacteria, are efficient producers of hydrogen. Despite having a higher evolution rate of hydrogen, the yield of hydrogen [mol H 2 (mol substrate −1)] from fermentative processes is lower than that achieved using other methods; thus, the process is not economically viable in its present form. The pathways and experimental evidence cited in the literature reveal that a maximum of four mol of hydrogen can be obtained from substrates such as glucose. Modifications of the fermentation process, by redirection of metabolic pathways, gas sparging and maintaining a low partial pressure of hydrogen to make the reaction thermodynamically favorable, efficient product removal, optimum bioreactor design and integrating fermentative process with that of photosynthesis, are some of the ways that have been attempted to improve hydrogen productivity. This review briefly describes recent advances in these approaches towards improvement of hydrogen yield by fermentation.
In the present study the esterification of palm fatty acid distillate (PFAD), a by-product from p... more In the present study the esterification of palm fatty acid distillate (PFAD), a by-product from palm oil industry, in the presence of super phosphoric acid (SPA) catalyst was studied. The effects of various physico-chemical parameters such as temperature, PFAD to methanol molar ratio and amount of catalyst on the conversion of biodiesel were investigated. The percent conversion of FFA and properties of the biodiesel were determined following standard methodologies. Percent conversion of biodiesel was found to increase with the increase in PFAD to methanol molar ratio and at 1:12 molar ratio and 70°C temperature 95% conversion was achieved. Thermodynamic parameters were also evaluated in terms of Gibbs free energy, enthalpy and entropy at different molar ratio and temperatures. Both pseudo first and second order irreversible kinetics were applied to a wide range of experimental data. However, according to regression coefficient (R2) the second order described better experimental beha...
The potential of activated fly ash has been investigated for the adsorption of copper (II) dissol... more The potential of activated fly ash has been investigated for the adsorption of copper (II) dissolved in wastewater. Physico-chemical parameters such as adsorbate concentration, pH, adsorbent dose, temperature, presence of interfering ions etc were optimized by employing batch adsorption technique. Adsorption was endothermic and followed Langmuir and Freundlich isotherms, however, the latter fitted well. Isotherms were used to estimate thermodynamic parameters for the adsorption process. Kinetic data were fitted to the models of intraparticle diffusion, pseudo second order and Lagergren model which followed more closely to the pseudo second order chemisorption model. The regeneration and reusability of the adsorbents were also assessed. Maximum removal of copper (II) was obtained at pH 4 and temperature 50°C (about 98% for adsorbent dose of 20 g/l and 50 mg/l initial feed concentration).
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