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Publication Date: 2025
Journal of Molecular Liquids (18733166)429
Natural gas is a valuable source of energy, however, it also contains hazardous compounds, such as hydrogen sulfide (H2S) acid gas, which needs to be eliminated to make it safe for use. If H2S is released, it can cause serious hazards like environmental issues and human respiratory or even death. Up to now, amine-based solvents have been used for gas sweetening. However, they are not environmentally friendly solvents, so replacing them with green solvents is required. Deep Eutectic Solvents (DESs) are the high-potential candidates of green solvents for this purpose. This study investigated comprehensive thermodynamic modeling of H2S solubilities in a wide range of different nature DESs using two thermodynamic approaches of φ-φ and γ-φ and one chemical absorption approach. The largest and most updated H2S solubility in DESs’ data bank was gathered from open literature including 338 data points for 33 different DESs over a wide range of temperature and pressure. For the investigated approaches, the SRK-SRK, SRK-NRTL, and RETM (1:2) models with the AARD% values of 13.42, 11.64, and 11.21, respectively led to the best results. According to comprehensive investigation and data analysis, general guidelines for using different thermodynamic models for H2S solubility in DESs were proposed. © 2025 Elsevier B.V.
Publication Date: 2024
Chemosphere (0045-6535)366
Sulfur dioxide (SO2), produced mainly from the combustion of coal, is the most important cause of acidic rain, skin diseases, and environmental issues. To overcome the environmental problems, SO2 must be captured on an industrial scale before it is released into the air. In chemical industries, organic solvents are used for partial absorption of SO2. However, those organic solvents have negative environmental effects. Thus, proposing environmentally friendly and green solvents for SO2 absorption is vital for industries. Recently, increased attention has been paid to capturing SO2 using Deep Eutectic Solvents (DESs) as the most recently introduced category of green solvents. This study performed a comprehensive screening study on the investigation of the performance of various simple and complicated models for SO2 solubilities in a wide range of different nature DESs. For this purpose, the most updated and largest SO2 solubility data bank in DESs involving 976 data points for 63 different nature DESs over wide temperature and pressure ranges has been gathered from open literature. For model screening, for the physical absorption models, the performances of SRK and CPA as the simple cubic and complicated sophisticated equations of state, NRTL and UNIQUAC as the well-known activity coefficient models, and for the chemical absorption models, RETM were investigated and compared. For physical absorption models, coupling an equation of state with the UNIQUAC activity coefficient model i.e. CPA-UNIQUAC, SRK-UNIQUAC, and also using simple SRK-SRK models led to the best performances. Compared to all investigated models, RETM as the chemical absorption model showed the best performance with the AARD% value of 12.95. This shows the importance of considering the chemical absorption mechanism for SO2 absorption by DESs. Finally, general guidelines for using different modeling approaches were proposed to be considered by the researchers. © 2024 Elsevier Ltd
Publication Date: 2021
Fuel (0016-2361)290
Cogongrass, one of the most invasive pest species worldwide, was considered as a promising bioresource for second-generation ethanol production. For the first time, it was successfully valorized to bioethanol using a novel sequential ionic liquid pretreatment assisted by synergistic effects of ultrasound irradiation and biosurfactant impregnation. The biomass was sonicated (50 and 100 W, 20 kHz) for 15 and 30 min, suspended in rhamnolipid solution (1, 2, and 3% w/w), and finally pretreated with 1-ethyl-3-methylimidazole acetate at 120 °C. Enzymatic digestibility of the regenerated biomass substantially enhanced by ~ 1.2-fold, upon a fast and low-intensity sonication (15 min, 50 W) followed by impregnation with the diluted rhamnolipid solution (2% w/w). Accordingly, non-isothermal simultaneous saccharification and fermentation of the pretreated Cogongrass by fungus M. hiemalis led to a maximum ethanol yield of ~ 195 (g/kg dry substrate), which was almost 1.6-fold higher than that obtained from the conventionally ionic liquid pretreated biomass. Comprehensive semi-quantitative analyses of the biomass together with FTIR and FESEM measurements revealed major improvements in surface area, surface hydrophilicity, pore sizes and volumes, cellulose crystallinity, and morphological features following the pretreatment. The findings may also provide a promising approach for enhanced recycling of the expensive ionic liquid and lignin in a biorefinery framework; however, more investigation should be dedicated to this subject. © 2020 Elsevier Ltd
Publication Date: 2021
International Journal of Environmental Science and Technology (17351472)18(2)pp. 297-316
Nanocrystalline metal oxides including TiO2, Fe2O3, and ZnO and their combinations were impregnated on activated carbon (AC) and characterized by XRD, FTIR, and FESEM analyses. The results showed the size of most Fe2O3/AC, TiO2/AC, TiO2/Fe2O3/AC, ZnO/AC, and ZnO/Fe2O3/AC particles are in the range of 25–60 nm. BET analysis verified the high surface area of the six adsorbents (201–448 m2/g). The adsorption results confirmed that the modification could improve the adsorption capacity and removal efficiency as the maximum monolayer adsorption capacity and cyanide removal efficiency were observed for ZnO/Fe2O3/AC (101.0 mg/g, 82.5%), TiO2/Fe2O3/AC (96.2 mg/g, 75.1%), ZnO/AC (91.7 mg/g, 73.5%), TiO2/AC (90.9 mg/g, 72.4%), Fe2O3/AC (86.2 mg/g, 69.2%,), and AC (78.1 mg/g, 66.3%), respectively. Moreover, the study of different isotherm models including Langmuir, Freundlich, and Redlich–Peterson indicated that the Langmuir model was the most suitable one for the six adsorbents with 0.56 < RL < 0.64. The kinetic modeling of experimental data revealed the cyanide adsorption on all adsorbents followed the pseudo second-order model confirming chemisorption can be a main mechanism of adsorption. The regeneration and reusability results showed modified AC adsorbents have more reusable and stable structure than AC to be used as adsorbents in industrial wastewaters. The performance of adsorption process was compared with different methods of cyanide removal. The results approved that adsorption process as a cost-effective and simple design method using bioadsorbents can be highly effective in full-scale applications for the removal of high concentration of cyanide. © 2020, Islamic Azad University (IAU).
Publication Date: 2021
Biomass Conversion and Biorefinery (21906815)11(6)pp. 2963-2973
Tobacco product waste (TPW) was considered as a novel and sustainable feedstock for second-generation ethanol production. TPW with over ~ 44% cellulose content was efficiently pretreated using concentrated (10% W/V) sodium hydroxide (SH) solution at different temperatures (0, 25, and 80 °C) and retention times (3 and 6 h). Subsequently, the pretreated biomass was subjected to separate enzymatic hydrolysis and fermentation by the filamentous fungus Mucor hiemalis. Promising results were achieved following 3 h pretreatment of TPW at 80 °C, whereas the hydrolysis yield was substantially increased up to 91.3%. Besides, comprehensive tacking of key features of biomass (e.g., composition, crystalline structure, surface hydrophilicity and morphology, and accessible surface area) by semi-quantitative methods together with FTIR and SEM observations revealed major improvements occurred after mild SH pretreatment. Consequently, the maximum ethanol production as high as ~ 97% of theoretical ethanol yield was obtained, while it was only 44.4% from the untreated TPW. The implication of the work could possibly support TPW utilization for large-scale ethanol production in a tobacco-based biorefinery framework. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
Publication Date: 2021
Environmental Nanotechnology, Monitoring and Management (22151532)15
TiO2/BiOBr/Bi2S3 nanostructure impregnated on the activated carbon (AC) was synthesized, in order to achieve considerable synergy between photocatalysis and adsorption for 2,4-dichlorophenoxyacetic acid (2,4-D) removal from polluted water. The XRD, XRF, EDX, FE-SEM, and FT-IR analyses confirmed successful formation of the catalyst. The results of UV-DRS analysis, showed the estimated band gaps obtained were about 2.8 eV and 2.55 eV for the TiO2/BiOBr and TiO2/BiOBr/Bi2S3 nanostructures respectively showing high potential for the wide range of visible and solar spectrum. The photocatalytic degradation results based on the response surface methodology (RSM) experimental design confirmed that initial 2,4-D concentration, pH, catalyst concentration, irradiation time and the interaction between TiO2/BiOBr/Bi2S3/AC concentration and irradiation time had the most effects, respectively. The best results were obtained under the optimum conditions (2,4-D = 90 mg/L, pH = 3, catalyst = 0.6 mg/L and irradiation time = 90 min) on which the pollutant removal efficiency was 98 % and TOC removal efficiency was determined 74 %. Increasing the visible light intensity to 120 mW/cm2 resulted in a complete degradation. The coexistence of 10 % BiOBr and 5%Bi2S3 compounds on TiO2 not only increased the absorption edge to 600 nm and charge transportation but also improved photocatalytic properties of TiO2/BiOBr/Bi2S3/AC nanostructure as it could be an appropriate compound for water treatment. © 2020 Elsevier B.V.
Publication Date: 2020
Industrial Crops and Products (09266690)152
The non-valuable non-edible Glycyrrhiza glabra residue (GGR) was efficiently subjected to inexpensive sodium carbonate pretreatment for enhanced enzymatic hydrolysis and ethanol production. The process included sodium carbonate pretreatment at different concentrations (0.5 and 1 M), temperatures (60, 100 and 120 °C), and retention times (3, 5 and 8 h), followed by separate hydrolysis and fermentation using a rarely-reported fungus Mucor hiemalis. The GGR pretreated with 0.5 M sodium carbonate solution at 120 °C for 3 h exhibited the maximum digestibility yield of 94.6% which was 6.2-fold higher than that observed for the untreated GGR. Consequently, fermentation of GGR hydrolyzates by M. hiemalis led to a maximum ethanol production yield of over 94%. Composition analysis of the biomass indicated that the process could substantially remove the majority of lignin part but left the cellulose relatively intact. Moreover, in-depth analyses of the materials by rapid semi-quantitative methods (e.g., Simons’ stain) as well as FTIR, XRD, and FE-SEM investigations revealed that sodium carbonate pretreatment could not only modify biomass composition, but also expanded cellulosic surface area, increased surface hydrophilicity, enlarged the pores, and improved morphological quality of GGR; thereby, rendered it more accessible to the cellulase. The implication of the study may potentially provide the first insight into commercial utilization of GGR for large-scale bioethanol production in a biorefinery framework. © 2020 Elsevier B.V.
Publication Date: 2019
Fuel (0016-2361)258
The present investigation evaluated Cogongrass as a prospective non-edible feedstock for second-generation bioethanol. An innovative recycling-based strategy was employed to minimize chemical consumption and wastewater generation during the mild-alkali pretreatment. The biomass was pretreated with 2% (W/V) sodium hydroxide (SH) solution at 85 °C for 90 min and subsequently subjected to separate saccharification and fermentation. Accordingly, the produced black liquor (BL) and waste wash-water (WWW) were sequentially withdrawn and partially fed back to the next pretreatment and washing processes, respectively. The results indicated that enzymatic hydrolysis of the biomass was substantially improved from 24.8% up to 90.8% following the alkali pretreatment; and afterward, it was progressively decreased to a minimum value of 66.4% upon recycling BL and WWW for ten times. Parallel hydrolysis experiments were conducted in the presence of three non-ionic environmentally-friendly surfactants at different concentrations (0.25–2% V/V). Notably, supplementation with 0.5% (V/V) Tween 80 significantly improved hydrolysis yield of recycled BL (RBL) pretreated substrate to a maximum value of ~88%. Fermentation of the RBL-pretreated Cogongrass did not reveal any cell inhibition and resulted in maximum ~76% ethanol production yield, while also saving 59% of the water consumption and over 45% of the alkali usage. Detailed analyses of the biomass using semi-quantitative techniques revealed that enhanced cellulose accessibility to the enzyme, decreased crystallinity, and extensive lignin and hemicellulose removal were the key factors contributing to the observed improvements. © 2019 Elsevier Ltd
Publication Date: 2019
Journal Of Renewable Energy And Environment (24237469)6(4)pp. 10-15
Glycyrrhiza glabra residue (GGR) was efficiently subjected to concentrated phosphoric acid (PA) pretreatment with/without surfactant assistance, and promising results were obtained following separate enzymatic hydrolysis and fermentation (SHF) of the biomass. Pretreatment was carried out using 85 % PA either at 50 or 85 °C with 12.5 % solid loading for 30 min. In parallel experiments, the intact GGR was impregnated in 2 % (w/w) surfactant (Polyethylene glycol) aqueous solution prior to the PA pretreatment. Consequently, the pretreated materials were subjected to enzymatic hydrolysis (50 °C, 72 h) using 25 FPU/g cellulase, and the most digestible biomass was nominated for conversion to bioethanol. Substantial improvement in digestibility of GGR (~92 % hydrolysis yield) was observed following surfactant-assisted PA pretreatment, whereas digestibility yield from the untreated biomass was only 16.1 %. Consequently, the ethanol production form GGR was significantly enhanced by 19.7-fold through separate hydrolysis and fermentation of biomass. Different analytical approaches including water retention value, Simons' staining, and crystallinity together with FESEM imaging revealed that the improved surface hydrophilicity, increased substrate accessibility to enzyme, and decreased crystallinity could be the major effects of PA pretreatment, leading to higher susceptibility of GGR to enzymatic hydrolysis and subsequent ethanol production. © 2019 Authors. All rights reserved.
Publication Date: 2018
Scientia Iranica (23453605)25(3C)pp. 1395-1411
The sol-gel method was used for the synthesis of zero-valent iron/titanium dioxide supported on activated carbon (Fe0/TiO2/AC) adsorbents, and the adsorbents were comprehensively characterized by XRF, XRD, FT-IR, BET, FE-SEM, and EDX analyses. The batch experiments were performed to evaluate the effect of adsorbent type, pH of solution, pollutant initial concentration, and contact time on the 2,4-dichlorophenoxyacetic acid (2,4-D) adsorption efficiency. The equilibrium experiments revealed that the Langmuir isotherm was in good agreement with the adsorption equilibrium data, whereas the adsorption kinetic experiments indicated that the adsorption procedure was described perfectly through a pseudo-first-order kinetic model. The obtained maximum adsorption capacities from Langmuir isotherms of 86.5, 87.5, 86,57, and 88.76 mg/g were achieved for Activated Carbon (AC), zero-valent iron/activated carbon (Fe0/AC), titanium dioxide/activated carbon (TiO2/AC), and Fe0/TiO2/AC at the 2,4-D initial concentration of 90 mg/L, pH = 4 and 25°C, respectively. © 2018 Sharif University of Technology.All rights reserved.
Publication Date: 2017
Industrial Crops and Products (09266690)108pp. 767-774
Glycyrrhiza glabra residue (GGR) contains 30.5% cellulose and 23.0% hemicellulose and can be considered as a promising low-cost and non-edible feedstock for production of ethanol. For the first time, GGR was subjected to inexpensive sodium hydroxide (SH) pretreatment to enhance fermentable sugars production through enzymatic hydrolysis and subsequent utilization by fungus Mucor hiemalis. The pretreatment was carried out at 5% (w/v) solid loading and different temperatures (0, 28 and 110 °C) with 2, 4, 6, 8 and 10% (w/v) SH solutions. When applying no pretreatment, the glucose and ethanol production yields through separated hydrolysis and fermentation of GGR were only 13.9% and 14.3%, respectively. However, a major improvement was achieved after alkali pretreatment of GGR and the maximum hydrolysis yield of 93.7% was observed when the substrate was pretreated with 4% SH solution at 28 °C for 24 h. Consequently, fermentation of the SH pretreated materials by M. hiemalis led to a maximum 5.9-fold increase in ethanol production yield (∼217 kg per ton of GGR), which was slightly higher than the ethanol yield through the yeast Saccharomyces cerevisiae (∼207 kg per ton of GGR). Semi-quantitative analyses of the substrate after pretreatment indicated that crystallinity reduction and expanded surface area were the main reasons for the observed improvements. In brief, the results revealed that SH pretreatment (4% w/v) at room temperature is an effective strategy to valorize GGR to ethanol through hydrolysis and fermentation by fungus M. hiemalis. © 2017 Elsevier B.V.
Publication Date: 2017
Carbohydrate Polymers (0144-8617)166pp. 104-113
The present study investigated for the first time the efficacy of surfactant-assisted ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) pretreatment of beech wood waste for enhanced ethanol production. The ionic liquid (IL) pretreatment included wood dissolution at 120 °C and 5% solid loading for 3 h followed by regeneration using water as an anti-solvent. The substrate was initially presoaked in different concentrations of surfactant solution (2%, 4%, 6% w/w) prior to IL pretreatment. Tween 20, Tween 80 and polyethylene glycol 4000 (PEG) surfactants were tested and the results revealed major improvements in the yield of enzymatic hydrolysis. More than 91% enzymatic digestibility was achieved for the PEG (2%)-assisted IL-pretreated wood, while yields from untreated and IL-pretreated wood were only 6.0% and 75.2%, respectively. A maximum ethanol yield of 82.1% was obtained. Comprehensive characterization of the pretreated materials using semi-quantitative methods indicated that synergistic surfactant-assisted [EMIM]OAc pretreatment significantly increased cellulose accessibility to cellulase and decreased the hemicellulose and lignin contents. © 2017 Elsevier Ltd
Publication Date: 2013
Carbohydrate Polymers (0144-8617)96(2)pp. 440-449
Aspen wood (Populus tremula) was pretreated with ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) and dilute sulfuric acid for improvement of ethanol production. The ionic liquid pretreatment included wood dissolution at 120 ?C and 5% solid loading for 1, 3, and 5 h followed by regeneration using water as an anti-solvent. More than 95% enzymatic digestibility was achieved for the ionic liquid treated wood, while the yield from the untreated wood was only 5.3%. Furthermore, over 81% of the maximum theoretical ethanol yield was attained after 24 h fermentation of the ionic liquid treated wood, whereas the yields were only 5.3% and 42.1% for the untreated and dilute acid treated materials, respectively. A side-by-side comparative analysis of the pretreated materials using semi-quantitative techniques (e.g., Simons' staining and enzyme adsorption) revealed that the ionic liquid treatment was much more successful in increasing the cellulose accessibility to cellulases and decreasing the lignin content. © 2013 Elsevier Ltd. All rights reserved.
Publication Date: 2013
Industrial Crops and Products (09266690)49pp. 580-585
Sweet sorghum is one of the most promising energy crops for ethanol production. Fungal solid state fermentation (FSSF) of dry sweet sorghum stalk particles (DSSSPs) for ethanol production was conducted using fungus Mucor indicus and followed by simultaneous saccharification and fermentation of the residual solid without any pretreatment and addition of fresh microorganism cells. The effects of important variables including temperature (28, 32, and 36°C), moisture level (65, 75, 80, and 85%), initial fungal biomass concentration (0.001, 1, and 5. g/L), and particle size (<80, 20-80, and >20. mesh) on the yield of ethanol production by FSSF were investigated. The results showed that M. indicus was able to utilize almost all the glucose and fructose within 48. h, whereas the maximum ethanol yield (0.48. g produced ethanol/g consumed sugars) was achieved by FSSF at 32°C, 80% moisture, and particle size of 20-80. mesh with 5. g/L fungal biomass concentration. Moreover, simultaneous saccharification and fermentation of the stalk glucan (10, 25, and 50. g/L) was performed at 32, 35, and 37°C with different cellulase and β-glucosidase enzymes loading for 48. h. In the best case, 85.6% of ethanol yield was achieved when 50. g glucan/L was saccharified using 15. FPU cellulase and 30. IU β-glucosidase per gram glucan and simultaneously fermented to ethanol at 37°C for 48. h. The results indicated that the FSSF acted as a pretreatment stage and assisted the subsequent simultaneous saccharification and fermentation process of the residual solid, resulted in up to 4.3 times improvement in the ethanol production yield. © 2013 Elsevier B.V.
Publication Date: 2013
Biomass and Bioenergy (09619534)49pp. 95-101
Birch wood was pretreated with N-methylmorpholine-N-oxide (NMMO or NMO) followed by enzymatic hydrolysis and fermentation to ethanol or digestion to biogas. The pretreatments were carried out with NMMO (wNMMO = 85%) at 130 °C for 3 h, and the effects of drying after the pretreatment were investigated. Enzymatic hydrolysis of the untreated wood resulted in 8%-10% of theoretical glucose yield after 4 days hydrolysis, while the NMMO pretreatment improved this yield to 91%. Consequently, ethanol production yield from NMMO-pretreated materials resulted in around 9-fold improvement compared to the untreated wood. On the other hand, drying of the pretreated wood had a negative impact and decreased the yield of enzymatic hydrolysis by 4%-10%. Digestion of the untreated wood with thermophilic bacteria resulted in maximum methane yield of 158 cm3 g-1 of VS in 30 days, while the NMMO pretreatment improved the methane yield up to 232 cm3 g-1 of VS (80% of the theoretical biogas yield) in just 9 days. © 2012 Elsevier Ltd.
Publication Date: 2011
Industrial Crops and Products (09266690)34(1)pp. 1219-1225
The present work deals with production of ethanol from sweet sorghum bagasse by a zygomycetes fungus Mucor hiemalis. The bagasse was treated with phosphoric acid and sodium hydroxide, with or without ultrasonication, prior to enzymatic hydrolysis by commercial cellulase and β-glucosidase enzymes. The phosphoric acid pretreatment was performed at 50°C for 30. min, while the alkali treatment performed with 12% NaOH at 0°C for 3. h. The pretreatments resulted in improving the subsequent enzymatic hydrolysis to 79-92% of the theoretical yield. The best hydrolysis performance was obtained after pretreatment by NaOH assisted with ultrasonication. The fungus showed promising results in fermentation of the hydrolyzates. In the best case, the hydrolyzate of NaOH-ultrasound pretreated bagasse followed by 24. h fermentation resulted in about 81% of the corresponding theoretical ethanol yield. Furthermore, the highest volumetric ethanol productivity was observed in the hydrolyzates of NaOH pretreated bagasse, especially after ultrasonication in pretreatment stage. © 2011 Elsevier B.V.
Publication Date: 2011
Desalination (0011-9164)269(1-3)pp. 170-176
Removal of C.I. Acid Blue 92(AB92) dye by exfoliated graphite (EG) was investigated. Batch adsorption test results proved that EG can remove the dye with a minimum removal efficiency of 70%. Equilibrium isotherm was analyzed by Freundlich, Langmuir, and Radke-Prausnitz models and the related parameters were estimated. It was found that both Langmuir and Radke-Prausnitz models fit the experimental data satisfactorily. A comprehensive series of column tests were performed to determine the breakthrough curves, and the effects of the feed flow rate, initial dye concentration, and adsorbent dosage on adsorption process were studied. The results showed that the breakthrough time increased in proportion to the increase in the dose of adsorbent, but decreased with increase in flow rate and initial dye concentration. The total uptake of AB92 was found 5.02 (gdye/gEG) at 27±2°C for the initial concentration of 30mg L-1 at 9.6mL min-1 feed flow rate. An axial dispersion mathematical model implementing nonlinear isotherm and linear driving force mass transfer assumption were developed for predicting the dynamic behavior of the adsorption column. The results obtained from the mathematical model were in good agreement with the experimental data, which proved the success of the model in predicting the process. © 2010.
