Activated mud has been employed to remove phenolic compounds, a common contaminant in wastewaters. Because of high surface area per unit area, activated mud is the most effective adsorbent and exhibits high capacity o...Activated mud has been employed to remove phenolic compounds, a common contaminant in wastewaters. Because of high surface area per unit area, activated mud is the most effective adsorbent and exhibits high capacity of adsorption of phenolic compounds. A complete study was undertaken on the adsorption of phenol starting from an aqueous solution on activated mud with ammonium chloride. The removal is found to be dependent on concentration of phenol and increasing of concentrations favour the uptake. The isotherms and kinetics of adsorption of phenol on activated mud were studied at 20oC. Equilibrium isotherm of phenol on activated mud is obtained and the results shows that the Langmuir model provided the best fit for the adsorption data. From the experimental results obtained, the adsorption process can be well described with the pseudo-second order model.展开更多
Competitive adsorption of malachite green (MG) in single and binary system on microwave activated epicarp of Ricinus communis (MRC) and microwave assisted zinc chloride activated epicarp of Ricinus communis (ZRC) were...Competitive adsorption of malachite green (MG) in single and binary system on microwave activated epicarp of Ricinus communis (MRC) and microwave assisted zinc chloride activated epicarp of Ricinus communis (ZRC) were analyzed. The preparation of ZRC from Ricinus communis was investigated in this paper. Orthogonal array experimental design method was used to optimize the preparation of ZRC. Optimized parameters were radiation power of 100 W, radiation time of 4 min, concentration of zinc chloride of 30% by volume and impregnation time of 16 h, respectively. The MRC and ZRC were characterized by pHzpc, SEM-EDAX and FTIR analysis. The effect of the presence of one dye solution on the adsorption of the other dye solution was investigated in terms of equilibrium isotherm and adsorption yield. Experimental results indicated that the uptake capacities of one dye were reduced by the presence of the other dye. The adsorption equilibrium data fits the Langmuir model well and follows pseudo second-order kinetics for the bio-sorption process. Among MRC and ZRC, ZRC shows most adsorption ability than MRC in single and binary system.展开更多
The present work aimed at the study of citric acid solvent extraction in order to establish the composition of the organic phase and to obtain thermodynamic and kinetic data for the chosen system. Discontinuous extrac...The present work aimed at the study of citric acid solvent extraction in order to establish the composition of the organic phase and to obtain thermodynamic and kinetic data for the chosen system. Discontinuous extraction experiments in a single stage were performed from a synthetic solution of citric acid, with the typical concentration (10% w/v) observed in industrial fermented musts. Exploratory experiments were carried out using different organic phases in order to select the most suitable solvent phase to further continuous extraction tests in a mechanically agitated column. The selected organic phase composition was: Alamine? 336, ExxalTM 13 tridecyl alcohol, and the aliphatic diluent EscaidTM 110. Next, the effects of the contact time and of the concentrations of extractant and modifier on the citric acid extraction were studied. Among the investigated conditions, the best one was 10 minutes of contact time, 30% w/v of Alamine? 336, and 10% w/v of ExxalTM 13 tridecyl alcohol. For this condition, the equilibrium isotherm (28°C ± 2°C) was determined, and the equilibrium constant was calculated (36.8 (mol·L-1)-1.5). It was considered that trioctylamine and citric acid complexation reaction occurs mainly with non-dissociated citric acid form, because the aqueous feed solutions’ pH is lower than the citric acid pKa1. It was found that 1.5 molecules of the extractant, on average, are required to react with one citric acid molecule, which can indicate that reactions with different extractant/citric acid ratios occur simultaneously. Next, the rate constants for the direct and inverse reactions, 2.10 (mol·L-1)-1.5·s-1 and 5.69 × 10-2 s-1, respectively, were calculated. Coefficients of determination (R2) values higher than 0.93 were found in these calculations, suggesting that the results obtained using a computer modeling would be very close to those results obtained experimentally. Therefore, the present work provides data required to future modelling, design, and simulation of citric acid solvent extract展开更多
文摘Activated mud has been employed to remove phenolic compounds, a common contaminant in wastewaters. Because of high surface area per unit area, activated mud is the most effective adsorbent and exhibits high capacity of adsorption of phenolic compounds. A complete study was undertaken on the adsorption of phenol starting from an aqueous solution on activated mud with ammonium chloride. The removal is found to be dependent on concentration of phenol and increasing of concentrations favour the uptake. The isotherms and kinetics of adsorption of phenol on activated mud were studied at 20oC. Equilibrium isotherm of phenol on activated mud is obtained and the results shows that the Langmuir model provided the best fit for the adsorption data. From the experimental results obtained, the adsorption process can be well described with the pseudo-second order model.
文摘Competitive adsorption of malachite green (MG) in single and binary system on microwave activated epicarp of Ricinus communis (MRC) and microwave assisted zinc chloride activated epicarp of Ricinus communis (ZRC) were analyzed. The preparation of ZRC from Ricinus communis was investigated in this paper. Orthogonal array experimental design method was used to optimize the preparation of ZRC. Optimized parameters were radiation power of 100 W, radiation time of 4 min, concentration of zinc chloride of 30% by volume and impregnation time of 16 h, respectively. The MRC and ZRC were characterized by pHzpc, SEM-EDAX and FTIR analysis. The effect of the presence of one dye solution on the adsorption of the other dye solution was investigated in terms of equilibrium isotherm and adsorption yield. Experimental results indicated that the uptake capacities of one dye were reduced by the presence of the other dye. The adsorption equilibrium data fits the Langmuir model well and follows pseudo second-order kinetics for the bio-sorption process. Among MRC and ZRC, ZRC shows most adsorption ability than MRC in single and binary system.
文摘The present work aimed at the study of citric acid solvent extraction in order to establish the composition of the organic phase and to obtain thermodynamic and kinetic data for the chosen system. Discontinuous extraction experiments in a single stage were performed from a synthetic solution of citric acid, with the typical concentration (10% w/v) observed in industrial fermented musts. Exploratory experiments were carried out using different organic phases in order to select the most suitable solvent phase to further continuous extraction tests in a mechanically agitated column. The selected organic phase composition was: Alamine? 336, ExxalTM 13 tridecyl alcohol, and the aliphatic diluent EscaidTM 110. Next, the effects of the contact time and of the concentrations of extractant and modifier on the citric acid extraction were studied. Among the investigated conditions, the best one was 10 minutes of contact time, 30% w/v of Alamine? 336, and 10% w/v of ExxalTM 13 tridecyl alcohol. For this condition, the equilibrium isotherm (28°C ± 2°C) was determined, and the equilibrium constant was calculated (36.8 (mol·L-1)-1.5). It was considered that trioctylamine and citric acid complexation reaction occurs mainly with non-dissociated citric acid form, because the aqueous feed solutions’ pH is lower than the citric acid pKa1. It was found that 1.5 molecules of the extractant, on average, are required to react with one citric acid molecule, which can indicate that reactions with different extractant/citric acid ratios occur simultaneously. Next, the rate constants for the direct and inverse reactions, 2.10 (mol·L-1)-1.5·s-1 and 5.69 × 10-2 s-1, respectively, were calculated. Coefficients of determination (R2) values higher than 0.93 were found in these calculations, suggesting that the results obtained using a computer modeling would be very close to those results obtained experimentally. Therefore, the present work provides data required to future modelling, design, and simulation of citric acid solvent extract
