Adsorption of 2, 4, 6-trichlorophenol(TCP) onto the calcined Mg/Al-CO_3 layered double hydroxide(CLDH) was investigated. The prepared Mg/Al-CO_3 layered double hydroxide(LDH) and CLDH were characterized by powde...Adsorption of 2, 4, 6-trichlorophenol(TCP) onto the calcined Mg/Al-CO_3 layered double hydroxide(CLDH) was investigated. The prepared Mg/Al-CO_3 layered double hydroxide(LDH) and CLDH were characterized by powder X-ray diffraction(XRD) and thermo gravimetric analyzer-differential scanning calorimeters(TG-DSC). Moreover, 2,4,6-trichlorophenol(TCP) was removed effectively(94.7% of removal percentage in 9h) under the optimized experimental conditions. The adsorption kinetics data fitted the pseudosecond-order model well. The Freundlich, Langmuir, and Tempkin adsorption models were applied to the experimental equilibrium adsorption data at different temperatures of solution. The adsorption data fitted the Freundlieh adsorption isotherm with good values of the correlation coefficient. A mechanism of the adsorption process is proposed according to the intraparticle diffusion model, which indicates that the overall rate of adsorption can be described as three steps.展开更多
This study presents the use of chicken eggshells waste utilizing palm kernel shell based activated carbon(PKSAC) through the modification of their surface to enhance the adsorption capacity of H2S. Response surface ...This study presents the use of chicken eggshells waste utilizing palm kernel shell based activated carbon(PKSAC) through the modification of their surface to enhance the adsorption capacity of H2S. Response surface methodology technique was used to optimize the process conditions and they were found to be: 500 mg/L for H2S initial concentration, 540 min for contact time and 1 g for adsorbent mass. The impacts of three arrangement factors(calcination temperature of impregnated activated carbon(IAC), the calcium solution concentration and contact time of calcination) on the H2S removal efficiency and impregnated AC yield were investigated. Both responses IAC yield(IACY, %) and removal efficiency(RE, %) were maximized to optimize the IAC preparation conditions. The optimum preparation conditions for IACY and RE were found as follows: calcination temperature of IAC of 880 ℃, calcium solution concentration of 49.3% and calcination contact time of 57.6 min, which resulted in 35.8% of IACY and 98.2% RE. In addition, the equilibrium and kinetics of the process were investigated. The adsorbent was characterized using TGA, XRD, FTIR, SEM/EDX, and BET. The maximum monolayer adsorption capacity was found to be 543.47 mg/g. The results recommended that the composite of PKSAC and Ca O could be a useful material for H2S containing wastewater treatment.展开更多
The adsorption of six kinds of chlorophenols on pristine, hydroxylated and carboxylated single-walled carbon nanotubes(SWCNTs) has been investigated. Pseudo-first order and pseudo-second order models were used to de...The adsorption of six kinds of chlorophenols on pristine, hydroxylated and carboxylated single-walled carbon nanotubes(SWCNTs) has been investigated. Pseudo-first order and pseudo-second order models were used to describe the kinetic data. All adsorption isotherms were well fitted with Langmuir, Freundlich and Polanyi–Manes models, due to surface adsorption dominating the adsorption process. The close linear relationship between log Kowand log Kdsuggested that hydrophobicity played an important role in the adsorption. The SWCNTs' adsorption capacity for chlorophenols was weakened by addition of oxygen-containing functional groups on the surface, due to the loss of specific surface area, the increase of hydrophilicity and the reduction of π–π interaction. The best adsorption capacity of pristine SWCNTs, SWCNT-OH and SWCNT-COOH for six chlorophenols varied from 19 to 84 mg/g, from 19 to 65 mg/g and from 17 to 65 mg/g,respectively. The effect of pH on the adsorption of 2,6-dichlorophenol(2,6-DCP), was also studied. When p H is over the pK aof 2,6-dichlorophenol(2,6-DCP), its removal dropped sharply. When ionic strength increased(Na Cl or KCl concentration from 0 to 0.02 mmol/L),the adsorption capacity of 2,6-DCP on pristine SWCNTs decreased slightly. The comparison of chlorophenols adsorption by SWCNTs, MWCNTs and PAC was made, indicating that the adsorption rate of CNTs was much faster than that of PAC. The results provide useful information about the feasibility of SWCNTs as an adsorbent to remove chlorophenols from aqueous solutions.展开更多
A novel Ce(Ⅲ)-incorporated cross-linked chitosan(Ce-CCS) was prepared and used for the removal of fluoride from aqueous solution. The structure and morphology of Ce-CCS were measured by Fourier transform infrared...A novel Ce(Ⅲ)-incorporated cross-linked chitosan(Ce-CCS) was prepared and used for the removal of fluoride from aqueous solution. The structure and morphology of Ce-CCS were measured by Fourier transform infrared spectroscopy(FTIR), X-ray diffraction(XRD), scanning electronic microscopy(SEM) and energy dispersive X-ray analyzer(EDAX) techniques. The factors affecting the fluoride adsorption such as adsorbent dosage, initial fluoride concentration, pH, coexisting anions and contact time were investigated. Increasing adsorbent dosage enhanced the removal towards fluoride while increasing initial fluoride concentration reduced the removal towards fluoride. The optimal pH value for fluoride adsorption was 3 or so. The presence of coexisting anions weakened the adsorption of fluoride, and the decreasing order of the removal towards fluoride was PO_4^(3–)〉CO_3^(2–)〉SO_4^(2–)〉Cl~–. The adsorption data were described by Freundlich isotherm model and the pseudo-second order kinetic model. The incorporation of Ce(Ⅲ) enhanced the adsorption capacity of CCS for fluoride ions, the adsorption capacity at equilibrium(q_e) of Ce-CCS increased by 5.0 mg/g or so as compared with the one of CCS at the same temperature tested. The exhausted Ce-CCS could regenerate with 0.1 mol/L HCl solution.展开更多
基金Funded by the National Natural Science Foundation of China(No.21476269)
文摘Adsorption of 2, 4, 6-trichlorophenol(TCP) onto the calcined Mg/Al-CO_3 layered double hydroxide(CLDH) was investigated. The prepared Mg/Al-CO_3 layered double hydroxide(LDH) and CLDH were characterized by powder X-ray diffraction(XRD) and thermo gravimetric analyzer-differential scanning calorimeters(TG-DSC). Moreover, 2,4,6-trichlorophenol(TCP) was removed effectively(94.7% of removal percentage in 9h) under the optimized experimental conditions. The adsorption kinetics data fitted the pseudosecond-order model well. The Freundlich, Langmuir, and Tempkin adsorption models were applied to the experimental equilibrium adsorption data at different temperatures of solution. The adsorption data fitted the Freundlieh adsorption isotherm with good values of the correlation coefficient. A mechanism of the adsorption process is proposed according to the intraparticle diffusion model, which indicates that the overall rate of adsorption can be described as three steps.
基金Funded by the Faculty of Chemical&Natural Resources Engineering,Universiti Malaysia Pahang through a Local Research Grant Scheme
文摘This study presents the use of chicken eggshells waste utilizing palm kernel shell based activated carbon(PKSAC) through the modification of their surface to enhance the adsorption capacity of H2S. Response surface methodology technique was used to optimize the process conditions and they were found to be: 500 mg/L for H2S initial concentration, 540 min for contact time and 1 g for adsorbent mass. The impacts of three arrangement factors(calcination temperature of impregnated activated carbon(IAC), the calcium solution concentration and contact time of calcination) on the H2S removal efficiency and impregnated AC yield were investigated. Both responses IAC yield(IACY, %) and removal efficiency(RE, %) were maximized to optimize the IAC preparation conditions. The optimum preparation conditions for IACY and RE were found as follows: calcination temperature of IAC of 880 ℃, calcium solution concentration of 49.3% and calcination contact time of 57.6 min, which resulted in 35.8% of IACY and 98.2% RE. In addition, the equilibrium and kinetics of the process were investigated. The adsorbent was characterized using TGA, XRD, FTIR, SEM/EDX, and BET. The maximum monolayer adsorption capacity was found to be 543.47 mg/g. The results recommended that the composite of PKSAC and Ca O could be a useful material for H2S containing wastewater treatment.
基金supported by the National Natural Science Foundation of China (No. 51290284)
文摘The adsorption of six kinds of chlorophenols on pristine, hydroxylated and carboxylated single-walled carbon nanotubes(SWCNTs) has been investigated. Pseudo-first order and pseudo-second order models were used to describe the kinetic data. All adsorption isotherms were well fitted with Langmuir, Freundlich and Polanyi–Manes models, due to surface adsorption dominating the adsorption process. The close linear relationship between log Kowand log Kdsuggested that hydrophobicity played an important role in the adsorption. The SWCNTs' adsorption capacity for chlorophenols was weakened by addition of oxygen-containing functional groups on the surface, due to the loss of specific surface area, the increase of hydrophilicity and the reduction of π–π interaction. The best adsorption capacity of pristine SWCNTs, SWCNT-OH and SWCNT-COOH for six chlorophenols varied from 19 to 84 mg/g, from 19 to 65 mg/g and from 17 to 65 mg/g,respectively. The effect of pH on the adsorption of 2,6-dichlorophenol(2,6-DCP), was also studied. When p H is over the pK aof 2,6-dichlorophenol(2,6-DCP), its removal dropped sharply. When ionic strength increased(Na Cl or KCl concentration from 0 to 0.02 mmol/L),the adsorption capacity of 2,6-DCP on pristine SWCNTs decreased slightly. The comparison of chlorophenols adsorption by SWCNTs, MWCNTs and PAC was made, indicating that the adsorption rate of CNTs was much faster than that of PAC. The results provide useful information about the feasibility of SWCNTs as an adsorbent to remove chlorophenols from aqueous solutions.
文摘A novel Ce(Ⅲ)-incorporated cross-linked chitosan(Ce-CCS) was prepared and used for the removal of fluoride from aqueous solution. The structure and morphology of Ce-CCS were measured by Fourier transform infrared spectroscopy(FTIR), X-ray diffraction(XRD), scanning electronic microscopy(SEM) and energy dispersive X-ray analyzer(EDAX) techniques. The factors affecting the fluoride adsorption such as adsorbent dosage, initial fluoride concentration, pH, coexisting anions and contact time were investigated. Increasing adsorbent dosage enhanced the removal towards fluoride while increasing initial fluoride concentration reduced the removal towards fluoride. The optimal pH value for fluoride adsorption was 3 or so. The presence of coexisting anions weakened the adsorption of fluoride, and the decreasing order of the removal towards fluoride was PO_4^(3–)〉CO_3^(2–)〉SO_4^(2–)〉Cl~–. The adsorption data were described by Freundlich isotherm model and the pseudo-second order kinetic model. The incorporation of Ce(Ⅲ) enhanced the adsorption capacity of CCS for fluoride ions, the adsorption capacity at equilibrium(q_e) of Ce-CCS increased by 5.0 mg/g or so as compared with the one of CCS at the same temperature tested. The exhausted Ce-CCS could regenerate with 0.1 mol/L HCl solution.