Modified peanut shell （MPS） was prepared by amination reaction with peanut shell （PS） as the starting material The sorption of Cr（VI） oxyanions on MPS in static and column tests were investigated. In addition, t...Modified peanut shell （MPS） was prepared by amination reaction with peanut shell （PS） as the starting material The sorption of Cr（VI） oxyanions on MPS in static and column tests were investigated. In addition, the sorption isotherm and kinetic models were applied to confirm the sorption capacity and the sorption mechanisms. BET surface area anysis showed the physicochemical characterist!cs of the samples. The results of zeta potential,Fourier transform infrared （FT-IR） and Raman spectra analysis illustrated that chemical adsorption and ion exi change are the potential sorption mechanism. The static sorption test showed that the maximum sorption capacity （qm） of MPS for Cr（VI） increased with temperature, which indicated that the Cr（VI） sorption rocess was endothermic. The saturated sorption capacity of Cr（VI） in the colunm sorption test was 138.34 mg.g-1, which accounted for 93.9% of the qmax at 25 ℃. The regeneration capacity of MPS was evaluated using HC1 solution as an eluent. The high regeneration efficiency （82.6%） validated the dominance of the ion exchange mechanism in the Cr（VI） sorption process with C1ions displacing Cr（VI） oxyanion on MPS. The Langmuir isotherm model showed a higher correlation coefficient than the other adsorption isotherm models. And in the kinetic study, a pseudo-second-order model fit the data best.展开更多
Bifunctional TiO2 photocatalysts co-doped with nitrogen and sulfur were prepared by the controlled thermal decomposition of ammonium titanyl sulfate precursor. They have both photocatalytic activity and Brφnsted acid...Bifunctional TiO2 photocatalysts co-doped with nitrogen and sulfur were prepared by the controlled thermal decomposition of ammonium titanyl sulfate precursor. They have both photocatalytic activity and Brφnsted acidity, and thus are active in the photoreduction of Cr（VI） under solar light irradiation without the addition of acids. The activity is superior to that of Degussa P25 in the acidified suspension at the same pH adjusted by H2SO4.展开更多
The photocatalytic properties of surface TiO2 supported zeolite in a semi batch reactor for the reduction of Cr（VI） in the presence of methyl orange dye were investigated. The prepared composite photocatalyst was ch...The photocatalytic properties of surface TiO2 supported zeolite in a semi batch reactor for the reduction of Cr（VI） in the presence of methyl orange dye were investigated. The prepared composite photocatalyst was characterized by SEM-EDS （scanning electron microscopy and energy dispersive spectroscopy）. The effects of operating parameters such as the pH and concentration of Cr（VI） in the absence and presence of dye were evaluated. The Cr（VI） reduction was more efficient in the ternary system （Cr（VI）/dye/TiO2-zeolite） than that of the corresponding binary system （Cr（VI）/TiO2-zeolite）. The extent of metal reduction after 210 min of irradiation was 68% at pH = 3 for the ternary system. In order to optimize the effectiveness of the composite photocatalyst on the photocatalytic reduction of Cr（VI）, kinetics and isotherm models were applied. The kinetics of Cr（VI） in the presence of dye on TiO2/zeolite composite photocatalyst followed the pseudo-first-order model while the equilibrium data correlated reasonably well with Freundlich isotherm.展开更多
Photocatalytic reduction of Cr（VI） by TiO2 suspension has been studied with the purpose of removing the toxic and carcinogenic Cr（VI） ions from water. The photocatalytic reduction was carried out in batch reactor,...Photocatalytic reduction of Cr（VI） by TiO2 suspension has been studied with the purpose of removing the toxic and carcinogenic Cr（VI） ions from water. The photocatalytic reduction was carried out in batch reactor, in which the influences of the presence ofmalonic and oxalic acids as well as of iron and lead ions on the degree of the reduction have been systematically evaluated. The results of the research indicated that the presence of malonic and oxalic acids with increasing concentration can improve the photoreduction. The increase in the Cr（V1） photoreduction is due to OH radical capturing by the organic acids so that it prevents the recombination of the OH radical and the free electron, and therefore can provide enough electron supply for Cr（VI） photoreduction. The effectiveness of Cr（VI） photoreduction is also enhanced by the addition of increasing concentration of both Fe（Ⅲ） and Pb（Ⅱ） ions through synergic effect. It is also found that the degree of the photopreduction is strongly influenced by solution acidity and the most effective Cr（VI） photoreduction is obtained at lower pH than 5, either in the absence or presence of the organic acids and the heavy metal ions.展开更多
The authors have prepared and characterized a chiral one-dimensional Cu（II）-Cr（VI） coordination polymer, [CuL2][Cr207] （L = （IR, 2R）-diaminocyclohexane）, which exhibited intense d-d bands as well as charge tra...The authors have prepared and characterized a chiral one-dimensional Cu（II）-Cr（VI） coordination polymer, [CuL2][Cr207] （L = （IR, 2R）-diaminocyclohexane）, which exhibited intense d-d bands as well as charge transfer bands in the solid state electronic and CD spectra. Thermally-accessible lattice distortion was observed along the crystallographic a axis, which corresponded to Jahn-Teller distortion of Cu（II） chromophores. After firing [CuL2][Cr207], they could obtain a Cu（II）-Cr（VI） complex bimetallic oxide showing ferromagnetism and isotropic thermally-accessible lattice distortion. Preparation of composite materials of the coordination polymers and a complex bimetallic oxide could be confirmed by IR spectra and magnetic properties. It should be noted that the complex bimetallic oxide as the composite exhibited anisotropic thermally-accessible lattice distortion by adsorption of the chiral one-dimensional coordination polymer.展开更多
Methacrylic acid was used together with a molecular imprinting technique to modify chitosan. In addition, the adsorption kinetics and adsorption isotherms were recorded and the results were analyzed to investigate rep...Methacrylic acid was used together with a molecular imprinting technique to modify chitosan. In addition, the adsorption kinetics and adsorption isotherms were recorded and the results were analyzed to investigate reparative adsorption for Cr（VI） from the polluted Xiangjiang River water. A comparative X-ray analysis shows that the degree of crystallization in the imprinted polymer was significantly weakened, the area of the non-crystalline region was larger. There were more adsorption sites in the imprinted polymer, and the adsorption capacity towards Cr（VI） was increased. The adsorption capacity of the imprinted polymer towards Cr（VI） increased with time and reaches saturation after 8 h. The optimal adsorption time was 4-8 h after the adsorption starting and the optimal pH value for the solution was in the range of 4.5-7.5. When the chitosan reaches saturation, the adsorption capacity achieves a state of equilibrium, and the maximum Cr（VI） extraction rate reaches 33.7%. Moreover, the adsorption capacity of the imprinted polymer towards Cr（VI） increases with increasing chitosan concentration. In this situation, the Cr（VI） extraction rate shows little variation, and the maximum removal rate can reach 98.3%. Furthermore, the Cr（VI） extraction rate increases with an increase in the degree of deacetylation in the chatoyant and chitosan, with the best adsorption effect corresponding to 90% deacetylation. Fitting the adsorption data to the quasi first- and second-order kinetic models yields correlation coefficients of 0.9013 and 0.9875, respectively. The corresponding rate constants for the two models are 0.0091 min-1 and 7.129 g/（mg.min）, respectively. Hence, the adsorption using Cr（VI）-imprinted chitosan is more consistent with the second-order kinetics. Comparing the data to Freundlich and Langrnuir adsorption isotherms shows that the latter has a better linear fit and a maximum adsorption capacity of 15.784 mg/g.展开更多
基金Supported by the Independent Innovation Foundation of Shandong University(2012TS036)
文摘Modified peanut shell （MPS） was prepared by amination reaction with peanut shell （PS） as the starting material The sorption of Cr（VI） oxyanions on MPS in static and column tests were investigated. In addition, the sorption isotherm and kinetic models were applied to confirm the sorption capacity and the sorption mechanisms. BET surface area anysis showed the physicochemical characterist!cs of the samples. The results of zeta potential,Fourier transform infrared （FT-IR） and Raman spectra analysis illustrated that chemical adsorption and ion exi change are the potential sorption mechanism. The static sorption test showed that the maximum sorption capacity （qm） of MPS for Cr（VI） increased with temperature, which indicated that the Cr（VI） sorption rocess was endothermic. The saturated sorption capacity of Cr（VI） in the colunm sorption test was 138.34 mg.g-1, which accounted for 93.9% of the qmax at 25 ℃. The regeneration capacity of MPS was evaluated using HC1 solution as an eluent. The high regeneration efficiency （82.6%） validated the dominance of the ion exchange mechanism in the Cr（VI） sorption process with C1ions displacing Cr（VI） oxyanion on MPS. The Langmuir isotherm model showed a higher correlation coefficient than the other adsorption isotherm models. And in the kinetic study, a pseudo-second-order model fit the data best.
文摘Bifunctional TiO2 photocatalysts co-doped with nitrogen and sulfur were prepared by the controlled thermal decomposition of ammonium titanyl sulfate precursor. They have both photocatalytic activity and Brφnsted acidity, and thus are active in the photoreduction of Cr（VI） under solar light irradiation without the addition of acids. The activity is superior to that of Degussa P25 in the acidified suspension at the same pH adjusted by H2SO4.
文摘The photocatalytic properties of surface TiO2 supported zeolite in a semi batch reactor for the reduction of Cr（VI） in the presence of methyl orange dye were investigated. The prepared composite photocatalyst was characterized by SEM-EDS （scanning electron microscopy and energy dispersive spectroscopy）. The effects of operating parameters such as the pH and concentration of Cr（VI） in the absence and presence of dye were evaluated. The Cr（VI） reduction was more efficient in the ternary system （Cr（VI）/dye/TiO2-zeolite） than that of the corresponding binary system （Cr（VI）/TiO2-zeolite）. The extent of metal reduction after 210 min of irradiation was 68% at pH = 3 for the ternary system. In order to optimize the effectiveness of the composite photocatalyst on the photocatalytic reduction of Cr（VI）, kinetics and isotherm models were applied. The kinetics of Cr（VI） in the presence of dye on TiO2/zeolite composite photocatalyst followed the pseudo-first-order model while the equilibrium data correlated reasonably well with Freundlich isotherm.
文摘Photocatalytic reduction of Cr（VI） by TiO2 suspension has been studied with the purpose of removing the toxic and carcinogenic Cr（VI） ions from water. The photocatalytic reduction was carried out in batch reactor, in which the influences of the presence ofmalonic and oxalic acids as well as of iron and lead ions on the degree of the reduction have been systematically evaluated. The results of the research indicated that the presence of malonic and oxalic acids with increasing concentration can improve the photoreduction. The increase in the Cr（V1） photoreduction is due to OH radical capturing by the organic acids so that it prevents the recombination of the OH radical and the free electron, and therefore can provide enough electron supply for Cr（VI） photoreduction. The effectiveness of Cr（VI） photoreduction is also enhanced by the addition of increasing concentration of both Fe（Ⅲ） and Pb（Ⅱ） ions through synergic effect. It is also found that the degree of the photopreduction is strongly influenced by solution acidity and the most effective Cr（VI） photoreduction is obtained at lower pH than 5, either in the absence or presence of the organic acids and the heavy metal ions.
文摘The authors have prepared and characterized a chiral one-dimensional Cu（II）-Cr（VI） coordination polymer, [CuL2][Cr207] （L = （IR, 2R）-diaminocyclohexane）, which exhibited intense d-d bands as well as charge transfer bands in the solid state electronic and CD spectra. Thermally-accessible lattice distortion was observed along the crystallographic a axis, which corresponded to Jahn-Teller distortion of Cu（II） chromophores. After firing [CuL2][Cr207], they could obtain a Cu（II）-Cr（VI） complex bimetallic oxide showing ferromagnetism and isotropic thermally-accessible lattice distortion. Preparation of composite materials of the coordination polymers and a complex bimetallic oxide could be confirmed by IR spectra and magnetic properties. It should be noted that the complex bimetallic oxide as the composite exhibited anisotropic thermally-accessible lattice distortion by adsorption of the chiral one-dimensional coordination polymer.
基金Project(41271332)supported by the National Natural Science Foundation of ChinaProject(2010YBB186)supported by the Social Science Foundation of Hunan Province,Chian
文摘Methacrylic acid was used together with a molecular imprinting technique to modify chitosan. In addition, the adsorption kinetics and adsorption isotherms were recorded and the results were analyzed to investigate reparative adsorption for Cr（VI） from the polluted Xiangjiang River water. A comparative X-ray analysis shows that the degree of crystallization in the imprinted polymer was significantly weakened, the area of the non-crystalline region was larger. There were more adsorption sites in the imprinted polymer, and the adsorption capacity towards Cr（VI） was increased. The adsorption capacity of the imprinted polymer towards Cr（VI） increased with time and reaches saturation after 8 h. The optimal adsorption time was 4-8 h after the adsorption starting and the optimal pH value for the solution was in the range of 4.5-7.5. When the chitosan reaches saturation, the adsorption capacity achieves a state of equilibrium, and the maximum Cr（VI） extraction rate reaches 33.7%. Moreover, the adsorption capacity of the imprinted polymer towards Cr（VI） increases with increasing chitosan concentration. In this situation, the Cr（VI） extraction rate shows little variation, and the maximum removal rate can reach 98.3%. Furthermore, the Cr（VI） extraction rate increases with an increase in the degree of deacetylation in the chatoyant and chitosan, with the best adsorption effect corresponding to 90% deacetylation. Fitting the adsorption data to the quasi first- and second-order kinetic models yields correlation coefficients of 0.9013 and 0.9875, respectively. The corresponding rate constants for the two models are 0.0091 min-1 and 7.129 g/（mg.min）, respectively. Hence, the adsorption using Cr（VI）-imprinted chitosan is more consistent with the second-order kinetics. Comparing the data to Freundlich and Langrnuir adsorption isotherms shows that the latter has a better linear fit and a maximum adsorption capacity of 15.784 mg/g.
