Brine,which is used to produce high-purity magnesia,was purified by XSC-700 to remove boron.Boron adsorption capacity of XSC-700 was investigated by varying the initial boron concentration,temperature,resin/brine rati...Brine,which is used to produce high-purity magnesia,was purified by XSC-700 to remove boron.Boron adsorption capacity of XSC-700 was investigated by varying the initial boron concentration,temperature,resin/brine ratio and stirring speed,while keeping the diameter at constant.The results show that boron adsorption capacity increases with increasing boron concentration,temperature,and decreases with increasing resin/brine ratio.And the stirring speed could slightly affect the boron adsorption capacity.The adsorption kinetics obeys the pseudo-second-order model.Equilibrium data were both examined by Freundlich and Langmuir isotherm equations and it can be well represented by the Freundlich isotherm equation.展开更多
The isotherm,mechanism and kinetics of carbon tetrachloride(CT) adsorption by polyacrylonitrile-based activated carbon fiber(PAN-ACF) were investigated in batch reactors and a continuous flow reactor,and the regenerat...The isotherm,mechanism and kinetics of carbon tetrachloride(CT) adsorption by polyacrylonitrile-based activated carbon fiber(PAN-ACF) were investigated in batch reactors and a continuous flow reactor,and the regeneration of PAN-ACF was also studied.Freundlich and Dubinin-Radushkevich(D-R) adsorption equations can well describe the adsorption isotherm.CT is mainly adsorbed on the exterior surface of PAN-ACF with low boundary layer effect and rate-controlling step of intra-particle diffusion.The adsorption dynamics in the batch reactor well fits with the pseudo-first-order model,and the breakthrough curves in the continuous flow reactor can be well described by the Yoon-Nelson model.The ACF can be recycled through thermal regeneration,whereas the adsorption capacity decreases from 7.87 to 4.98 mg/g after the fourth regeneration.78%-94%of CT can be removed from the wastewater of a fluorine chemical plant on a pilot scale,which confirms the efficacy of ACF under industrial conditions.The results indicate that PAN-ACF is applicable to CT removal from wastewater.展开更多
The biosorption mechanism of Cr （Ⅳ） ions on Synechococcus sp. biosorbent was studied by analyzing the biosorption kinetics as well as speciation change and bond formation during the biosorption process. The kinetic...The biosorption mechanism of Cr （Ⅳ） ions on Synechococcus sp. biosorbent was studied by analyzing the biosorption kinetics as well as speciation change and bond formation during the biosorption process. The kinetics study shows that the adsorption process of Cr （Ⅳ） consists of a very fast stage in the first several minutes, in which more than half of the saturation adsorption is attained, and a slower stage that approximately follows the first order kinetic model, basically Freundlich isotherm models were observed. Comparative studies of FT-LR spectra of K2Cr2O7, free cells of Synechococcus sp., and Cr-bound cells of Synechococcus sp show that the speciation of chromium that binds to the cells ofSynechococcus sp. is Cr （Ⅲ）, instead of Cr （Ⅳ）, and the carboxylic, alcoholic, amido and amino groups may be involved in the binding of Cr （Ⅲ）. Integrative analyses of the surface electric potential, the effect of pH value on adsorption behavior of Cr （Ⅵ）, and the results of FT-IR show that the biosorption of Cr （Ⅵ） follows two subsequent steps, biosorption of Cr2O7 ^2- by electrostatical force at the protonated active sites and reduction of Cr2O7^2- to Cr^3＋ by the reductive groups on the surface of the biosorbents.展开更多
The adsorption of sulfate in aqueous solutions onto organo-nano-clay prepared by natural zeolite and cationic surfactant cetyltrimethylammonium bromide （CTAB） was studied.Parameters such as adsorbent dosage,contact ...The adsorption of sulfate in aqueous solutions onto organo-nano-clay prepared by natural zeolite and cationic surfactant cetyltrimethylammonium bromide （CTAB） was studied.Parameters such as adsorbent dosage,contact time and temperature were investigated using batch adsorption studies.The results show that the uptake of sulfate increases with the increase of contact time and temperature,and decreases with the increase of dosage.The Freundlich isotherm model is fit to explain the sulfate adsorption onto organo-nano-clay.The maximum adsorption capacity is found to be 38.02 mg/g at 40 ℃.The kinetic data fit well the pseudo-second-order and Elovich models with a R2 more than 0.98.It is suggested that chemisorption is the rate-controlling step for adsorption of sulfate onto organo-nano-clay,meanwhile both intraparticle diffusion and boundary layer diffusion also contribute as well.Ion-exchange between sulfate anions and bromide ions and complexation between sulfate anions and CTAB cations are responsible for the mechanism of sulfate adsorption.Keywords：organo-nano-clay; cetyltrimethylammonium bromide （CTAB）; modification; sulfate; adsorption展开更多
The adsorption capacity of Pb(Ⅱ) on litchi pericarps was investigated as a function of temperature,pH,and adsorbent dose using batch experiments.The experimental data obtained were evaluated using adsorption equilibr...The adsorption capacity of Pb(Ⅱ) on litchi pericarps was investigated as a function of temperature,pH,and adsorbent dose using batch experiments.The experimental data obtained were evaluated using adsorption equilibrium isotherms and a kinetic model.Additionally,the removal of Pb(Ⅱ) in leachate of litchi pericarps was also evaluated.The results show that litchi pericarps exhibit a high adsorption capacity to Pb(Ⅱ),with the maximum removal efficiency occurring at a temperature of 25 ℃,a pH of 6.0-7.0 and an adsorbent dosage of 10 g/L.Langmuir and Freundlich isotherms and the pseudo-second-order kinetic model can all fit the equilibrium adsorption satisfactorily,with correlation coefficients(R^2) of 0.9935,0.9918 and 1.0,respectively.An average removal efficiency of 66.65% is found for Pb(Ⅱ) in leachate of litchi pericarps.展开更多
基金Project(2008BAB35B04) supported by the National Key Technology R&D Program of China
文摘Brine,which is used to produce high-purity magnesia,was purified by XSC-700 to remove boron.Boron adsorption capacity of XSC-700 was investigated by varying the initial boron concentration,temperature,resin/brine ratio and stirring speed,while keeping the diameter at constant.The results show that boron adsorption capacity increases with increasing boron concentration,temperature,and decreases with increasing resin/brine ratio.And the stirring speed could slightly affect the boron adsorption capacity.The adsorption kinetics obeys the pseudo-second-order model.Equilibrium data were both examined by Freundlich and Langmuir isotherm equations and it can be well represented by the Freundlich isotherm equation.
基金Project(2004C33068) supported by the Science and Technology Programs of Zhejiang Province,ChinaProject(20100933B17) supported by the Social Development and Science Research Program of Hangzhou,China
文摘The isotherm,mechanism and kinetics of carbon tetrachloride(CT) adsorption by polyacrylonitrile-based activated carbon fiber(PAN-ACF) were investigated in batch reactors and a continuous flow reactor,and the regeneration of PAN-ACF was also studied.Freundlich and Dubinin-Radushkevich(D-R) adsorption equations can well describe the adsorption isotherm.CT is mainly adsorbed on the exterior surface of PAN-ACF with low boundary layer effect and rate-controlling step of intra-particle diffusion.The adsorption dynamics in the batch reactor well fits with the pseudo-first-order model,and the breakthrough curves in the continuous flow reactor can be well described by the Yoon-Nelson model.The ACF can be recycled through thermal regeneration,whereas the adsorption capacity decreases from 7.87 to 4.98 mg/g after the fourth regeneration.78%-94%of CT can be removed from the wastewater of a fluorine chemical plant on a pilot scale,which confirms the efficacy of ACF under industrial conditions.The results indicate that PAN-ACF is applicable to CT removal from wastewater.
基金Project(50321402) supported by the National Natural Science Foundation of China
文摘The biosorption mechanism of Cr （Ⅳ） ions on Synechococcus sp. biosorbent was studied by analyzing the biosorption kinetics as well as speciation change and bond formation during the biosorption process. The kinetics study shows that the adsorption process of Cr （Ⅳ） consists of a very fast stage in the first several minutes, in which more than half of the saturation adsorption is attained, and a slower stage that approximately follows the first order kinetic model, basically Freundlich isotherm models were observed. Comparative studies of FT-LR spectra of K2Cr2O7, free cells of Synechococcus sp., and Cr-bound cells of Synechococcus sp show that the speciation of chromium that binds to the cells ofSynechococcus sp. is Cr （Ⅲ）, instead of Cr （Ⅳ）, and the carboxylic, alcoholic, amido and amino groups may be involved in the binding of Cr （Ⅲ）. Integrative analyses of the surface electric potential, the effect of pH value on adsorption behavior of Cr （Ⅵ）, and the results of FT-IR show that the biosorption of Cr （Ⅵ） follows two subsequent steps, biosorption of Cr2O7 ^2- by electrostatical force at the protonated active sites and reduction of Cr2O7^2- to Cr^3＋ by the reductive groups on the surface of the biosorbents.
基金Project(51178159)supported by the National Natural Science Foundation of ChinaProject(CXZZ12_0236)supported by the Postgraduate Technological Innovation Program of Jiangsu Province Education Department,China
文摘The adsorption of sulfate in aqueous solutions onto organo-nano-clay prepared by natural zeolite and cationic surfactant cetyltrimethylammonium bromide （CTAB） was studied.Parameters such as adsorbent dosage,contact time and temperature were investigated using batch adsorption studies.The results show that the uptake of sulfate increases with the increase of contact time and temperature,and decreases with the increase of dosage.The Freundlich isotherm model is fit to explain the sulfate adsorption onto organo-nano-clay.The maximum adsorption capacity is found to be 38.02 mg/g at 40 ℃.The kinetic data fit well the pseudo-second-order and Elovich models with a R2 more than 0.98.It is suggested that chemisorption is the rate-controlling step for adsorption of sulfate onto organo-nano-clay,meanwhile both intraparticle diffusion and boundary layer diffusion also contribute as well.Ion-exchange between sulfate anions and bromide ions and complexation between sulfate anions and CTAB cations are responsible for the mechanism of sulfate adsorption.Keywords：organo-nano-clay; cetyltrimethylammonium bromide （CTAB）; modification; sulfate; adsorption
基金Project(51208173)supported by the National Natural Science Foundation of ChinaProject(ZR2014EEM005)supported by the Natural Science Foundation of Shandong Province,China
文摘The adsorption capacity of Pb(Ⅱ) on litchi pericarps was investigated as a function of temperature,pH,and adsorbent dose using batch experiments.The experimental data obtained were evaluated using adsorption equilibrium isotherms and a kinetic model.Additionally,the removal of Pb(Ⅱ) in leachate of litchi pericarps was also evaluated.The results show that litchi pericarps exhibit a high adsorption capacity to Pb(Ⅱ),with the maximum removal efficiency occurring at a temperature of 25 ℃,a pH of 6.0-7.0 and an adsorbent dosage of 10 g/L.Langmuir and Freundlich isotherms and the pseudo-second-order kinetic model can all fit the equilibrium adsorption satisfactorily,with correlation coefficients(R^2) of 0.9935,0.9918 and 1.0,respectively.An average removal efficiency of 66.65% is found for Pb(Ⅱ) in leachate of litchi pericarps.
