Polyethyleneimine(PEI)modified palygorskite(Pal)was used for the adsorption of Cr(VI)in aqueous solution.The absorbent was characterized by Fourier transform infrared spectroscopy(FT-IR)and thermogravimetric analysis(...Polyethyleneimine(PEI)modified palygorskite(Pal)was used for the adsorption of Cr(VI)in aqueous solution.The absorbent was characterized by Fourier transform infrared spectroscopy(FT-IR)and thermogravimetric analysis(TGA).Characterized results confirmed that the Pal has been successfully modified by PEI.The modification of PEI increased the Cr(VI)adsorption performance of the Pal by the adsorption combined reduction mechanism,and amino groups of the adsorbent play the main role in the enhanced Cr(VI)adsorption.The maximum adsorption capacity was 51.10 mg·g^-1 at pH4.0 and 25°C.The adsorption kinetics of Cr(VI)on the adsorbent conforms to the Langmuir isotherm model.The maximum adsorption occurs at pH3,and then the adsorption capacity of PEI-Pal was decreased with the increase of p H values.The adsorption kinetics of Cr(VI)on PEI-Pal was modeled with pseudo-second-order model.The addition of Cl^-,SO4^2-and PO4^3-reduced the Cr(VI)adsorption by competition with Cr(VI)for the active sites of PEI-Pal.The Cr(VI)saturated PEI-Pal can be regenerated in alkaline solution,and the adsorption capacity can still be maintained at 30.44 mg·g^-1 after 4 cycles.The results demonstrate that PEI-Pal can be used as a potential adsorbent of Cr(VI)in aqueous solutions.展开更多
Coal fly ashes WSRA and BQRA were ball milled for 5 h to produce their ultrafine coal fly ashes WSUA and BQUA, respectively. Batch kinetic, isotherm and pH effect on adsorption were studied to evaluate removal of Cr ...Coal fly ashes WSRA and BQRA were ball milled for 5 h to produce their ultrafine coal fly ashes WSUA and BQUA, respectively. Batch kinetic, isotherm and pH effect on adsorption were studied to evaluate removal of Cr （VI） from aqueous solutions by ultrafine coal fly ashes comparing with raw coal fly ashes. The kinetics of adsorption indicates the process to be intraparticle diffusion controlled and follows the Lagergren first-order kinetics for all coal fly ashes. The first-order rate constants （k1） of Cr （VI） adsorption onto WSRA, WSUA, BQRA and BQUA are 1.981, 1.497, 2.119 and 1.500 （×10^-2） min^-1, respectively. The adsorption capacities of WSUA and BQUA are much better than those of WSRA and BQRA. Equilibrium adsorption data of all coal fly ashes well satisfy the Langmuir isotherm. The adsorbed amounts of Cr （VI） onto WSUA and BQUA decrease from pH 2 to pH 6 and then increase up to pH 12.展开更多
The bacterial cellulose prepared by ourselves was used in the adsorption of Cr（VI）. The effects of performance parameters such as adsorption time, pH, the adsorbent dosage on Cr（VI） were investigated. Results show...The bacterial cellulose prepared by ourselves was used in the adsorption of Cr（VI）. The effects of performance parameters such as adsorption time, pH, the adsorbent dosage on Cr（VI） were investigated. Results showed that pH was a very important parameter to the adsorbed efficiency. Removal rate of Cr（VI） approached to 15% under the condition of pH 1.5, adsorbent dosage 1.0 gL-1 and co（initial concentration of Cr）50 mgL-1. The saturated monolayer adsorption quantity was 5.13 mg/g dry BC. The adsorption rate could be well fitted by pseudo-second rate model, adsorption isotherm could be described by Langmuir model, and they have good linear. Typical single-molecule layer adsorption of bacterial cellulose for Cr（VI） could be descripted and electrostatic force was one of the main sorption mechanisms. HCl can desorb the Cr（VI） from the adsorbent effectively.展开更多
基金funded by the National Natural Science Foundation of China(21677092)the Scientific Research Program funded by Shaanxi Provincial Education Department(15JK1095)。
文摘Polyethyleneimine(PEI)modified palygorskite(Pal)was used for the adsorption of Cr(VI)in aqueous solution.The absorbent was characterized by Fourier transform infrared spectroscopy(FT-IR)and thermogravimetric analysis(TGA).Characterized results confirmed that the Pal has been successfully modified by PEI.The modification of PEI increased the Cr(VI)adsorption performance of the Pal by the adsorption combined reduction mechanism,and amino groups of the adsorbent play the main role in the enhanced Cr(VI)adsorption.The maximum adsorption capacity was 51.10 mg·g^-1 at pH4.0 and 25°C.The adsorption kinetics of Cr(VI)on the adsorbent conforms to the Langmuir isotherm model.The maximum adsorption occurs at pH3,and then the adsorption capacity of PEI-Pal was decreased with the increase of p H values.The adsorption kinetics of Cr(VI)on PEI-Pal was modeled with pseudo-second-order model.The addition of Cl^-,SO4^2-and PO4^3-reduced the Cr(VI)adsorption by competition with Cr(VI)for the active sites of PEI-Pal.The Cr(VI)saturated PEI-Pal can be regenerated in alkaline solution,and the adsorption capacity can still be maintained at 30.44 mg·g^-1 after 4 cycles.The results demonstrate that PEI-Pal can be used as a potential adsorbent of Cr(VI)in aqueous solutions.
基金Funded by the China Post Doctoral Science Foundation (20070411124)the Scientific and Technological Key Project of Shaanxi Province (2006k07-G19)+1 种基金the Industrialization Project of Shaanxi Provincal Department of Education(06JC11)the Scientific and Technological Key Project of Xi’anCity(GG06074)
文摘Coal fly ashes WSRA and BQRA were ball milled for 5 h to produce their ultrafine coal fly ashes WSUA and BQUA, respectively. Batch kinetic, isotherm and pH effect on adsorption were studied to evaluate removal of Cr （VI） from aqueous solutions by ultrafine coal fly ashes comparing with raw coal fly ashes. The kinetics of adsorption indicates the process to be intraparticle diffusion controlled and follows the Lagergren first-order kinetics for all coal fly ashes. The first-order rate constants （k1） of Cr （VI） adsorption onto WSRA, WSUA, BQRA and BQUA are 1.981, 1.497, 2.119 and 1.500 （×10^-2） min^-1, respectively. The adsorption capacities of WSUA and BQUA are much better than those of WSRA and BQRA. Equilibrium adsorption data of all coal fly ashes well satisfy the Langmuir isotherm. The adsorbed amounts of Cr （VI） onto WSUA and BQUA decrease from pH 2 to pH 6 and then increase up to pH 12.
基金Funded by the National Natural Science Foundation of China (No.50174014)
文摘The bacterial cellulose prepared by ourselves was used in the adsorption of Cr（VI）. The effects of performance parameters such as adsorption time, pH, the adsorbent dosage on Cr（VI） were investigated. Results showed that pH was a very important parameter to the adsorbed efficiency. Removal rate of Cr（VI） approached to 15% under the condition of pH 1.5, adsorbent dosage 1.0 gL-1 and co（initial concentration of Cr）50 mgL-1. The saturated monolayer adsorption quantity was 5.13 mg/g dry BC. The adsorption rate could be well fitted by pseudo-second rate model, adsorption isotherm could be described by Langmuir model, and they have good linear. Typical single-molecule layer adsorption of bacterial cellulose for Cr（VI） could be descripted and electrostatic force was one of the main sorption mechanisms. HCl can desorb the Cr（VI） from the adsorbent effectively.
