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Biosorption mechanism of Cr (Ⅵ) onto cells of Synechococcus sp.

Biosorption mechanism of Cr (Ⅵ) onto cells of Synechococcus sp.
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摘要 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. The biosorption mechanism of Cr (Ⅵ) 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 (Ⅵ) 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-IR spectra of K_2Cr_2O_7, free cells of Synechococcus sp., and Cr-bound cells of Synechococcus sp. show that the speciation of chromium that binds to the cells of Synechococcus sp. is Cr (Ⅲ), instead of Cr (Ⅵ), 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 Cr_2O_(7~)2-))by electrostatical force at the protonated active sites and reduction of Cr_2O_(7^(2-)) to Cr3+ by the reductive groups on the surface of the biosorbents.
出处 《Journal of Central South University of Technology》 2007年第2期157-162,共6页 中南工业大学学报(英文版)
基金 Project(50321402) supported by the National Natural Science Foundation of China
关键词 BIOSORPTION Synechococcus sp. Cr (Ⅳ) biosorption mechanism biosorption kinetics 蓝藻细胞 铬离子 生物吸附 机理 动力学 水污染
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