Kinetics and Thermodynamics of Adsorption of VB12 onto Mesoporous Carbon Coated with PMMA  

作　　者：GUO Zhuo ZHANG Wei-wei DING Xiang-ping LI Sha MA Lei 

机构地区：[1]School of Materials Science and Engineering, Shenyang Institute of Chemical Technology, Shenyang 110142, P R. China [2]State Key Laboratory of lnorgnic Synthesis and Preparative Chemistry, Jilin University, Changchun 130012, P. R. China

出　　处：《Chemical Research in Chinese Universities》2010年第3期431-435,共5页高等学校化学研究（英文版）

基　　金：Supported by the National Natural Science Foundation of China(No.20771049)

摘　　要：Ordered mesoporous carbons CMK-3, CMK-I coated with poly（methyl methacrylate）（PMMA）（CMK-3- PMMA and CMK-1-PMMA） and pristine mesoporous carbons CMK-3, CMK-1 were employed to adsorb vitamin B12（VB12） from water solution. Adsorption isotherm and kinetics of adsorption were investigated via batch experiments. It was found that the adsorption capacity of VB 12 at 30, 40 and 50 ℃ can reach 688.2, 572.4 and 428.7 mg/g, respectively. The adsorption isotherm can be described by Langmuir model. The pseudo first- and second-order kinetic models were employed to fit the dynamic adsorption. It was found that the dynamic adsorption follows the pseudo second-order model. The thermodynamic equilibrium coefficients obtained at different temperatures were used to evaluate the thermodynamic constants △G^0, △H^0 and △S^0. The negative value of Gibbs free energy, △G^0 indicates that the adsorption occurred via a spontaneous process. The increase in the value of-△G^0 with increasing temperature indicates that higher temperatures were favourable to the sorption process. The enthalpy values of △H^0〉40 kJ/mol（66.36 kJ/mol and 56.43 kJ/mol） for CMK-3-PMMA and CMK-1-PMMA confirm that chemisorption were involved in the adsorption process. This is consistent with the IR spectra and is another evidence for the formation of hydrogen bond between PMMA in the pore of CMK-3 and VB 12.Ordered mesoporous carbons CMK-3, CMK-I coated with poly（methyl methacrylate）（PMMA）（CMK-3- PMMA and CMK-1-PMMA） and pristine mesoporous carbons CMK-3, CMK-1 were employed to adsorb vitamin B12（VB12） from water solution. Adsorption isotherm and kinetics of adsorption were investigated via batch experiments. It was found that the adsorption capacity of VB 12 at 30, 40 and 50 ℃ can reach 688.2, 572.4 and 428.7 mg/g, respectively. The adsorption isotherm can be described by Langmuir model. The pseudo first- and second-order kinetic models were employed to fit the dynamic adsorption. It was found that the dynamic adsorption follows the pseudo second-order model. The thermodynamic equilibrium coefficients obtained at different temperatures were used to evaluate the thermodynamic constants △G^0, △H^0 and △S^0. The negative value of Gibbs free energy, △G^0 indicates that the adsorption occurred via a spontaneous process. The increase in the value of-△G^0 with increasing temperature indicates that higher temperatures were favourable to the sorption process. The enthalpy values of △H^0〉40 kJ/mol（66.36 kJ/mol and 56.43 kJ/mol） for CMK-3-PMMA and CMK-1-PMMA confirm that chemisorption were involved in the adsorption process. This is consistent with the IR spectra and is another evidence for the formation of hydrogen bond between PMMA in the pore of CMK-3 and VB 12.

关 键 词：Mesoporous carbon VB12 adsorption EQUILIBRIUM KINETICS THERMODYNAMICS 

分 类 号：O632.52[理学—高分子化学] S153[理学—化学]