螯合树脂对铜离子的吸附动力学和热力学

针对以谷氨酰胺-铜(II)配合物为供体酶法制备茶氨酸体系，研究了D401螯合树脂对Cu2+的吸附，探讨了吸附过程的热力学和动力学，通过红外光谱鉴定了树脂的配位结构. 结果表明，树脂吸附量随离子浓度和温度升高而增加，当pH为5.6时吸附量最大，达1.887 mmol/g. 不同温度下Langmuir方程均呈现很好的拟合度. 热力学平衡方程计算得DG<0, DH=21.5 kJ/mol, DS>0，表明该吸附过程是自发的、吸热、熵增加的过程. 动力学研究表明，该过程符合准二级动力学模型，吸附反应速率由颗粒扩散和液膜扩散共同控制. 该树脂在较宽的pH范围内对Cu2+具有很好的选择吸附性，可用于酶转化茶氨酸体系中Cu2+的去除.

Kinetics and Thermodynamics of the Adsorption of Copper(II) onto Chelating Resin

The kinetics and thermodynamics of copper(II) adsorption onto D401 chelating resin were studied as for removal of copper(II) from enzymatic synthesis of L-theanine using glutamine-copper(II) as donor substrate. The structures of copper loaded resin were confirmed by infrared spectroscopy. Adsorption capacity of copper(II) increased with increasing initial metal ion concentration and temperature. And its highest value was 1.887 mmol/g at pH 5.6. Experimental data fitted well to the Langmuir model at all temperatures studied. The thermodynamic equilibrium functions were also determined. DG<0, DH=21.5 kJ/mol, DS>0, so the adsorption was spontaneous, endothermic and entropy increasing. The kinetic experimental data were correlated with pseudo-second-order kinetic model. The adsorption rate was controlled by film diffusion and particle diffusion simultaneously throughout the entire adsorption period. The resin could be applied to the removal of copper(II) from theanine-copper complexes by enzymatic synthesis under wide pH range, with a good selectivity with copper(II).