阴离子交换树脂对茶氨酸的吸附动力学和热力学

以酶法制备茶氨酸，研究了碱性条件下阴离子交换树脂对茶氨酸的吸附与分离. 结果表明，强碱性树脂对茶氨酸的吸附性能优于弱碱性树脂，且其吸附容量受pH值的影响较小，pH=9.0时凝胶型强碱性树脂HZ202对茶氨酸的平衡吸附量可达96.3 mg/g. 对HZ202吸附茶氨酸的吸附等温模型及动力学、热力学参数进行了分析，结果表明，茶氨酸在HZ202树脂表面为非均一分布，Spis模型可较好模拟其吸附等温线数据；热力学参数计算结果显示，不同温度下吸附过程的吉布斯自由能变DG均为负值，表明吸附为自发的放热过程；吸附过程的焓变DH=20.9~418.4 kJ/mol，可判断其为化学吸附. 茶氨酸吸附过程符合准二级动力学方程，吸附过程受化学反应控制，提高茶氨酸初始浓度可提高吸附速率.

Adsorption Kinetics and Thermodynamics of Theanine onto Anion Exchange Resins

To separate the synthesized theanine by enzymatic method,the adsorption of theanine onto anion exchange resins under alkaline condition was investigated.The results revealed that the adsorption properties of strongly basic resins were better than that of weakly basic resins.While the gel-type basic resin of HZ202 was used,its equilibrium adsorption capacity for theanine was 96.3 mg/g at pH 9.0.The experimental results showed that theanine was loaded on the HZ202 resin with a non-uniform distribution.The isotherm data well fit to Sips model.The △G change was all negative at different temperatures,indicating that the adsorption process was exothermic and spontaneous.Enthalpy change lied between 20.9～418.4 kJ/mol,suggesting that the adsorption process was chemical adsorption.The kinetic data of adsorption fit well to the pseudo-second-order model.It suggested that the adsorption rate was limited by chemical reaction.The adsorption rate would be improved with increasing of initial concentration of theanine.