材料期刊网

以壳聚糖／蒙脱土插层复合物为载体，吸附法制备固定化多酚氧化酶，并以此催化氧化去除水中的苯酚、4?氯苯酚和2，4?二氯苯酚．考察了固定化多酚氧化酶的制备条件，对酚类化合物的催化氧化条件、动力学特性以及固定化酶的重复使用性能．结果表明，固定化多酚氧化酶的最佳制备条件为pH 5．0，酶与载体质量比20 mg·g－1，固定化6 h，所得固定化酶的载酶量为12．12 mg·g－1，每克单位载体酶活为12．76×103 U·g－1．固定化多酚氧化酶对酚类化合物的最佳去除条件为：苯酚溶液pH 7．0，温度30℃；4?氯苯酚溶液pH 5．0，温度20℃；2，4?二氯苯酚溶液pH 5．0，温度30℃．在最佳反应条件下，酶与底物质量比为20 mg·mg－1时，固定化多酚氧化酶对苯酚、4?氯苯酚和2，4?二氯苯酚溶液去除率分别为63．6％、85．8％和87．8％．苯酚、4?氯苯酚和2，4?二氯苯酚的米氏常数Km值依次减小，最大反应速率Vmax依次增大，表明固定化酶对2，4?二氯苯酚的亲和力最强，催化速度最快．固定化酶循环使用6次（24 h）后对苯酚、4?氯苯酚和2，4?二氯苯酚的去除率分别为15．7％、24．2％和27．8％．

Polyphenol oxidase ( PPO ) was immobilized on chitosan/montmorillonite intercalation composites by adsorption,and then used to remove phenol,4?chlorophenol and 2,4?dichlorophenol from aqueous solutions. The immobilization conditions, catalytic oxidation conditions of phenolic compounds, dynamics and reusability of immobilized PPO were investigated in detail. Optimal preparation conditions of immobilizated PPO were found to be pH 5.0,enzyme/support weight ratio 20 mg·g-1,immobilization time 6 h.The protein loading yield and enzyme activity of the unit support of immobilized PPO was 12.12 mg·g-1 and 12.76×103 U·g-1,respectively.Optimal conditions of the removal for phenolic compounds by immobilized PPO were pH 7.0 and 30℃ for phenol,pH 5.0 and 20 ℃ for 4?chlorophenol,pH 5.0 and 30 ℃ for 2,4?dichlorophenol.When enzyme/substrate weight ratio was 20 mg·mg-1 , the removal efficiency of phenol, 4?chlorophenol and 2, 4?dichlorophenol under optimal conditions was 63.6%,85.8% and 87.8%,respectively.Michaelis constant Km values of phenol,4?chlorophenol and 2, 4?dichlorophenol decreased, while the maximum reaction rate Vmax
increased gradually, indicating that 2,4?dichlorophenol possessed the highest affinity for the immobilized enzyme and fastest catalysis rate. The removal efficiency of phenol,4?chlorophenol and 2,4?dichlorophenol was 15. 7%, 24. 2% and 27. 8%, respectively, after 6 times repeated use of immobilized enzyme.