冷冻诱导相分离法制备CA/CS复合膜

Preparation of CA/CS Composite Filtration Membrane by Freeze-inducing Phase Separation

摘要:

以醋酸纤维素(CA)为过滤膜纤维基底层、壳聚糖(CS)为复合膜涂覆层，采用冷冻诱导相分离(CIPS)方法制备出底层纤维互相搭接，表层海绵多孔状结构的CA/CS复合膜。在CS铸膜液质量分数为3.5%条件下，采用直接液氮冷冻干燥的方式对复合膜进行处理，使得CS表层呈现出较多微米孔洞，截面厚度为1 μm的层状叠加结构，其纯水通量可达1.01×104 L/(m2•h)，对酸性蓝的过滤通量可达9.26×103 L/(m2•h)，截留率为98.6%，其吸附过程符合拟二级动力学模型，且符合Langmuir单分子层吸附。实验分别考察了膜对酸性蓝、酸性黄、分散黄和分散蓝染料的平衡吸附量结果显示：30 min时吸附基本趋于平衡，吸附量分别为92.10、89.09、85.03和79.62 mg/g。

Abstract:

In this study, cellulose acetate (CA) / chitosan (CS) composite membrane was prepared by freeze-inducing phase separation (CIPS) method. CA and CS were used as fiber bottom and coating layer, respectively. After treating the CA/CS membrane (3.5 % CS) by liquid nitrogen directly, CS surface layer with micron-sized pores was obtained and the cross-section exhibited a thin layer with 1 μm. Pure water flux of CA/CS membrane could reach to 1.01×104 L/(m2•h). The permeate flux of acid blue could reach to 9.26×103 L/(m2•h), and the rejection rate was 98.6%. The adsorption process conforms to the pseudo-second-order kinetics and the Langmuir monolayer adsorption model. Furthermore, the adsorption capacities of membranes were investigated. It tended to be equilibrium in 30 min for dyes. The equilibrium adsorption capacities of membranes for acid blue, acid yellow, disperse yellow, and disperse blue were 92.10, 89.09, 85.03, and 79.62 mg/g, respectively.