通过在商业纳滤膜表面接枝聚乙烯亚胺(PEI)和2,3-氯丙基三甲基氯化铵(EPTAC)对其进行表面改性,考察了PEI分子质量对改性膜表面特征和过滤性能的影响。结果表明,改性膜的zeta电位较原始膜明显升高,膜表面平均孔径减小。随着PEI分子质量的减小,膜表面孔径降低;采用小分子质量PEI(600 Da)制备的改性膜对Mg²⁺的截留率达到94.9%,Mg²⁺/Na⁺分离因子增至9.8。在32 h的混盐测试中,改性膜能保持较为稳定的水通量和离子截留性能,对重金属离子Mn²⁺、Ni²⁺、Cd²⁺截留效果及选择性较原始膜有明显提升。以牛血清蛋白为污染物的膜污染测试表明,改性膜较原始商业膜具有更好的抗有机污染性能,缘于改性膜具有更好的亲水性。

Commercial nanofiltration membranes are modified by grafting polyethyleneimine (PEI) and 2,3-chloropropyltrimethylammonium chloride (EPTAC) on their surface.The impact of PEI molecular weight on the surface properties and filtration performance of the modified membranes are investigated.It is shown that compared with the original membrane,the modified membranes have higher zeta potentials and smaller surface pores.With the decreasing PEI molecular weight,the size of pores on the surface of modified membranes decreases.As for the membranes modified by PEI with smaller molecular weight (600 Da),the rejection rate of Mg²⁺ reaches 94.9%,and the Mg²⁺/Na⁺ separation factor increases to 9.8.In the 32-h mixed salt filtration test,the modified membrane can maintain stable water permeability and ion rejection performance.The rejection and selectivity of modified membranes for heavy metal ions (Mn²⁺,Ni²⁺ and Cd²⁺) are significantly higher than that of the original membranes.The membrane fouling test using bovine serum albumin shows that the modified membranes have better fouling resistance,which may be due to their better hydrophilicity obtained from modification.

刘明侨(1998-),男,硕士研究生,研究方向为膜分离材料及废水资源化,1131320150@qq.com