离子吸附对中性超滤膜电性能和渗透性能的影响(英文)

ELECTROKINETICS AND PERMEATION EVALUATION ON IONIC ABSORPTION ON UF MEMBRANE WITH NO INTRINSIC CHARGE

选用截留分子量40000 Da表面没有固有电荷的PVDF中性超滤膜，重点考察了离子吸附对超滤膜表面电性能和渗透性能的影响．选用4种电解质溶液为考察对象，按阴阳离子价态可分为KCI（1：1），K2SOa（1：2），MgCl2（2：1）和MgS04（2：2）．基于溶度积的计算，5mM的镁离子会在pH9．52处开始产生沉淀，因而选择pH3～9为考察范围．膜在1mM4种电解质溶液中的等电点分别为pH7．4（MgCl2），7．0（MgSO4），6．9（KCl），5．5（K2SO4），这可由离子迁移速率来解释．膜的盐截留率在等电点附近为零，并往两侧逐渐增大。通量则在等电点处最大，而往两侧逐渐减小．

In order to neglect the intrinsic charge of membrane and focus on the effect of ion absorption on membrane surface, the present work focused on the electrokinetic and permeation performance of PVDF membrane with a MWCO of 40 000 to investigate the mechanism in UF process. Four types salts with different concentration were measured, those were KCI （1 ： 1）,K2SO4（1 ： 2）,MgCl2 （2 ： 1）,MgSO4 （2 ： 2）. pH range of 3 to 9 was chosen by the calculation of solubility product for 5 mM magnesium ions would deposit at pH 9.52. Isoelectric points （IEPs） in 1 mM electrolyte solutions were at pH 7. 4 （MgCl2）, 7. 0 （MgSO4）, 6. 9 （KCI）, 5.5 （K2SO4）, which can be explained by various ions mobility. Rejections were zero near isoelectric points （IEPs） and increased in both sides for the rejection of the co-ions. Fluxes were maximal near IEPs and decreased in both ways.