聚酰胺纳滤膜制备过程中溶剂对膜性能的影响

Effect of solvent on membrane properties in preparing polyamide nanofiltration membranes

以正己烷和甲苯的混合溶剂作为有机相溶剂,均苯三甲酰氯(TMC)和哌嗪(PIP)作为有机相和水相活性单体,采用界面聚合的方法在聚丙烯腈(PAN)超滤膜上制备得到一系列聚哌嗪酰胺纳滤复合膜.系统研究了不同正己烷与甲苯配比制备得到的纳滤复合膜活性分离层的表面化学组成、表面流动电位、平均孔径及表面形貌的变化规律,并解释了这些因素对纳滤复合膜分离性能的影响机理.结果表明:随着混合有机相溶剂中正己烷相对含量的增加,使得水相与有机相溶剂间界面张力增加,所制荷电纳滤复合膜活性分离层表面流动电位逐渐向负电转变,孔径逐渐变小,同时纳滤复合膜表面粗糙程度增加.复合膜表面粗糙度的增加使纳滤复合膜的透过性得到提高.

A series of polypiperazine-amide nanofiltration composite membranes were prepared through interfacial polymerization which used trimesoyl chloride （TMC） as organic phase monomer and piperazine （PIP） as aqueous phase monomer, and n-hexane and toluene as mixed organic phase solvent. Then, the influences of the ratio n-hexane to toluene on the surface chemical composition, streaming potential, average pore size and morphology of composite membranes were systematacially studied. In addition, the relationship between those properties and the separation performance of nanofiltration membranes were explained. In result, with the ratio of n-hexane to toluene increasing of organic phase solvent, the interfacial tension between aqueous phase and organic phase increased which resulted in the streaming potential of nanofiltration membranes surface transforming from positive to negative, the decrease of membrane pore size, and surface roughness improving. The enhancement of surface roughness made for membrane water flux.