界面聚合制备复合荷电镶嵌膜

Preparation of Composite Charge-Mosaic Membrane by Interfacial Polymerization

以聚醚砜中空纤维膜为支撑膜,通过界面聚合方法制备了能有效传递电解质而截留低分子量有机物的复合荷电镶嵌膜。水相单体溶液含有2,5-二胺基苯磺酸、聚乙烯亚胺;有机相单体溶液含有均苯三甲酰氯和4-氯甲基苯酰氯;通过三甲胺溶液化学修饰将界面聚合复合层中的氯甲基基团转换为阳离子季胺盐基团。讨论了界面聚合条件和操作条件对荷电镶嵌膜分离性能的影响,分别采用原子力显微镜(AFM)、扫描电镜(SEM)及压汞仪等现代分析手段,对荷电镶嵌膜断面结构、表面形貌及孔径尺寸进行了系列表征。研究结果表明:界面聚合时间越长,生成的复合选择层越厚,所得膜的水通量越小,膜对无机盐的截留率也就越高;而界面聚合单体浓度增加,膜的水通量及膜对无机盐的截留率都会减小;另外,操作压力增大,膜的水通量及膜对无机盐的截留率均会增加。在操作压力为0.2MPa条件下,复合荷电镶嵌膜对无机盐的截留率均小于20%,而对二价酚橙和甲基绿的截留率均大于95%。

The composite charge-mosaic membranes, which are permeable to salts but meanwhile not to non-electrolytes with low molecule weight, were prepared by interfacial polymerization (IP). The polyethersulfone (PES) hollow fiber membrane was used as the support membrane, 2,5-diaminobenzene sulfonic acid and polyethylenimine (PEI) as aqueous phase monomer of IP reaction, and a mixture of trimesoyl chloride (TMC) and 4-(chloromethyl) benzoyl chloride as organic monomer. Then the trimethylamine solution was applied to modify the IP layer through a quaternization reaction. The characterizations of the composite mosaic membranes were carried out through permeation experiments of different inorganic salts and dyes as well as by using AFM, SEM and Mercury Injection Apparatus. The experimental results show that the characteristics of the membrane are greatly influenced by IP time, concentrations of monomers and operating pressure. With the increases of IP time, the membrane flux will be decreased and the membrane retention will be increased. With the concentration of monomers increase, both the membrane flux and the membrane retention for salts will be decreased. However, when the operating pressure is increased, both the membrane flux and the membrane retention will be increased. Under the operating pressure of 0.2 MPa, the membrane retentions to the inorganic salts are less than 20%, while to Xylenol orange and Methyl green, more than 95%.