基于有机溶剂的中空纤维纳滤膜微结构调控

Microstructure control of nanofiltration membrane based on organic phase solvent

聚酰胺分离层的微结构调控是制备高性能纳滤膜的关键.通过改变溶剂类型调控水相单体在反应界面的溶解和扩散能力,进而改变界面聚合反应进程,获得了具有相对疏松的粗糙三维图案化分离层结构.结果表明,疏松的分离层赋予纳滤膜较高的单/二价盐选择性,对Na 2SO 4和NaCl的截留率分别为94.8%和17.6%;粗糙的膜表面显著提升了水接触面积,对Na2SO 4水溶液的水通量达到42.6 L/(m^2 h),为具有常规表面形貌膜的3倍.

The microstructure and the formation mechanism of the separation layer is the key affecting the performance of nanofiltration membrane.Three nanofiltration membranes were prepared in this work,the interfacial polymerization process was modified by adjusting the organic phase solvent.Owing to the difference of viscosity and surface tension of the solvents,the dissolution and diffusion of the active monomers in the two phase interface could be modified.So the structure and performance of the membranes were adjusted.Nanofiltration membrane with three dimensional rough patterned surface and relatively looser structure was obtained,when using n-decane as organic solvent.n-decane has moderate viscosity and surface tension,which slow down the monomers diffusion rate and lead to formation of a loose rough separation layer.The flux of the membrane for Na 2SO 4 aqueous solution reached 42.6 L/(m 2 h),about 3 times of the other two prepared with hexane and cyclohexane as organic solvent.It also possesses good salts separation performance with rejection to Na 2SO 4 of 94.8%and NaCl lower than 17.6%.