聚醚砜/磺化聚砜/磺化聚醚砜共混疏松纳滤膜的制备及其染料/盐选择分离性能

Preparation of polyethersulfone/sulfonated polysulfone/sulfonated polyethersulfone loose nanofiltration membrane for selective separation of dyes and salts

含盐染料废水的有效分离一直是工业废水处理领域亟需解决的难题,制备高性能的疏松纳滤膜是解决这一问题的有效途径.以聚醚砜(PES)、磺化聚砜(SPSf)和磺化聚醚砜(SPES)为原料,N,N-二甲基乙酰胺(DMAc)为溶剂,己二酸(AA)为添加剂配制铸膜液(固含量31%,质量分数),水为凝固浴,采用非溶剂致相分离(NIPS)法制备了PES/SPSf/SPES共混疏松纳滤膜,探究SPES添加量(0〜20%,质量分数)对膜结构以及染料/盐分离性能的影响.结果表明,PES/SPSf/SPES共混体系为完全相容体系,制备的共混膜横截面为完全海绵体结构.当SPES添加量为10%时,所制备疏松纳滤膜(M10)的切割分子量为5900,膜孔径为1.38 nm,纯水渗透率为605 L/(m^(2)·h·MPa);共混膜对分散红74(DR74)和分散蓝79(DB79)的截留率均>99%;共混膜持续处理DR74/Na_(2)SO_(4)混合溶液48 h,对DR74的截留率>99%,对Na_(2)SO_(4)的截留率<25%,表现出优异的染料截留性能和运行稳定性,实现了对分散染料/盐的选择性分离.

The effective separation of saline dye wastewater has always been an urgent issue in the field of industrial wastewater treatment.PES,SPES and SPSf as raw materials(31%polymeric concentration),N,N-dimethylacetamide as solvent,adipic acid as a small molecular additive and water as coagulanting bath were employed to fabricate PES/SPES/SPSf loose nanofiltration(LNF)membrane.The effect of SPES content in casting solution on the morphology and performance was investigated.Results showed that the PES/SPSf/SPES blend system was a completely compatible system.The resulting PES/SPSf/SPES LNF membranes displayed a typical asymmetric structure with a dense skin layer and a sponge like sub layer.Specifiaclly,when SPES centration was 10%of polymers in the casting solution,the LNF membrane(M10)with the molecular weight cut off of 5900 and pore size of 1.38 nm was obtained,the pure water permeability was 605 L/(m^(2)·h·MPa).In addition,the rejection rate of LNF membrane(M10)was>99%for DR74 and DB79.In a salt/dye mixed system,the rejection of M10 was over 99%for DR74 and lower than 25%for Na_(2)SO_(4).It also exhibited an excellent selective separation performance and operation stability.