PEG分子量对PVB超滤膜结构和性能的影响

Preparation of PVB ultrafiltration membranes using PEG with different molecular weights as additives

用聚乙烯醇缩丁醛(PVB)作为本体材料,以N-甲基-2-吡咯烷酮(NMP)为溶剂,以4种不同分子量(分别是2 000,6 000,10 000,20 000)的聚乙二醇(PEG)为添加剂,用浸没沉淀相转化法制备超滤膜.研究了PEG分子量对成膜凝胶动力学和膜性能的影响.利用扫描电镜(SEM)观察PVB膜的形貌,并对膜的性能,包括纯水通量、截留率、孔隙率等进行了研究.结果表明膜上孔的数目和大小都随着PEG分子量的增大而增大.当PEG分子量从2 000增大到20 000时,膜的纯水通量首先由62.8L/(m2·h)增大到104L/(m2·h),然后又降到50.1L/(m2·h).另外,随着PEG分子量的增大,膜的耐污染性逐渐变差,而孔隙率逐渐增大.

Poly（vinyl butyral） （PVB） ultrafiltration （UF） membranes were prepared by immerged phase- inversion process. N-methyl-2-pyrrolidone （NMP） was used as solvent. Polyethylene glycol （PEG） of four different molecular weights were used as the polymeric additives. The effects of the molecular weight of PEG on the precipitation kinetics and performances of membranes were investigated. The morphologies of membranes were analyzed by scanning electron microscope（SEM） and performances of membranes were evaluated in terms of pure water flux（PWF）, protein rejection, porosity. The results showed that with the increase in molecular weight of PEG, the pore number as well as pore size in membranes increases. With increase in molecular weight of PEG from 2 000 to 20 000, the PWF first increases from 62.8 L/（m2.h） to 104 L/（m2 .h） then decreases to 50. 1 L/（m2 . h）. Furthermore, the anti-fouling property of PVB membranes becomes worse but the porosity increases with the molecular weight of PEG increasing.