凝胶剂对PVA-PEG-H_2O体系凝胶动力学及膜性能的影响

Effect of Coagulant on the Coagulation Kinetics and Membrane Properties of PVA-PEG-H_2O System

考察了三元铸膜液PVA-PEG-H2O体系在丙酮-水混合凝胶剂、异丙醇(IPA)和四氢呋喃(THF)中的凝胶情况以及凝胶剂对膜微观结构、性能的影响。结果表明:该三元体系在丙酮中呈现瞬时分相行为,凝胶速率最快;当混合凝胶剂中丙酮的体积分数为0.6时,铸膜液体系出现延时分相迹象;在IPA和THF中呈现延时分相行为,凝胶速率基本相同。膜的微观结构表明:在上述凝胶剂中,PVA膜均形成蜂窝状孔。随着凝胶剂中H2O含量的增加,膜的纯水通量降低。在丙酮中形成的膜通量最高,而在IPA和THF中形成的膜通量很低。

Five kinds of coagulant, acetone-H2O solution with different volume fraction of acetone （ФAcetone ）, IPA, and THF, were chosen to prepare PVA membranes. The phase separation phenomena occurred during PVA-PEG-H2O solution immersed in these coagulants was studied and the effect of coagulant on PVA membrane morphology and properties were also considered. Instantaneous phase separation is observed when PVA-PEG-H2O solution is immersed in pure acetone and delay phase separation is occurred when ФAcetone decreasing to 0.6 in mixed coagulation. The delayed phase separation is also observed when PVA-PEG-H2O solution immersed in IPA and THF. The morphology of PVA membranes shows that only cell structure is formed in all coagulants. Pure water permeation experiments indicate that along with the decreasing of acetone in mixed coagulation, the PWP flux decreases, and that of PVA membrane prepared in IPA and THF is very low.