Design of new separation membrane for organic liquid mixtures by controlling nano-scale structure

为了获得高性能的有机液体混合物分离膜，研究了PVA基膜的纳米结构控制对分离性能的影响。通过皂化或共混制备了不同皂化度的PVA材料，考察了苯/环己烷(BZ/CHX)混合物的PV分离性能，发现皂化度为69%的膜对苯/环己烷(BZ/CHX)的分离性能最好。然后，测定了膜的溶胀度、结晶度和吸附平衡，讨论了表征结构与分离性能的关系。提出了两种纳米结构模型--致密结构和凝胶状结构。应用扩展的Flory-Huggins方程讨论了考虑压力和弹性效应时的溶胀度和分离性能。在方程中引入估计参数、压力和弹性效应，计算了膜的溶胀度和吸附平衡。基于凝胶结构的分析结果与实验数据吻合较好，所提出的分离性能与纳米结构相结合的模型可用于液体混合物渗透汽化膜的设计。

In order to obtain high performance separation membranes for organic liquid mixtures, effect, of nano-scale structure control of PVA based membranes on the separation performance was investigated. Various PVA materials with different degree of saponification were prepared by saponification of or blending base materials.Getting PV separation performance of Benzene/ Cyclohexane(Bz/Chx) mixture, first of all, membranes with degree of saponification of 69% were found to be excellent for such liquid separation. After that, degree of swelling, degree of crystallization and sorption equilibrium of membranes were measured, and relationship between characterized structure and separation performance was discussed.Two kinds of nano-scale structure model were proposed to analyze the performance-dense structure and gel like structure. Degree of swelling and separation performance were discussed applying the extended Flory-Huggins equation including pressure and elastic effect. Introducing estimated parameters, pressure and elastic effect into the equation, degree of swelling of membrane and sorption equilibrium were calculated. The analytical results on the basis of gel like structure were agreed fairly well to the experimental data.The proposed model to combine separation performance and nano-scale structure would be useful to design pervaporation membranes for separation of liquid mixtures.