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，研究了纳米级结构控制对聚乙烯醇基膜分离性能的影响。通过基料皂化或共混制备了不同皂化程度的聚乙烯醇材料。得到苯/环己烷（Bz/Chx）混合物的PV分离性能，首先发现皂化度为69%的膜最适合这种液体分离。测定了膜的溶胀度、结晶度和吸附平衡，并讨论了表征结构与分离性能的关系。提出了两种纳米尺度的结构模型来分析其性能：致密结构和凝胶状结构。应用包含压力和弹性效应的扩展Flory-Huggins方程，讨论了膨胀度和分离性能。将预估参数、压力和弹性效应引入方程，计算了膜的膨胀度和吸附平衡。基于凝胶结构的分析结果与实验数据吻合较好。该模型将分离性能与纳米级结构相结合，为液体混合物分离渗透汽化膜的设计提供了理论依据。

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.