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

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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.