FUNDAMENTAL STUDIES ON DESIGN OF SEPARATION MEMBRANES FOR ORGANIC LIQUID MIXTURES AND IMPROVEMENT OF MEMBRANE SEPARATION

为了制备高渗透、高选择性的有机液体混合物聚合物膜，采用不同的高分子材料对渗透汽化中渗透分离酒精水溶液的膜的制备条件进行了详细的研究。亲水聚合物膜，如聚乙烯醇和壳聚糖膜，主要渗透水从水性酒精溶液。此外，疏水聚合物膜如聚氯乙烯和聚苯乙烯膜选择性地渗透水。为了揭示这些现象，对膜上吸附的液体组成进行了分析。前者膜吸附水，后者膜吸附醇。结果表明，仅提高渗透物质在膜中的溶解度是不能获得良好的渗透分离效果的，提高渗透物质在膜中的扩散率是非常重要的。从分子水平的角度研究了热处理和交联反应对膜结构变化与分离特性的影响。研究发现，膜结构的微小变化会显著影响渗透和分离特性。本研究提出了一种新的膜分离技术——蒸发法，比较了蒸发法和渗透蒸发法对乙醇水溶液在不同聚合物膜上的渗透分离特性。总的来说，蒸发法的分离性优于渗透蒸发法，但渗透蒸发法的渗透性优于蒸发法。在蒸发过程中，可以控制膜邻域和进料溶液之间的温差。将这种控制温差的蒸发法应用于聚二甲基硅氧烷膜分离乙醇水溶液和壳聚糖膜分离二甲亚砜水溶液，前者膜选择性地渗透醇类，后者选择性地渗透水。从膜的物理化学性质和渗透物质的角度讨论了有机水溶液通过这些膜的机理。少

Purpose of preparing polymer membranes with high permeability and high selectivity for organic liquid mixtures, preparation conditions of the membrane for the permeation and separation of aqueous alcohol solutions in pervaporation was investigated in detail using various polymer materials.Hydrophilic polymer membranes such as poly(vinyl alcohol) and chitosan membrane predominantly permeated water from aqueous alcohol solutions. Also, hvdrophobic polymer membranes such as poly(vinyl chloride) and polystyrene membrane selectively permeated water. In order to reveal these phenomena, composition of liquid adsorbed in the membrane was analyzed. The former membranes adsorbed water and the latter one alcohol. From these results it was found that good performance for the permeation and separation could not be obtained only increase of solubility of the permeating species into the membrane and it was very important to increase diffusivity of the permeating species in the membrane.Relationship b … More etween the structural change of membrane with heat treatment and crosslink reaction and the separation characteristic was studied from the viewpoint of molecular level. It was found that slight change of the membrane structure significantly influenced the permeation and separation characteristics.In this study, we proposed a new membrane separation technique, which was named an evapomeation method, the permeation and separation characteristics for aqueous alcohol solutions through some polymer membranes by the evapomeation were compared with those by pervaporation. In general, the separation in evapomeation was superior to that in pervaporation, but the permeability in pervaporation was better than that in evapomeation.In evapomeation, it was possible to control temperature difference between the membrane neighborhood and the feed solution. When this evapomeation method with control of the temperature difference was applied to the separation of aqueous alcohol solutions through poly(dimethylsiloxane) membrane and aqueous dimethyl sulfoxide through chitosan membrane, the former merfibrane permeated alcohols and the latter one permeated water with high selectivity.Mechanisms for organic aqueous solutions through these membranes are discussed from the viewpoints of physicochemical nature of the membrane and the permeating species. Less