管式聚二甲基硅氧烷/陶瓷复合内膜的制备及其渗透汽化应用

Preparation and application of tube polydimethylsiloxane/ceramic inner composite membrane for pervaporation

采用浸渍-提拉法在多孔管式陶瓷支撑体内表面制备完整无缺陷的聚二甲基硅氧烷(PDMS)膜层。采用扫描电子显微镜(SEM)、渗透汽化(PV)性能测试等手段,研究支撑体孔径和涂膜时间对管式PDMS/陶瓷复合内膜的形貌和分离性能的影响。同时,考察丁醇-水体系中料液温度、料液中丁醇含量对管式PDMS/陶瓷复合内膜渗透汽化性能的影响,并对膜的渗透汽化长期稳定性进行了研究,将复合内膜的渗透汽化性能与复合外膜进行了比较。结果表明:复合膜均匀完整,有良好的过渡层。支撑体孔径较大的复合膜,其渗透通量更高。随涂膜时间的延长,膜厚依次增加,渗透通量下降,分离因子升高;随料液中丁醇含量增加,通量逐渐上升,分离因子先升高后下降;随操作温度的升高,通量和分离因子都有所增加。在料液温度为40℃、丁醇质量分数为1.5%的条件下连续运行180h,膜渗透总通量高达1 050 g/(m^2·h),选择性可达30。

Polydimethylsiloxane( PDMS) membrane was dip-coated in the inner surface of the tubular ceramic support. Scanning electron microscope( SEM) and pervaporation( PV) tests were utilized to investigate the effects of pore size of the ceramic support and coating time on the membrane morphology as well as the pervaporation separation performance. The operation parameters such as feed temperature and the feed concentration were investigated. Result showed that the composite membrane was complete uniform,and had a good transition. The composite membrane with larger pore diameters had higher permeation flux. With the coating time extending,the flux decreased and the separation factor increased.With the increase of alcohol content,the flux increased gradually and the separation factor decreased afterincreasing firstly. With the increase of operating temperature,the flux and separation factor increased. At temperature of 40 ℃,the as-prepared PDMS/ceramic composite membrane showed high separation performance with total flux of 1 050 g/( m^2·h) and separation factor of 30,and the membrane was stable during 180 h long-term operation tests.