PDMS-b-PPO非对称渗透汽化膜对乙醇/水的分离性能

摘要

The PDMS-PPO asymmetric membranes were prepared via sol-gel process, when the PDMS-PPO block copolymers as membrane material, N-butanol as an additive, and chloroform as the solvent. The prepared membranes morphology and the element distribution in surface were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) respectively. Effects of casting solution concentration, downstream pressure and flow velocity on the separation performance of asymmetric membrane were also studied. The results showed that the asymmetric membrane separation factor and permeation flux increased first and then declined with the growth of the polymer concentration in the membrane solution. With the increasing of downstream pressure of membrane, the asymmetric membrane separation factor increased and permeation flux declined. The asymmetric membrane separation factor increased first and then declined and permeation flux reduced with the growth of flow velocity. The total permeation flux and the separation factor for ethanol can be 850. 7 g/(m2 · h) and 8.78 respectively, when polymer concentration in casting solution is 11%, the feed concentration is 5%, the feed solution temperature is 60 ℃, the downstream pressure is 10 kPa and the flow velocity is 0. 267 L/min. The results showed that PDMS-PPO asymmetric membranes had a priority selectivity of ethanol and a higher permeate flux.%以聚二甲基硅氧烷-聚苯醚(PDMS-PPO)嵌段共聚物为膜材料,正丁醇为添加剂,氯仿为溶剂,采用凝胶溶胶法制备非对称渗透汽化膜,利用扫描电镜和能谱仪对膜进行形貌表征及元素分析.研究了铸膜液浓度、膜后侧压力、进料液流速对乙醇/水混合物渗透汽化分离性能的影响.结果表明,随着铸膜液中嵌段共聚物质量分数的增大,非对称膜的分离因子和渗透通量呈先上升后下降的趋势；随着膜后侧压力的增加,分离因子呈上升趋势,而渗透通量下降较快；随着料液流速的提高,分离因子先上升后下降,而渗透通量呈减小的趋势.以嵌段共聚物质量分数为11％制备的非对称膜,在进料液乙醇含量(质量分数)5％、温度60℃、膜后侧压力10kPa、料液流速0.267 L/min时,膜的渗透通量为850.7 g/(m2·h),分离因子为8.78.实验表明,PDMS-b-PPO非对称膜对乙醇具有优先选择性,并有较高的渗透通量.