支撑层对PDMS复合膜渗透汽化性能的影响

Effect of Support Layer on Pervaporation Performance of PDMS Composite Membranes

以相转化法制备的聚偏氟乙烯(PVDF)、聚丙烯腈(PAN)、聚砜(PSF)三种多孔膜作为支撑层,制备聚二甲基硅氧烷(PDMS)复合膜用于渗透汽化乙醇/水混合物的分离。采用能量色散X射线光谱仪(EDX)定量表征了PDMS在支撑层表面的厚度(L0)和支撑层内的渗入深度(Li),研究发现,PDMS在各支撑层表面的厚度、支撑层内渗入的厚度有显著差异,PDMS复合膜的渗透通量与(L0+Li)间存在近似的线性关系,表明PDMS在支撑层中渗入深度不同是造成不同底膜支撑的PDMS复合膜渗透汽化性能差异的根本原因。文中提出选择层总厚度(Lt=L0+Li)概念,通过线性拟合得到PDMS复合膜渗透通量与Lt之间的定量关系,可以用来估算PDMS复合膜的渗透通量,并预测复合膜渗透通量极大值。

Three kinds of porous membranes,polyvinylidene fluoride（PVDF）,polyacrylonitrile（PAN）,polysulfone（PSF）,were prepared via phase inversion method and used as support layer of polydimethylsiloxane（PDMS） membranes.PDMS composite membranes were prepared and applied for the pervaporation of ethanol/water mixtures.The thickness of PDMS layer on the surface（L0） and into the porous support layer（Li） was measured quantitatively through energy dispersive X-ray spectrometer（EDX）.It was found that the L0 and Li of PDMS membranes prepared with different support layers are notably different.It is found that a well linear co-relationship exists between total flux and the（L0＋Li）.This indicates that the differences of Li contribute to the notable differences in pervaporation performance.Total thickness of PDMS selective layer（Lt= L0＋Li） was proposed.The quantitative relationship between total flux and Lt was obtained through linear fitting process,which can be applied for the estimation of pervaporation performance and predicting the maximum total flux of PDMS composite membranes.