渗透汽化膜表面结构对分离过程的影响

用低温氧等离子体处理聚乙烯膜，被处理的膜通过红外、表面接触角、电子扫描显微镜、元素分析等手段证明在其表面形成了多量的羟基、羰基和羧基等含氧基团。当将这种处理膜的处理面对着原料液（ＵＰＥ）、处理面对着低压侧（ＤＰＥ）及原始膜（ＰＥ）分别用来渗透汽化分离乙醇水混合物，发现ＰＥ膜为优先透醇膜。ＵＰＥ渗透汽化产物的醇浓度下降，透量增加，并且透过速率对原料液浓度曲线呈反Ｓ形。ＤＰＥ膜则完全变成了优先透水膜，并且透过速率明显下降，说明渗透汽化膜表面的结构及组成对渗透汽化过程予以重大的影响，膜的上表面主要发生溶解，下表面则对被分离物予以强有力的扩散控制。

INFLUENCE OF SURFACE STRUCTURE OF MEMBRANCE ON THE PERVAPORATION PROCESS

Polyethylene membrance was treated by low temperature oxygen plasma. The treated PE membrance was characterised by IR, surface contact angle, element analysis and scanning election microscope, the result showed a great amount of carbonyl, hydroxyl, carboxyl groups were formed on the surface of the PE membrance, so that the hydrophobic surface was transformed into hydropholic. The original PE membrance and the treated membrance respectivity as a pervaporation membrance was used to separate the ethanol water solution. It was found that the PE membrance was ethanol preferential permeation membrance. When the treated surface of the membrance towards feed the ethanol concentration of the product decreased, flux increased and the diagram of flux vs ethanol concentration of feed solution presented as a reverse S shape. When the treated surface of membrance towards low pressure room, the membrance became a water preferential premeation membrance and the flux sharply decreased. It is suggested that the structure and composition affect on the pervaporation performance of the membrance. The top surface influence on the solubility performance of pervaporation membrance and the bottom surface influence on the diffusion performance of the pervaporationmembrance.