Morphology of Aromatic Polyamide Type Asymmetric Reverse Osmosis Membranes

抄録

The morphology of aromatic polyamide type reverse osmosis (RO) membranes has been investigated with the aid of the scanning and transmission electron microscopes (SEM and TEM). The majority of the samples are treated by the method of critical point drying (CPD) and then observed with a SEM. It has been found that in the dense layer of these asymmetric membranes prepared with significant solvent evaporation there also exists micellar structure, but in the same time various types of defects have been observed on the surface of some part of such membranes. The structural variation in the cross section of these membranes due to different membrane materials and preparation techniques adopted was observed. In the membranes that we have studied, it is noted that the RO performance is correlated not only with the degree of densification and integrity of the surface layer, but also with the structure of the cross sections. The cross section structure characteristics of such membranes with higher RO performance are rather different from those reported in the literatures on cellulose acetate membranes and Nomex membranes without notable evaporation. The influence of the casing conditions of membrane on the morphology is discussed preliminarily.