ABSTRACT
When a material is given, membranes should be prepared from the given material. The membranes so prepared should then be tested by separation experiments. While the separation depends on the pore size and the pore size distribution of the surface layer of the membrane that is in contact with the feed fluid, the permeation rate depends on the permeation rate, which is normally desirable, the thickness should be as small as possible. There are different methods to prepare membranes. The principle underlying the membrane preparation is, however, always the same; i.e., it is to control the pore size and the pore size distribution at the surface layer and to decrease the thickness of the surface layer. Cellulose acetate membranes developed by Loeb and Sourirajan for the purpose of seawater desalination continue to be useful in various membrane applications, despite the development of new membrane materials and new membrane preparation techniques.
