Effect of hydrolysis on porosity of cellulose acetate reverse osmosis membranes

The alkaline hydrolysis of asymmetric cellulose acetate membranes was inves tigated. The changes of cellulose triacetate and cellulose diacetate membra ne performances caused by hydrolysis of the membrane material were measured , and the data were analyzed in terms of pore size distributions and effect ive number of pores in the upper membrane layer before and after hydrolysis . The resulting membranes rejection factors decrease of 10-25%, and a notic eable permeation rates increase were caused by closing of a part of the sma llest "network" membrane pores and by increasing the size of the other pore s. (C) 2001 John Wiley & Sons, Inc.