Separation method and device with semipermeable membranes comprising sulfonated polyimides

Abstract

Membranes with improved permselectivity in electrolytic and electrodialysis cells in acidic media are based on sulfonated polyimides prepd. from two diamines, 1 of which has sulfo groups. A typical membrane was based on a polyimide with repeating units having structures based on 2,2'-disulfo-4,4'-biphenyldiamine, 4,4'-diaminodiphenyl ether, and 1,4,5,8-naphthalenetetracarboxylic aci