PROCEDIMENTO PER LA PRODUZIONE DI MEMBRANE SEMIPERMEABILI

摘要

A method for the preparation of semipermeable membranes comprises sulphonating porous membranes of acrylonitrile polymers containing 40 to 100 mole percent of acrylonitrile. A heterogeneous membrane which can be prepared by such a method comprises an acrylonitrile polymer membrane which has a dense surface layer of less than 1 mu in thickness and has pores increasing in size gradually away from the said dense surface layer of the membrane and is cross-linked more than 0.1 mu in thickness from the surface. The semipermeable membranes are useful e.g. for separating substances by reverse osmosis or ultrafiltration.