POROUS SEMIPERMEABLE MEMBRANE BASED ON POLYACRYLONITRILE MODIFIED BY AMIDOXIME GROUPS, PROCESS FOR ITS PREPARATION AND THEIR USE

摘要

Modified, polyacrylonitrile-containing membranes suitable for ultrafiltration are prepared by reacting polyacrylonitrile or copolymers of acrylonitrile and other ethylenically unsaturated monomers with, successively, hydroxylamine, at least difunctional compounds, which act as bridge members, e.g. cyanuric chloride, a polyfunctional oligomer or polymer, e.g. polyethyleneimine, and, finally, a reactive compound containing at least one ionic group, e.g. an anionic reactive azo dye. The latter compound must be able to react with the polyfunctional oligomer or polymer and is required only if the said polymer does not already itself contain ionic groups. The novel membranes show good mechanical, temperature and pH-stabilities and are suitable, for example, for separating monovalent ions of low ionic weight from polyvalent ions of low or relatively high ionic weight or from monovalent ions of relatively high ionic weight and for separating ionic compounds from non-ionic compounds or from ionic compounds which have a different molecular weight or opposite charge. They can be used for example for separating salts from organic compounds (dyes) or in waste-water treatment.