POROUS SEMIPERMEABLE CELLULOSE ACETATE MEMBRANES MODIFIED BY IONIC GROUPS, PROCESS FOR THEIR PRODUCTION AND THEIR USE

摘要

Cellulose acetate containing membranes which have pore diameters of about 10 to 1000 ANGSTROM are modified by reacting these membranes (a) with (b) an at least difunctional compound, e.g. cyanuric chloride, (c) a polyfunctional oligomer or polymer, e.g. polyethyleneimine, and then with (d) a compound which contains at least one ionic group and one group capable of reaction with component (c). Reactant (d) is necessary only if the polyfunctional component (c) does not already contain sufficient ionic groups. The novel membranes are suitable for ultrafiltration and can be used for example for separating monovalent ions of low ionic weight from polyvalent ions of low or relatively high ionic weight of from monovalent ions of relatively high ionic weight and for separating ionic compounds (salts) from non-ionic (organic) 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.