Patent ID: 6432314
Filing Date: 2002-08-13
Classification: A61L

Abstract:
An ion-exchange process in which an aqueous solution which contains dissolved or suspended anionic compound is contacted with anion exchange material having pendant cationic groups and anionic counterions whereby the anionic compound is ion exchanged with the counterion characterised in that the anion exchange material also has pendant zwitterionic groups, which comprise a cationic moiety and an anionic moiety, and in that the pendant cationic group Q1 is a group N+R53, P+R53 or S+R52 in which the groups R5 are the same or different and are each C1-4-alkyl or aryl or two of the groups R5 together with the heteroatom to which they are attached form a saturated or unsaturated heterocyclic ring containing from 5 to 7 atoms.