Polymeric membranes functionalized with EGTA ligands, and process of separating ions

A method for concentrating, removing or separating selected metal ions from a source solution comprising the steps of:

• (a) contacting said source solution having a first volume with a composition comprising an EGTA ligand covalently bonded to a membrane, said membrane-ligand composition having the formula:
• M—B—L
• where M is a membrane, L is an EGTA ligand, and B is a covalent linkage formed by the reaction between an activated polar group on the membrane (M) with a functional group on the EGTA ligand (L);
• (b) removing the source solution from contact with said composition to which said selected ions have been complexed;
• (c) contacting said composition having said selected ions completed thereto with a smaller volume of an aqueous receiving solution in which said selected ions are soluble, or which has greater affinity for such selected ions than does the ligand portion of the composition, or which has a greater affinity for said ligand than does the desired metal ion, thereby quantitatively stripping such selected ions from the ligand;
• and
• (d) recovering said selected ions in concentrated form in said receiving solution.