A MECHANISM FOR ENHANCING IONIC ACCESSIBILITY INTO SELECTIVE ION-EXCHANGE RESINS

A bifunctional monophosphonic/sulfonic acid ion exchange resin with hi gh capacity has been synthesized. Metal ion studies have been carried out with europium, americium, and ferric nitrate in solutions of varyi ng acidity, with and without sodium nitrate added. The bifunctional re sin complexes far higher levels of Eu(III) from 0.5 and 1 N nitric aci d than the monofunctional phosphonic acid resin. It is postulated that the sulfonic acid ligand provides an access mechanism for the metal i ons into the polymer matrix by hydrating the matrix and preventing its collapse in high ionic strength solutions thus allowing for rapid ion ic complexation by the selective phosphonic acid ligands. The;bifuncti onal monophosphonic/sulfonic acid resin has both ligands bound to a po lystyrene support. It complexes higher levels of metal ions than a com parable resin differing only by having the monophosphonic acid ligand directly bound to the C-C backbone. Results are compared to a diphosph onic/sulfonic acid resin.