PREPARATION OF PHOSPHORIC-ACID RESINS WITH LARGE CATION-EXCHANGE CAPACITIES FROM MACRORETICULAR POLY(GLYCIDYL METHACRYLATE-CO-DIVINYLBENZENE) BEADS AND THEIR BEHAVIOR IN UPTAKE OF METAL-IONS

In order to prepare phosphoric acid resins (RGPs) with large cation ex change capacities, effects of porosity and cross-linking of the precur sory poly( glycidyl methacrylate-co-divinylbenzene) beads on their fun ctionalization with phosphoric acid were studied. Two series of precur sory copolymers were prepared: one was prepared by changing the amount of divinylbenzene (1-25 mol %) but by fixing that of isobutyl acetate (porogen) at 140 vol % per monomer mixture; the other by changing the amount of the porogen (40-160 vol %) but by fixing that of the cross- linker at 10 mol %. It was clarified that porosity of the precursors p lays an important role in the functionalization. Highly porous precurs ors were functionalized with high efficiency; for example, even the pr ecursors containing 10 mol % of divinylbenzene resulted in RGPs having cation exchange capacities as large as 6-7 meq/g, so long as BET spec ific surface areas of the precursors were greater than ca. 30 m(2)/g. The selectivity study has revealed that RGP exhibits the characteristi c metal ion selectivity. Lithium ion was adsorbed in preference to sod ium and potassium ions; and so-called hard Lewis acid cations, such as uranyl, ferric, and aluminum ions, are adsorbed even from strongly ac idic media (1 < pH < 2). Among common divalent metal ions, in addition , the resin exhibits the highest selectivity toward lead ion. (C) 1997 John Wiley & Sons, Inc.