An apparatus containing crosslinked polymer for binding phosphate anions is provided, the polymer comprises a polyvalent cation attached to the polymer through at least one covalently bound anionic functional group, and wherein the anionic group is selected from a group consisting of sulfonate, carboxylate, phosphonate and mixtures thereof and wherein the cation is selected from a group consisting of aluminum, calcium, magnesium, molybdenum, manganese, titanium, barium, strontium, zirconium, vanadium, scandium, lanthanum, yttrium, cerium, nickel, iron, copper, cobalt, chromium, zinc and mixtures thereof.