Title: Studies on the Ammonium Form of Crystalline Zirconium Phosphate. III. Ammonium–Hydrogen Ion-exchange on α-Zirconium Phosphate Prepared by the Direct Precipitation Method
Abstract: Abstract The ammonium–hydrogen ion-exchange on α-zirconium phosphate prepared by the direct precipitation method has been investigated by means of pH titration and X-ray diffractometry. In the forward process (α-zirconium phosphate to the ammonium form) the ion-exchange reaction took place in one stage at the equilibrium pH of 5.9–6.0 and the α-zirconium phosphate exchanger was directly converted into the ammonium form. In the reverse process (the ammonium form to α-zirconium phosphate) the reaction proceeded in three stages, that is, the ammonium form→ a half-exchanged form→ an intermediate form→α-zirconium phosphate. The chemical composition of the half-exchanged form has been represented as Zr(NH4PO4)(HPO4)·nH2O (n>0.5). A small amount of ammonium ions in the exchanger could not be easily replaced with protons in the solution.