Ion-exchange property and thermal stability of hydrous metal oxide ion exchangers.

Abstract

Ion-exchange property and thermal stability were studied on four synthetic hydrous metal oxides from the viewpoint of applicability for the processing of liquid radioactive waste. Hydrous titanium (IV) oxide and hydrous niobium (V) oxide, consisting of metal ions having larger ionic potential, possessed large cation-exchange capacities, and showed high affinity for both the transition metal ions and the representative element ions. Hydrous tin (IV) oxide and hydrous zirconium (IV) oxide, consisting of metal ions having smaller ionic potential, were amphoteric ion exchangers possessing large anion-exchange capacities, and showed much higher affinity for the transition metal ions than for the representative element ions. The selectivity series are understood in terms of the formation of a bond partially covalent in character for the transition metals, and the purely electrostatic interaction between anionic exchange sites and unhydrated or hydrated cations for the representative elements. An examination of ...