Solid NMR Study of the Ion-Exchange Properties on γ-Titanium Phosphate

Abstract

Layered γ-titanium phosphate (γ-TiP), Ti (HPO₄) ₂⋅2H₂O, is well known as the host material of intercalation compounds and the inorganic ion-exchanger of H⁺/metal ion system. It was found to have high ion-exchange selectivity for Rb⁺ and Cs⁺ among alkali metal ions. The ionexchange reactions for these ions progressed in two steps according to pH. Part of water molecules in the mterlayer of γ-TiP was taken away during ion-exchange reaction and an amorphous γ-TiP resulted. This phenomenon was first studied by thermal analysis and further investigation was carried out using solid NMR of ¹H and ¹³³Cs in detail. Moreover, the interaction between Fe²⁺ and Cs⁺ for the ion-exchange reaction was investigated. Despite Fe²⁺ was hard to adsorb to γ-TiP, the amount of sorbed Fe²⁺ increased when Cs⁺ coexisted and the amount of sorbed Cs⁺ decreased.