Synthetic inorganic ion-exchange materials—I zirconium phosphate

Abstract

This paper describes some of the properties of zirconium phosphate as an example of a class of very stable synthetic inorganic ion-exchange materials, which may be prepared in granular form suitable for column operations. It exhibits properties typical of a polyfunctional, weakly acid cation exchanger, with capacities up to ∼5 mequiv/g in alkaline solution. Materials with a low phosphate : zirconium ratio possess in addition anion-exchange properties due to anions retained in the structure from the original zirconium salt. Cations may be exchanged rapidly and reversibly upon acid phosphate groups in the gel structure. Distribution coefficient measurements for alkali metal and alkaline earth ions have been made, and the material shows promise for separation purposes; uptake is reduced at elevated temperatures owing to hydrolysis. The stability of the material towards water at temperatures up to 300°C suggests its possible use for water treatment in high-temperature systems, as well as other possibilities.