The preparation of crystalline zirconium phosphate and some observations on its ion exchange behaviour

The stoicheiometry and dehydration behaviour of gelatinous zirconium phosphate preparations were determined. Refluxing the gelatinous products in phosphoric acid resulted in the formation of a truly crystalline product. The crystals have approximately the same composition as the gels but exhibit somewhat different dehydration behaviour. Both forms of zirconium phosphate are represented by the formula Zr(HPO4)2 · H2O. Sodium ion exchange capacity measurements show that the crystalline zirconium phosphate contains two replaceable hydrogen ions per zirconium phosphate molecule. The exchange capacity of the gels approach but never equal this value. The crystals do not exchange with cesium ion whereas the gels have a high cesium exchange capacity. A tentative explanation for this behaviour is presented based on structural considerations.