POTASSIUM-ION EXCHANGE ON α-HAFNIUM PHOSPHATE

Forward and backward pH titration curves were measured for potassium-ion exchange on crystalline α-hafnium phosphate which had been prepared by the direct-precipitation method. Exchange in each direction proceeded in two steps, and the hysteresis was observed in the region of smaller loadings of the potassium ions. Exchange in the ternary H+–Li+–K+ system was also preliminarily investigated, the selectivity of the potassium and lithium ions was what would be expected from the results of the binary hydrogen ion-alkali metal ion systems.