Studies of Inorganic Ion Exchangers. III. Ion Exchange Properties of Ti(HPO4)2·0–1/2H2O to Alkali Metal and Ammonium Ions

Abstract In order to develop an inorganic ion exchanger for industrial use, the ion exchange behaviour of Ti(HPO4)2·0–1/2H2O with alkali metal and ammonium ions has been investigated. The ion exchange capacities of Ti(HPO4)2·1/2H2O (hemihydrate) have been determined by forward and backward titration. The saturation ion exchange capacities (QA) of the hemihydrate to Li, Na, K, Cs, and NH4 (M) ions by the forward titration method were 1.9, 3.2, 4.1, 2.5, and 3.7 meq/g at pH 4.5, respectively. The ion exchange capacities (Q°) of the hemihydrate from 0.1 M MCl were 0.31, 1.84, 2.31, 0.21, and 1.01 meq/g to each of the ions. The selectivity quotients (KHM) estimated from the QA and Q° were 0.028, 3.77, 15.7 0.008, and 0.255 to each of the ions, and the selectivities of the hemihydrate increased in the order Cs+<Li+<NH4+<Na+<K+. The empirical formula of the 50% ion exchange products derived from the hemihydrate may be represented by TiMH(PO4)2·0–1/2H2O, (where, M=Na, K, and NH4). The ion exchange of Li and Cs ions did not take place completely however to give a 50% ion exchanger, and the hemihydrate was then converted into a non-stoichiometric compound.