NUCLEAR-MAGNETIC-RESONANCE STUDY OF ION-EXCHANGE REACTION ON CUBIC AMMONIUM MOLYBDATE .61. SYNTHETIC INORGANIC ION-EXCHANGE MATERIALS

Inorganic ion-exchangers generally exhibit high ion-exchange selectivity in comparison with organic ion-exchangers. The high selectivity has been ascribed to the rigid lattice of the crystal structure, e.g. ion-sieving properties of zeolites. Cubic ammonium molybdate prepared by the precipitation method (CAM) has been shown to have an unusual (compared with other inorganic ion-exchangers) selectivity for K+ among alkali-metal ions. The selectivity of K+ was assumed to result from the hydration of ions incorporated in the crystal lattice. The hydration property of alkali-metal ions incorporated in the lattice was revealed from the H-1 NMR study and the selectivity for K+ was accounted for by the hydration of K+ by analogy with the well known properties of electrolyte solutions.