Solid Phase Hydration Effect on the Selectivity of Alkali Metal Ions for Inorganic Ion Exchangers-Solid State NMR Study-

KANAZAKI Yasushi, CHITRAKAR Ramesh, OHSAKA Tohru, ABE Mitsuo

doi:10.1246/nikkashi.1993.1299

The ion exchange reactions of alklai metal ions on inorganic ion exchangers were examined with solid state NMR technique in related with the hydration phenomenon of metal ions. ¹H, ⁷Li, ²³No NMR spectra were measured on lithium ion selective tin antimonate and titanium antimonate. According to the NMR study as well as ion exchange study, it was found that these exchangers had two types of ion exchange sites, one was favorable for lithium ions and the other had poor selectivity for lithium and sodium ions. In the former site, lithium ions were adsorbed by dehydrating water molecules. The second and the third exchangers examined were monoclinic antimonate and cubic niobate, both are very selective for lithium ions. It was found that only lithium ions were selectively adsorbed on these ion exchangers by dehydrating their hydrated water molecules. Small space of ion exchange site result in the selectivity. The last ion exchanger was cubic ammonium molybdate, in which potasium ions as well as ammonium ions are very selective. Two types of ion exchange sites were found to present due to the I1 NMR study. One site, the population was about 25%, was found to adsorb any kind of univalent ions. The other site was very favorable for potassium ions and could not adsorb hydrogen ions. The phenomenon was well accountable from the analogy of hydration properties of metal ions in aqueous solution.

Solid Phase Hydration Effect on the Selectivity of Alkali Metal Ions for Inorganic Ion Exchangers-Solid State NMR Study-

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