Solid Phase Hydration Effect on the Selectivity of Alkali Metal lons for Inorganic lon Exchangers. Solid State NMR Study.

Solvation Structure of Bromide Ion in Anion-Exchange Resins

“…These factors affecting ion-exchange selectivity have been well investigated not only by batch partition experiments but also by chromatography, which have enabled simple determination of selectivity coefficients for a variety of combinations of ions, ion-exchange resins, and solvent systems. Compiled knowledge has suggested the important involvements of ion solvation in the ion-exchange mechanism. 3a,, However, the discussions of a solvation effect based on thermodynamic data have been severely restricted for some reasons; (1) thermodynamic data include the contributions both from a counterion and from an ion-exchange group, (2) ion-exchange data intrinsically have relative nature because partition selectivity is determined by a difference in affinity between two counterions, and (3) exchanging counterions should cause a change in the energetic state of the ion-exchange site. Thus, the origin in ion-exchange selectivity has not been completely elucidated despite an enormous number of partition data.…”

7Li/6Li Isotope Separation on Inorganic Ion-Exchangers and NMR Study of the H+/Li+ Ion-Exchange Reaction

“…The authors have assumed that the ion-exchangers that have high lithium ion selectivity and sorb lithium ions in the dehydrated state must have high isotope separation coefficient between 7 Li and 6 Li. The relation between the ion-exchange selectivity of lithium ions and the dehydration property has already been reported on the basis of the solid-state NMR study. − Some results on the relation between the dehydration property and 7 Li/ 6 Li isotope separation coefficient have already been reported as a preliminary note . This paper deals with the experimental and theoretical proofs on the assumption that the dehydration degree in the solid phase is dominant factor to determine 7 Li/ 6 Li isotope separation coefficient.…”

“…The selectivity of the inorganic ion-exchangers between similar ions is generally higher than those of organic ion-exchangers. , The high selectivity of the inorganic ion-exchangers has been accounted for the hydration property of ions of interest in the solid phase on the basis of 1 H, 7 Li, and 23 Na NMR study. For example, the selectivity of the ion-exchange reaction between alkali metal ions − and between trivalent metal ions was accounted satisfactorily on the basis of the hydration property in the solid phase. The NMR spectroscopy can detect the mobility of hydrated water molecules as well as the ions of interest in the solid phase.…”