Studies of the Synthetic Inorganic Ion Exchanger. II : The Properties of Stannic Phosphate

概要

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A recommended procedure for the preparation of stannic phosphate and a discussion of its ion exchange properties have been presented. The stannic phosphate, the density of which is 2.17 g/cm^3, is a weakly acidic cation exchanger and possesses several dissociable hydrogen atoms in the range of pKa values. In a weakly acidic solution, in which the exchanger is useful, the exchange group having the pKa value of approximately three is most important. The ion exchange equilibrium can be elucidated by the mass action law and the affinity series for alkali metals coincides with the usual relationship observed in the ion exchange resin. The rate-determining step in the ion exchange is assumed to be the migration of ions through the water retained in the gel structure. From the data of thermal decomposition curve, ion exchange capacity, pH titration curves and mutual separation of alkali metals, the stability against heat treatment and γ-ray irradiation is estimated ; that is, the separation of alkali metals does not go well with the exchanger dried at 110℃ due to the slow rate of exchange, but the exchanger is stable against irradiation of about 10^9r and undergoes only a slight decrease in ion exchange capacity even when it is treated in water at 250℃ for 8 days. The structure has been suggested on the basis of above results and X-ray diffraction patterns.
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