Studies of the Hydrous Zirconium(IV) Oxide Ion Exchanger. II. The Rate of Isotopic Exchange of Sodium Ions between the Exchanger in the Na+ Form and Aqueous Solutions

Abstract

The rate of the isotopic exchange of Na+ between hydrous ZrIV oxide in the Na+ form and aqueous solutions of sodium salts was determined radiochemically. The rate is controlled by particle diffusion, film diffusion, or both, according to the conditions. The exchange rate is controlled by particle diffusion, when the exchanger particles are large (radius, 171 μm), the solutions are more concentrated than 0.1 mol dm−3 Na+ and the flow rate through the exchanger particles is high, whereas under the opposite conditions film diffusion is the rate-controlling step. The activation energies of Na+ diffusion are 30±3 and 18.9±0.5 kJ mol−1 for particle and film diffusion, respectively.