Interdiffusion in alkali ion sorption by hydrous stannic oxide : mechanism and effect of co-ion
Abstract The kinetics of exchange of alkali ions with H + in hydrous stannic oxide was studied from hydroxide and hydroxide/chloride solutions. At ionic strength ⪖0.01 M, the rate is controlled by the interdiffusion of the alkali ion and H + inside the hydrous oxide. Co-ions seem to be sorbed to a limited extent. There effect on the interdiffusion coefficients seems to be related to the strength of alkali ion-OH − interaction near the mouths of the pores. The replacement of OH − by Cl − inside the oxide leads to the enhancement of the exchange rate for Li + and Na + , and particularly for Li + . For K + , practically no change is observed.