SYNTHETIC INORGANIC ION-EXCHANGE MATERIALS .18. ION-EXCHANGE EQUILIBRIA OF CRYSTALLINE ANTIMONIC(V) ACID WITH ALKALI-METAL IONS

Exchange isotherms for hydrogen ion/alkali metal ions have been measured at 20 and 40°C, with a solution ionic strength of 0.1, in crystalline antimonic(V) acid as a cation-exchanger. The isotherms showed S-shaped curves for the systems of H+ Na+, H+ K+, H+ Rb+ and H+ Cs+, but not for H+ Li+ exchange. The selectivity coefficients (logarithm scale) vs equivalent fraction (XM+) of alkali metal ions in the exchanger give linear functions for all systems studied. The selectivity sequences as a function of XM decrease in the order; Na+>Rb+>Cs+>K+ for 0.0 - 0.1 of XM+, Na+>Rb+>K+>Cs+ for 0.1 - 0.32 and Na+>K+>Rb+>Cs+ for 0.32 - 1.0. Overall and hypothetical (zero loading) thermodynamic equilibrium constants were evaluated for these ion-exchange reactions. © 1979.