A study on the kinetics and mechanism of exchange of rubidium and cesium in chromium ferrocyanide gel using radioactive tracers

The kinetics and mechanism of Rb+ and Cs+ exchange on the H+ form of chromium ferrocyanide gel have been studied as the function of particle size, temperature and solution concentration of the exchanging ions. At higher concentrations, the ion-exchange sorption of Rb+ has been observed to be accompanied by a slow non-exchangeable process. The conditions of experiments are set to study the particle-diffusion controlled ion-exchange kinetics. The kinetic and thermodynamic parameters, viz. effective diffusion coefficients, activation energies and entropies of activation have been evaluated. The effective diffusion coefficient, in both cases, has been found to consist of two components, which may be attributed to the simultaneous diffusion of the counter-ions through the pores of different size and electric fields. (author)