ISOTOPIC ION-EXCHANGE STUDIES IN HETERO-IONIC SYSTEMS

Isotopic ion-exchange studies were carried out for Mn2+ ions in the presence of Ba2+, Sr2+ Cs+ and Na+ ions, and for Na+ ions in the presence Ba2+ and Mn2+ ions, from 0.1 N chloride solutions. Single Particle Radioactive Tracer technique was employed, and the exchanger Dowex 5OW-X8 was used. The Nernst-Planck model, taking into account the diffusion processes both in the film and in the resin bead, was employed to analyse the data Resin-phase self-diffusion coefficients obtained from the isotopic exchanges in the homo-ionic systems, and liquid-phase diffusion coefficients calculated from limiting ionic conductance data, were used. The computer results agreed well with the experimental data for the following cases: (i), Na+ exchange in the presence of Ba2+ and Mn2+ ions; (ii), Mn2+ ion in the presence of Na+ ions; and (iii), Mn2+ exchange in the presence of Ba2+, Sr2+ and Cs+ ions at higher fractions of Mn2+ ions. However, lower values of diffusion coefficient of Mn2+ ions could correlate the data with smaller fractions of Mn2+ ions. It has been shown ibat resinphase diffusion mechanism of homovalent ions under similar environments is similar. © 1979.