Abstract: Experiments for determining cerium isotope ion exchange rates with macroporous resins Amberlyst 15, D001 and XN1010 are discribed. The kinetics of the isotope ion exchange reaction has been examined by a simple theoretical equation of intraparticle effective diffusivity De in a porous ion exchanger. The ion exchange proceeds by diffusion within the macropores and the solid phase of the resin. D_e of cerium was affected by the concentration of the bulk solution C. and was separated into a macropore diffusivity D_p and a solid phase diffusivity D by the equation. The diffusion coefficients of the exchanging ion are shown to have the values in the macro-pores comparable with their valuse in the bulk solution and to have the values in the solid phase comparable with their values in gel resin with the same crosslinkage as the resins used for the experiments.

Key words: Isotope exchange, Self-diffusion, Rare earths, Ion exchange