Abstract: A COMPARATIVE STUDY ON KINETICS OF ION EXCHANGE IN BINARY SYSTEM FITTED BY THREE MODELSSONG YINJIE；ZHAO AIMIN（Department of Modern Physics, Lanzhou University,730000）ABSTRACT A”three-necked flask”technique is employed for the study of the kinetics of H~--UO ionexchange system with strong acidic cation exchange resin. Three kinetic models are applied to theexperimental data，the diffusion coefficients are calculated，and the rate constants of chemical reac-tions are also obtained by Moving Boundary Model．The possible effect of chemical reaction on therate of ion exchange is disussed，and the view that the chemical reaction can retard the diffusion isdeveloped．By analysing the behavior of the kinetic curves and the fitting results of the computer，it is found that the Moving Boundary Model is the best one for describing the ion exchange mech-anism of this svstem.Key words Ion exchange kinetic model Fitting analysis Diffusion coefficient