Abstract: THE KINETICS OF BINARY SYSTEM WITH CHANGING RESIN VOLUME DURING ION EXCHANGESONG YINJIE；YANG QINGDONG；ZHAOAIMIN（Department of Modern Physics,Lanzhou University，Lanzhou 730000）ABSTRACT A mathematical model the moving boundary mechanism with changimn exchanger volumeduring ion exchange in binary system of is presented．The kinetic data observed on001×7 strong acidic cation exchange resin are treated by the model，the mechanism of ion ex-change reaction and under various experimental conditions is discussed，and the diffusion coefficients are calculated．The conformitv of this model with experimental re-sults is demonstrated.Key words Binary system Moving boundary model Resin volume Diffusion coeffi-Cient