Abstract: STUDY ON THE KINETICS OF ION EXCHANGE IN TERNARY SYSTEM OF H~+-Na~+-UO~(2+)_2ZHAO AIMIN; SONG YINJIE（Department of Modern Physics，LanZhou University,730000）ABSTRACT The kinetics of ion exchange in the ternary system of H~+-Na~+-UO~(2+)_2 is studied with strongacidic cation exchange resin. The valuable conclusions are made by comparing the experimentalresults in this system with that in binary systerm. The particle diffusion coeffieients for givencounter ion in the system are calcalated by simulating the experimental data. Results show thatthe diffusions of the three kinds of counter ions in the solution are interdependent．Therefore，thethree Nernst-planck equations can only be approximately applied to the ternary system wheneach of the equations is used to describe the diffusion flux of a given counter ion respectively. Theequalibrium selectivity coefficients of each counter ion in the system are reported. Key words Kinetics of ion exchang Ternary system Nernst-planck equation Particle diffusion coefficient Equalibrium selectivity coefficient