The ion exchange kinetics of 235UO22+-238UO22+, UO22+-H+ were studied with macrorecticular sulfonic ion exchange resin. The latter two processes start from film diffusion changing gradually to inner diffusion and the former process begins at inner diffusion as soon as dead time passed. The results were explained by boundary mass-transfer models based on absorption double elec. layer theory. Each inner diffusion coefficient (D) of these processes was determine and the results showed that D of the first and second processes are nearly equal to each other and that of the last process remains only 1/5 as that of the second one.

Key words: REACTION KINETICS, ISOTOPE EXCHANGE, URANIUM, URANIUM ISOTOPES, ION EXCHANGING, HYDROCHLORIC ACID, MASS TRANSFER, CATION EXCHANGE RESINS, MACRORETICULAR STRUCTURE ION EXCHANGE RESINS, ISOTOPE SEPARATION