Abstract: The kinetics of the stripping of UO₂(NO₃)₂ in tri-n-butyl phosphate(TBP)-cyclohex-ane with nitric acid solution has been investigated by using constant-interface cell and single drop techniqueUnder the conditions of the constant-interface cell method, the rate of stripping of uranium (VI) increased steadily with the stirring speed and was nearly independent of temperatureThe rate equation was R = k₁[U]_(o)[TBP]_(o)^-1.17[HNO₃]^-1.70 The rate of stripping might be controlled by the diffusion process of complex UO₂(NO₃)₂·2TBP from the organic, phase to the interfaceIn the case of single drop method, the rate of stripping of uranium (VI) increased with increasing temperature and the apparent activation energy was found to be 278 kJ/molThe rate equation was R = k₂[U]_(o)[TBP]⁰_(o) in 3 mol/L HNO₃. It is suggested that the rate-controlling step might be the dissociation reaction of the complex UO₂(NO₃)₂·2TBP at the interface.

Key words: Uranium, Nitric acid, Tri-w-butyl phosphate, Kinetics of stripping