Abstract: The kinetics of extraction of uranium (Ⅵ) from nitric acid solution by tributyl phophate (TBP) in cyclohexane was investigated using single drop and Lewis cell technique.The extraction rate were found to be pseudo-first order with respect to the concentration of uranium (Ⅵ). It was increased with increasing concentration of TBP between 0～0.5 mol/L TBP and had a max/mum at about 4 mol/L nitric acid or nitrate in aqueous solution. The rate was almost independent of the extraction temperature. It is suggested that the extraction rate of uranium(Ⅵ) is controlled by the diffusion of complex UO₂(NO₂)₃·2TBP from interface into organic phase.

Key words: uranium, nitric acid, extraction, kinetics, tributyl phosphate