International Union of Pure and Applied Chemistry Analytical Chemistry Division Commission on Electroanalytical Chemistry a Critical Evaluation of the Redox Properties of Uranium, Neptunium and Plutonium Ions in Acidic Aqueous Solutions

Standard redox potentials, E8s and redox processes of U, Np and Pu ions in acidic aqueous solutions are reviewed and evaluated critically. The E8s of reversible redox processes, MO2 /MO2 ‡ and M/M (M: U, Np or Pu) adopted are those proposed mainly by Riglet et al. on the basis of the precise correction of formal potentials, E8 s, according to the improved theoretical approach to estimate the activity coef®cient. Electrode processes of the U, Np and Pu ions are discussed in terms of current±potential curves, measured so far by polarography, voltammetry or ̄ow coulometry. Special attention is paid to the irreversible MO2 / M reactions. Disproportionation reactions of MO2 ‡ are also discussed. New substances are introduced as intermediates during reductions of MO2 ‡ to M or disproportionations of MO2 .