THE KINETICS OF FAST REDOX REACTIONS OF ACTINIDE IONS IN AQUEOUS-SOLUTIONS AS STUDIED BY PULSE-RADIOLYSIS

ThiS paper is a brief review of the results of the study of the kinetics of fast redox reactions (rate constants are 10(6) - 10(10) dm3 mol-1 s-1) of actinide ions (uranium, neptunium, plutonium, and americium) in aqueous solutions by micro- and nanosecond pulse radiolysis with spectrophotometric detection of short-lived species. The processes studied include the reactions of actinide ions in different valence states with the primary products of water radiolysis, many inorganic free radicals (Cl2-, NO3, SO4-, CO3-, etc.), and some organic free radicals. In addition, the kinetics of fast reactions of the type U(V) + Ce(IV) was measured. In this case, the reacting ions were produced via the reduction of U(VI) and the oxidation of Ce(III) by free radicals during the action of the electron pulse or immediately after it. Particular attention was paid to acid solutions with high concentrations. On the basis of the results obtained, the conclusions on the specific features of the reaction kinetics studied were drawn.