Radiopolarographic Study of Americium and Curium

Abstract

The radiopolarographic behavior of americium and curium in non-complexing aqueous media was examined as a function of concentration, specific activity and pH. At pH=3.0, a single wave of americium was observed below [Am]=8.0×10^-7 M having a plateau at a potential more negative than -2.02 V (main wave). An additional pre-wave was observed above [Am]=9.6×10^-7 M. At lower pH(<2.6), the pre-wave appeared even at a concentration smaller than 8.0×10^-7 M and the potential at maxmium height was shifted slightly with the concentration. The radiopolarographic behavior of curium was found to be similar to that of americium. The main waves of americium and curium were diffusion-controlled, but the pre-waves were not. It was found that the pre-waves occured independently of the main waves, and that the main waves were due to the reduction to the metallic state. The transfer coefficients ol and the cathodic rate constants K ⁰_c at E=0 V were obtained as α=0.41 and K ⁰_c = 8.8×10^-40 cm/s for Am(III)/Hg(Am); α=0.50 and K ⁰_c =9.1×10^-48 cm/s for Cm(III)/Hg(Cm), respectively.