Abstract
O wing to the relatively high redox potential of Pu(III)_??_Pu(IV) system (Eo=+0.97 volt vs. THE) and PU(IV)_??_Pu(VI) system (Eo=+1.04 volt vs. NHE), 1) polarographic study of plutonium with the dropping mercury electrode (D.M.E.) is fairly limited to the plutonium complex ions formed in strongly complexing agents. Therefore, most of studies have been made with the solid electrodes; Harvey and others'examined the electrolytic reduction of plutonium in 1 N sulfuric acid and 1 N hydrochloric acid at the platinum electrode, but they could not obtain good reporducible results and hence the reliable half-wave potentials. The reason was attributed to the easiness of the disproportionation and the hydrolysis of Pu(IV) to form polymers which would deposit on the surface of the platinum electrode. Similarly, Cook and others3) have investigated the polarographic oxidation of Pu(III) in 1 N hydrochloric acid and determined the half-wave potential as +0.66 volt vs. SCE. Koyama4) also examined Pu(III) in 2 N nitric acid and 1 N hydrochloric acid using square wave polarograph. D.C. polarographic studies with the D. M. E . were made by Nebel and Schwabe5) and Cook and others3) in acetate, citrate and oxalate solutions, and A. C, polarographic studies in citrate solution by Milner and Wood.6) The results are summarized in the Table 1. In the present study, the authors have investigated the polarographic behaviors of Pu(III) and Pu(IV) in mineral acid media at the rotating platinum electrode (R.-P.E.). Special attention was paid to the control of the oxidation state of plutonium throughout the experiments.
