| Abstract: | Abstract The U(VI) reduction at mercury electrode in sulfuric acid solutions was examined by cyclic voltammetry (C. V.). A diffusion coefficient, D, was (5.30 ± 0.08) × 10?6 cm2/sec was obtained for the depolarizer at 25.0±0.2°C in 1 N K2SO4 (pH = 2). In 1 N K2SO4/1 N H2,SO4 systems the disproportionation of U(V) was found to occur with the constant rate of Kd/H+] = 6.500 ± 1.000 M?2 sec?1. In 1 M H2SO4 supporting electrolyte pure kinetic control was achieved over the range of scan rates and uranyl concentration (C) investigated, hence linear correlation between cathodic peak current and C (above 5x10?6 M) was obtained. Strong complexing oxyanions, such as phosphate and pyrosulphate, do not interfere with the cathodic peak current. Rapid determination of O/U ratios in uranium oxides and of U in mixed U-Th materials were performed respectively in 1 M H2SO4/1.5 M H3PO4 and 1 M H2SO4/0.2 M K2S204 supporting media, with a reproducibility of ± 1.3% standard deviation. |
