Kinetic parameters for the reduction of U(VI) in Carbonate solutions from measurements at thin Mercury film electrodes

The reduction of U(VI) ion in 1M of sodium carbonate solutions (pH=11.2) at deposition potentials -1000 to -1500 mV and anodic stripping voltammetry using PDV 2000 equipped with glassy carbon thin mercury film disk electrode was done. The stability of TMF electrode and reproducibility of voltammetric curves was tested with respect to different amounts of mercury deposited (100 μL - 1 ml) and rotation rates (500 to 2000 rpm). It was found that this electrode was stable at 500 - 700 μL mercury deposited and can be used for rotation rate up to 2000 rpm. The DC polarogram shown that reduction of U(Vl) to U(V) was irreversible and included one electron. Anodic stripping voltammetry in potential ranges of -1100 to 0 mV showed two peaks (at deposition pot. of -1000 to -1200 mV) and one peak (at deposition potentials of -1300 to -1500 mV). The kinetic parameters data of diffusion coefficient (D0), standard heterogeneous rate coefficient (ks) and transfer coefficient (α) for irreversible reduction were 3.06 x 10-6 cm2 sec-1, -4.56 cm sec-1 and 0.50 respectively