The influence of high pressure (up to 10 kbar) on the limiting currents of the Cd(II)/Cd(Hg) system

The electroreduction of cadmium(II) at a mercury electrode and the oxidation of cadmium amalgam in 4.0 M NaCl at pressures ranging from 0.001 to 10 kbar, using cyclic voltammetry and chronoamperometry, revealed a moderate decrease in the limiting currents and diffusion coefficients of CdII in solution and Cd in mercury. The partial molar volume of the diffusion activation calculated from these dependences is equal to 1.1–1.2 and 0.93 cm3 mol−1 for diffusion in 4.0 M NaCl and in mercury, respectively. The formal potentials of the CdII/Cd(Hg) system expressed versus the ferrocene-ferricinium ion electrode as a function of pressure led to a value of 10.7 cm3 mol−1 for the volume of the electroreduction reaction of CdII.