ANODIC-STRIPPING VOLTAMMETRY AT HYDRODYNAMIC MERCURY-ELECTRODES - SQUARE-WAVE VOLTAMMETRY - NUMERICAL THEORY FOR ELECTROCHEMICALLY REVERSIBLE-SYSTEMS

Numerical simulations exploiting the time-dependent backward implicit method are used to develop the theory of square wave voltammetry as ap plied to electrochemically reversible processes undergoing anodic stri pping at planar mercury electrodes having arbitrary film and diffusion layer thicknesses. Computations made using a time scale distorted to reflect the Cottrellian character of the transient response at shea ti mes are found to be extremely efficient when applied to this problem. For the limiting case of semi-infinite diffusion in the solution phase , excellent agreement with existing analytical theory is noted (Kounav es et al. Anal. Chem. 1987, 59, 386). The effects of the pulse frequen cy are investigated and, in particular, the effect of diffusion layer thickness characterized. Deviations from semi-infinite theory are pred icted and rationalized for the case when the magnitude of the latter i s comparable to the diffusion length of the solution-phase species dur ing a single pulse width as might occur when measurements are made usi ng hydrodynamic electrodes or sonotrodes.