Effect of pH on the Mediated Oxidation of [Fe(CN)6]4- at Polyaniline Film Electrodes. An Impedance Study

The [Fe(CN)6] 4- oxidation at polyaniline (PANI) modified electrodes was studied by electrohydrodynamical (EHD) and a.c. impedances at moderate acid concentrations (pH range 2-3). Experimental diagrams were obtained for different values of pH, potential, [Fe(CN)6] 4- concentration, electrode rotation rate and film thickness and compared with a kinetic model developed by taking into account PANI acid-base equilibria. This model accounts for low frequency relaxation observed by both impedance techniques and explains in a semiquantitative way the influence of the experimental parameter