USE OF ISOPOTENTIAL POINTS TO ELUCIDATE ION-EXCHANGE REACTION-MECHANISMS - CR(BPY)3(3)+ AT MONTMORILLONITE CLAY-MODIFIED ELECTRODES

A model for the occurrence of isopotential points in ion exchange voltammetry is developed. The model is applied to the reaction of Cr(bpy)3(3+) at clay-modified electrodes and is tested via variations in the solution concentration of Cr(bpy)3(3+), the charge of the clay, and the electrolyte concentration. The experimental observation of isopotential points is well described by the simulated multisweep cyclic voltammograms for the suggested reaction mechanism. The results indicate that the mode of the reaction of Cr(bpy)3(3+) is easily controlled via the predominating pore size within the film and by the presence of the competing ion-exchange cation.