Anodic dissolution of iron microparticles in chloride-containing acetate buffer electrolytes studied by elimination voltammetry

Elimination voltammetry with linear scan (EVLS) was used for the study of the anodic dissolution process of iron microparticles immobilized on paraffin-impregnated graphite electrode. This process was investigated in acetate buffer solutions in the range of pH 4 to 6 and the effect of chloride ions was evaluated. It was found that the anodic dissolution process of iron powder proceeded in two peaks with different pH and KCl-dependent characterizations. Both the more negative process at about −300 mV and the positive process at about 1,200 mV are influenced by chloride and hydroxyl ions. Chloride ions incorporate into the intermediate species and form more soluble species in the passivation layer, leading to its degradation. Detailed information about the processes was provided by the EVLS functions conserving diffusion current components. The mechanism of anodic dissolution of iron powder in acetate solutions representing passive ions and chloride ions appearing in the role of corrosion activators was discussed.