Electrochemical behavior of zinc in aqueous Cr(VI) solution with pH 1.8

The electrochemical behavior of zinc in aqueous Cr(VI) at pH 1.8 was studied using cyclic voltammetry and chronoamperometry. The typical potentiodynamic profile shows an anodic current peak, which was associated with the formation of a thin film of, possibly, ZnO. The formation of the film follows the model for irreversible adsorption of a monolayer controlled by the charge transfer reaction. Reduction of the film occurs through a nucleation and growth model. Analysis of the current transients of the potentiostatic reduction of the film confirms the model. During the cathodic scan appears a limiting current which is attributed to the reduction of Cr(VI) to Cr(III) species.