Importance of surface preparation in electrochemical investigations of the copper system in dilute copper sulfate solutions

The electrochemistry of the copper-copper sulfate system has been investigated with the purpose of using this system in measurements of secondary and tertiary distributions of current density in electrochemical reactors. The copper concentration was in the range 1 to 10 mol m(-3) in the presence of sulfuric acid as supporting electrolyte. Efforts were mainly concentrated on the preparation technique of the surface of a rotating disk electrode and its influence on the polarization curves. Impedance measurements and scanning electron microscopy observations of the copper surface were used to characterize the surface. Polarization of the electrode at limiting current in the investigated solution for a few minutes was shown to be the most reliable technique of preparation. Then kinetic parameters of the copper system and the diffusion coefficient were determined under controlled conditions of the electrode surface by low scan rate voltammetry. The i-E were modeled by the Butler-Volmer model proposed by Bockris et al. The obtained data are compared with published results and discussed.