DISSOLUTION BEHAVIORS OF COPPER METAL IN ALKALINE H2O2-EDTA SOLUTIONS

Abstract

The dissolution behavior of Cu metal in hydrogen peroxide (H2O2)-ethylenediaminetetraacetic acid (EDTA) solution was studied through both electrochemical and chemical tests. In the electrochemical experiments, the open circuit potential (OCP) of Cu electrode at low H2O2 concentration below 0.5 wt% was determined by Cu anodic reaction and H2O2 cathodic reaction. On the other hand, the OCP in higher concentration above 2 wt% of H2O2 approached to 70 mV vs. SCE, since the redox reaction of H2O2 was so dominant reaction that the Cu anodic reaction was masked. The anodic polarization curve of Cu around the OCP of 70 mV in the range between -200 and 200 mV in the solution without H2O2 showed the maximum Cu dissolution reaction front, while those of both carbon steel and Inconel 600 in the same potential range were situated in the passivation region. The anodic polarization behaviors of Cu in the H2O2 concentrations above 1 wt% were examined by a potentiostatic method along with a weight loss measurement. The anodic Cu dissolution current estimated from the weight loss measurement in the solution containing more than 1 wt% of H2O2 was higher than that predicted by the polarization curve of Cu in the H2O2-free solution. The dissolution reaction rate of Cu in the H2O2 solution linearly increased with H2O2 concentration. This result indicated that the dissolution reaction rate of Cu in the presence of H2O2 was enhanced by a reaction between Cu and H2O2, resulting in the shift of the polarization curves depending on H2O2 concentration. The experimental correlation equation based on the above results described well the overall dissolution reaction rate of Cu in H2O2 concentration ranges below 1 wt% and above 2 wt% in the EDTA solution.