Corrosion of copper in both aqueous ethylenediamine and its complexes with some transition metal ions

Abstract

The corrosion of copper in both 0.2 M ethylenediamine (en) /buffer and buffer containing complexes of some transition metal ions with ethylenediamine has been studied at the open-circuit potential ( E corr) using impedance spectroscopy. Impedance parameters, such as the polarization resistance R p, solution resistance R s and electrode capacitance C, were computed and compared. In all solutions investigated, the results showed that the electrode capacitance C gradually increased, whereas both R p and R s decreased as the time of immersion was increased. This behaviour has been attributed to a continuous change in the electrode surface area as a result of Cu dissolution. On the basis of the evaluated experimental results, it is established that the rates of electrode corrosion in the case of [Cd(en) 2] 2+, [Zn(en) 2] 2+and [Ni(en) 2] 2+ complexes are comparable. On the other hand, the rate of corrosion of Cu in the presence of [Cu(en) 2] 2+ complex is found to be much higher (7.0 times ). The data showed that the corrosion of Cu decreases in the following order: en > > Cu complex > > Cd complex > Zn complex > Ni complex.