Electrochemical Behavior of Copper in 0.5 M H2SO4 Solutions in the Absence and Presence of Fe(III) and Benzotriazole

The electrochemical behavior of copper in 0.5 M deaerated sulfuric acid in the absence and presence of benzotriazole (BTAH) and ferric ions has been investigated with rotating disk electrodes. The BTAH inhibitive effect initiates at concentrations as low as 10−7 M. The mechanism of Cu/Cu(II) reaction is the same in the absence and presence of low BTAH concentrations (<10−5 M). For higher inhibitor concentrations, different processes must be considered to understand the interface metal-solution behavior: the formation of a Cu(I)BTA film, the presence of disproportionation reaction Cu + Cu(II) → 2Cu(I) and the complexation of Cu(II) ions by BTAH. The presence of Fe(III) ions in 0.5 M H2SO4 does not affect the anodic dissolution of copper. However, in the presence of BTAH, the addition of Fe(III) makes the inhibitor less effective. From anodic polarization measurements at constant potential the film adsorption has been evaluated by using the Langmuir adsorption isotherm.