Inhibition of Copper Corrosion in Aqueous Sodium Chloride Solution by Various Forms of the Piperidine Moiety

The inhibition of copper (Cu) corrosion in 1.5% sodium chloride (NaCl) solution was studied in the presence of different concentrations of piperidine, piperidine dithiocarbamate, and its Cu(II) complex at 25°C. All three additives were found to be excellent inhibitors of Cu corrosion. The difference in inhibition efficiencies (IE) of the three inhibitors was not large, but the optimum concentration for maximum efficiency was very dependent on the nature of the inhibitor. These molecules may be classified as mixed inhibitors, although this classification was less certain in the case of piperidine, which conferred a large IE without markedly influencing the anodic or cathodic polarization curves.