Inhibition Effect of Cysteine and Glycine towards the Corrosion of Cu10Ni Alloy in Sulfide Polluted Saltwater: Electrochemical and Impedance Study

Inhibition effect of cysteine (Cys) and glycine (Gly) towards the corrosion of Cu10Ni alloy in sulfide polluted NaCl solution was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results drawn from the two techniques are comparable. Addition of sulfide ions to NaCl solutions was found to accelerate the corrosion of the alloy. It was found that these investigated compounds act as good inhibitors for the corrosion of Cu10Ni alloy in polluted NaCl solutions. Potentiodynamic polarization curves revealed that both cysteine and glycine acted as mixed-type inhibitors. It was found that the adsorption of these compounds on Cu10Ni alloy surface follows Langmuir isotherm. EIS was used to investigate the mechanism of corrosion inhibition. The addition of KI was found to have a synergistic effect which enhanced the inhibition efficiency. The SEM results showed the formation of a protective film on the alloy surface in the presence of these additives.