Corrosion inhibition and adsorption behavior of methionine on copper in HCl and synergistic effect of zinc ions

The efficiency of methionine (MTI) as a non-toxic corrosion inhibitor for copper in 0.5 M HCl has been studied by using cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Methionine has shown limited inhibiting properties for copper corrosion in 0.5 M HCl. The presence of Zn2+ ions increases the inhibition efficiency to 92%. Results obtained from potentiodynamic polarization and impedance measurements are in good agreement. The adsorption of methionine on copper surface follows Langmuir isotherm. The adsorption free energy of methionine on copper (∼−26 kJ mol−1) reveals a strong physical adsorption of the inhibition on the copper surface.