Inhibition of copper corrosion in acidic chloride solution by methionine combined with cetrimonium bromide/cetylpyridinium bromide

Methionine (MET) is non-toxic and easily biodegradable so that it is an alternative corrosion inhibitor in the water treatment and industrial pickling process. In this article, the inhibition behavior of MET combined with cetrimonium bromide (CTAB) and cetylpyridinium bromide (CPB) for copper corrosion in 0.5 M HCl solution has been investigated by using the electrochemical impedance spectroscopy (EIS), cyclic voltammetry, and polarization curve methods. It shows that combination of MET with CTAB or CPB improves the inhibition performance effectively, and produces strong synergistic inhibition effect. The combined inhibitors suppress cathodic reaction and shift the corrosion potential toward more negative values. The mixed CTAB/MET has a better synergistic effect compared with the mixed CPB/MET. The quantum chemical parameters were calculated by PM3 semi-empirical quantum method. The better synergistic inhibition between MET and CTAB is attributed to their stronger electrostatic interaction.