engleski

Copper Corrosion Inhibition in Sulphate Media

The aim of this work was to investigate the mechanism of inhibiting action of two imidazole compounds, 1-(p-tolyl)-4-methylimidazole and 1-phenyl-4-methylimidazole on copper corrosion in sulphate media. Our previous investigations have shown that these compounds efficiently inhibit copper corrosion in different aggressive media. The studies in this work were performed in sulphate solutions of different pH value, ranging from acid to neutral. Influence of the pH of the solution is interesting not only because of change in the agressivity of the solution but also because of the change of the inhibitor molecule due to the acid-base equlibrium. Investigations have been performed by electrochemical methods: Tafel extrapolation, polarization resistance determination and electrochemical impedance spectroscopy. Inhibiting effect observed was almost the same for all pH values examined but the amount of inhibitor necessary to obtain this protection level significantly differs. In acid solutions much higher inhibitor concentrations are needed than in neutral solutions. Polarization measurements have shown that investigated imidazole compounds inhibit both anodic and cathodic corrosion process. Addition of studied imidazole derivatives increases the anodic Tafel slope while the corrosion potential is shifted towards cathodic direction. This effect is especially pronounced in neutral solutions. EIS measurements have shown that the main contribution of studied inhibitors to corrosion rate reduction is by hindering corrosion kinetics.

copper; corrosion inhibitor; electrochemical methods; sulphate

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