The inhibition effect of a palm-oil modified hydroxyethyl imidazoline on the corrosion of copper in 1.0 M sulphuric acid (H2SO4) has been studied by using potentiodynamic polarization curves, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) measurements. Modified imidazoline resulted a good corrosion inhibitor for Cu in acid environment, with its inhibition efficiency increasing with its concentration, reaching its highest value when 10 ppm are added, but it decreased with a further increase in its concentration. Additionally, inhibitor efficiency increased with an increase in the immersion time. Polarization curves showed that modified imidazoline suppresses in a greater extent the cathodic oxygen reduction reaction than the anodic dissolution, acting, therefore, as a mixed type of inhibitor. EIS data indicated the decrease in the double layer capacitance and an increase in the charge transfer resistance due to the adsorption of the modified imidazoline on to the copper surface, with the formation of protective corrosion products.
Keywords: Copper; Acid Corrosion; Imidazoline; Electrochemical Impedance;