Evaluation of Corrosion Inhibition of 1018 Carbon Steel using an Avocado Oil-Based Green Corrosion Inhibitor

Abstract: The present study is focused on evaluating the corrosion resistance of 1018 carbon steel and the influence of using a corrosion inhibitor in its corrosion behavior. In particular, the corrosion inhibitor prepared in the present study consists in an organic compound of hydroxyethyl-imidazoline derivate based on avocado oil. A mixture of brine-diesel saturated with CO₂ was used as a corrosive medium at 70°C. The electrochemical techniques employed to evaluate the performance of the inhibitor were polarization curves, open circuit potential, linear polarization resistance and electrochemical impedance spectroscopy. The results revealed that a high efficiency was obtained when the inhibitor was added in 25 ppm. This fact was supported by scanning electron microscopy, where a uniform corrosion process was observed with the formation of an iron carbonate film. This film was formed when the inhibitor was added in 5, 10 and 25 ppm. However, when the concentrations used were 50 and 100 ppm, a localized corrosion process was promoted. In the present study, some calculations were performed to determinate the chemical adsorption process energy (ΔG⁰_ads = –50.89 kJ/mol) through isotherm adsorption of Langmuir.