Essential Oil of Origanum vulgare as a Green Corrosion Inhibitor for Carbon Steel in Acidic Medium

In this study, Oregano (Origanum vulgare) leaf essential oil was studied as an environmental-friendly anticorrosion agent for carbon steel in aggressive hydrochloric acid. The corrosion inhibition of O. vulgare was characterized by surface morphology, electrochemical, weight loss, theoretical and computational methods. It was found that the highest inhibition performance of O. vulgare was 85.64% at 2 g/l in 1 M HCl. The results of Langmuir isotherm and adsorption thermodynamics investigation demonstrated that the O. vulgare inhibitor adsorbed on the metal surface by the formation of rigid covalent bonds. The adsorption and inhibition centers of the selected inhibitor were studied by the computational methods, resulting in that the hydroxyl functional groups and benzoyl rings are mainly responsible for the high inhibition efficiency.

Automated summary

In this study, Oregano (Origanum vulgare) leaf essential oil was investigated as an environmentally friendly corrosion inhibitor for carbon steel in hydrochloric acid. The corrosion inhibition mechanism was studied through surface morphology analysis, electrochemical tests, weight loss measurements, theoretical calculations, and computational methods. The results showed that O. vulgare had the highest inhibition performance of 85.64% at a concentration of 2 g/l in 1 M HCl. The adsorption of the O. vulgare inhibitor on the metal surface was attributed to the formation of rigid covalent bonds, and the hydroxyl functional groups and benzoyl rings were found to be the main contributors to the high inhibition efficiency.