Experimental and Theoretical Studies on Cinnamomum verum Leaf Extract and One of Its Major Components, Eugenol as Environmentally Benign Corrosion Inhibitors for Mild Steel in Acid Media

Abstract

The corrosion inhibition property of Cinnamomum verum leaf extract (CVE) for mild steel in hydrochloric and sulphuric acid media has been studied using weight loss technique, polarization method and impedance spectroscopy. The inhibition efficiency exhibited a linear relationship with inhibitor concentration up to an optimum concentration. While the temperature increase caused inhibition efficiency to drop down into lower values. Monitoring the inhibitive action of the major component eugenol, has also been a part of the study. The assumptions made on the basis of theoretical calculations for eugenol supported the experimental observations. The ΔE, EHOMO, ELUMO, and dipole moment values for eugenol and the protonated form of eugenol clearly suggests the electron-donating ability of the component which in turn stands for the inhibition potential of CVE. The adsorption of eugenol on Fe (1 1 0) surface has been simulated using Monte Carlo simulation studies. Adsorption studies revealed that the mode of adsorption obeys Langmuir isotherm. CVE exhibited better inhibition efficiency in hydrochloric acid compared to sulphuric acid medium.