Exploring Basil Essential Oil as a Green Corrosion Inhibitor of Mild Steel in 1.0 M HCl: Experimental and Theoretical Investigations

This study investigated the efficacy of basil essential oil as a defensive agent for metal from the corrosion-oxidation. By using the experimental and theoretical methods, this research aimed to elucidate the mechanism and effectiveness of basil oil in mitigating corrosion. Key electrochemical studies demonstrated an important reduction in both cathodic and anodic current densities, with a remarked inhibition efficiency surpassing 83% at a concentration of 400 ppm. The stability of the E_corr across varying concentrations of basil oil suggested that it functioned as a mixed-type inhibitor. Temperature-dependent studies indicated moderate corrosion rates across a range from 298 K to 328 K, demonstrating the effectiveness of oil under varying thermal conditions. Surface analysis indicated the establishment of a uniform defensive film on the metal surface, which effectively blocked corrosion sites. Furthermore, theoretical insights provided a deeper understanding of the interactions between the active components of the oil (estragol, linalol, and methyl eugenol) and the steel surface. These components adsorb in a flat orientation, enhancing surface coverage and protection. The study also highlighted the increase in activation energy and the favourable thermodynamic changes associated with the presence of the inhibitor, reflecting an enhanced energy barrier against corrosion. The positive results from the electron back-donation (ΔE_b−d) and electron transfer (ΔN) parameters further supported the protective mechanism. This comprehensive investigation not only underscores the potential of basil essential oil as a sustainable and powerful anti-corrosion agent but also aligns with the global trend towards eco-friendly corrosion management solutions in the oil and gas industry.