Corrosion Inhibition Potential of Mentha spicata Extract on Mild Steel in Acidic Medium

The corrosion inhibition effect of Mentha spicata extract has been investigated for mild steel in an acidic medium by using weight loss and thermometric methods. Qualitative and Quantitative analysis of the extract was carried out using GC/MS analysis. Two major phytochemical components were identified by their mass spectra and retention indices. The inhibition capacity of Mentha spicata extract observed was carried at different temperatures (303 K, 313 K, 323K, and 333 K) which were found to increase with increasing concentration but decrease with increasing temperature. As the extract components got adsorbed on the metal surface, inhibition efficiency also increased and finally reached 86.01% at 303 K. The adsorption isotherm and free energy values were also calculated. Results have demonstrated that Mentha spicata is a mixed-type of corrosion inhibitor. Surface analysis by SEM documented the formation of a protective layer on the mild steel surface. Quantum chemical parameters such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), energy gap (ΔE), dipole moment (µ), and Total Energy (TE) were calculated. Quantum chemical calculations were also discussed to support the experimental data and the adsorption of inhibitor molecules onto the metal surface. It has been found that the extract acts as an effective corrosion inhibitor for mild steel in a hydrochloric acid medium. The results obtained show that Mentha spicata extract could serve as an excellent eco-friendly green corrosion inhibitor.