Combined experimental and computational evaluation of Mentha pulegium L., for sustainable corrosion protection

Abstract

Developing eco-friendly alternatives to toxic synthetic corrosion inhibitors is crucial for advancing sustainable industrial practices. In this study, the crude hydromethanolic extract of Mentha pulegium L ., (EMMP) was evaluated as a green inhibitor for copper corrosion in 0.5 M H 2 SO 4 . GC-MS analysis revealed 29 compounds with glucose (33.74 %), mannose (16.40 %), and d -galactofuranose (15.91 %) as the predominant constituents, representing 66.05 % of the extract's composition. Electrochemical measurements demonstrated that EMMP achieved a maximum inhibition efficiency of 96.5 % at 2.0 g/L, lowering the corrosion current density from 29.0μA/cm 2 to 1.0 μA/cm 2 . EIS analysis confirmed the formation of a compact protective film, consistent with the adsorption study, while thermodynamic parameters (ΔG ads ) indicated that the adsorption process mainly physical. Temperature studies (298–328 K) further showed that the inhibitor maintained high efficiency (>92 %), in agreement with adsorption isotherm analysis. In addition, SEM/EDX analysis provided direct morphological and elemental evidence of the protective layer formed on the copper surface. Complementary Density Functional Theory (DFT) calculations of glucose, mannose, and d -galactofuranose supported the experimental findings by confirming their strong interfacial reactivity. This integrated experimental computational evaluation establishes EMMP as a highly effective, eco-friendly, and locally available copper corrosion inhibitor.