Exploring geranium essential oil as a sustainable corrosion inhibitor for XC48 carbon steel in 1 M HCl

• W. Zriouel¹, M. Oubahou² and B. Hammouti³

¹ Laboratory of Engineering and Materials (LIMAT), Faculty of Sciences Ben M’sick, Hassan II University of Casablanca, 7955, Casablanca, Morocco
² Laboratory of Physical Chemistry of Materials, Faculty of Sciences Ben M’sick, Hassan II University of Casablanca, 7955, Casablanca, Morocco
³ Euromed Research Center, Euro-Mediterranean University of Fes, BP 51, Fes 30070, Morocco

Abstract: This study explores the effectiveness of geranium essential oil (GEO) as an environmentally sustainable corrosion inhibitor for XC48 carbon steel in a 1 M HCl solution. The chemical composition of GEO, characterized by GC/FID, identified geraniol (19.53%) and β-citronellol (17.25%) as the main components. Electrochemical analyses, including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), indicated that GEO functions as a mixed-type inhibitor, achieving a maximum inhibition efficiency of 89.82% at a concentration of 2.0 g/L. Gravimetric analysis further showed a significant decrease in corrosion rate with increasing GEO concentration, though inhibition efficiency declined at elevated temperatures (298–328 K), likely due to the desorption of inhibitor molecules from the steel surface. Activation energy (E_a) values increased with GEO concentration, suggesting the formation of a physical adsorption layer that hinders corrosion. Positive activation enthalpy (ΔH*) values confirmed the endothermic nature of the steel dissolution process, while increased entropy (ΔS*) with GEO concentration pointed to enhanced system disorder due to water displacement on the surface. Computational modeling provided additional insights, with quantum chemical calculations pointing to (E)-citral and citronellyl tiglate as particularly reactive constituents based on favorable electronic properties. Monte Carlo simulations corroborated these findings by highlighting strong interactions between specific GEO molecules, such as β-citronellol and α-costol, and the steel surface. The results confirm that GEO offers a promising eco-friendly alternative to conventional corrosion inhibitors.

Keywords: carbon steel, corrosion inhibition, Monte Carlo simulation, activation energy, geranium essential oil

Int. J. Corros. Scale Inhib., 2025, 14, no. 1, 353-380
doi: 10.17675/2305-6894-2025-14-1-22

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