Investigating the corrosion inhibition efficiency of 2-(5-(2-methyl-1H-benzo[d]imidazol-5-yl)-1,3,4-oxadiazol-2-yl)aniline on C38 steel in 1 M HCl solution: Electrochemical, adsorption and theoretical analysis

• L. Naciri¹, S. Jebbari², K. Bouiti¹, A. Barhoumi³, M. Omari⁴, I. Bouhouche¹, S. Lakhloufi¹, N. Labjar¹, H. Nasrellah⁵ and S. El Hajjaji⁶

¹ LS3MN2E, CERNE2D, ENSAM, Mohammed V University in Rabat, Rabat, Morocco
² Laboratory of Bio-organic Chemistry, Department of Chemistry, Faculty of Sciences, Chouaib Doukkali University, El Jadida, Morocco
³ Laboratory of Organic Bioorganic Chemistry and Environment, Faculty of Sciences, University Chouaib Doukkali, Morocco
⁴ Agro-industrial, Environmental and Ecological Processes Team, Faculty of Science and Techniques of Beni Mellal, Sultan Moulay Slimane University, Beni Mellal, Morocco
⁵ ESEF, Chouaib Doukkali University of El Jadida, Morocco
⁶ LS3MN2E, CERNE2D, Faculty of Sciences, Mohammed V University in Rabat, Rabat, Morocco

Abstract: This study evaluates the corrosion inhibition performance of 2-(5-(2-methyl-1H-benzo[d]-imidazol-5-yl)-1,3,4-oxadiazol-2-yl)aniline (ANL1) on C38 steel in a 1 M hydrochloric acid solution. Electrochemical techniques, including polarization measurements and electrochemical impedance spectroscopy (EIS), demonstrated that ANL1 significantly reduces the corrosion current density while increasing the charge transfer resistance. The inhibition efficiency improved with increasing inhibitor concentration. Surface analysis by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) confirmed the formation of a protective film on the steel surface. Adsorption experiments fit well with the Langmuir isotherm model, indicating monolayer adsorption. The adsorption mechanism likely involves both physisorption and chemisorption, supported by a negative value of the standard free energy of adsorption. The optimum inhibition efficiency of 97.81% was achieved at an ANL1 concentration of 2.5×10^–4 M, revealing its potential as an effective inhibitor in acidic media. Furthermore, density functional theory (DFT) calculations provided insights into the electronic properties of ANL1, showing high reactivity and strong interaction with the steel surface. Monte Carlo (MC) simulations corroborated these results by modelling the inhibitor-metal interface adsorption behavior.

Keywords: corrosion, inhibition, aniline derivative, DFT, MC simulation

Int. J. Corros. Scale Inhib., 2026, 15, no. 1, 117-146
doi: 10.17675/2305-6894-2026-15-1-6

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