Exploring the resistance of C38 steel by a new bisimidazole derivative as corrosion inhibitor: Experimental and theoretical studies

• N. Lahrache¹, S. Jebbari², A. Barhoumi³, M. Omari⁴, N. Labjar¹, H. Nasrellah⁵, A. Dahrouch², B. Hammouti⁶ and S. El Hajjaji²

¹ Laboratory of Molecular Spectroscopy Modelling, Materials, Nanomaterials, Water and Environment, CERNE2D, ENSAM, Mohammed V University in Rabat, Morocco
² Laboratory of Molecular Spectroscopy Modelling, Materials, Nanomaterials, Water and Environment, CERNE2D, Faculty of Science, Mohammed V University in Rabat, Morocco
³ Laboratory of Organic Bioorganic Chemistry and Environment, Faculty of Sciences, El Jadida, Morocco
⁴ Agro-industrial, Environmental and Ecological Processes Team, Faculty of Science and Techniques of Beni Mellal, Morocco
⁵ Higher School of Education and Training, Chouaib Doukkali University, El Jadida, Morocco
⁶ EPS, Euromed University of Fes, UEMF, 30000 Fes, Morocco

Abstract: The protective efficiency of a new bisimidazole compound, namely 1,2-bis(2-(1H-benzo(bisimidazol-2-yl)thio)ethoxy)ethane (BBT2E), was studied for C38 steel submerged in 1 M hydrochloric acid. The synthesized molecule was characterized using proton nuclear magnetic resonance (¹H NMR), carbon-13 nuclear magnetic resonance (¹³C NMR) and infrared spectroscopy (IR). The corrosion resistance was evaluated by two electrochemical methods: potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). The results reveal that the studied molecule provided 97.8% protection efficiency at 10^–4 M. Scanning electron microscopy coupled with energy-dispersive X-ray analysis reveals the presence of the inhibitor on the metal surface. Moreover, an isothermal study shows that the Langmuir model is the most suitable for this molecule. The studied molecule creates a protective layer that forms an obstacle and prevents aggressive agents from penetrating to the substrate surface. A theoretical study by DFT quantum physical chemistry calculations and molecular dynamics simulations was utilised to confirm the experimental results.

Keywords: 1,2-bis(2-(1H-benzo(bisimidazol-2-yl)thio)ethoxy)ethane, C38 steel, EIS, PDP, DFT, ¹H NMR, ¹³C NMR, IR, MD and SEM-EDX simulations

Int. J. Corros. Scale Inhib., 2025, 14, no. 3, 1391-1421
doi: 10.17675/2305-6894-2025-14-3-19

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