Synthesis, electrochemical evaluation, and theoretical analysis of novel benzimidazole derivatives as efficient corrosion inhibitors for mild steel in acidic media

• H. Elmrayej¹, W. Ettahiri^1,2, J. Lazrak¹, M. Adardour², S. El-houssaine¹, A. Baouid², B. Hammouti³ and M. Taleb¹

¹ Laboratory of Engineering, Electrochemistry, Modeling and Environment, Faculty of Sciences, Sidi Mohamed Ben Abdellah University, Fez, Morocco
² Laboratory of Molecular Chemistry, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech, Morocco
³ Engineering Polytechnic School, Euromed University of Fes, UEMF, 30000 Fes, Morocco

Abstract: This study includes the development and examination of two compounds derived from benzimidazole: 1-(cyclopent-1-en-1-yl)-3-methyl-1H-benzimidazol-2(3H)-one (known as P1) and 1-(cyclohex-1-en-1-y)-3-methyl-1H-benzimidazol-2(3H)-one, also known as P2. These molecules were used to test their effectiveness in defending mild steel against a 1 M hydrochloric acid solution. Electrochemical studies, particularly EIS and PDP, revealed significant inhibitory efficiencies, reaching 99.1% for P1 and 98.9% for P2 at 298 K and a concentration of 10^–4 M. The effect of temperature on inhibition efficiency showed a slight decrease with increasing temperature, suggesting a combination of adsorption processes. Analysis of adsorption phenomena indicated that the inhibitors primarily adsorb via chemical adsorption (chemisorption) and follow the Langmuir isotherm model. Additionally, the thermodynamic parameters confirmed that the adsorption process is spontaneous and energetically favorable. Theoretical investigations based on DFT, Monte Carlo and molecular dynamics simulations, accompanied by scanning electron microscopy observations, led to the identification of the fundamental electronic properties and predominant interaction regions on the metal. Observations at the surface attested to the formation of a protective coating on the steel, with a superior efficiency noted for P1. This combined method, combining numerical modeling and experimental validation, highlights the potential of these compounds as effective and durable corrosion inhibitors in acidic environments.

Int. J. Corros. Scale Inhib., 2025, 14, no. 3, 1555-1588
doi: 10.17675/2305-6894-2025-14-3-27

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