Experimental and theoretical investigation of corrosion inhibition in carbon steel using a benzimidazole derivative

To assess the corrosive inhibitive property of 2-[(dodecylthio)methyl]-1H-benzo[d]imidazole (LF3) for carbon steel (C.stl) in 1 M hydrochloric acid, electrochemical studies were used, including potentiodynamic-polarization, and electrochemical impedance spectroscopy (EIS), scanning-electron-microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) atomic force microscope (AFM) analysis, contact-angle, and UV-visible were employed as experiment techniques, quantum chemical computation (QC) & molecular dynamics simulation as theoretical approaches. The protection rate of material increased with increasing concentration in the range 1 × 10−6 M to 1 × 10−3 M LF3 at 303 K. The Nyquist-impedance curve for C.stl in 1 M hydrochloric typically shows a depressed capacitive behavior, suggesting that the inhibitor’s adsorption follows the Langmuir-isotherm and involves chemisorption/metal-surface with a ΔGads value of −45 kJ mol−1, indicating strong adsorption onto the metal surface. The results revealed excellent anticorrosion properties, with maximum inhibition efficiency (ηEIS%) reaching 95.3% at 10−3 M concentrations. The polarization graphs for LF3 exhibits mixed behavior. Evidence from surface morphology analysis, such as scanning electron microscopy with energy-dispersive X-ray analysis (SEM/EDS), atomic force microscope (AFM), contact angle and UV-Visible, confirms this observation. The corrosion inhibition mechanisms are supported by various theoretical analyses, including global quantum chemical descriptors (GQCDs), Fukui/functions, dual local/descriptors, and molecular dynamics (MD) simulations. These theoretical methods back up the experimental results, validating LF3 as an effective-inhibitor for C.stl corrosion acidic-environment.