Mechanistic insight into the corrosion inhibition behavior of a benzimidazolic derivative on C38 steel in hydrochloric acid

Purpose This study aims to investigate the corrosion inhibition performance of the benzimidazolic derivative OSMBZ for C38 steel in 1 M HCl and to clarify its inhibition mechanism through combined experimental and theoretical approaches. Design/methodology/approach OSMBZ was synthesized and characterized by proton and carbon nuclear magnetic resonance spectroscopy. Its inhibition performance was evaluated using weight-loss measurements, potentiodynamic polarization, electrochemical impedance spectroscopy, SEM/EDX surface analysis, adsorption isotherm analysis, temperature-dependent measurements, density functional theory calculations and molecular dynamics adsorption simulations on the Fe(110) surface. Findings The inhibition efficiency increased with OSMBZ concentration, reaching 95.22% at 3 × 10–4 M and 298 K. Electrochemical results showed that OSMBZ acts as a mixed-type inhibitor with predominant cathodic influence. The adsorption process followed the Langmuir isotherm and involved both physical and chemical contributions. SEM/EDX observations confirmed the formation of a protective adsorbed layer, while theoretical calculations supported the role of molecular planarity, heteroatom-rich adsorption centers, p-conjugation and favorable interaction with the Fe(110) surface. Originality/value This work provides an integrated mechanistic assessment of a benzimidazolic derivative as an efficient corrosion inhibitor by correlating gravimetric, electrochemical, surface, thermodynamic, DFT and molecular dynamics results.