Synthesis, Characterization and Evaluation of Anticorrosion Properties of a New Benzimidazole Derived: 5-Bromo-1,3-dihydro-4,6,7-trinitrobenzimidazol-2-one

In this work, the new benzimidazole derivative, 5-Bromo-1,3-dihydro-4,6,7-trinitrobenzimidazol-2-one (BTB), was synthesized, characterized, and evaluated as a corrosion inhibitor for N80 carbon steel in a 1 M HCl medium. The comprehensive study of BTB’s inhibitory action was conducted through mass loss measurements and electrochemical analyses, including potentiodynamic polarization curves and electrochemical impedance spectroscopy. The results of electrochemical studies revealed a remarkable corrosion inhibition efficiency, exceeding 95% at 298 K in presence of 10⁻³M of BTB in solution. This efficiency showed a proportional increase with concentration, though slightly attenuated with rising temperature. Electrochemical impedance spectroscopy characterized the corrosion inhibition process, revealing a charge transfer mechanism. Polarization curves suggested that BTB acted as a mixed-type inhibitor. While the adsorption mode followed the Langmuir adsorption isotherm. The free energy of adsorption, evaluated at − 41.19 KJ.mol⁻¹, supported a chemisorption process. Scanning electron microscopy (SEM) observations complemented this study by revealing the formation of a protective layer on the metal surface in the presence of the inhibitor. Additionally, density functional theory (DFT) calculations were integrated for a theoretical investigation of the inhibitor’s reactivity and its interaction with the iron surface. The combined analysis of experimental and theoretical results highlighted that the inhibition potential of the tested inhibitor depends on its electron donation/acceptance capacity. The findings indicate that BTB has the potential to serve as a good corrosion inhibitor for N80 steel in a 1 M HCl medium.