Corrosion inhibition potential of 2-[(5-methylpyrazol-3-yl)methyl] benzimidazole against carbon steel corrosion in 1 M HCl solution: Combining experimental and theoretical studies

The bi-heterocyclic system, namely 2-[(5-methylpyrazol-3-yl) methyl] benzimidazole (MPMB) has been synthesized and characterized by H-1 and C-13 NMR methods. Its inhibitory property for carbon steel (C38) in 1 M HCl solution has been investigated using electrochemical impedance spectroscopy, potentiodynamic polarization, and weight loss measurements at 293 K. Besides, DET/B3LYP-based calculations and Monte Carlo simulations are used under the solvation condition. The inhibition efficiency increases with the inhibitor concentration and attains a maximum value of 97.0% at 5 mM. The polarization curves show that the examined compound act as a mixed type inhibitor. The increase of temperature induces a decrease in the inhibition efficiency of the studied compound. Also, the adsorption of this compound obeyed the Langmuir adsorption isotherm. The carbon steel surface examination confirmed the presence of a protective adsorbed film of MPMB on the surface. According to the computational results. MPMB in its neutral and protonated forms exhibited an accurate affinity to adsorb onto the metal surface, which leads to the formation of a protective film. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The bi-heterocyclic system MPMB exhibits good inhibition performance for carbon steel in 1 M HCl solution, with its efficiency increasing with concentration. The compound acts as a mixed type inhibitor, and higher temperatures result in decreased inhibition efficiency.