Abstract
The bi-heterocyclic system, namely 2-[(5-methylpyrazol-3-yl) methyl] benzimidazole (MPMB) has been synthesized and characterized by 1H and 13C 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, DFT/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.
[Display omitted]
•Synthesis and the corrosion inhibition efficiency of a bi-heterocyclic named MPMB.•MPMB efficiency increases with concentration and decreases with temperature.•The Adsorption of MPMB obeys the isothermal adsorption of Langmuir.•The corrosion mechanism is controlled by a load transfer process.•The experimental results were supported by DFT and Monte Carlo simulations.