The study on corrosion inhibition effect of 2-Phenylbenzimidazole for X70 steel in HCl solution at 308 K

The inhibition behavior of X70 steel with different concentrations of 2-Phenylbenzimidazole in 1 M HCl solution at 308 K was evaluated through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) curves and scanning electron microscopy (SEM). It was found that the inhibition efficiency increased with increasing of 2-Phenylbenzimidazole concentration, and the best inhibition efficiency was achieved at 5 mM. Analysis of the polarization curves showed that 2-Phenylbenzimidazole belonged to mixed type inhibitor, inhibiting concurrently cathode and anode, and the inhibition effect was more significant for cathode. Moreover, the adsorption isotherm study showed that the adsorption of 2-Phenylbenzimidazole inhibitors on the surface of X70 steel followed the Langmuir adsorption model, and the calculation of the standard free energy of adsorption (ΔG0ads) indicated the presence of both physical and chemical adsorption. Furthermore, molecular dynamics (MD) simulations were applied to display the mechanism of the strong anticorrosion effect of 2-Phenylbenzimidazole molecules.