Electrochemical, thermodynamic and theoretical studies of some imidazole derivatives compounds as acid corrosion inhibitors for mild steel

• Published in: Journal of molecular liquids 2020-12, Vol.319, p.114063, Article 114063
• Main Authors: Ouakki, M., Galai, M., Rbaa, M., Abousalem, Ashraf S., Lakhrissi, B., Touhami, M. Ebn, Cherkaoui, M.
• Format: Article
• Language: English
• Subjects: Corrosion; Electrochemical techniques; HCl; Imidazole; Inhibition; Theoretical results
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2020.114063

Mild steel is a common material and has found widespread use in many industries. However, its ability to corrode in aggressive environments limits its application. The present study aims to investigate the corrosion inhibition in 1.0 M HCl on mid steel using two organic compounds, based on imidazole derivatives, namely 2-(1,4,5-triphenyl-1H-imidazol-2-yl) phenol (P1) and 3-methoxy-4-(1,4,5-triphenyl-1H-imidazol-2-yl) phenol (P2) using weight loss measurements (WL) and electrochemical techniques such as polarization plots and electrochemical impedance spectroscopy (EIS). The results obtained from the electrochemical methods show that P1 and P2 imparted high resistance and behave as mixed type inhibitors with anodic predominance. Inhibition efficiency (IE %) increases with the increase of inhibitors concentration to attain 94.4% and 96.2% at 10−3 M of P1 and P2 respectively. EIS data is analyzed to model the inhibition process through appropriate equivalent circuit model. Thermodynamic and kinetic parameters controlling the adsorption process are calculated and discussed. Scanning Electron Microscopy (SEM) coupled with EDX was also used to characterize the morphology of the mild steel (MS). DFT calculations are carried out at the B3LYP levels of theory with 6-31G (d,p) basis stein gas and aqueous phase for neutral and protonated forms. Quantum chemical calculations section of the study provides enough calculation and discussion on the relationship between corrosion inhibition and global reactivity descriptors. [Display omitted] •Imidazole derivatives acted as efficient corrosion inhibitors.•The adsorption of the inhibitors obeys the Langmuir adsorption isotherm.•Surface analysis by MEB/EDX shows the existence of an insoluble adherent deposit.•Monte Carlo shows the great interaction between these compounds and the surface.