New N‑Heterocyclic Compounds Based on 8‑Hydroxyquinoline as Efficient Corrosion Inhibition for Mild Steel in HCl Solution: Experimental and Theoretical Assessments

摘要

Both new benzimidazole derivatives based on 8-hydroxyquinoline, namely 4-(1-((4-hydroxynaphthalen-1-yl)methyl)-5-methyl-1H-benzo[d]imidazol-2-yl)benzoic acid (QN1) and 4-(1-((4-hydroxynaphthalen-1-yl)methyl)-1H-benzo[d]imidazol-2-yl)benzoic acid (QN2), were synthesized and characterized, and their corrosion inhibition behavior as well as the mechanism ofinhibition was investigated by different techniques. Structural characterization includes NMR, IR and elemental analysis. Theanticorrosive activity of these compounds was evaluated by the potentiodynamic polarization and impedance spectroscopy.Experimental data show that the QN1 and QN2 are effective against corrosion of steel in 1.0 M HCl and that the inhibitoryefficiency reached at an optimum value of 97.7% for the QN1 compound at 1 mm. Polarization Tafel curves show that QN11and QN2 act as a mixed type of inhibitors. After evaluating the anticorrosive activity of these two compounds, we used thesurface techniques, namely SEM coupled with EDS and the gravimetric solutions were analyzed by UV–visible spectrometry.Quantum mechanical investigations density functional theory calculations and the Monte Carlo simulation on corrosionbehavior of QN1 and QN2 compounds were also conducted, and satisfying correlation was noticed between the results ofcorrosion measurement methods and quantum mechanical evaluations.