Effect of aromatic rings on mild steel corrosion inhibition ability of nitrogen heteroatom-containing compounds: Experimental and theoretical investigation

Abstract

Effect of aromatic rings on mild steel corrosion inhibition ability of Pyridine, Quinoline, and 1,10-Phenanthroline was investigated by utilizing methods including potentiodynamic polarization measurement (PPM), electrochemical impedance spectroscopy (EIS), scanning electrochemical microscopy (SEM), quantum calculation and molecular dynamics (MD) simulation. The results reveal that 1,10-Phenanthroline can inhibit mild steel corrosion best with the highest efficiency of 80.40% at the concentration of 10−2 M according to PPM. Corrosion inhibition efficiencies of Pyridine and Quinoline are 46.00% and 64.00%, respectively in the same condition. EIS and PPM methods give similar results. The appearance of aromatic rings and nitrogen heteroatoms in the molecules improves significantly the mild steel inhibition ability of inhibitors. The study of adsorption isotherm models exhibits that the adsorption of Pyridine, Quinoline, and 1,10-Phenanthroline on the steel surface follows the modified Langmuir isotherm. Besides, the theoretical assessment indicates that 1,10-Phenanthroline is the best inhibitor through the molecular parameters. Molecular dynamics simulation not only provides top and side views of protonated inhibitors on Fe(110) surface but also calculates their binding energies in a simulated environment. Generally, the theoretical calculation results are very consistent with the experimental studies.