Inhibitory effect of novel synthesized imidazolone-derived heterocyclic compounds on mild steel corrosion in hydrochloric acid: Electrochemical, surface analysis, and theoretical studies

Abstract

This study focuses on the inhibitory effect of novel synthetized imidazolone-derived heterocyclic compounds, namely 5,5-diphenyl-2-(2-(pyridin-2-ylmethylene)hydrazineyl)-3,5-dihydro-4H-imidazol-4-one (IMID2) and (E)-5,5-diphenyl-2-(2-(pyridin-3-ylmethylene)hydrazineyl)-3,5-dihydro-4H-imidazol-4-one (IMID3) on mild steel (MS) corrosion in 1.0 M HCl solution using electrochemical studies, surface and elementary composition analyses with scanning electronic microscopy (SEM) coupled with energy dispersive X-ray (EDX) and theoretical studies based on Density Functional Theory (DFT) calculation and Molecular Dynamic (MD) simulations. Firstly, these products were prepared and identified using FT-IR, ¹H NMR and ¹³C NMR. Electrochemical impedance spectroscopy (EIS) results indicated that the inhibition efficiency of IMID2 and IMID3 depends on their concentrations and the –N positions in their structures. So, this inhibition efficiency reaches up to 94.85 % and 92.02 % at 10⁻³ M IMID2 and IMID3, respectively. In addition, the potentiodynamic polarization (PDP) results indicated that these compounds react as cathodic mixed-type inhibitors. Moreover, it is found that the IMID2 and IMID3 inhibitors react via Langmuir isotherm adsorption, which is a confirmed SEM/EDX examination by the establishment of a defensive layer on the MS area. The effect of the temperature solution indicated that the IMID3 and IMID2 take their performance at high temperature. The DFT calculation showed that IMID3 and IMID2 interact with MS area via their heteroatoms and aromatic rings, where IMID2 exhibits superior inhibition properties. Finally, MD simulation indicated that these molecules adopt a horizontal orientation upon adsorption, promoting optimal contact with the MS surface and confirm the performance inhibition of IMID2 than IMID3.