The effect of functional groups on the inhibitory efficacy of newly synthesized Imidazopyridines compounds against the corrosion of mild steel in acidic environments: Electrochemical, thermodynamic, surface and computational investigations (Part B)

The primary objective of this research paper was to investigate the inhibitory effects of two new derivatives of Imidazopyridines, namely: (E)-N-(7-methyl-2-phenylimidazo[1,2-a]pyridin-3-yl)-1-(3-nitrophenyl)methanimine (N-Imid) and (E)-2-methoxy-4-(((7-methyl-2 phenylimidazo[1,2-a]pyridin-3-yl)imino)methyl)phenol (MHImid), on mild steel (MS) in 1 M hydrochloric acid at 308 K. The study also aimed to compare the protection capacities of these compounds. Additionally, the impact of (-OH & OCH3-) and (-NO2) groups on the inhibition efficiency was analyzed. The inhibition performance was measured using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and weight loss (WL) methods at 308 K, and confirmed by Scanning Electron Microscopy (SEM),UV-visible, and computational modeling, The study results showed that the both inhibitors displayed potent inhibition capacities, and their effectiveness grew notably with rising concentration and diminishing temperatures. Among the two compounds investigated, MH-Imid is the best with an inhibition efficiency over 96%. The substitution of functional groups was found to influence the inhibition efficiency. The electrochemical tests findings were consistent. The outcomes indicated that both inhibitors exhibited cathodic/anodic behavior (mixed type). SEM analysis was used to assess the surface morphology and showed the presence of a protective layer on the MS surface, The two studied inhibitors were adsorbed on the MS surface by the Langmuir adsorption model. Analysis of the inhibited and uninhibited solution using UV-visible spectroscopy showed evidence of a complex between Fe and two imidazopyridine molecules forming in 1 M HCl. The computational modeling matches experimental data well and demonstrates that the inhibition efficiency ranking (MH-Imid > N-Imid) holds consistently.