Imidazole/pyridine-based derivative as a novel protectivity agent for mild steel corrosion in acidic solution: Comprehensive investigations

•Inhibition efficiency of IPA increases by increasing its concentration.•Electrochemical measurements revealed mixed-type IPA inhibitor.•SEM/EDX and UV-Vis. analysis reveal the formation of a protective film on steel surface.•Computational outputs are in good agreement with experimental results. Mild steel protection activity in hydrochloric acid poses an important industrial challenge. In this study, an imidazole/pyridine derivative, i.e., 3-(imidazole [1,2-a]pyridine-2-yl)aniline (IPA), was synthesized, and its protectivity activity properties were evaluated using multifaceted comprehensive methods. Electrochemical measurements (PDP and EIS techniques) showed that IPA acted as a mixed-type protective agent with over 91 % efficiency at a 10−3 M concentration. Thermodynamic analysis via activation parameters and adsorption modelling revealed the formation of an adherent protective layer on metal surface. SEM-EDX and UV‒Vis spectroscopy validated protective film formation through adsorption and metal complexation. DFT calculations identified key functional groups actively donating electrons to steel surfaces. Monte Carlo simulations provided atomic-level insights into IPA's superior adsorption behavior. A combined approach established IPA as a promising green protective agent for acidized mild steel, with the potential applications in industrial areas utilizing hydrochloric acid, such as in acid pickling. By unveiling protection mechanisms at experimental and theoretical levels, this study facilitates protective agent design with optimized protective properties.