Isoniazid-derived ionic liquids for enhanced C-steels surface finishing via electrochemistry, supported by Monte Carlo, mechanistic study, theoretical, and docking methodology

Abstract Ecological concerns, stringent environmental laws, and the ongoing need for innovation motivated this investigation into improved metal-finishing techniques. Proper polishing methods can improve qualities such as corrosion and wear resistance by drastically reducing surface roughness and the coefficient of friction. However, traditional polishing methods have certain limitations that cause them to consume the metal. In this study, we introduced a newly aromatic pyridinium salt based isoniazid hybrid compounds ( APyHC ) as eco-friendly synthesized ionic liquids (ILs) to diminish the electrochemical dissolution rates (Electropolishing EP) of carbon steels (CSs) improving surface protection and demonstrate inhibition efficiencies (%IE) mostly 80% at relatively low concentration 5.93 × 10 − 5 M in 8M H 3 PO 4 , offering a sustainable alternative to harmful inhibitors. To comprehensively evaluate the inhibitor’s performance, we employed Galvanostatic mass-transfer analysis over a temperature range of 293–308 K. This test revealed a significant improvement in surface finish. The kinetic and thermodynamic coefficient values were calculated. The results show that increasing APyHC concentration enhanced inhibition efficiency, whereas rising temperature reduced it, confirming a temperature-sensitive process. Adsorption followed a mixed physicochemical mechanism obeying the El-Awady model ( R² = 0.99 at 298 K). Thermodynamic parameters confirmed endothermic, spontaneous adsorption, with E a below 80 kJ/mol, positive ΔH° , and ΔG° ranging from − 37.40 to -39.77 kJ/mol. The surface characteristics of CSs, as measured by composition ( EDX , XPS ), morphology ( SEM ), and topography ( AFM ), confirmed the presence of surface shielding. In line with experimental techniques, theoretical insights, such as DFT calculations and quantum-based Monte Carlo simulations ( MC ), were integrated with experiments to clarify reactivity, adsorption mechanisms at the atomistic scale, deepening understanding of inhibition and supporting a sustainable strategy for designing green ionic-liquid-based protection systems. Additionally, docking simulations examined APyHC ’s biological affinity for the sulfate-reducing bacteria ( SRB ) protein, evaluating its potential as a dual-purpose inhibitor of CSs dissolution in harsh media.