Green colloidal composites from Putranjiva roxburghii wall extract (PRWE) for the prevention of mild steel corrosion in an acidic medium of 1.0 M HCl

Despite the fact that various studies have proved the efficacy of plant-based extracts as green corrosion inhibitors, the possibility of using unwanted and invasive species as sustainable corrosion inhibitors is still underexplored. In the current study, Putranjiva roxburgii extract (PRWE), which is an abundantly available weed, is, explored as a value-added, eco-friendly corrosion inhibitor to mild steel in a 1.0 M HCl acidic environment. The electrochemical method, the gravimetric analysis, scanning electron microscopy (SEM), and the computational evaluation were used to analyze the PRWE corrosion inhibition performance. These findings indicated the presence of a concentration-related inhibition behaviour, with PRWE being a mixed-type inhibitor, as shown by anodic and cathodic polarization slopes. The corrosion inhibition potential of PRWE was systematically assessed via potentiodynamic polarisation (PDP), Electrochemical impedance spectroscopy (EIS) and weight loss (WL). PRWE exhibited efficiency of 95.57% as determined by EIS and 97.51% as obtained via WL at 298 K that decreased as the temperature was elevated. Increases in charge transfer resistance (Rct) and polarization resistance (Rp) and a reduction in the constant phase element value, confirming the presence of a protective adsorbed layer over the mild steel surface. Theoretical computations also indicated the vigorous adsorption of PRWE components on the steel surface, characterized by a low energy gap (ΔE), which showed good agreement with experimental results. Based on all the above findings, the present work presents weeds as a low-cost, low-utilized, sustainable source of corrosion inhibitors, which have the dual advantage of resisting corrosion and environmental management.