Development of eco-friendly corrosion inhibitor from the ethanolic extract of Chromolaena odorata flower for mild steel in acidic media

Plant-based inhibitors are preferred over chemical ones due to their safety and environmental friendliness, despite the high effectiveness of chemical inhibitors. This study investigates Chromaolaena odorata flower extract (COFE) inhibits mild steel (MS) corrosion in HCl. For the corrosion experiments, standard electrochemical (EIS, PDP) and non-electrochemical (weight loss) investigations were carried out. The maximum inhibition efficiency (93.82% in weight loss study, 92.15% in EIS, and 91.86% in PDP at room temperature) was obtained at the optimal inhibitor concentration of 3%. With increasing temperature, the charge transfer resistance (Rct) decreases and the corrosion current density (Icorr) increase due to the desorption of COFE from the metal surface. The GCMS method was used to analyse the phytochemical profile. Gaussian 09 software was used for the computational study of active inhibitor compounds found during GCMS research. Single-point energy calculations and geometry optimisation were done. Cyclooctasulfur has the lowest ΔE value of 3.694 eV among the major phytochemicals. The strong adsorption potential of phytoextracts on the iron (110) surface was confirmed through Monte Carlo simulations. FESEM analysis examined MS surfaces with and without the inhibitor. This work demonstrates COFE as a green, eco-friendly corrosion inhibitor for mild steel using experimental, computational, and surface analyses.