Corrosion Inhibition by Piliostigma Thoningii Extract on Mild Steel in Acidic Environment: RSM and Molecular Modeling Approach

The study aimed to optimize the corrosion inhibition performance of an extract from Pilliostigma thoningii stem bark on mild steel in ۱M HCl environment using Response Surface Methodology (RSM). The optimal inhibitor concentration, temperature, and reaction time were found to be ۱.۰ g/L, ۳۳۳ K, and ۱ hour, respectively, resulting in an inhibition efficiency of ۹۳.۷۵%. The inhibitor's efficacy was confirmed through various analytical methods, including SEM, FTIR, and UV-Visible spectroscopy. The results suggest that the experimental and predicted data are in reasonable agreement, showing that the quadratic model was the fittest for optimizing the inhibition process. The study identified ۳۳ compounds through GC-MS, with PT-۱, PT-۲, and PT-۳ being the major compounds. Quantum chemical calculations and molecular dynamics simulations further confirmed the effectiveness of the three selected inhibitor molecules, with PT۳ being the most effective. The study concludes that Pilliostigma thoningii stem bark extract has the potential to be an effective corrosion inhibitor for mild steel in acidic environments.