LAUSR

Abstract Allium -sativum L. was explored as an environment-friendly inhibitor for mild steel in 5 M hydrochloric acid. The extract was characterized by NMR and FTIR techniques and found that Allicin is the major component that is acting as an inhibitor. The mechanism of adsorption and inhibition was investigated by weight loss, electrochemical (impedance spectroscopy and polarization), gasometric, SEM, metallurgical microscopy, DFT, and molecular dynamic simulation techniques. Thermodynamic, electrokinetic, and adsorption parameters were obtained from different theoretical techniques. Impedance data were analyzed to understand the structure of the metal-inhibitor interface with the help of an equivalent circuit model. Langmuir adsorption isotherm, metallurgical microscopy, SEM, and adsorption module proves that thickness of adsorbed barrier film increase with inhibitor concentration. Pore length and percentage porosity decreases with inhibitor concentration. The maximum inhibition efficiency shown was 94.76%. Mild steel-inhibitor interaction was investigated by DFT, Fukui function, and molecular dynamic simulation study. The DFT shows a very less energy gap between HOMO and LUMO. Molecular dynamic simulation shows high binding and adsorption energy of environment-friendly inhibitor for MS. Chemical and biochemical O2 need of wastewater after corrosion study was found in permissible limit.