Experimental, quantum chemical and monte carlo simulation studies on the corrosion inhibition of mild steel by three new schiff base derivatives

The corrosion inhibition of newly synthesized Schiff base derivatives, namely (E)-3-(1-((2-aminophenyl)imino)ethyl)-4-hydroxy-6-methyl-2H-pyran-2-one (FMO), (E)-3-(1-((3-aminophenyl)imino)ethyl)-4-hydroxy-6-methyl-2H-pyran-2-one (FMM), and (E)-3-(1-((4-aminophenyl)imino)ethyl)-4-hydroxy-6-methyl-2H-pyran-2-one (FMP) was investigated for mild steel, in a 1.0 M HCl medium, using weight loss, electrochemical impedance spectroscopy, potentiodynamic polarization and theoretical calculations. FMO, FMM and FMP inhibition effectiveness increased with higher inhibitors concentrations, and decreased with a rise in temperature. Polarization studies showed that FMO, FMM and FMP were of mixed type nature. The results obtained from AC-impedance technique were analyzed to model the corrosion inhibition process through a suitable equivalent circuit model, where a constant phase element (CPE) has been used. FMO, FMM and FMP were found to obey Langmuir adsorption isotherm and Kinetic-Thermodynamic Model of El-Awady. Quantum chemical calculations were used to provide molecular based explanations for FMO, FMM and FMP inhibitive effects. Monte Carlo simulation studies and experimental results were in good agreement.