Density Functional Theory modeling and Monte Carlo simulation assessment of inhibition performance of two Quinoxaline Derivatives for Steel Corrosion

Quantum chemical calculations using the density functional theory (DFT) at the B3LYP/6-31G(d,p) level were performed ontwo quinoxaline derivatives named: 1-ethyl-3-methylquinoxalin-2(1H)-one (Et-N-Q=O) and 1benzyl-3-methylquinoxalin-2(1H)-one (Bz-N-Q=O) in order to correlate the structural and electronic properties, such as HOMO, LUMO energy values, frontier orbital energy gap, molecular dipole moment (μ), electron affinity (A), ionization potential (I), electronegativity (χ), global hardness (η), softness (σ), the fraction of electron transferred (ΔN), electrophilicity index (ω), back-donation (ΔEback-donation) and Mulliken charges with the inhibitive action of these inhibitors on the mild steel corrosion in molar hydrochloric acid. Monte Carlo simulations were also executed to simulate the adsorption of the two quinoxaline derivatives on Fe (111) surface in the presence of molecules of water and the results show that Bz-N-Q=O is the most effective as corrosion inhibitor for mild steel in 1 M HCl medium.