Quantum chemical studies and atomistic simulations of some inhibitors for the corrosion of al surface

Abstract

Atomistic simulations are becoming increasingly important in the field of corrosion inhibition. New research and development efforts using computational chemistry in studying the behavior of corrosion inhibitors on the metal surfaces are introduced. Accordingly, the density functional theory (DFT) at the B3LYP/6-31G++(d,p) basis set level, ab initio calculations using the HF/6-31G++(d,p) and MP2/321G+(d) methods are performed on some triazoles and sulphur containing compounds, namely, 1,2,4-triazole (TA), 3-amino-1,2,4-triazole (ATA), benzotriazole (BTA) and 2-mercaptobenzothiazole (MTA), used as corrosion inhibitors. The correlation between its quantum chemical parameters and the corresponding inhibition efficiency (IE%) is investigated. Quantum chemical parameters, such as the energy of the highest occupied molecular orbital energy (E_HOMO), the energy of the lowest unoccupied molecular orbital energy (E_LUMO), energy gap (ΔE), dipole moment (µ), sum of total negative charges (TNC), molar volume (MV), polarizability (α), chemical potential (Pi), electronegativity (χ), hardness (η), softness (σ), electrophilicity (ω) and the total energy change (ΔE_T), are calculated. Furthermore, Monte Carlo simulation technique incorporating molecular mechanics and molecular dynamic is used to simulate the adsorption of the investigated inhibitors on Al (1 1 1) surface. A good correlation is found between the theoretical data and the experimental results.