Density Functional Theory Studies On The Corrosion Inhibition Of Benzoin, Benzil, Benzoin-(4-Phenylthiosemicarbazone) And Benzil-(4-Phenylthiosemicarbazone) Of Mild Steel In Hydrochloric Acid

摘要

The density functional theory (DFT) at the B3LYP/6-31G (d,p) and B3LYP/6-311G (d,p) basis set levels were performed on benzoin, benzil, benzoin-(4-phenylthiosemicarbazone) and benzil-(4-phenlthiosemicarbazone used as corrosion inhibitors for mild steel in acidic medium. The quantum chemical parameters/descriptors, namely, EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), the energy difference (△E) between EHOMO and ELUMO, dipole moment (μ), electron affinity (A), ionization potential (I), the absolute electronegativity (X), absolute hardness (η), softness (σ), polarizability (α), the Mulliken charges, and the fraction of electrons (△N) transfer from inhibitors to iron, were calculated and correlated with the experimental %IE. Condensed Fukui function and condensed softness have been used to determine the sites for electrophilic and nucleophilic attacks on each of the inhibitors.