Theoretical study for evaluation of corrosion inhibition performance of two thiocarbohydrazide inhibitors

Abstract

Molecular dynamics (MD) simulation and Density functional theory (DFT) methods were applied to the two thiocarbohydrazides derivatives (T1 and T2) as corrosion inhibitors for carbon steel in aqueous phase. Experimental results have shown that the corrosion rate follows the below order: T1>T2. Quantum chemical parameters such as hardness (η), electrophilicity (ω),polarizability (α), dipole moment (μ ) ,EHOMO (the energy of the highest occupied molecular orbital), ELUMO (the energy of the lowest unoccupied molecular orbital), Electronegativity (χ), the total amount of electronic charge transferred (ΔN), Lipophilicity, total negative charges on the whole of the molecule (TNC), molecular volume (MV), surface area and Fukui index were calculated. The results of quantum chemical confirm that T2 is a better inhibitor than T1. MD simulation results showed that T2 inhibitor has the higher negative interaction energy as compared to the T1 inhibitor.Results of DFT and MD calculations confirm that T2 has more inhibition efficiency than T1, which is in good agreement with the experimentally inhibition efficiency of the reported data.