A DFT and Molecular Dynamics Study on Inhibitory Action of Three Amine Derivatives on Corrosion of Carbon Steel

Inhibition efficiencies of three amine derivatives (Diethylenetriamine (I), Triethylenetetramine (II), and Pentaethylenehexamine (III)) have been studied on corrosion of carbon steel using density functional theory (DFT) method in gas phase. Quantum chemical parameters such as EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), hardness (η), polarizability (α), dipole moment (μ), electrophilicityindex (ω) totalnegative charges on atoms (TNC) and molecular volume (MV) have been calculated at the B3LYP level of theory with 6-311 ** basis set. Moreover, adsorption behavior of the inhibitor molecules on Fe (110) surface has been analyzed using molecular dynamics simulation. The binding strength of the concerned inhibitor molecules on Fe (110) surface follows the order III>II>I, which is in good agreement with the experimentally determined inhibition efficiencies. In consistent with experimental data, theoretical results showed that the order of inhibition efficiency is Pentaethylenehexamine (III)>Triethylenetetramine (II)>Diethylenetriamine (I). This study has shown that DFT along with MD can be successfully be used as a reliable approach to screen organic corrosion inhibitors prior to experimental validation.