Theoretical study of aspartic and glutamic acids as corrosion inhibitors on aluminium metal surface

Abstract

The present study describes the inhibition of aluminium corrosion using amino acids including aspartic and glutamic acids through computational studies. Quantum chemical approach was used to calculate some electronic properties of the molecules to ascertain the correlation between inhibitive effect and molecular structure of the inhibitors. The corrosion inhibition efficiencies of these molecules and the global chemical reactivity was established through some parameters, such as E_HOMO, E_LUMO, energy gap (∆E), electronegativity (χ), global hardness (η), and the fraction of electrons transferred from the inhibitor molecule to the aluminium metallic atom (∆N). In addition, the local reactivity has been analyzed through the Fukui function and condensed softness indices. The molecular dynamic method results showed that the more negative the binding energy of the inhibitor-metal surface is, the better the adsorption of the inhibitor onto the metal surface and subsequently the higher the inhibition. The trend could be inferred in terms of inhibition efficiencies of the inhibitors in respect of their binding energies as glutamic acid greater than aspartic acid.