Theoretical Evaluation Of Corrosion Inhibition Performance Of Decylamides Of α-amino Acids Derivatives

For three corrosion inhibitors, including 2-amino-N-decyl-3-(4-hydroxyphenyl) propionamide (A), 2-amino-N-decylacetamide (B) and 2-amino-N-decylpropionamide (C), the relationship between molecular structure and inhibition performance, regularity of absorption on the metal surface, film-forming mechanism and diffusion mechanism were studied by the combination of quantum chemical calculation and molecular dynamics simulation methods. The quantum chemical calculation method indicated that HOMO and LUMO of A, B and C were located on the polar head groups, which could form coordinate bond and back-donating bond with the metal surface. When A, B and C adsorbed on the surface of Fe(001), the polar head groups preferably adsorbed on the metal surface. And under the influence of solvent, alkyl chain pointed in the solvent with different angle of inclination. The bonding force between the corrosion inhibitor and metal surface increased in the order A > B > C, which was attributed to the different polar groups and adsorption characteristics. When the corrosion inhibitor formed a membrane on the metal surface, the cohesive energy made the membrane more compact and stable. The effects of the fractional free volume, the self-diffusion coefficient and the interaction energy on the diffusion coefficient were investigated that the diffusion coefficients of H3O+, H2O and Cl- in three decylamides of a-amino acids inhibitor membranes were in increasing order D(A) < D(B) < D(C). It suggested that the inhibition efficiency increased in the order A > B > C, which was in accordance with the experimental result.