Understanding the corrosion inhibition of carbon steel and copper in sulphuric acid medium by amino acids using electrochemical techniques allied to molecular modelling methods

• Published in: Corrosion science Vol. 115; pp. 41 - 55
• Main Authors: Mendonça, Glaydson L.F., Costa, Stefane N., Freire, Valder N., Casciano, Paulo N.S., Correia, Adriana N., Lima-Neto, Pedro de
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.02.2017; Elsevier BV
• Subjects: Amino acid; Amino acids; Carbon steel; Carbon steels; Computer simulation; Copper; Corrosion; Corrosion inhibition; Corrosion inhibitors; Corrosion tests; Density functional theory; Electrochemistry; Impedance; Molecular modelling; Molecular orbitals; Monte Carlo simulation; Sulfuric acid; Theory; Electrochemistry; Carbon steel; Amino acid; Molecular modelling; Corrosion inhibition; Copper
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2016.11.012

•Corrosion inhibition of carbon steel and of copper by the amino acids was studied.•Inhibition efficiencies were experimentally achieved by electrochemical impedance.•DFT and Monte Carlo methods allowed correlating molecular properties with inhibition efficiency.•The corrosion inhibition followed the electron donation the electron-back donations process. Six amino acids were evaluated as corrosion inhibitors for carbon steel and copper in 0.5molL−1H2SO4 solution by potentiodynamic polarization and electrochemical impedance techniques allied to Density Functional Theory (DFT) and Monte Carlo computations The corrosion inhibitor rankings were: Arg>Gln>Asn>Met>Cys>Ser, for copper, and Met >Cys >Ser >Arg>Gln>Asn, for carbon steel. The DFT approach failed to explain the corrosion inhibition rating based on the HOMO and LUMO energies of the isolated amino acid molecules, while the simpler classical Monte Carlo approach, performed considering the interaction energies between the corrosion inhibitor and the metallic substrate, was successful.