Electrochemical and Quantum Chemical Studies on Calmagite and Fast Sulphone Black F dyes as Corrosion Inhibitors for Mild Steel in Hydrochloric Medium

摘要

The corrosion inhibitive effects of two naphthylazo anionic dyes namely Calmagite (CG) and Fastsulphone black F (FSBF) on mild steel surface in hydrochloric acid solution was studied usingelectrochemical impedance spectroscopy (EIS),Tafel polarization techniques and quantum chemicalcalculation methods. Inhibition efficiency increased with increase in concentration of the inhibitors.Trends in the calculated molecular properties (e.g., dipole moment, HOMO and LUMO energies) werecompared with trends in the experimentally determined inhibition efficiency. The results show thattrends in the quantum chemical descriptors are in agreement with the experimentally determinedinhibition efficiencies. The adsorption on the metal surface might be due to both chemisorption andphysisorption mechanisms arising from the anionic nature of the molecules in solution (which promotephysisorption) and the electron donating effects of the electron rich centres (which promoteschemisorption). The solvent effects have minimal influences on the characteristics of the calculatedmolecular properties of the dyes.