Electrochemistry and XPS study of an imidazoline as corrosion inhibitor of mild steel in an acidic environment

• Published in: Materials and corrosion 2009-01, Vol.60 (1), p.14-21
• Main Authors: Olivares-Xometl, O., Likhanova, N. V., Martínez-Palou, R., Domínguez-Aguilar, M. A.
• Format: Article
• Language: English
• Subjects: Applied sciences; Corrosion; Corrosion environments; corrosion inhibitor (CI); Corrosion prevention; electrochemical impedance spectroscopy (EIS); Exact sciences and technology; Metals. Metallurgy; mild steel; oleic imidazoline (OI); polarization scans; X-ray photoelectron spectroscopy (XPS)
• ISSN: 0947-5117; 1521-4176
• DOI: 10.1002/maco.200805044

The effect of 2‐(2‐heptadec‐8‐enyl‐4,5‐dihydro‐imidazol‐1‐yl)‐ethylamine on the corrosion behavior of mild steel in aqueous hydrochloric acid was investigated using weight loss measurements, polarization scans, electrochemical impedance, and X‐ray photoelectron spectroscopy (XPS). The inhibition efficiencies and coverage degrees increased with the concentration of inhibitor but decreased proportionally with temperature. It appears that the steric hindrance of the aliphatic chain on the imidazoline ring adsorption may affect inhibitor efficiency. Polarization curves showed that the oleic imidazoline (OI) acted essentially as a mixed type inhibitor, in which the blocking of active sites occurred. As a result of film formation, impedance spectra revealed a considerable increase in the charge transfer resistance as indicated by the second capacitive loop. XPS depth profile analysis observed the presence of nitrogen and carbon species on the inhibitor film, which were associated to the OI.