Sour corrosion of C1018 carbon steel and its inhibition by 1–benzylimidazole: electrochemical, SEM, FTIR and computational assessment

Abstract

The sour corrosion of C1018 carbon steel in CO₂-saturated 3.5% NaCl + 100 ppm H₂S solution and its inhibition by a low-toxic molecule, 1–benzylimidazole (1–Benz), has been investigated. Electrochemical impedance spectroscopy (EIS) results reveal that 1–Benz can form a strongly-adsorbed and highly protective inhibitor layer on the steel surface. Potentiodynamic polarization (PDP) results confirm that 1–Benz is a mixed–type corrosion inhibitor with slightly more anodic tendency. An optimum concentration of 150 ppm provided up to 83% inhibition efficiency. Based on FTIR characterization, 1–Benz interacts with the steel surface using its nitrogen atom and C=C pi-electrons and it adsorbs following the Temkin isotherm. The adsorption reduces localized corrosion, according to SEM-EDX observations. Theoretical parameters confirm that the electron–rich imidazole N atoms and electron-deficient C atoms in the phenyl ring ensure easy electron transfer between 1–Benz and the steel surface.

Keywords:

• Sour corrosion
• carbon steel
• imidazole
• DFT
• EIS
• FTIR

Acknowledgements

The authors are grateful to the Interdisciplinary Research Center for Advanced Materials, King Fahd University of Petroleum and Minerals, Saudi Arabia, for granting permission to use some of its equipment during this work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Support from the World Bank Africa Centers of Excellence for Impact (ACE Impact) Project (NUC/ES/507/1/304) is also gratefully acknowledged.