Assessment of Salen Schiff base as a corrosion inhibitor on low carbon steel in HCl media: Practical and computational studies

Eltohamy, Amal R.; Kamel, Medhat M.; Aboelmagd, Ahmed; Rashwan, Salah M.; Fouda, Abd El-Aziz E.; Awad, Mohamed K.; Atlam, Faten M.

doi:10.21608/cat.2024.240867.1211

Assessment of Salen Schiff base as a corrosion inhibitor on low carbon steel in HCl media: Practical and computational studies

Document Type : Original Article

Authors

¹ Department of Chemistry, Faculty of Science, Suez Canal University, Ismailia, 41522, Egypt

² Department of Chemistry, Faculty of Science, Mansoura University, Mansoura, 35516, Egypt

³ Department of Chemistry, Faculty of Science, Tanta University, Tanta, 31527, Egypt

10.21608/cat.2024.240867.1211

Abstract

Corrosion poses a significant challenge to the longevity and performance of metallic materials, particularly low-carbon steel, in acidic environments such as hydrochloric acid (HCl). The use of corrosion inhibitors is a widely adopted strategy to mitigate this issue, enhancing the durability and service life of metal components. Thus, the objective of this work is to study the inhibition performance of N,N′-bis(salicylidene)ethylene-1,2-diamine Schiff base (Salen SB) for low-carbon steel (CS) in 0.5 M HCl. The study was conducted using weight loss (WL), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP) techniques. The Salen SB was prepared and characterized using ¹H NMR and FTIR techniques. The efficiency of inhibition increased with an increase in Salen SB concentration. At a concentration of 300 ppm, the inhibitor exhibited the highest efficiency of 75.4% at 298 K. However, this efficiency decreased to 69.5% when the temperature was raised from 298 K to 333 K. The tested compound reduced both the double-layer capacitance (C_dl) and the corrosion current (I_corr), indicating the formation of a protective layer on the carbon steel (CS) surface. Additionally, the inhibitor demonstrated a mixed-type behavior, which was consistent with the Langmuir adsorption isotherm. It was revealed through scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) investigations that the presence of the Salen SB facilitates the formation and adsorption of a stationary film on the CS surface. To further elucidate the interactions between Salen SB molecules and CS, density functional theory (DFT) and Monte Carlo (MC) simulations were employed. The quantum properties of Salen SB demonstrate its efficacy as an inhibitor. The findings from the DFT and MC simulations indicated that Salen SB interacts with the CS surface via the lone pair of electrons from the heteroatoms, as well as the p-electrons of the benzene ring. The calculated binding energy for this interaction was -160.150 kJ/mol.

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