Synthesis, experimental and theoretical studies on the inhibition of corrosion of C38 steel in a molar hydrochloric acid solution by bis-5,6-methylbenzimidazole-2-thione

Abstract

The protection against corrosion by a newly synthesized compound, bis-5,6-methylbenzimidazole-2-thione ( MBMS ), was assessed using two alternative methods: Potentiodynamic polarization investigation (PDP) and Electrochemical Impedance Spectroscopy (EIS). The results conclude that this new organic inhibitor effectively prevents the deterioration of C38 steel immersed in an aggressive solution of 1 M HCl. Also, the protective coating interacts with the C38 surface to form an obstacle that prevents aggressive agents from penetrating the substrate surface. The findings demonstrate that the MBMS under investigation achieved an inhibition efficiency of 97 % at 10 −4 M. Scanning electron microscopy coupled with energy-dispersive X-ray analysis revealed the presence of the inhibitor on the metal surface and the isothermal study showed that the Langmuir model is the most suitable for this molecule. Additionally, theoretical studies were conducted, including DFT calculations and MC simulations, further validating these results.