Gravimetrical, theoretical, and surface morphological investigations of corrosion inhibition effect of 4-(benzoimidazole-2-yl) pyridine on mild steel in hydrochloric acid

• Published in: Korose a ochrana materiálu Vol. 64; no. 4; pp. 122 - 130
• Main Authors: Resen, A.M., Hanoon, M., Salim, R.D., Al-Amiery, A.A., Shaker, L.M., Kadhum, A.A.H.
• Format: Journal Article
• Language: English
• Published: Prague Sciendo 01.12.2020; De Gruyter Poland
• Subjects: Corrosion; Corrosion effects; Corrosion inhibitors; Corrosion mechanisms; Density functional theory; Dipole moments; Energy gap; Gravimetry; Hydrochloric acid; Investigations; Isotherms; Low carbon steels; Mathematical analysis; Metal surfaces; Molecular orbitals; Molecular structure; Morphology; Parameters; Quantum chemistry
• DOI: 10.2478/kom-2020-0018
• ISSN: 1804-1213; 0452-599X

The corrosion inhibition efficiency of the novel pyridine namely, 4-(Benzoimidazole-2-yl)pyridine has been studied for mild steel in a 1 M hydrochloric acid environment by utilizing gravimetrical techniques. The synthesized inhibitor exhibits a significant inhibitive efficiency of 93.8% at 0.005 M. The adsorption isotherm of the investigated inhibitor on mild steel surface obeys the Langmuir isotherm. Surface morphology investigated by utilizing scanning electron microscopy (SEM) demonstrates a smooth metal surface with the addition of 4-(Benzoimidazole-2-yl)pyridine in a hydrochloric acid environment. Quantum chemical calculations using density functional theory (DFT) have been used to investigate the molecular structure and behavior of 4-(Benzoimidazole-2-yl) pyridine as a corrosion inhibitor. Different parameters have been calculated using DFT, such as energies of highest occupied molecular orbital and lowest occupied molecular orbital (EHOMO and ELUMO), energy gap (∆E), and dipole moment (μ). These parameters were important to elucidate the behavior of the investigated molecule as a corrosion inhibitor in acidic solution and also suggest the mechanism of inhibition.