Corrosion Inhibitive Potentials Of (E)-5-((4-Benzoylphenyl)Diazenyl)-2-Hydroxybenzoic Acid On Mild Steel Surface In 0.5 M HCl- Experimental And DFT Calculations

Abstract

One of the ways of reducing metal corrosion and its devastating effects is by using organic corrosion inhibitors. This is because of the π-conjugation in their moieties, their ability to donate electrons to the metal’s vacant d-orbitals, and their low lying LUMO orbitals for accepting electrons as well from the metal, all these improve their adsorption on the metal surface. (E)-5-((4-benzoylphenyl)diazenyl)-2-hydroxybenzoic acid (AD4) was synthesized via the coupling reaction of p-aminobenzonephenone and Salicylic acid, characterized via FTIR, UV/Vis, 1H-NMR, and 13C-NMR spectroscopy. The melting point of AD4 is 103oC–106oC indicating that it is thermally stable and pure. Gravimetric and potentiodynamic polarization techniques were employed to obtain the corrosion rates (Cr) and percentage inhibition efficiency (%IE) at different concentrations of the inhibitor and at different temperatures. The thermodynamic parameters like Enthalpy, ∆Hoads, Entropy, ∆Soads and free energy of adsorption (∆Gads) of Adsorption were calculated. The Langmuir adsorption isotherm was used to describe the adsorption of AD4 molecules on mild steel. Quantum mechanical calculations were employed to calculate the electronic properties and global reactivity descriptors of AD4. The theoretical results are broadly consistent with experimental results. From the results obtained AD4 could be used as a corrosion inhibition agent in the oil and gas industries.