Adsorption of (E)-4((2-(Benzylamino)phenyl)diazenyl)phenol on steel surface and synergistic corrosion inhibition with iodide ions: Experimental and computational studies

Abstract

A new azo dye, ( E )-4((2-(benzylamino)phenyl)diazenyl)phenol [BPDP] was synthesized via diazotization-coupling reaction and characterized with major spectroscopic techniques. The inhibitory capacity of the compound on mild steel corrosion in 1 M HCl solution was evaluated via weight-loss, electrochemical, scanning electron microscope, and computational techniques. The weight loss revealed that on increasing the concentration of the inhibitor, there was a substantial increase in the inhibition efficiency, and at every 10 K rise in temperature for a particular concentration, the inhibition efficiency was reduced. Synergistic interaction was inferred between iodide ions and BPDP molecule as the synergistic index was greater than 1, resulting in a formulation with enhanced corrosion inhibition. BPDP inhibited both cathodic and anodic corrosion half-reactions and increased charge transfer resistance for mild steel corrosion in 1 M HCl. Adsorption of BPDP molecules on steel surface conforms to the Langmuir isotherm model. Scanning electron microscope (SEM) images revealed the formation of a protective layer on the mild steel surface in the presence of the inhibitor. The density functional theory (DFT) and Monte Carlo simulations laid credence to the adsorption potentials of BPDP molecules on the steel surface.