A Novel Approach for Tailoring of a Corrosion Inhibitor for Mild Steel in 1 M Hydrochloric Acid Medium: Combined Advanced Computational and Experimental Studies for Developing a Novel Quinoline Based Corrosion Inhibitor

Chemical synthesis of a novel [1,2,3]triazino[4,5-b]quinoline (TQ) was formulated as an efficient corrosion inhibitor against mild steel in 1 M hydrochloric acid medium. The formulation of the structure was based on DFTB+, Dmol³ modules investigation and Molecular dynamic simulation studies. The efficacy of the novel quinoline derivative was predetermined in terms of its adsorption behavior towards mild steel surface by advanced computational adsorption [B3LYP/6-311+G(d,p) level of theory] and MD simulation methods prior to the experimental findings. The efficiency of TQ was also compared with some of the preexisting heterocycles having some structural similarities in terms of Global molecular variables such as fractional electron charge transfer, dipole moment, and HOMO and LUMO energies. The computational studies suggested that TQ would be a promising corrosion inhibitor against mild steel corrosion in 1 M HCl solution. The synthesis of TQ was realized by retrosynthetic analyses, and its chemical characterization was accomplished by ¹H-NMR, GC–MS, UV, and IR studies. The theoretical investigations were corroborated by experimental findings. Electrochemical impedance spectroscopy, potentiodynamic polarization, and gravimetric studies showed that the inhibitor acted as a mixed-type corrosion inhibitor, and its efficiency reached 95.5% at 200 ppm concentration and at 298 K. The adsorption followed Langmuir isotherm. Activation parameters were determined by studying the corrosion rate at different temperatures. Analysis of the surface morphology of mild steel was carried out by scanning electron microscopy, energy dispersive X-ray analysis, and atomic force microscopy. The present work opens an avenue for saving time and manpower, omitting the luck factor while synthesizing a new organic corrosion inhibitor molecule.