Novel oxazole and imidazole based on 8-hydroxyquinoline as a corrosion inhibition of mild steel in HCl solution: Insights from experimental and computational studies

Hydrochloric acid pickling treatment is used to remove mill scales from mild steel (MS) surface at diverse temperatures up to 328 +/- 5 K. In order to minimize the metal dissolution newly multifunctional heterocycles based on 8-hydroxyquinoline derivatives, have been synthesized and characterized. These compounds have been tested as corrosion inhibitors of mild steel in 1M HCl at 298 +/- 5 K was studied using mass-loss, hydrogen evolution and electrochemical methods combined with DFT calculations. It is found also that these heterocycles based on 8-hydroxyquinoline compounds acted as excellent inhibitors and their inhibition efficiencies depend on the type of the substituent and which acted as mixed type inhibitors. In addition, UV-visible studies reveal the formation of a complex that may also be responsible for the observed inhibition. Furthermore, the Scanning Electron Microscope (SEM) images of the corrosion product confirmed the protection offered by both synthesized compounds on the surface of the mild steel immersed in molar HCl media. It is found that the theoretical parameters confirmed those obtained by experimental studies.