Experimental and Quantum Chemical Evaluation of 8-Hydroxyquinoline as a Corrosion Inhibitor for Copper in 0.1 M HCl

The corrosion inhibition properties of 8-hydroxyquinoline (8-HQ) in 0.1 M HCl for copper have been investigated by using experimental (electrochemical impedance spectroscopy (EIS), dynamic electrochemical impedance spectroscopy (DEIS), and potentiodynamic polarization) and theoretical methods complemented by surface morphological examination with the aid of scanning electron microscopy (SEM) and electron dispersive X-ray spectroscopy (EDAX). Results obtained from all of these applied techniques are in agreement and demonstrate that 8-HQ inhibited copper corrosion in 0.1 M HCl solution significantly and the inhibition efficiency varies directly with 8-HQ concentration. Potentiodynamic polarization results show that 8-HQ behaved like a cathodic-type inhibitor in the studied system. EDAX results reveal that 8-HQ is most stable and effective at 10 h of immersion time. Inhibition of Cu corrosion by 8-HQ is due to electrostatic interaction between the Cu surface and salt of 8-HQ according to the Delta G(ads)(0) value and FTIR results. E-HOMO, E-LUMO, and Delta E values support the proposed physisorption mechanism. SEM and EDAX results confirm the adsorption of 8-HQ molecules on a Cu surface.