Abstract
CoO/Co3O4 nanoparticles (CoO/Co3O4 NPs) were synthesized with egg white. The effectiveness of CoO/Co3O4 NPs to inhibit the corrosion of carbon steel has verified in acidic medium (1 M HCl). It has been found that Langmuir adsorption isotherm is the dominant adsorption process of CoO/Co3O4 NPs on the surface of low-carbon steel. The thermodynamic parameters also demonstrated that the adsorption process of CoO/Co3O4 NPs was a physicochemical, spontaneous, and exothermic process. The electrochemical impedance spectroscopy technique and potentiodynamic polarization were applied. The results obtained in this study showed that CoO/Co3O4 NPs acted as a mixed inhibitor for the anodic reaction and the cathodic reaction, and the efficiency to inhibit the corrosion was 93% at 80 ppm of the inhibitor. The results of scanning electron microscopy (SEM) technique, energy-dispersive X-ray spectroscopy (EDS), and X-ray electron spectroscopy (XPS) confirmed the effectiveness that was obtained using the inhibitor to protect the surface of low carbon steel. Thus, low-carbon steel can be protected against corrosion in acidic medium using CoO/Co3O4 NPs as inhibitors.