Corrosion inhibitive behavior of 7-hydroxyphenoxazone on mild steel in 1.0 M HCl

The corrosion inhibition of 7-hydroxyphenoxazone was investigated on mild steel (MS) in 1.0 M HCl solution using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) methods. Results obtained reveal that 7-hydroxyphenoxazone is a good inhibitor for MS in 1.0 M HCl solution and its inhibition efficiency is significantly increased by increasing its concentration. Also, electrochemical measurements showed that 7-hydroxyphenoxazone acts as a mixed-type inhibitor by suppressing the cathodic and anodic processes through a combination of chemical and physical adsorption on the MS surface followed by Langmuir isotherm. Incidentally, enhancement in inhibition efficiency was observed by the addition of KI due to synergism. Further evidence for inhibitive properties of 7-hydroxyphenoxazone was provided by SEM. Quantum chemical calculations were performed to provide illustrative explanation for the inhibition mechanism and adsorption of 7-hydroxyphenoxazone on the MS surface.