Dapsone: A Novel Corrosion Inhibitor for Mild Steel in Acid Media

Abstract

Corrosion inhibition of mild steel in 1 M HCl and 0.5 M H 2 SO 4 by dapsone were studied by polarization resistance , Tafel polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurement. Results obtained revealed that inhibition occurs through adsorption of the drug on metal surface without modifying the mechanism of corrosion process. Potentiodynamic polarization suggested that it acts as a mixed type predominantly cathodic in HCl and predominantly anodic in H 2 SO 4. Electrochemical impedance spectroscopy was used to investigate the mechanism of corrosion inhibition. Thermodynamic parameters such as a E , ° a H , ° a S , ° ads H were calculated to investigate mechanism of inhibition. The adsorption of dapsone followed Langmuir adsorption isotherm.