Abstract
The effect of extracts of Damsissa, Corchours itorius on the corrosion of aluminum in aqueous 0.1M sodium carbonate were investigated by gasometry, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. EIS measurements showed that the Nyquist plots consist of capacitive semicircle followed by inductive loop indicating that the dissolution process of aluminum occurs under activation control. Potentiodynamic polarization curves indicated that the plants extracts behave as mixed-type inhibitors. Gasometry results indicated that the plants extracts retard the alkaline corrosion of aluminum. The corrosion rates of aluminum and the inhibition efficiencies of the extracts were calculated. The results obtained show that the extract solutions of the plants could serve as an effective inhibitors for the corrosion of aluminum in sodium carbonate media. Inhibition was found to increase with increasing concentration of the plants extracts. Theoretical fitting of different isotherms, Langmuir, Flory-Huggins, and the kinetic-thermodynamic model, were tested to clarify the nature of adsorption. A mechanism of the corrosion reaction of aluminum in the alkaline media was proposed.