Abstract
The inhibitive effect of Lupine, Hlfabar and Damssisa extracts on the corrosion of zinc in aqueous solution of 0.5 M sodium chloride were investigated at 30 °C by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Potentiodynamic polarization curves indicated that lupine, hlfabar and damssesa act as mixed type inhibitors. EIS measurements showed that the total resistance and consequently the inhibition efficiency increase with increasing concentration of lupine, hlfabar and damssesa indicating the inhibitive effect of these extracts on zinc corrosion. The inhibition of the extract was assumed to occur via adsorption of active ingredients on the metal surface. Theoretical fitting of different isotherms, Langumir, Florry-Huggins and the Kinetic- Thermodynamic model were tested to clarify the nature of adsorption.