Study of Stevia rebaudiana Leaves as Green Corrosion Inhibitor for Mild Steel in Sulphuric Acid by Electrochemical Techniques

The inhibition for the corrosion of mild steel in sulphuric acid solution by the extract of Stevia rebaudiana leaves has been studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. Inhibition was found to increase with increasing concentration of the leaves extract. The effect of temperature on the corrosion behavior of mild steel in 0.5M H2SO4 with addition of extract was also studied. The inhibition was assumed to occur via adsorption of the inhibitor molecules on the metal surface. The adsorption of the extract on the mild steel surface obeys the Langmuir adsorption isotherm. The activation energy as well as other thermodynamic parameters (Ea, ΔH and ΔS) for the inhibition process was calculated. These thermodynamic parameters show strong interaction between inhibitor and mild steel surface. The results obtained show that the extract of Stevia rebaudiana leaves could serve as an effective inhibitor for the corrosion of mild steel in sulphuric media.