Asian Research Journal of Current Science

Corrosion inhibition of copper in acidic environment by leaf extracts of [Chromolaena odorata (CO) and Newbouldia laevis (NL)] were studied using Galvanometric Measurement (weight loss) techniques. Inhibition efficiencies increases as the inhibitor concentrations increases and decreases with temperature while corrosion rate decreases with concentrations and increases with rise in temperature. The adsorption isotherm plot of this study fit more to Langmuir adsorption isotherm plot as the R² were all greater than 0.95 compared to Temkin isotherm plot were the entire R² coefficient are less than 0.95. The inhibition efficiencies were further confirmed with the Electrochemical Impendence Spectroscopy (EIS), and the results were in good agreement with that of weight loss. At the optimum concentration (1000mg/L), the Inhibition efficiencies of the plants extract were found to be highest in both weight loss method and EIS method. However, increase in temperatures decreases the inhibition efficiency at the temperature range studied. The phenomenon of physical adsorption has been proposed as the activation energy values were all lower than 40kJ mol^-1 with both [Chromolaena odorata (CO) and Newbouldia laevis (NL)] leaves extract and the heat of adsorption, Q_ad were all negative implying that the reaction was spontaneous and exothermic for all concentration of inhibitors studied. The surfaces of copper were examined using SEM to confirm and compare the nature of surfaces before and after inhibition. Furthermore, XRD analysis was done to confirm the crystalline nature of copper.