Adsorptive, Kinetic, Thermodynamic and Inhibitive Properties of Cissus Populnea Stem Extract on the Corrosion of Aluminum in Acid Medium.

Abstract

The adsorption of Cissus populnea stem extract and its subsequent corrosion inhibition properties on aluminum in 0.5 M HCl solutions have been investigated using weight loss measurements. Inhibition efficiency of the plant extract increased with concentration but decreased with rise in temperature. The adsorption of the inhibitor on the aluminum surface was spontaneous and found to align with Langmuir, Freundlich, Temkin and Flory- Huggins adsorption isotherms. From the values of E a and ΔG 0 obtained, the mechanism of physical adsorption has been proposed. Some thermodynamic and activation parameters were also calculated. Keywords : Adsorption isotherm, Cissus populnea, corrosion, physisorption, thermodynamics