Natural Corrosion Inhibition and Adsorption Characteristics of Tribulus terrestris Plant Extract on Aluminium in Hydrochloric Acid Environment

Abstract

Corrosion inhibitive and adsorption capabilities of Tribulus terrestris plant extract on aluminum in 1.0 N HCl solution was evaluated by mass loss and electrochemical methods. The inhibition efficiency increased with increasing extract concentration, whereas it decreased with increasing immersion time. The adsorption of the extract on the metal surface was physisorption, supported by ΔGads values( around -20 kJ mol−1) and obeyed by Langmuir, Temkin and Freundlich adsorption isotherms. Electrochemical studies revealed mechanistic aspects of corrosion inhibition like Potentiodynamic polarization measurements indicated the nature of inhibitor is a mixed type and impedance studies supported the formation of a protective layer of inhibitor on a metal surface. SEM micrograms were also applied to study surface morphology. These images confirmed the creation of a protective film over the metal surface.