Influence of Eco-Friendly Vernonia Amygdalina Leaf Extract on the Acid Corrosion of Aluminium

Abstract

The corrosion inhibition influence of Vernonia amygdalina extract on aluminium in 1M HCl solution was investigated using the gravimetric techniques at 30⁰C and 60⁰C temperatures. Aluminium coupons (type AA1060 and 98%) of dimension 3cm x 3cm were immersed into test solutions of uninhibited acid system and a five-test system containing different extract concentrations of 200mg/L, 400mg/L, 600mg/L, 800mg/L and 1000mg/L for 3 hours at 30⁰C and 60⁰C temperatures to check the effect of temperature increase in order to elucidate the nature of adsorption of the plant extract species onto the aluminium surface. Results obtained indicated that the Vernonia amygdalina was found to be a good green inhibitor of aluminium corrosion in a very aggressive, acidic, environment. The efficiency of inhibition increased with Vernonia amygdalina concentrations at 30⁰C but decreased at 60⁰C, which suggested physical adsorption mechanism, as the adsorption intermediate formed at the metal/solution interphase became soluble at higher temperature. Also, the inhibitor acted by being adsorbed on the surface of the aluminium according to classical Langmuir adsorption isotherm.