Green Corrosion Inhibition of Aluminium in Acidic Environment Using Hibiscus sabdariffa Leaf Extracts

Abstract

The study aimed to evaluate the potential of Hibiscus sabdariffa leaf extract (HSLE) to retard the corrosion of aluminum in 0.1 M and 1 M HCl. Aluminium is an important material used in fabrication of industrial vessels, and understanding its corrosion behaviour will provide the industrialist with vital information about the choice of protection methods used to prolong its lifespan. Weight loss measurements and potentiodynamic polarization techniques were employed for the study. These methods are common and complementary methods used for corrosion studies, as they validate the corrosion rate measurements. The mechanism of corrosion was also determined using Langmuir adsorption isotherm. Ethanolic extracts of Hibiscus sabdariffa leaves were used to prepare different concentrations ranging from 500 mg/l to 3000 mg/l and corrosion rate measurements were taken over time intervals of 24-120 hours for aluminium immersed in 0.1 M and 1 M HCl in the presence and absence of HSLE, at a temperature of 303 K. The results showed that HSLE is a good inhibitor of aluminum corrosion under the studied conditions. Excellent inhibition efficiencies of 95.1 % and 96.2 % were obtained for 0.1 M and 1 M HCl respectively. The corrosion rate was reduced with an increase in concentration of HSLE and almost approached zero. The mechanism of corrosion inhibition was physiosorption. Electrochemical result showed HSLE as a mixed-type inhibitor, shifting the cathodic and anodic arms of the curve.