Green Corrosion Inhibition of Aluminium in Acidic Environment Using <em>Hibiscus sabdariffa </em>Leaf Extracts

The study aimed at evaluating the potential of Hibiscus sabdariffa leaf extract (HSLE) to retard the corrosion of aluminum in 0.1 M and 1 M HCl. Weight loss measurements and potentiodynamic polarization techniques were employed for the study. The mechanism of corrosion was also determined using Langmuir adsorption isotherm. Ethanolic extracts of Hibiscus sabdariffa leaves were obtained and 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 mild steel immersed in 0.1 M and 1 M HCl in the presence and absence of HSLE. 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 retarded with an increase in concentration of HSLE and almost approached zero at 24 hours for 1 M HCl and at 96 and 120 hours for 0.1 M HCl. The mechanism of corrosion inhibition was physiosorption. Electrochemical result showed HSLE as a mixed-type inhibitor, retarding the corrosion potential and current density, and shifting the cathodic and anodic arms of the curve.