Abstract:
This study investigates the anticorrosive efficiency of a natural inhibitor extracted from Hibiscus sabdariffa seeds for the protection of ASTM A53 steel in two corrosive environments: a synthetic water solution simulating real water transport conditions, and an acidic medium with a pH of 2.9. The experimental approach is based primarily on gravimetric measurements to evaluate the corrosion rate in the absence and presence of the inhibitor, under varying conditions of immersion time, inhibitor concentration, and temperature.
The results revealed a significant inhibitory effect of the plant extract, with maximum inhibition efficiency observed at optimal concentrations of 450 ppm in synthetic water and 600 ppm in the acidic medium. The influence of temperature showed a decrease in efficiency with increasing temperature, suggesting a physical adsorption mechanism.
The experimental data were modeled using different adsorption isotherms (Langmuir, Temkin, Freundlich, and Frumkin), with a good fit obtained with the Langmuir model. Thermodynamic parameters, particularly the standard free energy of adsorption (ΔG⁰_ads), confirmed the spontaneous nature of the inhibitor’s adsorption onto the steel surface.
This work highlights the potential of Hibiscus sabdariffa as a green, eco-friendly corrosion inhibitor and offers promising prospects for the development of natural protective formulations for metals in water transport systems and acidic environments.
