Unveiling the Corrosion Inhibition Potential of Orbea variegata Extract: A Sustainable, Bio-Based Novel Inhibitor for Mild Steel in HCl

This study explores the corrosion inhibition performance of an aqueous extract derived from Orbea variegata, a succulent plant commonly known as “Carrion cactus” as a green, bio-based inhibitor for mild steel electrode in 1.0 M hydrochloric acid. The corrosion behaviour was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) following a 1-hour immersion period in acidic medium. Four different extract concentrations (0.005%, 0.010%, 0.050%, and 0.200% w/v) were tested to assess dose-dependent inhibition efficiency. Surface morphological changes of the mild steel samples were also surveyed via field-emission scanning electron microscopy (FE-SEM). Electrochemical results revealed a marked improvement in corrosion resistance with increasing extract concentration, demonstrating that O. variegata extract effectively suppresses corrosion processes owing to adsorption on the metallic surface. At all tested concentrations, the inhibition efficiency exceeded 90%, highlighting the potential of this plant as a sustainable alternative to conventional inhibitors. The findings suggest that Orbea variegata extract could serve as an eco-friendly, efficient and sustainable corrosion inhibitor for industrial applications where acidic environments are prevalent.