Green silver-based nanomaterials derived from kiwi peel biowaste for sustainable protection of mild steel in acidic media

Green silver nanoparticles (AgNPs) were prepared as green and sustainable anticorrosion agents using kiwi peels aqueous extract (KPAE) as a natural reductant, providing a feasible route for biowaste valorization. Structural and morphological analysis of the biosynthesized KPAE-AgNPs validated the successful formation of spherical crystalline AgNPs with an average core size of 53 nm and high colloidal stability, with silver being the principal element of the nanocomposite. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) assessed the anticorrosion properties of the green nanoparticles on mild steel in 0.5 M HCl. The nanoparticles demonstrated a mixed-type inhibition with cathodic predominance, and achieved maximum corrosion inhibition of 60% at 1250 ppm. At the same concentration, the plant extract achieved a modest 40% inhibition efficiency. Thermodynamic analyses revealed that adsorption process was primarily physisorption-driven, and the corrosion inhibition was endothermic. Overall, the superior corrosion inhibition performance of the nanoparticles underscored their promise as effective, low-cost green anticorrosion agents for the protection of mild steel in acidic environment, and their applicability in environmentally benign surface protection strategies, as well as industrial acid cleaning and pickling. • Kiwi peels were successfully valorized into green silver nanoparticles • AgNPs demonstrated enhanced anticorrosion activity compared to plant extract • SEM of mild steel in acidic medium showed that AgNPs dramatically reduced cracks • Physisorption governed the spontaneous adsorption of AgNPs on metal surface • Accessible raw materials and easy synthesis make green AgNPs good corrosion inhibitors