Eco-Friendly Synthesis of Zirconium Dioxide Nanoparticles from Toddalia asiatica: Applications in Dye Degradation, Antioxidant and Antibacterial Activity

Zirconium dioxide nanoparticles (ZrO₂ NPs) have gained significant attention due to their excellent bioavailability, low toxicity, and diverse applications in the medical and industrial fields. In this study, ZrO₂ NPs were synthesized using zirconyl oxychloride and the aqueous leaf extract of Toddalia asiatica as a stabilizing agent. Analytical techniques, including various spectroscopy methods and electron microscopy, confirmed the formation of aggregated spherical ZrO₂ NPs, ranging from 15 to 30 nm in size, with mixed-phase structure composed of tetragonal and monoclinic structures. UV-visible spectroscopy showed a characteristic band at 281 nm with a bandgap energy of 3.7 eV, indicating effective stabilization by the phytochemicals in T. asiatica. EDX analysis revealed that the NPs contained 37.18 mol.% zirconium (Zr) and 62.82 mol.% oxygen. The ZrO₂ NPs demonstrated remarkable photocatalytic activity, degrading over 95% of methylene blue dye after 3 h of sunlight exposure. Additionally, the ZrO₂ NPs exhibited strong antibacterial effects, particularly against Gram-negative bacteria such as E. coli, and significant antioxidant activity, with low IC₅₀ values for hydroxyl radical scavenging. In conclusion, the green synthesis of ZrO₂ NPs using T. asiatica leaf extract is an effective, eco-friendly method that produces nanoparticles with remarkable antioxidant, antimicrobial, and photocatalytic properties, highlighting their potential for applications in water treatment, environmental remediation, and biomedicine.