Green Synthesis of ZrO2 Nanoparticles From Gardenia resinifera for Efficient Photocatalytic Methylene Blue Dye Degradation With Antimicrobial and Antioxidant Properties

ABSTRACT This study focuses on the green synthesis of zirconium oxide nanoparticles (ZrO 2 NPs) using Gardenia resinifera leaf extract and evaluates their multifunctional applications. The synthesized ZrO 2 nanoparticles (Gr‐ZrO 2 NPs) were characterized through various optical and structural analyses. UV‐Vis spectroscopy showed peak absorbance at 294 and 404 nm. FTIR analysis identified phytochemical functional groups from the leaf extract involved in nanoparticle formation. X‐ray diffraction confirmed the monoclinic and tetragonal phases of the Gr‐ZrO 2 NPs, supported by SAED patterns. SEM images revealed spherical morphology, while EDX spectra confirmed the presence of Zr (60.79%) and O (39.21%) elements. TEM analysis indicated spherical nanostructures with a diameter of approximately 10 nm. Gr‐ZrO 2 NPs demonstrated a significant methylene blue dye removal efficiency of over 91% within 3 h under the sunlight. They also showed notable antibacterial activity, with MIC value ranging from 2.80 ± 0.27 to 6.03 ± 0.10 μg/mL. Gr‐ZrO 2 NPs exhibited significant antioxidant activity; the lowest IC 50 value (14.88 ± 0.04 μg/mL) was recorded for nitric oxide radical scavenging. These results suggest that the synthesized Gr‐ZrO 2 NPs are effective as antioxidants and antimicrobials and hold promise as photocatalytic agents, potentially serving as candidates for environmental remediation, water treatment, and biomedicine.