Crystalline ZrO2 nanoparticles via phyto-synthesis for UV-driven dye adsorption and antimicrobial activity: A dual-functional approach

In this study, leaf extract of Shorea robusta was used as a natural capping and reducing agent for phyto-synthesis of zirconium oxide nanoparticles (ZSR). UV–Vis spectroscopy, FTIR, XRD, BET, SEM/EDS, HRTEM, and XPS studies were used to characterize the nanoparticles. A characteristic absorption peak at 219 nm confirmed the formation of ZrO₂, which exhibited a predominantly tetragonal crystalline phase with an average particle size of ∼10 nm. The adsorption performance of ZSR was evaluated for Acid Blue 74 (Indigo Carmine) dye under batch conditions by varying pH, dosage, initial concentration, and contact time. Under UV-assisted conditions, ZSR achieved a maximum removal efficiency of 98%. The pseudo-second-order model best described the kinetic data, while equilibrium data fitted the non-linear Freundlich isotherm, supported by higher R² values and lower error functions. Significant inhibitory action against Staphylococcus aureus, Escherichia coli, and Candida albicans was found in antimicrobial testing. The latter exhibited the strongest response, with an inhibition zone of 7.0 ± 0.33 mm at 62.5 µL. These results establish ZSR as a dual-functional, cost-effective, and reusable nanomaterial with promising applications in wastewater treatment and microbial control.