C. Vijayaraj, G. Nedunchezhian, S. Sozhaveni and S. Sofiya Lawrence Mary
Abstract
The development of sustainable nanomaterials for wastewater treatment has attracted considerable attention due to the increasing discharge of dye-containing industrial effluents. In this study, zirconium oxide (ZrO2) nanoparticles were synthesized via a green route using waste Terminalia catappa leaf extract as a natural reducing and stabilizing agent. The synthesized nanoparticles were characterized using UVâVisible spectroscopy, FTIR, XRD, SEMâEDX, and TEM analyses. XRD confirmed the formation of crystalline monoclinic ZrO2 nanoparticles with an average crystallite size of 24 nm, while SEM and TEM revealed predominantly spherical particles with an average size of approximately 27 nm. FTIR analysis indicated the involvement of phytochemicals from the leaf extract in nanoparticle formation and stabilization. The optical band gap was determined to be 3.2 eV, indicating suitability for photocatalytic applications under visible-light irradiation. The photocatalytic activity of the synthesized ZrO2 nanoparticles was evaluated using methylene blue as a model pollutant. A maximum degradation efficiency of 99.8% was achieved within 90 min under visible-light illumination. Kinetic studies followed pseudo-first-order behavior, and radical scavenging experiments confirmed the significant role of reactive oxygen species in the degradation process. The enhanced photocatalytic performance was attributed to efficient charge separation, high surface area, and abundant active sites. These findings demonstrate that waste-derived ZrO2 nanoparticles are promising eco-friendly photocatalysts for the efficient treatment of dye-contaminated wastewater and support the sustainable utilization of agricultural bio waste in environmental remediation.