Rapid photocatalytic degradation of 2, 4-dichlorophenoxy acetic acid by ZnO nanoparticles synthesized using the leaf extract of Muntingia calabura

This is the first report describing the photocatalysis-based degradation of 2,4-dichlorophenoxy acetic acid (2,4-D) under sunlight irradiation with zinc oxide nanoparticles (ZnO NPs) obtained by utilizing the phytocomoponents present in the leaf extract of Muntingia calabura. The synthesized ZnO NPs were seen as agglomerated nanoflower structures on the SEM image. The purity of the ZnO NPs was ascertained from the results of EDS (only Zn and O peaks) and XRD (only hexagonal wurtzite phase). UV-vis spectrum showed the characteristic surface plasmon resonance peak at 364 nm, which yielded bandgap energy of 3.41 eV. The crystallinity nature of the ZnO NPs was verified from the intense Raman spectrum signal at 440 cm^–1. The PL spectrum signified the optical properties by showing blue and green-yellow bands. The TGA/DTA spectra emphasized the thermal resistance of ZnO NPs with 5.47% weight loss up to 800 °C. XPS affirmed the valence states of Zn as well as O atoms and the results were consistent with EDS. BET analysis revealed the mesoporous texture with 15.54 m²/g specific surface area - relatively larger than the few of the published reports. The sunlight-mediated degradation of 2,4-D showed rapid degradation of 99.34% (10 ppm, at 0.2 g/L dosage) within 3 h. Therefore, the photocatalyst prepared in this study with the aqueous extract of M. calabura leaves can be effectively used for the degradation of various contaminants present in the wastewater.