Eco-friendly flower-like ZnO nanostructures for photocatalytic treatment of levofloxacin-contaminated wastewater

Abstract

Abstract This work reports an environmentally benign strategy for producing zinc oxide (ZnO) nanoflowers from rubber fig ( Ficus elastica ) leaf extract and assesses their efficacy in sunlight-assisted degradation of levofloxacin. UV-visible spectrum displayed a clear absorption band at 373 nm, characteristic of ZnO nanoparticles. Field-emission scanning electron microscopic images showed flower-like nanostructures, and Fourier transform infrared spectra showed phytochemical functional moieties from the leaf extract that assist nanoparticle formation and stabilize the surface. X-ray diffraction patterns endorsed the crystallinity with a mean crystallite dimension of 44.86 nm and lattice parameters matching the hexagonal wurtzite structure. X-ray photoelectron spectroscopy further verified Zn 2+ through Zn 2p3∕2 and Zn 2p1∕2 peaks at 1021.32 and 1044.42 eV, a lattice oxygen signal at 529.9 eV, and minor C 1s contributions from residual phytochemicals, indicating high purity and a structurally stable lattice. Photoluminescence spectra showed a near-band-edge ultraviolet emission at 403 nm together with visible bands associated with defect-related states. Under natural sunlight, the ZnO nanoflowers consistently degraded levofloxacin, and the removal improved as the catalyst dose increased. The dataset follows a pseudo-first-order expression; the estimated rate constants span 0.0044 to 0.0056 min − 1 and R 2 > 0.99. The rise in performance at higher loadings aligns with a larger number of accessible surface sites and more efficient formation of reactive oxygen species. Collectively, ZnO nanoflowers synthesized by a green route show strong promise for the sustainable treatment of pharmaceutical wastewater.