Biosynthesis zinc oxide nanoparticles using Apium graveolens L. leaf extract and its use in removing the organic pollutants in water

This study consists of a reliable process for synthesizing ZnO NPs by green method. Here, Apium graveolens L. leaf extract is utilized as an efficient chelating and capping agent. The plant ingredients, structure, morphology, thermal behavior, chemical composition, and optical properties of ZnO nanoparticles were investigated using several characterization techniques, namely X-ray diffraction (XRD), field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscope (HRTEM), differential scanning calorimetry (DSC) analysis, Fourier transform infrared (FTIR) analysis, and UV-visible (UV-Vis) spectroscopy. The UV-Vis and FTIR analysis of A. graveolens L. leaf extract verified that this extract is a promising candidate for biosynthesizing ZnO NPs. The XRD spectrum, HRTEM, and the scanning electron microscope images confirmed the crystallinity and the spherical-shape of the ZnO NPs with an average size between 30 and 35 nm. The band-gap of the ZnO were measured to be around 3.132 eV. DSC analysis exhibits two endothermic peaks related to the water evaporation absorbed by the NPs and modification of zinc complex to zinc hydroxide, with a single exothermic peak related to the crystallization of ZnO NPs and degradation of organic materials. The ZnO NPs was employed for removing organic pollutants, that is, methyl orange (MO) from water using UV-Vis spectroscopy. Nearly an entire degradation of MO was achieved within 3 min of UV light radiation.