Treatment of pharmaceutical wastewater by heterogeneous Fenton process: an innovative approach

Abstract

With indiscriminate use and disposal, antibiotics enter the water bodies and thus are categorized as emerging pollutants. We report the studies on the degradation of norfloxacin, a well-known antibiotic, using hydrogen peroxide (H2O2) and zinc oxide nanoparticles (ZnO) by heterogeneous Fenton process in the presence of sunlight. We fabricated ZnO nanoparticles by hydrothermal method. The geometry of norfloxacin was optimized using Hartree–Fock density functional theory. We used UV–Vis spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy techniques to determine various crystal properties, i.e., structure, morphology, size and shape of the ZnO nanoparticles. However, we evaluated the crystal size, particle size and their distribution employing Debye–Scherrer equation and ImageJ processing. The catalytic efficacy of ZnO nanoparticles was assessed by the abatement of norfloxacin at pH 10. The activity and stability of used ZnO catalyst for norfloxacin degradation were established. The recovered catalyst is reusable up to six times without activity loss. Liquid chromatography–mass spectrometry analysis confirmed the presence of various intermediates. A probable reaction mechanism for degradation of norfloxacin is proposed. The ZnO-catalyzed heterogeneous Fenton process proves to be the ideal approach for the degradation of antibiotics in wastewater. Herein, we report that generation of hydroxyl radical by the action of sunlight along with ZnO nanoparticles from hydrogen peroxide effectively degrades norfloxacin. Its structure has been optimized by density functional theory using Gauss view computational software. ZnO nanoparticles have been characterized by various techniques, e.g., XRD, SEM, TEM, etc. Various intermediate products have been recognized by LCMS analysis.