English abstract
Pharmaceuticals, newly recognized classes of environmental pollutants, are becoming increasingly problematic contaminants of either surface water or ground water around industrial and residential communities. Pharmaceuticals are constantly released into aquatic environments, mainly due to their widespread consumption and complicated removal in wastewater treatment plants. Heterogeneous photocatalysis appear to be one of the most destructive advanced oxidation processes (AOPs) for organic contaminants and it is possible to obtain complete mineralization of organic pollutants into ecofriendly end products under visible and solar light irradiation. In this work six types of zinc oxide and cerium doped zinc oxide photocatalysts with different particle size and morphology have been prepared by a simple hydrothermal method. The prepared samples were characterized by various analytical techniques such as XRD, Raman, XPS, UV-DRS, FT-IR, SEM and EDX. XRD studies revealed that the prepared ZnO samples are wurtzite hexagonal structure. Morphological studies examined by SEM showed that the synthesised ZnO and Ce doped ZnO shows chrysanthemum like structure and were constructed by several nanorods and nanosheets. The grain size of ZnO and Ce doped ZnO particles were calculated by using Debye-Scherrer formula and varied from 31 nm to 77 nm. XPS and EDX analysis confirmed the stoichiometry of pure ZnO and Ce doped ZnO nanostructures. The optical properties were investigated by UV-vis DRS, which indicated that the ZnO and Ce-ZnO possess a band gap from 3.20 eV to 3.15 eV. The Ce doping into ZnO slightly altered the band gap from 3.20 eV to 3.15 eV. Furthermore, the photocatalytic activity studies revealed that the as-prepared ZnO and Ce-doped nanostructured materials exhibit an excellent photocatalytic performance for degradation of pharmaceutical solution, such as nizatidine, levofloxacin and acetaminophen under UV-B light irradiation. The photocatalytic mineralization of pharmaceuticals has been enhanced over the as-prepared Ce-doped ZnO when compared to pure Zno. Around 95% of the degradation of these pharmaceuticals was achieved within 4 hrs. These results suggest that ZnO and Ce-doped ZnO will be the promising candidate for the decontamination of hazardous low concentrated pollutions in water.
