Synthesis and characterization of surfactant-assisted ZnO–CeO2 nanocomposites for the photocatalytic degradation of bentazon under UV light irradiation

Nowadays, organic pollutants such as pesticides and herbicides have harmful effects on ecosystems and human health due to intensive agriculture. In this study, The ZnO–CeO2 photocatalysts were fabricated with and without Sodium Dodecyl Sulfate (SDS) and Hexamethylenetetramine (HMT) surfactants by using co-precipitation method. The synthesized photocatalysts were characterized by using various techniques to determine the effect of composition on the structural, optical, morphological and photocatalytic properties. The XRD pattern exhibited the presence of diffraction peaks related to ZnO (hexagonal) and CeO2 (cubic) in the nanocomposite. The optical bandgap energy was 2.5 eV, 2.1 eV, and 2.6 eV for ZnO–CeO2, ZnO–CeO2-SDS and ZnO–CeO2-HMT, respectively. SEM images revealed the nanorods morphology of ZnO decorated with CeO2 nanoparticles confirmed the formation of nanocomposite. The photocatalytic activity of ZnO–CeO2 photocatalysts was assessed for the removal of bentazon as a model pollutant. Under UV-light irradiation, ZnO–CeO2, ZnO–CeO2-SDS and ZnO–CeO2-HMT showed degradation efficiency 84%, 96% and 90% respectively in 180 min. Among them, ZnO–CeO2-SDS showed the highest degradation efficiency and maintained good stability after three reuse cycles. Furthermore, scavenger studies revealed that hydroxyl radicals were the dominant reactive species responsible for bentazon degradation during the photocatalytic process.