Photocatalytic degradation of tetracycline in aqueous medium using ZnWO4/Bi2MoO6 nanocomposites under natural sunlight

Upsurge in the usage of antibiotics in medical treatment has led to their spikes in water bodies, including drinking water causing health concerns. Here, we report a very efficient method of photocatalytic degradation of tetracycline antibiotic in an aqueous medium using 0.10ZnWO 4 /Bi 2 MoO 6 nanocomposites as Z-scheme heterojunction based solar photocatalyst. The structure, composition, and morphology of the photocatalyst have been thoroughly characterized. The photocatalytic degradation of tetracycline is initiated by spiking a trace quantity of hydrogen peroxide (H 2 O 2 ) in the reaction medium. Compared to pristine Bi 2 MoO 6 photocatalyst, the photocatalytic degradation of tetracycline by 0.10ZnWO 4 /Bi 2 MoO 6 nanocomposites is 5.3 times enhanced. This is attributed to improved inhibition of charge carrier recombination owing to the Z-scheme heterojunction formed in 0.10 ZnWO 4 /Bi 2 MoO 6 and due to better charge carrier mobility. More than 95% of tetracycline is degraded in 90 min, corresponding to a photocatalytic degradation rate of 0.123 L mg −1 min −1 . The total organic carbon analysis suggested 66.4% mineralization of TC. The generation of reactive oxygen species (ROS), e.g., hydroxyl radicals, superoxide radicals, and their role towards photocatalytic degradation of tetracycline is confirmed by showing negative results in the presence of ROS scavengers. The sustained generation of H 2 O 2 in the reaction medium is discussed. The degradation mechanism has been discussed by analyzing the degradation products via coupled ultra-performance liquid chromatography to quadrupole time-of-flight mass spectrometry technique (UPLC–Q-Tof–MS).