Energy-saving photo-degradation of three fluoroquinolone antibiotics under VUV/UV irradiation: Kinetics, mechanism, and antibacterial activity reduction

Due to the inefficient treatment by the biotic and UV-disinfection processes in wastewater treatment plants, the broad-spectrum Fluoroquinolone antibiotics (FQs) are frequently detected in water environment around the world. In this work, the photo-degradation of three FQs (norfloxacin-NOR, ciprofloxacin-CIP, levofloxacin-LEV) by VUV/UV irradiation was investigated. The results showed that the degradation of FQs in VUV/UV irradiation system were more effective than that in UV irradiation system by enhanced the defluorination and decarboxylation . FQs could be degraded more efficiently with high temperature and low initial concentration, and the effect of flow rate was small. Initial pH played a key role in degradation of NOR and CIP. Most anions could slightly affect the FQs removal in water, except the carbonate and phosphate species. 1 O 2 and ·OH played the primary role in FQs degradation in VUV/UV system. Defluorination, decarboxylation, and piperazine ring oxidation were the main degradation pathways for three FQs degradation, but demethylation was a particular degradation pathway of LEV. Antibacterial activities of FQs aqueous sample were reduced in both VUV/UV and UV system, while the removal of antibacterial activities in the VUV/UV process were more efficient than UV process for NOR and LEV. VUV/UV system was more energy-saving for removing FQs. These results suggested that VUV/UV system is potential alternative in replacing or enhancing UV system in wastewater treatment plants for FQs removal in the future.