Activation of peroxymonosulfate via a novel UV/hydrated Fe(III) oxide coupling strategy for norfloxacin removal: Performance and mechanism

Abstract

Advanced oxidation processes (AOPs) have been successfully applied for the degradation of fluoroquinolones, but most studies ignored the removal of fluorine ions (F−) generated after the degradation, and the remaining F− would cause secondary pollution to the water body. In this study, a novel UV radiation/hydrated Fe(III) oxide (HFO) coupling strategy was utilized to activate peroxymonosulfate (PMS) for the comprehensive enhanced removal of norfloxacin (NX) and the generated F−. Results showed that UV/HFO/PMS process significantly improved NX degradation efficiency compared with individual system, and NX degradation efficiency of 97.3% could be achieved by reactive oxygen species (ROS) generated in the process, in which singlet oxygen (1O2) was the main ROS. Moreover, the remaining concentration of F− was generally below 0.35 mg/L within a wide pH range (4–10). And the simultaneous adsorption of HFO for F− is mainly related to coordination and electrostatic interaction. After five cycles, the catalytic efficiency of HFO for NX removal only dropped by 4.4%. Besides, UV/HFO/PMS system had great anti-interference ability on coexisting anions. UV/vis two-dimensional correlation spectroscopy (2DCOS) analysis revealed that ROS would preferentially degrade the piperazine ring, and the quinolone group would be destroyed before the heteroatom during the degradation of NX. This work provides new insights for the treatment of antibiotic pollution.