Nano-sized iron oxides supported on polyester textile to remove fluoroquinolones in hospital wastewater†
In this study, we examined the removal kinetics of two fluoroquinolones (FQs), flumequine (FLU) and ciprofloxacin (CIP), in synthetic wastewater (SWW) and real hospital wastewater (RHW) using FeOx thin films, peroxymonosulfate (PMS) and visible light. Nano-sized iron oxides (FeOx) supported on polyester textile (PES) were synthesized by a novel high-power impulse magnetron sputtering (HiPIMS) method. The O2/Ar ratio is an important factor to tune Fe oxidation, which controls the composition of the thin film and thus the capability of the resulting FeOx for PMS activation. Based on scavenging experiments, sulfate radicals were shown to be predominantly involved in the heterogeneous oxidation reaction. Competitive effects with reactive species could explain the lower degradation rate constants in mixtures relative to those in single systems. In contrast to chlorides, organic matter, sulfates and phosphates commonly found in RHW dramatically decreased the removal performance of both target compounds, FLU and CIP. However, increasing the PMS concentration to 3 mM improved considerably the degradation and mineralization, even in real wastewater. The good stability and reusability of the FeOx/PES material have been confirmed in hospital wastewater over five successive oxidation cycles.