Eco-friendly fabrication of multifunctional magnetic plasmonic photocatalyst for adsorption, SERS monitoring and photodegradation of residual fluoroquinolone antibiotics in water

In this work, a kind of multifunctional magnetic plasmonic photocatalyst was prepared by a green and efficient process. Magnetic mesoporous anatase titanium dioxide (Fe3O4@mTiO2) was synthesized by microwave-assisted hydrothermal, and Ag NPs were simultaneously in-situ grown on Fe3O4@mTiO2 (Fe3O4@mTiO2@Ag), graphene oxide (GO) was then wrapped on Fe3O4@mTiO2@Ag (Fe3O4@mTiO2@Ag@GO) to increase its adsorption capacity for fluoroquinolone antibiotics (FQs). Owing to the localized surface plasmon resonance (LSPR) effect of Ag, as well as the photocatalytic capacity of TiO2, a multifunctional platform based on Fe3O4@mTiO2@Ag@GO was constructed for adsorption, surface-enhanced Raman spectroscopy (SERS) monitoring and photodegradation of FQs in water. The quantitative SERS detection of norfloxacin (NOR), ciprofloxacin (CIP), and enrofloxacin (ENR) was demonstrated with LOD of 0.1 μg mL-1, and the qualitative analysis was confirmed by density functional theory (DFT) calculation. The photocatalytic degradation rate of NOR over Fe3O4@mTiO2@Ag@GO was about 4.6 and 1.4 times faster than that of Fe3O4@mTiO2 and Fe3O4@mTiO2@Ag, indicating the synergetic effects of Ag NPs and GO, the used Fe3O4@mTiO2@Ag@GO can be easily recovered and recycled for at least 5 times. Thus, the eco-friendly magnetic plasmonic photocatalyst provided a potential solution for the removal and monitoring of residual FQs in environmental water.