One-pot synthesis of magnetic CuO/Fe2O3/CuFe2O4 nanocomposite to activate persulfate for levofloxacin removal: Investigation of efficiency, mechanism and degradation route

A cost-effective one-pot hydrothermal route was used to prepare novel magnetic CuO/Fe2O3/CuFe2O4 nanocomposites activating persulfate (PS) to remove levofloxacin from water. The optimized CuO/Fe2O3/CuFe2O4 sample (denoted as CuFeO-2) possessed a higher catalytic performance for levofloxacin degradation by activating PS than those of CuO, Fe2O3, CuFe2O4 and recently reported heterogeneous catalysts. After 120 min, the degradation efficiency and the mineralization degree of levofloxacin (10 mg∙L−1) in CuFeO-2/PS system reached 75.5% and 64.5%, respectively. The influence of some significant reaction parameters (e.g., PS dosage, catalyst dosage, initial pH, temperature and coexisting inorganic anions) on levofloxacin removal in CuFeO-2/PS system was studied and analyzed. Although the catalytic activity of magnetic CuFeO-2 slightly declined after each cycle due to the loss of active Cu(II), the recyclability of CuFeO-2 was significantly better than that of CuO. The trapping experiments and ESR studies confirmed that singlet oxygen (1O2), sulfate radical (SO4•−) and hydroxyl radical (•OH) were generated in CuFeO-2/PS system, thus, the degradation of levofloxacin can be achieved via the non-radical and radical oxidation processes. The role of copper, iron and oxygen elements in CuFeO-2 on PS activation was investigated by ART-FTIR and XPS. The possible degradation routes of levofloxacin were put forward according to the detected intermediate products. Moreover, the performance of CuFeO-2/PS system for levofloxacin degradation in real water matrix was also investigated.