Efficient fenton-like degradation of ofloxacin over bimetallic Fe-Cu@Sepiolite composite

An effective method for increasing the utilization efficiency of active components in heterogeneous Fenton-like catalysts was provided. 1.5 at.% Fe-Cu bimetal on 1D sepiolite (Sep) (D-FeCu@Sep) with high dispersion and reduced chemical valence was prepared via complexation-carbonization process of glutathione. 93% of ofloxacin (OFX, a typical antibiotic of emerging concern) was degraded over D-FeCu@Sep without any extra energy input at the optimum conditions (100 mL 10 mg/L OFX, pH 5.0, 3.0 g/L catalyst and 0.03 M H₂O₂), which was enhanced by 2.3, 3.0 and 1.7 times compared with aggregated Fe-Cu on Sep (A-FeCu@Sep), monometallic Fe on Sep (D-Fe@Sep) and Fe-Cu on blocky Celite (D-FeCu@Celite), respectively. Moreover, it exhibited an excellent performance at a wide working pH range from acidic to neutral conditions (pH 3.2-7.2) with a satisfied stability. Based on the characterizations of X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM), hydrogen temperature-programmed reduction (H₂-TPR) and electrochemical impedance spectroscopy (EIS), the proposed complexation-carbonization process of glutathione played an important role in the good Fenton performance of D-FeCu@Sep. The complexation of Fe and Cu ion by glutathione favors the high dispersion of Fe-Cu active component, afterward the reduced chemical valence results from carbonization process of glutathione. Moreover, the 1D nanofibrous structure of D-FeCu@Sep could greatly increase the surface electron transfer efficiency compared with D-FeCu@Celite. This study provides a method alternative to the heterogeneous Fenton chemistry by increasing the utilization efficiency of active components.