Magnetic field-enhanced radical intensity for accelerating norfloxacin degradation under FeCu/rGO photo-Fenton catalysis

Abstract Improving the efficiency of photo-induced carriers (e-/h+) is one of the most effective routes to accelerate the heterogeneous photo-Fenton process. Herein, inspired by inverse Lorentz forces of opposite charges in a magnetic field, an external magnetic field intensified photo-Fenton catalysis for norfloxacin (NOR) degradation was constructed under visible light irradiation. The reduced graphene oxide-supported Fe-Cu bimetal (FeCu/rGO), obtained by employing common iron powder as a reducing agent, was served as a model catalyst. Impressively, the intensities of both carriers and radicals (•OH and •O2–/•HO2) were increased after the normal photo-Fenton reactor was placed into two fixed permanent magnets (200 mT), leading to a 34.1% improvement in NOR removal. Meanwhile, the consumption of H2O2 was also critically boosted (from 65.1% to 92.1%). Combined with theoretical studies, the enhanced radicals were not only resulted from accelerated carrier separation but also extended O-O and O–H bonds in H2O2 and facilitated spin evolutions of 1[HO•↑···↓•OH] → 3[HO•↑···↑•OH] and 1[HOO•↑···↓•H] → 3[HOO•↑···↑•H]. This study offers an insight into the specific role of an external magnetic field in promoting heterogeneous photo-Fenton catalysis.