Effective and continuous degradation of levofloxacin via the graphite felt electrode loaded with Fe3O4

Abstract

• Fe 3 O 4 /GF electrode was prepared by moderate solvothermal method. • The Fe 3 O 4 /GF cathode can be used in electro-Fenton (EF) with a wide pH range. • The Fe 3 O 4 /GF cathode can directly use the generated H 2 O 2 to obtain more •OH. • Levofloxacin (LEV) can be mineralized continuously under neutral conditions. • The Fe 3 O 4 /GF can maintain a good catalytic activity after 6 cycles. Electro-Fenton (EF) generally relies on the addition of iron in acidic conditions, which caused an increase in cost and secondary pollution. In this paper, Fe 3 O 4 was in-situ loaded on the surface of the graphite felt (GF) electrode by a moderate solvothermal synthesis method. The modified electrode (Fe 3 O 4 /GF) could be used in a wide pH range (acid, and even neutral conditions), and Fe dissolution was not detected under neutral conditions. Compared with the pre-activated graphite felt electrode (aGF), the Fe 3 O 4 /GF electrode could directly utilize the generated hydrogen peroxide (H 2 O 2 ) to obtain more hydroxyl radicals (•OH). The influence of electrolyte types was also investigated, and the results showed unstable or reductive electrolytes were not conducive to the degradation of levofloxacin (LEV). The Fe 3 O 4 /GF electrode had good reusability, and could maintain a LEV degradation ratio of over 70% during 6 cycles. The degradation effect of EF with unmodified GF is poor under neutral conditions, but the degradation with the Fe 3 O 4 /GF cathode is continuous and has a high total organic carbon (TOC) removal ratio of 81.4% at 6 h. The Fe 3 O 4 /GF cathode is conducive to promote the application of EF technology in the field of wastewater treatment, especially under neutral conditions.