Enhanced electro-Fenton degradation of sulfamethazine using Co-based selenite modified graphite cathode via in-situ generation of •OH

Abstract

Electro-Fenton (EF) reaction has been regarded as a promising technology for practical wastewater treatments. However, the generation of H2O2 and •OH was limited by low O2 utilization and protonation efficiency in the conventional EF system. This research synthesized a novel electrocatalyst, Co12(OH)2(SeO3)8(OH)6 (CoSeO) to achieve efficient wastewater treatment via in-situ H2O2 generation in the EF system. The modified graphite plate-based cathode (CoSeO@GP) was fabricated by using a facile hydrothermal method combined with a simple coating. The CoSeO@GP cathode that had both hydrophilic and aerophilic properties achieved efficient H2O2 production (26.15 mgL-1h−1) at low air flow rate. Moreover, the average protonation rate was significantly improved to 0.00803 molH-1min−1 with this cathode. The presence of Co2+/Co3+ could significantly promote the in situ H2O2 decomposition, and boost the production of •OH. Sulfamethazine (SMZ) was completely degraded in 90 min with the kinetic constant of 0.05959 min−1 by using the CoSeO@GP cathode. In addition, this cathode maintained high stability and applicability after a 10-cycle continuous operation. This study provided a proof-of-concept design strategy for developing novel EF cathodes for the treatment of recalcitrant pollutants.