The electro-Fenton/sulfite process with Fe-Mn bimetallic catalyst for diclofenac degradation at neutral pH

The application of bimetallic catalysts in heterogeneous electro-Fenton (Hetero-EF) is limited due to its poor performance over a wide pH range. In this work, the Hetero-EF/sulfite process was constructed with FeMn@C as the catalyst to improve the degradation of pollutants under neutral pH. The removal efficiency of diclofenac (DCF) (97.8%) was significantly higher than that of Hetero-EF (15.0%) at pH 7, in which the degradation rate constant k was increased by 19.75 times. The existence and transformation process of various active species ( • OH, SO 4 •- , O 2 •- , and 1 O 2 ) in the process were verified by capture experiments and electron paramagnetic resonance (EPR) test. The possible DCF degradation pathway was also proposed. The introduction of sulfite could reduce Fe 3+ and Mn 3+ , promote the Fe(II)/Fe(III) and Mn(II)/Mn(III) cycles, strengthen the generation of active species, and thus promote the degradation of pollutants. The removal efficiency was still maintained 76.6% after five cycles. The Hetero-EF/sulfite process is a simple, feasible, and efficient method to degrade pollutants, which has a broad application prospect.