Confining Fe2O3 in Silicalite-1 for effective catalytic activity in bias-assisted photo-Fenton system for nitrobenzene degradation

Abstract

Removal of refractory organic pollutants by photo-Fenton process is of great significance to cleaner production. Low yield and utilization of photogenerated carriers limit the application of photo-Fenton process. Positive bias voltage is introduced into the photo-Fenton system for the first time so that the photogenerated electrons no longer flow to the external circuit but participate in the redox cycle of the photo-Fenton reaction. Under the applied bias voltage of +0.3 V, the efficiency of the system to degrade nitrobenzene reaches 95.4% in 60 min and still has 90.3% of nitrobenzene degradation efficiency after five runs while the photo-Fenton system without bias voltage is 80.0%. The bias voltage makes the band bending so that the band gap narrow, leading to easier generation of photogenerated electrons. Then the separated photogenerated electrons combine with Fe3+, which promotes the rapid redox cycle of Fe3+/Fe2+ in the photo-Fenton reaction. Both photogenerated electrons and holes are efficiently utilized in this work, which provides a new method for chemical treatment of refractory organic pollutants.