The type II MIL-100/BiOBr heterojunctions promote efficient photo-Fenton degradation of tetracycline hydrochloride

The low efficiency of photogenerated carriers separation and slow cycling of Fe 2+ /Fe 3+ in Fe-based metal–organic frameworks (MOFs) have limited the improvement of their photo-Fenton activity. Therefore, in this work, MIL-100/BiOBr heterogeneous photo-Fenton catalyst was constructed by compositing MIL-100 with BiOBr nanosheets through a simple solvent evaporation method. In this system, the type II heterojunctions formed by the close contact of MIL-100 and BiOBr can promote the separation of photogenerated carriers and accelerate the redox cyclic of Fe 2+ /Fe 3+ , thereby significantly enhancing the photo-Fenton activity. Under visible light irradiation for 60 min, the best removal rate of tetracycline hydrochloride (TCH) by MIL-100/BiOBr is 94.3 %. Remarkably, the MIL-100/BiOBr exhibits a nearly fourfold increase in degradation rate constant compared to MIL-100 at photo-Fenton system. In addition, the catalysts can maintain high degradation performance over a wide pH range (3–9) and the co-existence of different anions. An in-depth investigation of the degradation mechanism reveals that superoxide radicals ( · O 2 – ) and hydroxyl radicals (·OH) play major roles in the photo-Fenton system. Based on this, the possible degradation pathways were proposed. Therefore, this study provides a new strategy for Fe-based MOFs to remove emerging pollutants from wastewater by photo-Fenton reaction.