MoO2-enhanced Fe-loaded biochar promotes Fe2+/Fe3+ cycling for activation of peroxydisulfate to degrade organic pollutants

Biochar loaded with bimetallic Fe/Mo (Fe/Mo-BC) was prepared as a cost-effective catalyst for the degradation of organic matter by activated peroxydisulfate, in which MoO2 was used as a co-catalyst to enhance Fe2+/Fe3+ cycling. The tetracycline-degradation efficiency of the system reached 74.49 % within 10 min, and it showed high removal rates over a wide pH range (3–9). Quenching experiments and electron paramagnetic resonance analyses showed that 1O2, •OH, O2•-, and SO4•− produced by the Fe/Mo-BC/PDS system are involved in tetracycline degradation, with 1O2 and •OH being the dominant active substances. X-ray photoelectron spectroscopy analysis revealed that Mo(IV) reduces Fe3+ to Fe2+ and oxidizes itself to Mo(VI). In addition, the Fe/Mo-BC remained stable and could be recycled three times, indicating the feasibility of this system for practical applications. The possible pathways of TC degradation by this system were investigated by LC-MS and DFT calculations. Thus, the present study provides a feasible strategy for the use of biochar-loaded bimetallic materials and PDS for the degradation of organic matter.