Highly efficient photo-degradation for tetracycline elimination in pharmaceutical wastewater by α-Fe2O3/V2O5/BC assisted peroxymonosulfate activation

In this study, a novel α-Fe2O3/V2O5/BC catalyst with high peroxymonosulfate (PMS) activation performance was constructed by co-pyrolysis method and 99.58% of tetracycline is degraded within 120 min. The electrons conversion of Fe-V on biochar surface induces the continuous generation of sulfate radical and singlet oxygen molecules (1O2). The XPS results show that it is Fe3+ and Fe0 rather than Fe3+ and Fe2+ in the iron cycle after the introduction of vanadium, indicating a more efficient electron transfer efficiency between interface. The optical properties characterization and density function theory calculation (DFT) of α-Fe2O3/V2O5/BC reveal that the electrons of the entire α-Fe2O3 and the vanadium atoms are redistributed to new molecular orbitals due to strong interfacial chemical bonding, inducing a direct transfer of electrons to generate 1O2 for tetracycline removal that is the main cause of selective degradation. Besides, the possible degradation mechanism and tetracycline degradation pathways were also proposed. The α-Fe2O3/V2O5/BC maintains a high removal efficiency of tetracycline only decrease by 7.09% after six cycles. This study provides a better strategy and recyclable purification material for the efficient treatment of antibiotic pharmaceutical wastewater.