Visible-Light-Driven p-n Type BiMSbO6(M=Ti, Sn)/BiOBr Heterojunction Photocatalyst toward Degradation of Levofloxacin

A new visible light-driven p-n type BiMSbO6(M=Ti, Sn)/BiOBr heterojunction photocatalyst was prepared in this paper. The XRD results showed that pure BiTiSbO6 and pure BiSnSbO6 crystallized well with the pyrochlore-type structure, stable cubic crystal system by space group Fd3 m and the XPS results further confirmed its high crystallinity. The crystal parameters of pure BiSnSbO6 and pure BiTiSbO6 were 10.23459 angstrom and 9.87708 angstrom, respectively. After visible light irradiation for 100 minutes, the removal rate of levofloxacin with 5 wt%, 10 wt% or 20 wt% BiMSbO6(M=Ti, Sn)/BiOBr heterojunction photocatalyst could all reach more than 85%, which was far higher than that with pure BiSnSbO6 (4.79%) as a photocatalyst or that with pure BiTiSbO6 (5.35%) as a photocatalyst. In addition, the form of p-n heterojunction improved the reusability of pure BiOBr. After four cycles of photodegradation experiments for levofloxacin, the removal rate of levofloxacin with 20 wt% BiTiSbO6/BiOBr heterojunction photocatalyst or 10 wt% BiSnSbO6/BiOBr heterojunction photocatalyst decreased by 11.48% or 11.02%. However, the removal rate of levofloxacin with pure BiOBr decreased by 18.68%. Moreover, h(+) contributed the most during the degradation procedure of levofloxacin with BiMSbO6(M=Ti, Sn)/BiOBr heterojunction photocatalyst. Eventually, working mechanism of BiMSbO6(M=Ti, Sn)/BiOBr heterojunction photocatalyst was described in detail.