Magnetic dual Z-scheme g-C3N4/BiVO4/CuFe2O4 heterojunction as an efficient visible-light-driven peroxymonosulfate activator for levofloxacin degradation

The coupling of photocatalysis and peroxymonosulfate (PMS) activation is considered as a promising strategy for the removal of organic pollutants. However, the development of visible-light-excited efficient photocatalysts for PMS activation remains challenging. Herein, a new recyclable dual Z-scheme g-C3N4/BiVO4/CuFe2O4 (CN/BVO/CFO) heterojunction was first fabricated employing a simple hydrothermal approach. The results showed that the photocatalytic degradation behavior of levofloxacin (LEV) by CN/BVO/CFO under visible light illumination was enhanced compared with single BVO, CN, CFO and binary CN/BVO. Moreover, after adding PMS, the removal efficiency of LEV over CN/BVO/CFO/Vis/PMS system reached 96.2% within 60 min, which was 3.5 and 4.3 times higher than that of CN/BVO/CFO/Vis and CN/BVO/CFO/PMS, respectively. Characterization test and mechanism analysis indicated that the improved catalytic activity resulted from the dual Z-scheme heterostructure and the synergistic effect between photocatalysis and PMS activation, making the production of multiple active species. Additionally, CN/BVO/CFO/Vis/PMS system exhibited supreme mineralization ability, low degradation product toxicity and acceptable adaptability to solution pH, coexisting anions and organics. More importantly, the favorable magnetic separation and stability would provide convenience for the potential practical application of CN/BVO/CFO. This research may give a perspective on the design of efficient dual Z-scheme photocatalyst for PMS activation in environmental remediation.