Photocatalytic degradation of levofloxacin by a novel Sm₆WO₁₂/g-C₃N₄ heterojunction: Performance, mechanism and degradation pathways

Recent year pharmaceutical pollutants have highly detected in environment, because they do not completely mineralized and remain toxic. Semiconductor photocatalyst materials have well recognized as promising technology for environmental pollutants removal in the presence of visible light. In this work, a novel binary Sm₆WO₁₂ modified g-C₃N₄ nanosheets heterojunction was fabricated via simple facile method. The morphology of the newly prepared g-C₃N₄ and Sm₆WO₁₂ was confirmed as nanosheets and nanorods by using microscopy techniques. The sequence of characterization results verified that the Sm₆WO₁₂/g-C₃N₄ synergistically integrate the excellent properties and successful construction of hetero-structure between the Sm₆WO₁₂ and g-C₃N₄. The Sm₆WO₁₂/g-C₃N₄ nanocomposite heterojunction catalyst shows higher photocatalytic efficiency towards degrading pharmaceutical pollutant levofloxacin compared to individual g-C₃N₄ and Sm₆WO₁₂ photocatalyst. The results indicate that about 90.8% of levofloxacin was degraded after 70 min in the presence of Sm₆WO₁₂/g-C₃N₄ nanocomposite. Through radical trapping experiments, O₂^•− and ^•OH were proved to be the leading reactive oxidative species contributing to degradation of levofloxacin. Possible photodegradation pathways were proposed based on the detected intermediate products and transformation products. Furthermore, the synthesized Sm₆WO₁₂/g-C₃N₄ heterojunction demonstrated excellent reusability and stability without of loss of photocatalytic activity. Favorably, this study might provide a deep insight into mechanism and possible degradation pathways of levofloxacin by Sm₆WO₁₂ modified g-C₃N₄ heterojunction photocatalyst.