Magnetically recyclable nanophotocatalysts in photocatalysis-involving processes for organic pollutant removal from wastewater: current status and perspectives

Photocatalysis, a promising technology for the removal of recalcitrant organic pollutants from wastewater has attracted global attention. The rational development of photocatalysts is crucial to the circular economy of photocatalytic water treatment. Furnishing highly efficient nanophotocatalysts with magnetism allows the breakthrough and practicability of the photocatalysis-involving processes inhibited by materials' poor recoverability. The strategy of embedding magnetic components in nanophotocatalysts and obtaining the magnetically recyclable nanophotocatalysts (MRNPCs) ensures the facile separation of photocatalyst materials from the treated water. The literature from 2012 to 2023 is reviewed to discuss the recent applications, mechanisms, and challenges of MRNPCs for organic pollutant removal. Various synthesis methods provide the desirable morphologies and properties of MRNPCs and therefore can be selected based on the application. In conventional photocatalysis, element doping, heterojunction construction, and hybrid material functionalization, have been applied to modify MRNPCs for better performance. Applications of MRNPCs in the photocatalysis-involving processes, including photocatalytic Fenton-like process, photocatalytic sulfate radical-based process, photocatalytic ozonation, and sono-photocatalytic process, are also overviewed. These processes have an increased production of reactive oxygen species, which ultimately improve the performance in contaminant removal. Furthermore, the perspectives and challenges of the MRNPCs are also discussed to shed light on the practicality of the technology. The critical review covers the applications, associated mechanisms, challenges, and prospects of magnetically recyclable nanophotocatalysts in photocatalysis-related processes.