Emerging Strategies for the Photoassisted Removal of PFAS from Water: From Fundamentals to Applications

Per- and polyfluoroalkyl substances (PFAS) are a diverse group of synthetic fluorinated compounds widely used in industrial and consumer products due to their exceptional thermal stability and hydrophobicity. However, these same properties contribute to their environmental persistence, bioaccumulation, and potential adverse health effects, including hepatotoxicity, immunotoxicity, endocrine disruption, and increased cancer risk. Traditional water treatment technologies, such as coagulation, sedimentation, biological degradation, and even advanced membrane processes, have demonstrated limited efficacy in removing PFAS, as they primarily separate or concentrate these compounds rather than degrade them. In response to these limitations, photoassisted processes have emerged as promising alternatives capable of degrading PFAS into less harmful products. These strategies include direct photolysis using UV or VUV irradiation, heterogeneous photocatalysis with materials such as TiO2 and novel semiconductors, light-activated persulfate oxidation generating sulfate radicals, and photo-Fenton reactions producing highly reactive hydroxyl radicals. Such approaches leverage the generation of reactive species under irradiation to cleave the strong carbon–fluorine bonds characteristic of PFAS. This review provides a comprehensive overview of emerging photoassisted technologies for PFAS removal from water, detailing their fundamental principles, degradation pathways, recent advancements in material development, and integration with hybrid treatment processes. Moreover, it discusses current challenges related to energy efficiency, catalyst deactivation, incomplete mineralization, and scalability, outlining future perspectives for their practical application in sustainable water treatment systems to mitigate PFAS pollution effectively.