Potential of photocatalytic nanomaterials for PFOA and PFOS degradation: Challenges and opportunities

Per- and polyfluoroalkyl substances (PFAS) are persistent chemicals that pose significant environmental and health risks due to their widespread presence in water systems and their accumulation in the human body. Their strong carbon-fluorine bonds provide exceptional structural stability, making them extremely recalcitrant to conventional degradation processes. PFAS exposure has been linked to health issues including reproductive disorders, liver damage, and cancer, prompting growing concern from the scientific community, World Health and Environmental Organizations, and global regulatory bodies. This issue also attracted significant global media attention. In response, regulations are being implemented, and new technologies developed to enhance PFAS removal in wastewater treatment plants (WWTPs), as existing methods are ineffective. Photocatalytic processes, capable of breaking strong molecular bonds, show promise as a complementary solution to conventional treatments. This review provides a comprehensive assessment of semiconductor-based photocatalysis as a promising alternative for PFAS degradation, particularly focusing on nanomaterials like titanium dioxides (TiO 2 ), Gallium oxides (Ga 2 O 3 ), Indium oxides (In 2 O 3 ) and bismuth oxyhalides (BiOX). A systematic evaluation of recent advancements in photocatalyst design, including the effects of nanomaterial structure, functionalization, and operational conditions on treatment efficiency, is provided. Critical gaps in current research, such as the limited understanding of degradation mechanisms and the identification of degradation products are highlighted. The need for comprehensive toxicity assessments both before and after treatment is also emphasized, as this is crucial for developing safe and effective PFAS remediation strategies. By addressing these challenges, the review aims to provide new insights and future directions for the development of innovative photocatalytic technologies, contributing to the broader effort to create efficient solutions for PFAS degradation. • Nanomaterials show promise for efficient PFAS degradation via photocatalysis. • Stability, surface area and charge separation are key parameters. • Scaling up nanomaterials for photocalatysis of real wastewater faces challenges. • Nanomaterials' environmental and health impacts must be wisely assessed for safe use.