Application of photocatalytic ozonation with a WO₃/TiO₂ catalyst for PFAS removal under UVA/visible light

This research evaluates photocatalytic ozonation for removing 5 PFAS (PFOA/PFHxS/PFBS/6:2 FTS/GenX) from water using a WO₃/TiO₂ catalyst under UVA-visible radiation. Four catalysts of varying WO₃ content (0/1/3/5 wt%) were synthesized by sol-gel and characterized by XRD, TEM, STEM-EDS, HAADF-STEM, adsorption/desorption N₂ isotherms, and DRS-UV-vis. 5 wt% WO₃/TiO₂ was the optimal composition based on physicochemical properties and photocatalytic activity tests with methylene blue. PFAS degradation showed that photocatalytic ozonation inefficiently degraded PFAS with WO₃/TiO₂ under UVA-visible light after 4 h (ΣPFAS removal 16 %, [range 4 %-26 %]). Photocatalysis had comparable removal to photocatalytic ozonation, photolysis and ozone photolysis showed lower removal, and ozonation had no effect. Microtox analysis showed the initial acute toxicity was no longer detectable after photocatalysis and photocatalytic ozonation treatment. Low PFAS removals under tested conditions require that future work evaluate different catalysts or treatment conditions, while disparities between tested PFAS removals demonstrate the need to evaluate multiple compounds. ENVIRONMENTAL IMPLICATION: The research presented in this manuscript involves the preparation and characterization of WO₃/TiO₂ catalysts used, for the first time, to remove multiple PFAS in water via photocatalytic ozonation. This manuscript supports the development of a catalytic process for the elimination of hard to degrade environmental pollutants, provides new knowledge on aspects of photocatalytic processes, and provides insights on environmental pollution abatement.