Photocatalysis: A Different Approach to PFAS Destruction
Photocatalysis using titanium dioxide (TiO2) under UV irradiation generates highly reactive species capable of initiating organic compound degradation. While conventional UV and AOP treatment cannot effectively destroy PFAS, specialized photocatalytic approaches operating at different wavelengths and with different photocatalyst formulations show more promise for PFAS degradation—though significant challenges remain for practical drinking water application.
Indium Oxide and UV-254 Photolysis
Research teams have demonstrated that UV photolysis in the presence of specific photosensitizers—including indium oxide (In2O3) and bismuth-based compounds—can cleave C–F bonds in PFAS through ligand-to-metal charge transfer (LMCT) reactions. These reactions generate reductive radicals (eₐᵧ⁻) capable of attacking the highly oxidized C–F bonds that resist conventional oxidative AOP treatment.
Vacuum UV Photolysis for PFAS
Vacuum UV (VUV) at 185 nm wavelength generates both hydroxyl radicals and free electrons that can attack PFAS through multiple pathways. Studies show VUV photolysis achieving 40–70% PFAS degradation at lab scale, with defluorination producing shorter-chain intermediates before ultimate mineralization. Energy requirements for VUV treatment at drinking water flow rates remain high compared to adsorption-based approaches.
From Laboratory to Practice
Photocatalytic PFAS destruction technologies remain at bench and pilot scale for drinking water applications. Key challenges include catalyst reuse and separation, energy requirements, transformation intermediate toxicity, and performance in complex real water matrices. These technologies represent an important research frontier for comprehensive PFAS treatment that goes beyond what adsorption-based approaches can achieve