Decomposition of Carboxylic PFAS by Persulfate Activated by Silver under Ambient Conditions

Abstract

Perfluoroalkyl and polyfluoroalkyl substances (PFAS), widely used in many commercial and military products, have been notorious due to their environmental persistence. Even radical-based advanced oxidation technologies have been reported to be less effective for decomposition of PFAS, particularly perfluoroalkyl ones, while commonly requiring energy-intensive extreme conditions and tools such as ultraviolet, ultrasound, microwave, electron beam, and high temperatures. Herein, for the first time, the potential of a modified Fenton system, i.e., homogeneous persulfate (PS) conjugated with silver (Ag+), to decompose PFAS under ambient conditions is communicated. Among many combinations of common oxidants and transition metals tested, only the PS/Ag pair showed significant reactivity at 20°C exclusively toward carboxylic PFAS including perfluorooctanoic acid, resulting in evolution of fluoride ion release and reaction by-product formation. Although sulfonic PFAS still remain challenging, and follow-up assignments are raised to investigate in-depth mechanisms and examine other oxidant and metal pairs, this study offers one step closer to establishing an energy-independent and more practical treatment system for PFAS.