Enhanced and accelerated degradation of PFOA using visible light—Applying semiconductor carbon nitride as an accelerator

Due to the high toxicity, persistence and resistance of perfluorooctanoic acid (PFOA), developing convenient and efficient methods to degrade such highly recalcitrant contaminants is urgently needed. Herein, a visible light-responsive semiconductor carbon nitride (CN) was introduced to realize enhanced degradation of PFOA by providing the strong oxidizing radical •OH. In this study, 365 nm UV light and 456–760 nm visible light were applied as two comparable light sources, highlighting the fact that under simple visible light irradiation, both the degradation rate and defluorination rate of PFOA ultimately reached over 95 % with the aid of the Fe3+/CN system in at most 70 h. In addition, possible influencing factors, including the dosage of ferric ions (varying from 0–0.01 mol/L), the contaminant itself (ranging from 20 μg/L to 5 mg/L) and semiconductor CN (5–20 mg/L), were also investigated, and an accelerated reaction mechanism was proposed. Our results shed light on the most recent development of effective and sustainable technologies for PFOA breakdown in the environment.