Degradation of perfluoroheptanoic acid in water by electron beam irradiation

Per- and polyfluoroalkyl substances (PFASs) are lipophilic pollutants of increasing health concern due to their environmental persistence, bioaccumulation, and toxicity. Remediation techniques have been set up for PFAS removal, such as electron beam, which exhibits excellent performance due to its cost-effective ability of producing large amounts of both reducing and oxidizing species. However, the degradation efficiency and mechanisms of the shorter-chain PFASs by eBeam irradiation are poorly known. Herein, perfluoroheptanoic acid was exposed to different eBeam doses of 0–75 kGy. We tested the effect of pH (6.0 and 13.0), nitrate ions, and fulvic acids in water. Results show that highly alkaline conditions favored the removal of perfluoroheptanoic acid at 100.0 μg/L with complete elimination at eBeam doses of 50 kGy and 75 kGy. Nitrate, fulvic acid, and CaCO3 alkalinity did not inhibit perfluoroheptanoic acid degradation. Defluorination and decarboxylation are proposed to be the major degradation pathways based on the identification of two degradation products. Overall, our findings show that eBeam irradiation is a promising remediation technique to break down the shorter-chain PFASs.