Photochemical decomposition of perfluorooctanoic acids in aqueous carbonate solution with UV irradiation

Perfluorooctanoic acid (PFOA) is a persisted organic pollutant and a common contaminant in wastewater because of its widespread occurrence in the environment and its ability to bioaccumulate. Recent studies indicate that PFOA is toxic and carcinogenic to animals such as rats, fishes, monkeys, and even humans. In this study, PFOA was decomposed in water using carbonate radical anions (CO3-) under 254 nm UV irradiation at 400 W. CO3- is a strong oxidizing and selective radical, however it works efficiently in decomposing PFOA solution. In this study, the results showed that PFOA was decomposed 100% after 12 h by using a combination of UV irradiation and CO3-, while under only UV irradiation, 52.1% of PFOA was decomposed. In addition, the decomposition of PFOA with CO3- under UV irradiation was more favorable in a slightly alkaline (pH = 8.8) solution and sodium hydrogen carbonate (NaHCO3) 40 mM. Moreover, the intermediates included the shorter-chain perfluorinated carboxylic acids and fluorine ions.

► Using CO3- under 254 nm UV emission, 400 W completely decomposed PFOA after 12 h.
► After 12 h irradiation in H2O2/NaHCO3, 100% of PFOA decomposition has been observed.
► Decomposing PFOA with CO3- is more favorable in a slightly alkaline solution.
► The intermediates include PFCAs with shorter carbon chains and F−.