Abstract
Fluorotelomers have been systematically developed in bulk quantities and extensively applied in the fluoropolymer industry. Reductive treatments of fluorotelomers are different from those of perfluoroalkyl substances. In this study, vacuum UV/peroxydisulfate (VUV/PDS) was used for the first time to preoxidize 8:3 fluorotelomer carboxylates (8:3FTCA). Subsequently, it was integrated with the VUV/sulfite/iodide reductive process to accomplish the comprehensive defluorination of the oxidized products. The performance and mechanisms of 8:3FTCA degradation in the preoxidation process were mainly explored. pH values from 6.0 to 8.0 were conducive to 8:3FTCA decomposition. Hydrogen peroxide, hydroxyl radical (•OH), and hydroperoxyl radical (HO2•) were observed to be in a dynamic equilibrium state of mutual transformation, and the contributions of •OH and HO2• were 76.8 % and 17.4 %, respectively. The investigation of the influences of background water matrices demonstrated minimal adverse effects of sulfate and chloride, whereas bicarbonate, carbonate, and natural organic matter exhibited inhibitory effects. The degradation pathways of 8:3FTCA were speculated through density functional theory calculation and intermediate identification. The Ecological Structure–Activity Relationships simulation showed that VUV/PDS preoxidation decreased the aquatic toxicity of 8:3FTCA. These findings provide valuable insights for addressing challenges associated with fluorotelomer carboxylates.
Published Version
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