Degradation of OBS (Sodiump-Perfluorous Nonenoxybenzenesulfonate) as a Novel Per- and Polyfluoroalkyl Substance by UV/Persulfate and UV/Sulfite: Fluorinated Intermediates and Treatability in Fluoroprotein Foam

Sodiump-perfluorous nonenoxybenzenesulfonate(OBS) is a novelfluorosurfactant used as the alternative toperfluorooctanesulfonic acid (PFOS) in several applications such asfire-fighting foams and chemical enhanced oil recovery (EOR)inChina, with the annual production capacity of about 3,500 t. Here,for thefirst time, we investigated the degradability of OBS underthe conditions of UV/persulfate (UV/PS) and UV/sulfite (UV/SF)as typical redox processes. A higher reaction rate (1.05 min-1) andtotal organic carbon (TOC) reduction (46.9%) but a lowdefluorination rate (27.6%) along with the formation of a seriesoffluorinated intermediates were found in UV/PS, while a highdefluorination rate (87.7%) was realized in UV/SF. In particular, anontargeted workflow using high performance liquid chromatog-raphy-quadrupole time-of-flight mass spectrometry (HPLC/Q-TOF-MS) was established to detectfluorinated intermediates.Combined with the theoretical calculation, the distinctive degradation pathways in both oxidation and reduction processes wereproposed. The degradation mechanism of OBS in UV/SF was proposed to be H/F exchange and subsequent HF elimination.Furthermore, the diluted OBS-basedfluoroprotein (FP) foam was used to investigate the degradation of OBS, which confirms thetreatability using the redox approach. This work provides insights into the degradability of OBS,fluorinated intermediate search, andproper treatment of related contamination.

Automated summary

This study investigated the degradability of Sodiump-perfluorous nonenoxybenzenesulfonate (OBS) under typical redox processes and proposed the distinctive degradation pathways through experimental and theoretical calculations. The feasibility of using redox approach to treat OBS was confirmed through experiments using diluted OBS-based fluoroprotein foam. This research provides important insights into the degradability of OBS, search for fluorinated intermediates, and proper treatment of related contamination.