The UV-sulfite reductive treatment using hydrated electrons (e aq − ) is a promising technology for destroying perfluorocarboxylates (PFCAs, C n F 2n+1 COO − ) in any chain length. However, the C−H bonds formed in the transformation products strengthen the residual C−F bonds and thus prevent complete defluorination. Reductive treatments of fluorotelomer carboxylates (FTCAs, C n F 2n+1 −CH 2 CH 2 −COO − ) and sulfonates (FTSAs, C n F 2n+1 − CH 2 CH 2 −SO 3 − ) are also sluggish because the ethylene linker separates the fluoroalkyl chain from the end functional group. In this work, we used oxidation (Ox) with hydroxyl radicals (HO•) to convert FTCAs and FTSAs to a mixture of PFCAs. This process also cleaved 35−95% of C−F bonds depending on the fluoroalkyl chain length. We probed the stoichiometry and mechanism for the oxidative defluorination of fluorotelomers. The subsequent reduction (Red) with UV-sulfite achieved deep defluorination of the PFCA mixture for up to 90%. The following use of HO• to oxidize the H-rich residues led to the cleavage of the remaining C−F bonds. We examined the efficacy of integrated oxidative and reductive treatment of n = 1−8 PFCAs, n = 4,6,8 perfluorosulfonates (PFSAs, C n F 2n+1 −SO 3 − ), n = 1−8 FTCAs, and n = 4,6,8 FTSAs. A majority of structures yielded near-quantitative overall defluorination (97−103%), except for n = 7,8 fluorotelomers (85−89%), n = 4 PFSA (94%), and n = 4 FTSA (93%). The results show the feasibility of complete defluorination of legacy PFAS pollutants and will advance both remediation technology design and water sample analysis.

Per- and polyfluoroalkyl substances (PFASs) are widely detected in the environment, while a large number of them cannot be identified and/or quantified by current analytical methods. As a surrogate total PFAS analysis, the adsorbable organic fluorine (AOF) method was improved and validated in this study. The improved method has limits of detection and quantification of 300 and 400 ng/L, respectively, more sensitive than the previously reported AOF methods. AOF recovery for 29 individual PFASs ranged 53–113%, while three short-chain PFASs yielded lower recovery (19–39%) due to low adsorption efficiency. Recovery for PFAS mixtures in different environmental water matrices was 64–84%, and was negligibly impacted by the presence of fluoride, dissolved organic matter, or other matrix constituents. The validated method was applied to different environmental water samples, and AOF data were compared to results from other total PFAS analyses, including total fluorine, extractable organic fluorine, total oxidizable precursors, and summed individual PFASs. The fluorine contents from targeted PFAS analysis only contributed 0.4–29% of AOF concentrations in all except two samples, indicating the significance of AOF for estimating unknown PFAS concentrations, screening PFAS contamination, and assessing PFAS exposure.

Anti-fog sprays and solutions are used on eyeglasses to minimize the condensation of water vapor, particularly while wearing a mask. Given their water-repellent properties, we sought to characterize per- and polyfluorinated alkyl substance (PFAS) compounds in four anti-fog spray products, five anti-fog cloth products, and two commercial fluorosurfactant formulations suspected to be used in preparing anti-fog products. Fluorotelomer alcohols (FTOHs) and fluorotelomer ethoxylates (FTEOs) were detected in all products and formulations. While 6:2 FTOH and the 6:2 FTEO polymeric series were predominant, one anti-fog cloth and one formulation contained 8:2, 10:2, 12:2, 14:2, and 16:2 FTOH and FTEO polymeric series. PFAS concentrations varied in samples and were detected at levels up to 25,000 μg/mL in anti-fog sprays and 185,000 μg (g cloth)−1 in anti-fog cloth products. The total organic fluorine (TOF) measurements of anti-fog products ranged from 190 to 20,700 μg/mL in sprays and 44,200 to 131,500 μg (g cloth)−1 in cloths. Quantified FTOHs and FTEOs accounted for 1–99% of TOF mass. In addition, all four anti-fog sprays and both commercial formulations exhibited significant cytotoxicity and adipogenic activity (either triglyceride accumulation and/or pre-adipocyte proliferation) in murine 3T3-L1 cells. Results suggest that FTEOs are a significant contributor to the adipogenic activity exhibited by the anti-fog sprays. Altogether, these results suggest that FTEOs are present in commercial products at toxicologically relevant levels, and more research is needed to fully understand the health risks from using these PFAS-containing products.

This column reviews the general features of PHT3D Version 2, a reactive multicomponent transport model that couples the geochemical modeling software PHREEQC-2 (Parkhurst and Appelo 1999) with three-dimensional groundwater flow and transport simulators MODFLOW-2000 and MT3DMS (Zheng and Wang 1999). The original version of PHT3D was developed by Henning Prommer and Version 2 by Henning Prommer and Vincent Post (Prommer and Post 2010). More detailed information about PHT3D is available at the website http://www.pht3d.org.The review was conducted separately by two reviewers. This column is presented in two parts.

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