Destruction of Per- and Polyfluoroalkyl Substances (PFASs) in Aqueous Film-Forming Foam (AFFF) with UV-Sulfite Photoreductive Treatment

Abstract

Ultraviolet photochemical reaction of sulfite (SO3 2–) photosensitizer generates strongly reducing hydrated electrons (eaq –; NHE = −2.9 V) that have been shown to effectively degrade individual per- and polyfluoroalkyl substances (PFASs), including perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). However, treatment of complex PFAS mixtures in aqueous film-forming foam (AFFF) remains largely unknown. Here, UV-sulfite was applied to a diluted AFFF to characterize eaq – reactions with 15 PFASs identified by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) targeted analysis. Results show that reactivity varies widely among PFASs, but reaction rates observed for individual PFASs in AFFF are similar to rates observed in single-solute experiments. While some structures, including long-chain perfluoroalkyl sulfonic acids (PFSAs) and perfluoroalkyl carboxylic acids (PFCAs) were readily degraded, other structures, most notably short-chain PFSAs and fluorotelomer sulfonic acids (FTSs), were more recalcitrant. This finding is consistent with results showing incomplete fluoride ion release (up to 53% of the F content in AFFF) during reactions. Furthermore, results show that selected PFSAs, PFCAs, and FTSs can form as transient intermediates or unreactive end-products via eaq – reactions with precursor structures in AFFF. These results indicate that while UV-sulfite treatment can be effective for treating PFOS and PFOA to meet health advisory levels, remediation of the wider range of PFASs in AFFF will prove more challenging.

Photochemical Degradation of Short-Chain Chlorinated Paraffins in Aqueous Solution by Hydrated Electrons and Hydroxyl Radicals

“…72,[95][96][97] In this context, e -(aq) have received renewed attention with the report of e -(aq) mediated degradation of the emerging per-and polyfluoroalkyl substances (PFAS). 45,46,52,98,99 The results of this study also imply that e -(aq)generating engineered systems for water treatment would likely be effective for degrading SCCPs, and provides further support to the notion that e -(aq) is a versatile PPRI for degrading persistent organic pollutants.…”

Managing and treating per‐ and polyfluoroalkyl substances (PFAS) in membrane concentrates

“…However, AOPs tend to be limited in the extent of degradation of PFAS because of the high oxidation potential of C F bonds. Barisci and Suri (2021) (Hori et al, 2005;Tenorio et al, 2020).…”

Transitioning Per‐ and Polyfluoroalkyl Substance Containing Fire Fighting Foams to New Alternatives: Evolving Methods and Best Practices to Protect the Environment

“…Relevant destructive mechanisms for PFAS associated with liquid wastes are limited to molecular decomposition or chemically mediated sequential defluorination (Vecitis et al 2009). Practically speaking, that limits PFAS destruction technologies for liquids to various forms of extreme thermal treatment (SCWO and/or high‐pressure afterburner chambers following gasification), sonochemical degradation, electrochemical oxidation, or advanced reducing processes (e.g., plasma, electron beam, and/or ultraviolet activated catalysts and/or reductants; Hori et al 2004; Mader et al 2008; Schaefer et al 2015; Wang et al 2016; Stratton et al 2017; Wu et al 2019; Tenorio et al 2020).…”