The widespread detection of per- and polyfluoroalkyl substances (PFAS) in environmental compartments across the globe has raised several health concerns. Destructive technologies that aim to transform these recalcitrant PFAS into less toxic, more manageable products, are gaining impetus to address this problem. In this study a 9 MeV electron beam accelerator was utilized to treat a suite of PFAS (perfluoroalkyl carboxylates: PFCAs, perfluoroalkyl sulfonates, and 6:2 fluorotelomer sulfonate: FTS) at environmentally relevant levels in water under different operating and water quality conditions. Although perfluorooctanoic acid and perfluorooctane sulfonic acid showed >90% degradation at <500 kGy dose at optimized conditions, a fluoride mass balance revealed that complete defluorination occurred only at/or near 1000 kGy. Non-target and suspect screening revealed additional degradation pathways differing from previously reported mechanisms. Treatment of PFAS mixtures in deionized water and groundwater matrices showed that FTS was preferentially degraded (∼90%), followed by partial degradation of long-chain PFAS (∼15–60%) and a simultaneous increase of short-chain PFAS (up to 20%) with increasing doses. The increase was much higher (up to 3.5X) in groundwaters compared to deionized water due to the presence of PFAS precursors as confirmed by total oxidizable precursor (TOP) assay. TOP assay of e-beam treated samples did not show any increase in PFCAs, confirming that e-beam was effective in also degrading precursors. This study provides an improved understanding of the mechanism of PFAS degradation and revealed that short-chain PFAS are more resistant to defluorination and their levels and regulation in the environment will determine the operating conditions of e-beam and other PFAS treatment technologies.

中文翻译：

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应用电子束技术分解水中全氟烷基和多氟烷基物质

全球环境区域中全氟烷基物质和多氟烷基物质 (PFAS) 的广泛检测引起了一些健康问题。旨在将这些顽固的 PFAS 转化为毒性更低、更易于管理的产品的破坏性技术正在获得解决这一问题的动力。在这项研究中，使用 9 MeV 电子束加速器在不同的操作和水质条件下处理水中的一套 PFAS（全氟烷基羧酸盐：PFCA、全氟烷基磺酸盐和 6:2 氟调聚物磺酸盐：FTS），使其达到环境相关水平。尽管在优化条件下，全氟辛酸和全氟辛烷磺酸在 <500 kGy 剂量下表现出 >90% 的降解，但氟化物质量平衡显示，仅在/或接近 1000 kGy 时才发生完全脱氟。非目标和可疑筛选揭示了与之前报道的机制不同的额外降解途径。在去离子水和地下水基质中处理 PFAS 混合物表明，FTS 优先降解（~90%），其次是长链 PFAS 部分降解（~15-60%），同时短链 PFAS 增加（高达20%）随着剂量的增加。总可氧化前体 (TOP) 测定证实，由于存在 PFAS 前体，地下水中的增加量比去离子水高得多（高达 3.5 倍）。电子束处理样品的 TOP 测定没有显示 PFCA 有任何增加，证实电子束也能有效降解前体。这项研究加深了对 PFAS 降解机制的理解，并揭示了短链 PFAS 更耐脱氟，其在环境中的水平和调节将决定电子束和其他 PFAS 处理技术的操作条件。