Application of Hydrothermal Alkaline Treatment to Spent Granular Activated Carbon: Destruction of Adsorbed PFASs and Adsorbent Regeneration,Environmental Science & Technology Letters

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Application of Hydrothermal Alkaline Treatment to Spent Granular Activated Carbon: Destruction of Adsorbed PFASs and Adsorbent Regeneration
Environmental Science & Technology Letters ( IF 8.9 ) Pub Date : 2023-04-10 , DOI: 10.1021/acs.estlett.3c00161
Ori Soker ₁ , Shilai Hao ₁ , Brian G. Trewyn ₂ , Christopher P. Higgins ₁ , Timothy J. Strathmann ₁

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Granular activated carbon (GAC) adsorption is the most common technology applied to treat water contaminated with per- and polyfluoroalkyl substances (PFASs), but rapid exhaustion of the media necessitates frequent replacement and costly off-site thermal regeneration. Here, we extend the application of hydrothermal alkaline treatment (HALT), which uses strong alkali and near-critical temperatures and pressures (e.g., 350 °C, 16.5 MPa, and 1 M NaOH) to degrade and mineralize PFASs, to the regeneration of spent GAC. Mass balance experiments wherein a known mass of perfluorooctanesulfonate (PFOS) was adsorbed onto GAC prior to treatment showed that HALT achieved >99% destruction of PFOS and 96 ± 4% defluorination with no observed fluoro-organic intermediates [167 g L^–1 GAC, 350 °C, 1 M NaOH, t_rxn = 400 min, and 10–15 mg of PFOS (g of GAC)⁻¹]. Treatment of GAC collected from a field pilot study also showed effective destruction of the range of adsorbed PFASs. Moreover, repeated HALT cycles did not significantly affect the GAC specific surface area, and similar adsorption isotherms for perfluoropentanoic acid and PFOS were recorded for virgin and HALT-treated GAC. These findings suggest a promising strategy for on-site regeneration of PFAS-contaminated GAC and other adsorbent media that may be an alternative to off-site thermal regeneration practices.

中文翻译：

水热碱处理对废颗粒活性炭的应用：吸附的 PFAS 的破坏和吸附剂再生

颗粒活性炭 (GAC) 吸附是处理被全氟烷基物质和多氟烷基物质 (PFAS) 污染的水的最常用技术，但介质的快速耗尽需要频繁更换和昂贵的场外热再生。在这里，我们扩展了水热碱处理 (HALT) 的应用，该处理使用强碱和近临界温度和压力（例如，350 °C、16.5 MPa 和 1 M NaOH）来降解和矿化 PFAS，以再生花了GAC。质量平衡实验，其中已知质量的全氟辛烷磺酸盐 (PFOS) 在处理前被吸附到 GAC 上，表明 HALT 实现了 >99% 的 PFOS 破坏和 96 ± 4% 的脱氟，没有观察到含氟有机中间体 [167 g L –1 ^GAC， 350 °C，1 M 氢氧化钠，吨_rxn = 400 分钟，以及 10–15 毫克的全氟辛烷磺酸（克活性炭）^-1 ]。对从现场试验研究中收集的 GAC 进行的处理也显示出对吸附的 PFAS 范围的有效破坏。此外，重复的 HALT 循环不会显着影响 GAC 比表面积，并且记录了原始和 HALT 处理的 GAC 对全氟戊酸和 PFOS 的类似吸附等温线。这些发现提出了一种有前途的策略，用于现场再生 PFAS 污染的 GAC 和其他吸附介质，这可能是异地热再生实践的替代方案。

更新日期：2023-04-10

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