Potential-Driven Electron Transfer Lowers the Dissociation Energy of the C-F Bond and Facilitates Reductive Defluorination of Perfluorooctane Sulfonate (PFOS)
Potential-Driven Electron Transfer Lowers the Dissociation Energy of the C-F Bond and Facilitates Reductive Defluorination of Perfluorooctane Sulfonate (PFOS)
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DOI：
10.1021/acsami.9b10449
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发表时间：
2019-09-18
影响因子：
9.5
通讯作者：
Jassby, David
中科院分区：
文献类型：
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作者：
Su, Yiming;Rao, Unnati;Jassby, David
全氟烷基物质和多氟烷基物质 (PFAS) 在环境中广泛存在，因其毒性、难降解性和生物累积能力而引起了监管、研究和媒体的广泛关注。全氟辛烷磺酸 (PFOS) 是 PFAS 家族中特别麻烦的一员，因为它对生物修复和自由基氧化具有免疫力。在本研究中，我们提出了一种异质还原降解过程，该过程使用紫外线产生的水合电子将直接电子转移（ET）从表面改性的碳纳米管电极（在低电位条件下）耦合到吸附的全氟辛烷磺酸分子，而无需任何进一步的化学添加。我们证明，ET 过程显着提高了 PFOS 脱氟率，同时产生较短链 (C-3-C-7) 全氟酸，并提供了实验和从头算证据，证明吸附分子的电子添加与其与还原性水合电子反应的能力之间存在协同关系。由于 ET 工艺能耗低、使用标准中压紫外线灯且无需进一步添加化学物质，因此这种还原降解工艺是销毁持久性有机污染物（包括 PFAS 和其他顽固性卤代有机化合物）的一种很有前途的方法。
The widespread environmental occurrence of per- and polyfluoroalkyl substances (PFAS) has attracted significant regulatory, research, and media attention because of their toxicity, recalcitrance, and ability to bioaccumulate. Perfluorooctane sulfonate (PFOS) is a particularly troublesome member of the PFAS family due to its immunity to biological remediation and radical-based oxidation. In the present study, we present a heterogeneous reductive degradation process that couples direct electron transfer (ET) from surface-modified carbon nanotube electrodes (under low potential conditions) to sorbed PFOS molecules using UV-generated hydrated electrons without any further chemical addition. We demonstrate that the ET process dramatically increases the PFOS defluorination rate while yielding shorter chain (C-3-C-7) perfluorinated acids and present both experimental and ab initio evidence of the synergistic relationship between electron addition to sorbed molecules and their ability to react with reductive hydrated electrons. Because of the low energy consumption associated with the ET process, the use of standard medium-pressure UV lamps and no further chemical addition, this reductive degradation process is a promising method for the destruction of persistent organic pollutants, including PFAS and other recalcitrant halogenated organic compounds.