The first quantitative investigation of compounds generated from PFAS, PFAS-containing aqueous film-forming foams and commercial fluorosurfactants in pyrolytic processes
The first quantitative investigation of compounds generated from PFAS, PFAS-containing aqueous film-forming foams and commercial fluorosurfactants in pyrolytic processes
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DOI：
10.1016/j.jhazmat.2022.129313
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发表时间：
2022-08-15
影响因子：
13.6
通讯作者：
Xiao，Feng
中科院分区：
文献类型：
--
作者：
Yao，Bin;Sun，Runze;Xiao，Feng
热解作为一种热化学技术，通常用于废物管理和有机污染土壤的修复。这项研究首次研究了全氟烷基物质和多氟烷基物质 (PFAS) 及相关产品在热解（200–890 °C）时释放的氟化和非氟化化合物及其形成机制。加热后，从含 PFAS 的水性成膜泡沫 (AFFF) 和市售表面活性剂浓缩物 (SC) 中检测到约 30 种非氟化化合物，其中包括在 200 °C 下主要存在的乙二醇和乙二醇醚。在较高温度（300-890°C）下意外地观察到氧（例如 1,4-二恶烷）、氮杂环和苯，它们可能是由于二醇和二醇醚的热脱水、脱氢和分子间环化而形成的。在低温和中温（200-500°C）下检测到六大类氟化挥发物，包括全氟烯烃、全氟烷基醛、氟调聚物醇和多氟烷烃/烯烃。 PFAS 热解的几个特征表明潜在的分解机制是自由基介导的。全氟庚烯在 200 °C 下按照自由基断链机制热分解为短链同系物。在低/中温度下观察到的大多数挥发物在 890 °C 时未检测到。未发现超短链氟化温室气体（例如全氟甲烷）。
Pyrolysis as a thermochemical technology is commonly used in waste management and remediation of organic-contaminated soil. This study, for the first time, investigated fluorinated and non-fluorinated compounds emitted from per- and polyfluoroalkyl substances (PFAS) and relevant products upon pyrolysis (200–890 °C) and their formation mechanisms. Approximately 30 non-fluorinated compounds were detected from PFAS-containing aqueous film-forming foams (AFFFs) and commercial surfactant concentrates (SCs) after heating, including glycols and glycol ethers that were predominant at 200 °C. Oxygen (e.g., 1,4-dioxane) and nitrogen heterocycles and benzene were unexpectedly observed at higher temperatures (300–890 °C), which were likely formed as a consequence of the thermal dehydration, dehydrogenation, and intermolecular cyclization of glycols and glycol ethers. Fluorinated volatiles in six major classes were detected at low and moderate temperatures (200–500 °C), including perfluoroalkenes, perfluoroalkyl aldehydes, fluorotelomer alcohols, and polyfluorinated alkanes/alkenes. Several features of the pyrolyses of PFAS suggest that the underlying decomposition mechanism is radical-mediated. Perfluoroheptene thermally decomposed at 200 °C to shorter-chain homologues following a radical chain-scission mechanism. Most of these volatiles observed at low/moderate temperatures were not detected at 890 °C. Ultra-short-chain fluorinated greenhouse gases (e.g., perfluoromethane) were not found.