Weber Nathan H, West Gabrielle V, Roberson William R, Mackie John C, Mattila James M, Burnette Preston, Allen Matthew, Preston William, Linak William P, Krug Jonathan D
US. Environmental Protection Agency, Office of Research and Development, Center for Environmental Measurement and Modeling, Research Triangle Park, NC 27711, USA; Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN 37830, USA.
US. Environmental Protection Agency, Office of Research and Development, Center for Environmental Measurement and Modeling, Research Triangle Park, NC 27711, USA; Department of Chemistry, College of Arts and Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA.
J Hazard Mater. 2025 Sep 5;495:138905. doi: 10.1016/j.jhazmat.2025.138905. Epub 2025 Jun 11.
The thermal decomposition of single-component aqueous solutions of hexafluoropropylene oxide dimer acid (HFPO-DA), a "GenX" process chemical, was investigated in a pilot-scale research combustor. Two solutions containing target HFPO-DA concentrations of ∼500 and 4000 mg/L were atomized at three post-flame temperatures of ∼920, 860, and 750 °C, during which the stack gases were characterized for combustion products including fluorocarbon products of incomplete combustion (PICs). Analytical techniques included Other Test Method 50 (OTM-50) and real-time analysis using Fourier transform infrared spectroscopy (FTIR) and chemical ionization mass spectrometry (CIMS). Quantum chemical calculations were performed to identify pathways for the thermal decomposition of HFPO-DA. Identified PICs included 1H-perfluoroalkanes, fluoroether E-1 (heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether), and two ultra short-chain perfluorocarboxylic acids (PFCAs): trifluoroacetic acid (TFA) and perfluoropropionic acid (PFPrA). Most PIC concentrations increased with decreasing peak temperatures with ∼40-60 % of the fluorine in the HFPO-DA converted into PICs at the lowest peak temperature examined (∼750 °C). At higher peak temperatures, lower PIC concentrations were observed, suggesting that temperature is a critical parameter for mineralization. Modeling results proposed that the thermal decomposition of HFPO-DA can pass through 1,1,1,2,2,3,3-heptafluoro-3-[(1,2,2-trifluoroethenyl)oxy]propane (perfluoropropylvinyl ether, or PPVE) or fluoroether E-1 intermediate species with the PPVE route offering lower energy barriers.
在中试规模的研究燃烧器中，对“GenX”工艺化学品六氟环氧丙烷二聚酸（HFPO - DA）单组分水溶液的热分解进行了研究。将两种含有目标HFPO - DA浓度分别约为每升500毫克和4000毫克的溶液，在约920、860和750°C的三个火焰后温度下进行雾化，在此期间对烟道气中的燃烧产物进行表征，包括不完全燃烧的含氟碳产物（PICs）。分析技术包括其他测试方法50（OTM - 50）以及使用傅里叶变换红外光谱（FTIR）和化学电离质谱（CIMS）的实时分析。进行了量子化学计算以确定HFPO - DA热分解的途径。鉴定出的PICs包括1H - 全氟烷烃、氟醚E - 1（七氟丙基1,2,2,2 - 四氟乙基醚）以及两种超短链全氟羧酸（PFCA）：三氟乙酸（TFA）和全氟丙酸（PFPrA）。大多数PIC浓度随峰值温度降低而增加，在所研究的最低峰值温度（约750°C）下，HFPO - DA中约40 - 60%的氟转化为PICs。在较高的峰值温度下，观察到较低的PIC浓度，这表明温度是矿化的关键参数。建模结果表明，HFPO - DA的热分解可以通过1,1,1,2,2,3,3 - 七氟 - 3 - [(1,2,2 - 三氟乙烯基)氧基]丙烷（全氟丙基乙烯基醚，或PPVE）或氟醚E - 1中间物种进行，其中PPVE途径具有较低的能垒。
