Perfluorooctanoic acid (PFOA), as a pollutant, is widely distribution in the environment. Owing to its stable C-F bond and high toxicity, PFOA seriously threatens ecological and biological health. In this paper, three-dimensional (3D) gliding arc plasma discharging in gas-liquid phase is used to degrade PFOA in the artificially polluted water. We obtain that the defluorination rate reaches 50.37 %, the defluorination energy efficiency is 769.37 mg/kWh, and an energy consumption (EE/O) is 44.68 kWh/m3 after 60 min treatment in 3D gliding arc air plasma. Active radical concentrations of ·O2−, O3, H2O2, NO2− and NO3− in the gaseous and liquid phases varying with the solution pH and conductivity during the degradation process is noticed, and ·O2− playing the most important role in PFOA defluorination is conformed. Besides, the discharge characteristics are investigated by high-speed camera in whole discharge cycle, and the radical sorts in gaseous plasma are detected by optical emission spectroscopy (OES) for well understanding the degradation mechanism. With liquid chromatograph mass spectrometer (LC-MS) measurement, the intermediate and final products during PFOA degradation are found, and then the degrading pathways are proposed. Furthermore, the toxicity of the intermediates is simulatively analyzed, which demonstrates that the toxicity and bioaccumulation factors of the intermediates are greatly reduced after plasma treatment. Therefore, we believe that gliding arc plasma may be a promising plasma source for green, fast and efficient wastewater treatment.

中文翻译：

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重新认识全氟辛酸 （PFOA） 通过三维旋转滑翔电弧等离子体的降解


全氟辛酸 （PFOA） 作为一种污染物，在环境中广泛分布。PFOA 由于其稳定的 C-F 键和高毒性，严重威胁生态和生物健康。本文采用气液相三维 （3D） 滑移电弧等离子体放电降解人工污染水中 PFOA。我们得到，在 3D 滑流弧空气等离子体中处理 60 min 后，脱氟率达到 50.37 %，脱氟能效为 769.37 mg/kWh，能耗 （EE/O） 为 44.68 kWh/m3。活性自由基浓度 ·在降解过程中，气相和液相中的 O2−、O3、H2O2、NO2− 和 NO3− 随溶液 pH 值和电导率的变化而存在，并且 ·O2− 在 PFOA 脱氟中起着最重要的作用是一致的。此外，利用高速摄像机研究了整个放电循环中的放电特性，并通过直读光谱 （OES） 检测气态等离子体中的自由基分选，以更好地了解其降解机制。通过液相色谱质谱仪 （LC-MS） 测量，找到 PFOA 降解过程中的中间产物和最终产物，然后提出降解途径。此外，对中间体的毒性进行了模拟分析，表明等离子体处理后中间体的毒性和生物累积因子大大降低。因此，我们相信滑移电弧等离子体可能是一种很有前途的等离子体源，用于绿色、快速和高效的废水处理。