Department of Chemical Engineering, University of Melbourne, Victoria, 3010, Australia.
Department of Chemical Engineering, University of Melbourne, Victoria, 3010, Australia.
Chemosphere. 2020 Jan;238:124615. doi: 10.1016/j.chemosphere.2019.124615. Epub 2019 Aug 21.
Perfluorooctanesulfonic acid (PFOS) is a widespread and persistent pollutant of concern to human health and the environment. Although incineration is often used to treat material contaminated with PFOS and related per- and polyfluoroalkyl substances (PFAS), little is known about the precise chemical mechanism for the thermal decomposition of these substances of concern. Here, we present the first study of the thermal decomposition kinetics of PFOS and related perfluorinated acids, using computational chemistry and reaction rate theory methods. We discover that the preferred channel for PFOS decomposition is via an α-sultone that spontaneously decomposes to form perfluorooctanal and SO. At 1000 K the halflife for PFOS is predicted to be 0.2 s, decreasing sharply as temperature increases further. These results show that the acid headgroup in PFOS can be efficiently destroyed in incinerators operating at relatively modest temperatures. The new insights provided into the exact decomposition mechanism and kinetics of PFOS will help to improve remediation technologies actively under development.
全氟辛烷磺酸（PFOS）是一种广泛存在且具有持久性的污染物，对人类健康和环境构成了关注。尽管焚烧通常用于处理被 PFOS 和相关的全氟及多氟烷基物质（PFAS）污染的材料，但对于这些关注物质的热分解的确切化学机制知之甚少。在这里，我们使用计算化学和反应速率理论方法，首次研究了 PFOS 和相关全氟酸的热分解动力学。我们发现，PFOS 分解的首选途径是通过α-砜，它会自发分解形成全氟辛醛和 SO。在 1000 K 时，PFOS 的半衰期预计为 0.2 s，随着温度进一步升高，半衰期急剧缩短。这些结果表明，在相对适中的温度下运行的焚烧炉中，可以有效地破坏 PFOS 中的酸基。对 PFOS 确切分解机制和动力学的新见解将有助于改进正在积极开发的修复技术。
