Thermolysis of fluoropolymers as a potential source of halogenated organic acids in the environment
Thermolysis of fluoropolymers as a potential source of halogenated organic acids in the environment
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DOI：
10.1038/35085548
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发表时间：
2001-07-19
期刊：
影响因子：
64.8
通讯作者：
Muir, DCG
中科院分区：
文献类型：
--
作者：
Ellis, DA;Mabury, SA;Muir, DCG
在引入氢氯氟烃(HCFCs)和氢氟烃(HFCs)气体作为破坏臭氧的氯氟烃(CFCs)的替代品后，人们发现，HCFCs/HFCs可以在大气中降解产生三氟乙酸(1)，这是一种在环境中未知的损失机制(2，3)，并且已证明在自然水域中浓度较高的化合物(4)具有温和的植物毒性(5)。目前环境中的三氟乙酸水平不能仅以氟氯烃/氢氟碳化合物的降解来计算(8-10)。在这里，我们报告了含氟聚合物的热分解，例如商业聚合物特氟龙和Kel-F，也可以产生三氟乙酸酯和类似的化合物二氟乙酸氯酯。这可以直接发生，也可以通过已知可在大气中降解为这些卤代乙酸酯的产物间接发生(11)。这些发现的环境意义通过模型得到了证实，该模型表明，工业和消费高温应用(烤箱、不粘烹饪用具和内燃机)中氟聚合物的热分解很可能是城市雨水中三氟乙酸酯的重要来源(类似于多伦多估计的25 ng L(-1))。热分解还会产生更长链的多氟和/或多氯氟(C3-C14)羧酸，它们可能是同样持久的。其中一些产品最近被认为可能对健康和环境造成不利影响，正在逐步淘汰美国市场(7)。此外，我们在其他热降解产品中检测到氯氟烃和氟碳化合物--分别可以破坏臭氧和充当温室气体--这表明继续使用氟聚合物也可能加剧平流层臭氧消耗和全球变暖。
Following the introduction of hydrochlorofluorocarbon (HCFCs) and hydrofluorocarbon (HFCs) gases as replacements for the ozone-destroying chlorofluorocarbons (CFCs), it has been discovered that HCFCs/HFCs can degrade in the atmosphere to produce trifluoroacetic acid(1), a compound with no known loss mechanisms in the environment(2,3), and higher concentrations in natural waters(4) have been shown to be mildly phytotoxic(5). Present environmental levels of trifluooracetic acid are not accounted by HCFC/HFC degradation alone(8-10). Here we report that thermolysis of fluorinated polymers, such as the commercial polymers Teflon and Kel-F, can also produce trifluoroacetate and the similar compound chlorodifluoroacetate. This can occur either directly, or indirectly via products that are known to degrade to these haloacetates in the atmosphere(11). The environmental significance of these findings is confirmed by modelling, which indicates that the thermolysis of fluoropolymers in industrial and consumer high-temperature applications (ovens, nonstick cooking utensils and combustion engines) is likely to be a significant source of trifluoroacetate in urban rain water (similar to 25 ng l(-1), as estimated for Toronto). Thermolysis also leads to longer chain polyfluoro- and/or polychlorofluoro- (C3-C14) carboxylic acids which may be equally persistent. Some of these products have recently been linked with possible adverse health(6) and environmental impacts and are being phased out of the US market(7). Furthermore, we detected CFCs and fluorocarbons- groups that can destroy ozone and act as greenhouse gases, respectively-among the other thermal degradation products, suggesting that continued use of fluoropolymers may also exacerbate stratospheric ozone-depletion and global warming.