Hori Hisao, Nagaoka Yumiko, Murayama Misako, Kutsuna Shuzo
National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba West, 16-1 Onogawa, Tsukuba 305-8569, Japan.
Environ Sci Technol. 2008 Oct 1;42(19):7438-43. doi: 10.1021/es800832p.
Decomposition of C5-C9 perfluorocarboxylic acids (PFCAs) and perfluoroether carboxylic acids (alternatives to PFCA-based surfactants) in hot water in a sealed reactor was investigated. Although PFCAs showed almost no decomposition in hot water at 80 degrees C in the absence of persulfate (S2O8(2-)), the addition of S2O8(2-) to the reaction system led to efficient decomposition, even at this relatively low temperature. The major products in the aqueous and gas phases were F- ions and CO2, respectively, and short-chain PFCAs were also detected in the aqueous phase. For example, when an aqueous solution containing perfluorooctanoic acid (PFOA, 374 microM) and S2O8(2-) (50.0 mM) was heated at 80 degrees C for 6 h, PFOA concentration in the aqueous phase fell below 1.52 microM (detection limit of HPLC with conductometric detection), and the yields of F- ions [i.e., (moles of F- formed) /(moles of fluorine content in initial PFOA)] and CO2 [i.e, (moles of CO2 formed) /(moles of carbon content in initial PFOA)] were 77.5% and 70.2%, respectively. This method was also effective in decomposing perfluoroether carboxylic acids, such as CF3OC2F4OCF2COOH, CF3OC2F4OC2F4OCF2COOH, and C2F5OC2F4OCF2COOH, which are alternatives to PFCA-based surfactants, producing F- and CO2 with yields of 82.9-88.9% and 87.7-100%, respectively, after reactions at 80 degrees C for 6 h. In addition, the method was successfully used to decompose perfluorononanoic acid in a floor wax solution. When PFOAwastreated at a higher temperature (150 degrees C), other decomposition reactions occurred: the formation of F- and CO2 was dramatically decreased, and 1H-perfluoroalkanes (C(n)F(2n+1)H, n = 4-7) formed in large amounts. This result clearly indicates that treatment with high-temperature water was not suitable for the decomposition of PFCAs to F-: surprisingly, the relatively low temperature of 80 degrees C was preferable.
研究了在密封反应器中热水中C5 - C9全氟羧酸（PFCA）和全氟醚羧酸（PFCA基表面活性剂的替代品）的分解情况。尽管在没有过硫酸盐（S2O8(2-)）的情况下，PFCA在80℃的热水中几乎不分解，但向反应体系中添加S2O8(2-)会导致即使在这个相对较低的温度下也能有效分解。水相和气相中的主要产物分别是F-离子和CO2，并且在水相中也检测到了短链PFCA。例如，当含有全氟辛酸（PFOA，374 microM）和S2O8(2-)（50.0 mM）的水溶液在80℃加热6小时后，水相中PFOA浓度降至1.52 microM以下（电导检测的HPLC检测限），F-离子的产率[即（形成的F-的摩尔数）/（初始PFOA中氟含量的摩尔数）]和CO2的产率[即（形成的CO2的摩尔数）/（初始PFOA中碳含量的摩尔数）]分别为77.5%和70.2%。该方法对于分解全氟醚羧酸，如CF3OC2F4OCF2COOH、CF3OC2F4OC2F4OCF2COOH和C2F5OC2F4OCF2COOH（PFCA基表面活性剂的替代品）也有效，在80℃反应6小时后，分别产生产率为82.9 - 88.9%和87.7 - 100%的F-和CO2。此外，该方法成功用于分解地板蜡溶液中的全氟壬酸。当PFOA在较高温度（150℃）下处理时，发生了其他分解反应：F-和CO2的形成显著减少，并且大量形成了1H - 全氟烷烃（C(n)F(2n + 1)H，n = 4 - 7）。这一结果清楚地表明，高温水处理不适用于将PFCA分解为F-：令人惊讶的是，80℃这个相对较低的温度更合适。
