TiO2-induced heterogeneous photodegradation of a fluorotelomer alcohol in air.
TiO2-induced heterogeneous photodegradation of a fluorotelomer alcohol in air.
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DOI：
10.1021/es060852k
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发表时间：
2006-09
影响因子：
11.4
通讯作者：
S. Kutsuna;Yumiko Nagaoka;K. Takeuchi;H. Hori
中科院分区：
文献类型：
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作者：
S. Kutsuna;Yumiko Nagaoka;K. Takeuchi;H. Hori
本文首次报道了空气中C4F9C2H4OH在二氧化钛颗粒上的气固相多相光化学降解氟调聚醇(FTOHs)，它可能是环境中全氟甲酸(PFCA)的前体。C4F9C2H4OH在空气中通过C4F9CH2CHO、C4F9CHO、CNF(2n+1)COF(n=2和/或3)和COF2依次光照射(>；290 nm)生成CO2。X-射线光电子能谱分析表明，随着C_4F_9C_2H_4OH在空气中的降解，TiO_2表面氟的键合量减少，F-的量增加。在初始C_4F_9C_2H_4OH(78.8ppmv)中，90.7%的碳被转化为CO_2，生成的主要氟物种为F-。在FTOHs的生物降解中观察到的被认为是有毒的含氟调聚物不饱和酸没有形成。空气中相对湿度的增加加速了反应中间产物的分解，从而导致二氧化碳和氟离子的生成增加。这一结果表明，湿度是抵消室内空气中FTOHs的关键因素。虽然据报道，水中的全氟烷基物质，如全氟烷基物质，在二氧化钛上几乎没有光降解，但我们的数据表明，空气中的C4F9C2H4OH可以通过二氧化钛实现矿化。
Degradation of C4F9C2H4OH in air over TiO2 particles was examined in this first report of gas-solid heterogeneous photochemical degradation of fluorotelomer alcohols (FTOHs), which may be precursors of perfluorocarboxylic acids (PFCAs) in the environment. Photoirradiation (>290 nm) of C4F9C2H4OH in air flowing over TiO2 produced CO2, via C4F9CH2CHO, C4F9CHO, CnF(2n+1)COF (n=2 and/or 3), and COF2, in that order. X-ray photoelectron spectroscopy of the Ti02 surface showed a decrease in the amount of fluorine bonded to carbon and an increase in the amount of F- as the degradation of C4F9C2H4OH in air proceeded. Of the carbon content in the initial C4F9C2H4OH (78.8 ppmv), 90.7% was transformed to CO2, and the predominant fluorine species produced on the TiO2 surface was F-. Fluorotelomer unsaturated acids, which are considered to be toxic and have been observed in the biodegradation of FTOHs, did notform. Increased relative humidity in the air accelerated the decomposition of the reaction intermediates, which led to increased CO2 and F- formation. This result indicates that humidity is a key factor for counteracting FTOHs in indoor air. Although perfluoroalkyl substances such as PFCAs in water reportedly undergo little photodegradation over TiO2, our data show that mineralization of C4F9C2H4OH in air can be achieved with TiO2.