Chen Jing, Zhang Peng-Yi, Liu Jian
Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China.
Huan Jing Ke Xue. 2007 Apr;28(4):772-6.
Perfluorinated carboxylic acids (PFCAs) especially perfluorooctanoic acid (PFOA) are a new type of persistent and bioaccumulative organic pollutants, and they have been widely detected in various environmental media. Photodegradation of five types of PFCAs i.e. PFOA, perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA) and perfluorobutanoic acid (PFBA) by 185 nm vacuum ultraviolet (VUV) were examined to develop an effective method to deal with PFCAs pollution. All five PFCAs degrade significantly under the irradiation of 185 nm light and fluoride ion correspondingly forms, though PFCAs hardly degrade under irradiation of 254 nm UV light. After 6h irradiation by 185 nm light, more than 60% of PFBA degrades, while other four PFCAs degrade more than 90%, and defluorination ratio range from 71% to 21% decreasing with increasing carbon atoms contained by PFCAs. Three reaction atmosphere i.e. nitrogen, air and oxygen have no significant effect on degradation and defluorination of PFCAs. LC/MS measurement shows, PFOA degrades to PFHpA, PFHxA, PFPeA and PFBA step by step. Under irradiation of 185 nm light, PFCA firstly is decarboxylated, and the radical thus formed reacts with water to form shorter-chain PFCA and fluoride ion.
全氟羧酸（PFCA）尤其是全氟辛酸（PFOA）是一类新型的持久性和生物累积性有机污染物，已在各种环境介质中被广泛检测到。研究了185nm真空紫外光（VUV）对五种全氟羧酸即全氟辛酸（PFOA）、全氟庚酸（PFHpA）、全氟己酸（PFHxA）、全氟戊酸（PFPeA）和全氟丁酸（PFBA）的光降解作用，以开发一种处理全氟羧酸污染的有效方法。在185nm光照射下，所有五种全氟羧酸均有显著降解，并相应生成氟离子，而在254nm紫外光照射下全氟羧酸几乎不降解。在185nm光照射6小时后，超过60%的全氟丁酸降解，而其他四种全氟羧酸降解率超过90%，脱氟率范围为71%至21%，随着全氟羧酸所含碳原子数的增加而降低。氮气、空气和氧气这三种反应气氛对全氟羧酸的降解和脱氟没有显著影响。液相色谱/质谱测量显示，全氟辛酸逐步降解为全氟庚酸、全氟己酸、全氟戊酸和全氟丁酸。在185nm光照射下，全氟羧酸首先发生脱羧反应，生成的自由基与水反应生成短链全氟羧酸和氟离子。
