201. Photocatalytic mineralization of hydroperfluorocarboxylic acids with heteropolyacid H₄SiW₁₂O₄₀ in water
- Author
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Hisao, Hori, Kyoko, Ishida, Naoko, Inoue, Kazuhide, Koike, and Shuzo, Kutsuna
- Subjects
Kinetics ,Surface-Active Agents ,Hydrocarbons, Fluorinated ,Ultraviolet Rays ,Silicon Compounds ,Carboxylic Acids ,Photochemical Processes ,Tungsten ,Water Pollutants, Chemical - Abstract
The decomposition of hydroperfluorocarboxylic acids [H-PFCAs; HC(n)F(2)(n)COOH (n=4 and 6)] induced by heteropolyacid photocatalyst H(4)SiW(12)O(40) in water was investigated, and the results are compared with the results for the corresponding perfluorocarboxylic acids (PFCAs; C(n)F(2)(n)(+1)COOH). This is the first report on the photochemical decomposition of H-PFCAs, which are being developed as alternative surfactants to environmentally persistent and bioaccumulative PFCAs. H-PFCAs were not decomposed by irradiation with UV-Visible light (290 nm) in the absence of H(4)SiW(12)O(40). In contrast, UV-Visible light irradiation of H-PFCAs in the presence of H(4)SiW(12)O(40) efficiently decomposed H-PFCAs to F(-) and CO(2). The decomposition reactions showed pseudo-first-order kinetics, and the decomposition rate constants were 1.8-2.5 times higher than those for the corresponding PFCAs. The reaction mechanism can be explained by elimination of H(+) from the ω-H atom of the H-PFCAs by the excited catalyst, followed by formation of perfluorodicarboxylic acids.
- Published
- 2010