Efficient Decomposition of Perfluorocarboxylic Acids in Aqueous Suspensions of a TiO2 Photocatalyst with Medium-Pressure Ultraviolet Lamp Irradiation under Atmospheric Pressure

详细信息    查看全文

• 作者：Tsuyoshi Ochiai ; Yuichi Iizuka ; Kazuya Nakata ; Taketoshi Murakami ; Donald A. Tryk ; Yoshihiro Koide ; Yuko Morito ; Akira Fujishima
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2011
• 出版时间：October 5, 2011
• 年：2011
• 卷：50
• 期：19
• 页码：10943-10947
• 全文大小：773K
• 年卷期：v.50,no.19(October 5, 2011)
• ISSN：1520-5045

文摘

Decomposition of environmentally persistent perfluorooctanoic acid (PFOA) in aqueous suspensions of a TiO₂ photocatalyst, with use of medium-pressure ultraviolet (MPUV) lamp irradiation alone, was examined under atmospheric pressure. Compared to direct photolysis, TiO₂ photocatalysis led to efficient PFOA decomposition and production of CO₂ and F^{鈥?/sup>. PFOA decomposition followed pseudo-first-order kinetics, with observed rate constants of 1.3 脳 10鈥? and 8.6 脳 10鈥? dm3 h鈥? in direct photolysis and TiO₂ photocatalysis, respectively. The latter (photocatalytic) rate constant is 5鈥?00 times greater than those obtained in other published research on the photocatalytic decomposition of PFOA. In the proposed decomposition pathway, PFOA molecules adsorb onto the TiO₂ surface according to adsorption equilibrium in an aqueous suspension and could be easily decomposed by holes and radicals generated by MPUV lamp irradiation. Under the present reaction conditions, a narrow region of TiO₂ concentrations around 1.5 wt % showed the maximum extent of PFOA decomposition, CO₂ formation, and F鈥?/sup> formation. The optimum rate can be attributed to a trade-off between an increase of photon absorption by TiO₂ and a decrease in UV penetration below the surface of the TiO₂ suspension. In the 1.5 wt % TiO₂ photocatalyst concentration, 5 mM PFOA was almost totally decomposed during 4 h of MPUV lamp irradiation under atmospheric pressure.}