UV photolysis of perfluorooctanoic acid (PFOA) in dilute aqueous solution
UV photolysis of perfluorooctanoic acid (PFOA) in dilute aqueous solution
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DOI：
10.2166/wst.2011.050
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发表时间：
2011-01-01
影响因子：
2.7
通讯作者：
Takanami, R.
中科院分区：
文献类型：
--
作者：
Giri, R. R.;Ozaki, H.;Takanami, R.
全氟辛酸（PFOA）在环境中具有很强的持久性，在水环境中被广泛检测。只有一些具有极端反应条件的先进方法才能有效降解该化合物，几乎所有早期的研究都使用了非常高的PFOA浓度。该化合物在水环境中通常以非常低的浓度被检测到，而其降解的温和反应条件是优选的。本文旨在阐明在一个新设计的紫外线夹套组合的紫外波长（185 nm + 254 nm）和254 nm的光降解全氟辛酸稀水溶液。PFOA的降解大大增强了与组合的波长与几乎百分之百的PFOA去除在四个小时的反应。一级反应动力学能很好地描述去除过程。去除效率和速率值显着降低，较小的初始浓度PFOA。但是，随着PFOA浓度的降低，脱氟作用大大增强，这可能是由于PFOA的氟化中间体的加速分解。甲酸和乙酸是两个初步确定的PFOA光解的中间体，而前者是一个主要的中间体，主要控制溶液的pH值在氧化过程中。结果表明，通过适当的紫外线夹套和反应器系统设计，可以在温和的反应条件下大大增强组合波长下PFOA的光解。
Perfluorooctanoic acid (PFOA) is very persistent in the environment and widely detected in the water environment. Only some advanced methods with extreme reaction conditions are shown to be capable of degrading the compound efficiently, and almost all the earlier investigations used very high PFOA concentrations. The compound is detected normally at very low concentrations in the water environment, while mild reaction conditions for its degradation are preferable. This article aimed to elucidate photodegradation of PFOA in dilute aqueous solutions by combined UV wavelengths (185 nm + 254 nm) and 254 nm using a newly designed UV jacket. PFOA degradation was greatly enhanced with the combined wavelengths with almost one hundred percent PFOA removals in four-hour reaction. The removals were well described by the first-order reaction kinetic. The removal efficiencies and rate values significantly decreased with smaller initial PFOA concentrations. But defluorination was greatly enhanced with smaller PFOA concentrations possibly due to accelerated decomposition of fluorinated intermediates of PFOA. Formic acid and acetic acid were two tentatively identified intermediates of PFOA photolysis while the former was a major intermediate predominantly controlling solution pH during the oxidation. The results demonstrated that PFOA photolysis by the combined wavelengths with mild reaction conditions can be greatly enhanced by proper design of UV jacket and reactor system.