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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Reductive Defluorination of Aqueous Perfluorinated Alkyl Surfactants: Effects of Ionic Headgroup and Chain Length
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Reductive Defluorination of Aqueous Perfluorinated Alkyl Surfactants: Effects of Ionic Headgroup and Chain Length

机译：水性全氟烷基表面活性剂的还原脱氟：离子头基和链长的影响。

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摘要

Perfluorinated chemicals (PFCs) are distributed throughout the environment. In the case of perfluorinated alkyl carboxylates and sulfonates, they can be classified as persistent organic pollutants since they are resistant to environmentally relevant reduction, oxidation, and hydrolytic processes. With this in mind, we report on the reductive defluorination of perfluorobutanoate, PFBA (C3F7CO2~-), perfluorohexanoate, PFHA (C5F_(11)CO_2~-), perfluorooctanoate, PFOA (C7F_(15)CO_2~-), perfluorobutane sulfonate, PFBS (C4F9SO_3~-), perfluorohexane sulfonate, PFHS (C6F_(13)SO_3~-), and perfluorooctane sulfonate, PFOS (C8F_(17)SO_3~-) by aquated electrons, e_(aq)~-, that are generated from the UV photolysis (λ = 254 nm) of iodide. The ionic headgroup (-SO_3~- vs -CO_2~-) has a significant effect on the reduction kinetics and extent of defluorination (F index = -[F~-]_(produced)/ [PFC]_(degraded)). Perfluoroalkylsulfonate reduction kinetics and the F index increase linearly with increasing chain length. In contrast, perfluoroalkylcarboxylate chain length appears to have a negligible effect on the observed kinetics and the F index. H/F ratios in the gaseous fluoro-organic products are consistent with measured F indexes. Incomplete defluorination of the gaseous products suggests a reductive cleavage of the ionic headgroup occurs before complete defluorination. Detailed mechanisms involving initiation by aquated electrons are proposed.
机译：全氟化学品（PFC）分布在整个环境中。对于全氟烷基羧酸盐和磺酸盐，由于它们对环境相关的还原，氧化和水解过程具有抵抗力，因此可以归为持久性有机污染物。考虑到这一点，我们报告了全氟丁酸酯，PFBA（C3F7CO2〜-），全氟己酸酯，PFHA（C5F_（11）CO_2〜-），全氟辛酸酯，PFOA（C7F _（（15）CO_2〜-），全氟丁烷磺酸， PFBS（C4F9SO_3〜-），全氟己烷磺酸盐，PFHS（C6F_（13）SO_3〜-）和全氟辛烷磺酸盐，PFOS（C8F_（17）SO_3〜-）是由电子e_（aq）〜-生成的水电子碘化物的紫外光解（λ= 254 nm）。离子头基（-SO_3〜-与-CO_2〜-）对还原动力学和脱氟程度（F指数=-[F〜-] _（产生）/ [PFC] _（降解））有显着影响。全氟烷基磺酸盐的还原动力学和F指数随链长的增加而线性增加。相反，全氟烷基羧酸盐的链长似乎对观察到的动力学和F指数的影响可忽略不计。气态氟有机产物中的H / F比与测得的F指数一致。气态产物的不完全脱氟表明在完全脱氟之前发生了离子头基的还原裂解。提出了涉及水电子引发的详细机理。

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