Plasma-Based Water Treatment: Efficient Transformation of Perfluoroalkyl Substances in Prepared Solutions and Contaminated Groundwater
Plasma-Based Water Treatment: Efficient Transformation of Perfluoroalkyl Substances in Prepared Solutions and Contaminated Groundwater
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DOI：
10.1021/acs.est.6b04215
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发表时间：
2017-02-07
影响因子：
11.4
通讯作者：
Thagard, Selma Mededovic
中科院分区：
文献类型：
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作者：
Stratton, Gunnar R.;Dai, Fei;Thagard, Selma Mededovic
研究了一种基于放电等离子体的全氟辛酸(PFOA)转化过程。基于等离子体的工艺适用于两种情况，即高去除效率和高去除效率。在30min内，高速(76.5W输入功率)和高效(4.1W输入功率)工艺对1.4 L水溶液中全氟辛酸的浓度分别降低了90%和25%。与领先的替代技术相比，这两种技术都实现了非常高的全氟辛酸去除和脱氟效率。高效工艺还被用于处理含有全氟辛烷磺酸和包括全氟辛烷磺酸(PFOS)在内的几种共污染物的地下水，表明该工艺不受共污染物的显著影响，而且该工艺能够快速降解全氟辛烷磺酸。对副产品的初步调查表明，只有大约10%的全氟辛烷酸和全氟辛烷磺酸被转化为短链全氟烷基酸(PFAA)。对与全氟辛烷酸主反应有关的活性物种类型的研究表明，羟基和超氧阴离子自由基通常是等离子体衍生的主要活性物种，但没有起到明显的作用。取而代之的是，清道夫实验表明，水电子在转化中占了相当大的比例，自由电子和/或Ar离子被认为占了剩余部分。
A process based on electrical discharge plasma was tested for the transformation of perfluorooctanoic acid (PFOA). The plasma-based process was adapted for two cases, high removal rate and high removal efficiency. During a 30 min treatment, the PFOA concentration in 1.4 L of aqueous solutions was reduced by 90% with the high rate process (76.5 W input power) and 25% with the high efficiency process (4.1 W input power). Both achieved remarkably high PFOA removal and defluorination efficiencies compared to leading alternative technologies. The high efficiency process was also used to treat groundwater containing PFOA and several cocontaminants including perfluorooctanesulfonate (PFOS), demonstrating that the process was not significantly affected by cocontaminants and that the process was capable of rapidly degrading PFOS. Preliminary investigation into the byproducts showed that only about 10% of PFOA and PFOS is converted into shorter-chain perfluoroalkyl acids (PFAAs). Investigation into the types of reactive species involved in primary reactions with PFOA showed that hydroxyl and superoxide radicals, which are typically the primary plasma-derived reactive species, play no significant role. Instead, scavenger experiments indicated that aqueous electrons account for a sizable fraction of the transformation, with free electrons and/or argon ions proposed to account for the remainder.