Enhanced photochemical decomposition of environmentally persistent perfluorooctanoate by coexisting ferric ion and oxalate
Enhanced photochemical decomposition of environmentally persistent perfluorooctanoate by coexisting ferric ion and oxalate
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DOI：
10.1007/s11356-016-6205-4
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发表时间：
2016-02
影响因子：
5.8
通讯作者：
Y. Wang;Pengyi Zhang
中科院分区：
文献类型：
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作者：
Y. Wang;Pengyi Zhang
全氟辛酸（PFOA）是一种环境持久性污染物，在254 nm的紫外线照射下，在铁离子和草酸存在下迅速分解。为了解该工艺分解PFOA的机理，研究了反应气氛、铁离子浓度、草酸浓度以及分解中间体对PFOA分解的影响。PFOA主要通过两种途径分解：一是通过Fe(III)-PFOA配合物进行光化学氧化；二是通过草酸铁配合物光解产生羧酸阴离子自由基（CO2•−）进行单电子还原。过量草酸作用下，随着铁浓度从7 μM增加到80 μM， PFOA的分解速度加快，半衰期从114 min缩短至34 min。除氟离子外，还鉴定出6种含c2 - c7的短链全氟羧酸（PFCAs）为主要中间体。o2的存在促进了Fe3+/Fe2+的氧化还原循环，从而避免了Fe（III）的耗尽。
Perfluorooctanoic acid (PFOA), an environmentally persistent pollutant, was found to be quickly decomposed under 254 nm UV irradiation in the presence of ferric ion and oxalic acid. To understand the PFOA decomposition mechanism by this process, the effects of reaction atmosphere and concentrations of ferric ions and oxalic acids on PFOA decomposition were investigated, as well as decomposition intermediates. PFOA mainly decomposes via two pathways: (i) photochemical oxidation via Fe(III)-PFOA complexes and (ii) one-electron reduction caused by carboxylate anion radical (CO2•−), which was generated by photolysis of ferrioxalate complexes. Under excess oxalic acid, PFOA decomposition was accelerated, and its corresponding half-life was shortened from 114 to 34 min as ferric concentration increased from 7 to 80 μM. Besides fluoride ions, six shorter chain perfluorinated carboxylic acids (PFCAs) bearing C2-C7were identified as main intermediates. The presence of O2promoted the redox recycling of Fe3+/Fe2+and thus avoided the exhaustion of the Fe(III).