Sonication-assisted photocatalytic decomposition of perfluorooctanoic acid.
Sonication-assisted photocatalytic decomposition of perfluorooctanoic acid.
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DOI：
10.1016/j.chemosphere.2008.12.065
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发表时间：
2009-05
期刊：
影响因子：
8.8
通讯作者：
Sri Chandana Panchangam;A. Lin;Jia-Hong Tsai;Cheng‐Fang Lin
中科院分区：
文献类型：
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作者：
Sri Chandana Panchangam;A. Lin;Jia-Hong Tsai;Cheng‐Fang Lin
从科学和工业的角度来看，全氟化学品的分解具有重大意义。本文报道了在254 nm紫外光照射下，以商品TiO_2（RdH）和自制TiO_2（sol-gel）为光催化剂，在室温、常压和近中性pH条件下，超声辅助光催化降解全氟辛酸（PFOA）的实验结果。PFOA分解为氟离子和几种具有较短碳链长度的全氟羧酸（PFCAs），如全氟庚酸（PFHpA）、全氟己酸（PFHxA）、全氟丙酸（PFPA）和三氟乙酸（TFA）。超声波辅助灭菌的效率为64%。在所有的情况下，更高的效率时，溶胶-凝胶TiO 2被用作光催化剂比商业RdH TiO 2催化剂。溶胶-凝胶TiO 2的比表面积是商业RdH TiO 2的三倍，这似乎是观察到的相应效率差异的可能原因。这也是有趣的注意到，pH值起着决定性的作用，在PFOA的分解和相应的光催化进行不同的控制pH值下。全氟烷基自由基可能被氧化的超氧化物和羟基自由基在TiO 2介导的氧化过程中产生的pH值分别为4和10。在超声辅助骨愈合中，超声作用被认为是骨愈合的辅助工具，而不是工具本身。超声处理通过物理分散TiO 2增强了TiO 2的分散性，并简化了传质过程，使TiO 2表面不断再生。
Decomposition of perfluorinated chemicals is of significant interest in both scientific and industrial perspectives. Here, we report the decomposition of perfluorooctanoic acid (PFOA) under sonication-assisted photocatalysis by utilizing commercial TiO2(RdH) and home-made TiO2(sol–gel) as photocatalysts at ambient temperature, pressure and near neutral pH with the irradiation of 254nm UV light. PFOA was decomposed into fluoride ions and to several perfluorinated carboxylic acids (PFCAs) with a shorter carbon chain length such as perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), perfluoropropanoic acid (PFPA), and trifluoroacetic acid (TFA). The efficiency of sonication-assisted photocatalysis was found to be 64%. In all the cases, higher efficiencies were obtained when sol–gel TiO2was used as a photocatalyst than the commercial RdH TiO2catalyst. The specific surface area is three times higher for sol–gel TiO2than commercial RdH TiO2and appears to be the probable reason for the observed differences in the corresponding efficiencies. It is also interesting to note that pH plays a determining role in the decomposition of PFOA and correspondingly photocatalyses were carried out under different controlled pH. Perfluoroalkyl radicals are presumably oxidized by superoxide and hydroxyl radicals generated during the TiO2-mediated photocatalysis at pH 4 and 10, respectively. The role of sonication in sonication-assisted photocatalysis was construed to be an aid to photocatalysis than a tool itself. Sonication enhances photocatalysis through physical dispersion of TiO2and eases mass transfer which keeps on rejuvenating the TiO2surface.