Effect of thermal treatment on the photocatalytic degradation of ethylene, trichloroethylene, and chloroform
Effect of thermal treatment on the photocatalytic degradation of ethylene, trichloroethylene, and chloroform
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DOI：
10.1007/s11164-008-0001-9
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发表时间：
2009-01
影响因子：
3.3
通讯作者：
S. Yamazaki;H. Abe;Toshifumi Tanimura;Yousuke Yamasaki;K. Kanaori;K. Tajima
中科院分区：
文献类型：
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作者：
S. Yamazaki;H. Abe;Toshifumi Tanimura;Yousuke Yamasaki;K. Kanaori;K. Tajima
热处理降低了溶胶-凝胶法制备的TiO 2颗粒的光催化活性。对于乙烯或氯仿的完全矿化，活性除以粒料的比表面积在400°C的烧制温度下最大化。三氯乙烯（TCE）的光催化降解过程中，大部分TCE被转化为氯代副产物，如二氯乙酸、三氯甲烷和光气，生成的[CO2]/降解的[TCE]的化学计量比在400°C时出现最大值。流动注射系统中5，5-二甲基-1-吡咯啉-N-氧化物（DMPO）的电子自旋共振（ESR）自旋捕获表明，在400°C下烧制时，DMPO-OH加合物的信号强度最高。结果表明，在400°C下焙烧的TiO 2上产生OH自由基的效率最高，且OH自由基的产生与TiO 2中金红石和金红石的含量有关。在TCE生成氯化副产物方面，在较低的烧成温度下，生成较多的二氯乙酸（DCAA），较少的三氯甲烷（CHCl 3）和三氯甲烷（COCl 2），这表明氯乙氧基自由基对DCAA或三氯甲烷（CHCl 3）和三氯甲烷（COCl 2）生成的支化率与烧成温度有关。
The thermal treatment of TiO2pellets prepared by the sol–gel method decreased the photocatalytic activity. The activity divided by the specific surface area of the pellets for the complete mineralization of ethylene or chloroform was maximized at the firing temperature of 400°C. For the photocatalytic degradation of trichloroethylene (TCE), most of them were converted to chlorinated by-products, such as dichloroacetic acid, chloroform, and phosgene, and the stoichiometric ratio of [CO2]formed/[TCE]degradedshowed a maximal value at 400°C. The electron spin resonance (ESR) spin-trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) in the flow injection system indicated that firing at 400°C gave the highest signal intensity of DMPO–OH adducts. These findings indicated that the OH radical was produced most effectively on the TiO2fired at 400°C, which would be related to the content of anatase and rutile. Concerning the formation of chlorinated by-products from TCE, more dichloroacetic acid (DCAA) were detected and less CHCl3and COCl2were formed at lower firing temperatures, suggesting that the branching ratio of chloroethoxy radicals to the formation of DCAA or CHCl3and COCl2by C–C bond scission depended on the firing temperature.