Degradation of organic gases using ultrasonic mist generated from TiO2 suspension.
Degradation of organic gases using ultrasonic mist generated from TiO2 suspension.
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DOI：
10.1016/j.chemosphere.2010.07.009
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发表时间：
2010-09
期刊：
影响因子：
8.8
通讯作者：
K. Sekiguchi;Daisuke Noshiroya;Misako Handa;Keisuke Yamamoto;K. Sakamoto;N. Namiki
中科院分区：
文献类型：
--
作者：
K. Sekiguchi;Daisuke Noshiroya;Misako Handa;Keisuke Yamamoto;K. Sakamoto;N. Namiki
用三种不同的紫外光光源对超声雾化二氧化钛悬浮液形成的雾化颗粒光催化降解有机气体进行了研究。选择三种芳香族挥发性有机化合物(VOCs；甲苯、对二甲苯和苯乙烯)和醛(甲醛和乙醛)作为降解实验的模型有机气体。在UV365的照射下，甲苯在雾粒表面发生光催化降解反应。在UV254+185照射下，VOC气体的去除效率和矿化率均高于UV365和UV254照射下的VOC气体。在UV254+185的照射下，由于几种有机气体的去除效率取决于与OH自由基的反应速度，生成的臭氧的主要作用是完成中间产物的矿化，因此VOC气体不仅通过直接光解，而且还被OH自由基氧化，立即被降解并转化为水溶性中间体。另一方面，水溶性的乙醛气体在表面反应前会被雾状颗粒迅速捕获。此外，通过VOC气体分解形成的水溶性中间体完全被困在雾中，在反应器出口处没有检测到。因此，即使在UV254+185辐照下，也没有观察到显著的二次粒子产生。根据这些结果以及雾滴的尺寸分布，发现主要是亚微米级的液滴对光催化反应有贡献。最后，提出了有机气态污染物在雾粒表面的降解机理。
The photocatalytic degradation of organic gases with mist particles that were formed by ultrasonic atomization of a TiO2suspension was performed with three different ultraviolet light sources. Three aromatic volatile organic compounds (VOCs; toluene, p-xylene, and styrene) and aldehydes (formaldehyde and acetaldehyde) were chosen as model organic gases for the degradation experiment. Under UV365irradiation, toluene was decomposed by a photocatalytic reaction on the surface of mist particles. Under UV254+185irradiation, the removal efficiency and mineralization ratio of the VOC gases were higher than those under UV365or UV254irradiation. Under UV254+185irradiation, it was found that VOC gases were immediately degraded and converted to water-soluble intermediates by not only direct photolysis but also oxidation by OH radical, since the removal efficiency of several organic gases depended on the reaction rate with OH radical and the primary effect of generated ozone was to complete the mineralization of the intermediates. On the other hand, water-soluble aldehyde gases were rapidly trapped by mist particles before reaction on their surface. Furthermore, water-soluble intermediates that formed via the decomposition of VOC gases were completely trapped in the mist and were not detected at the reactor exit. Therefore, notable secondary particle generation was not observed, even under UV254+185irradiation. Based on these results as well as the size distribution of the mist droplets, it was found that primarily submicron-scale droplets contributed to the photocatalytic reaction. Lastly, we propose a mechanism for the degradation of organic gaseous pollutants on the surface of mist particles.