Horikoshi Satoshi, Hidaka Hisao, Serpone Nick
Frontier Research Center for the Global Environment Protection, Meisei University, Hino, Tokyo, Japan.
Environ Sci Technol. 2002 Mar 15;36(6):1357-66. doi: 10.1021/es010941r.
The photocatalytic decomposition of the cationic rhodamine-B (RhB) dye was examined in aqueous TiO2 dispersions using an integrated microwave/UV-illumination (PD/MW) method. This procedure proved to be superior in the degradation of the dye than the TiO2 photocatalytic degradative method alone. With few exceptions, the integrated PD/MW method also proved superior for other chemical systems. The greater efficacy of the PD/MW technique appears to be the result of the following two considerations: (i) there is enhanced formation of reactive oxygen species (.OH radicals), as attested to by DMPO spin-trap ESR methods and their attack on the dye; and although speculative at this time, (ii) the activity of bulk water or the TiO2 particle surface is somehow affected by microwave radiation. The greater efficacy of the PD/MW degradation method was also observed at low concentrations of molecular oxygen and at low radiant excitance of the light source. A brief mechanistic description is given on the basis of results obtained on the two model compounds, (i) benzoic acid and (ii) pyronin-B dye.
采用集成微波/紫外光照射（PD/MW）方法，在TiO₂水性分散液中研究了阳离子罗丹明B（RhB）染料的光催化分解。该方法在染料降解方面比单独的TiO₂光催化降解方法更具优势。除了少数例外情况，集成的PD/MW方法对其他化学体系也同样具有优势。PD/MW技术的更高效率似乎源于以下两个因素：（i）通过DMPO自旋捕获ESR方法证明，活性氧物种（·OH自由基）的形成增加，并且它们会攻击染料；尽管目前只是推测，（ii）大量水或TiO₂颗粒表面的活性受到微波辐射的某种影响。在低浓度分子氧和低光源辐射激发下，也观察到了PD/MW降解方法的更高效率。基于对两种模型化合物（i）苯甲酸和（ii）吡啰红B染料的研究结果，给出了简要的机理描述。
