Development of a Photocatalytic Module for Environmental Management Using the Ice Templating Method

在此之前，我们已经证明了通过对其母体水凝胶的单向冷冻，可以以纤维或微蜂窝的形式合成各种多孔凝胶。利用这种新方法，我们将其命名为“冰模板法”，可以实现多孔材料的精密微成型。这种形态控制必然会导致这种多孔材料性能的增强。本工作旨在利用这种新开发的方法开发用于环境管理的光催化模块。在第一年，我们专注于模块中使用的关键材料的开发。成功地合成了钛基材料的微纤维和微蜂窝。结果表明，所制备的材料不仅具有极高的光催化活性，而且具有传统光催化剂所不具备的高比表面积。在最后一年，我们实际使用获得的材料构建模块。将纤维型光催化剂包装在玻璃柱中，作为模块使用。由于纤维的透明度普遍高于微型蜂窝，因此采用纤维形态可以预期更高的辐照效率。使用含有100 ppm甲苯的空气作为模型VOC物质来测试模块的性能。结果发现，即使在SV值超过3000的情况下，经UV灯照射的组件仍能在超过一周的时间内去除甲苯。考虑到微纤维的高表面积，即使模块只是周期性照射，也可以实现类似的性能。此外，由于光催化材料的独特形态，模块只产生轻微的压降。因此，期望利用本工作获得的模块可以构建高效紧凑的光催化装置。

Previously, we showed that various porous gels can be synthesized in the forms of fibers or microhoneycombs, through the unidirectional freezing of their parent hydrogels. By using this new method which we named the "Ice Templating" method, the precise micromolding of porous materials can be achieved. Such morphology controlling is sure to lead to the enhancement of the performance of such porous materials. This work was conducted to develop a photocatalytic module for environmental management using this newly developed method.In the first year, we focused on the development of key materials to be used in the modules. Microfibers and microhoneycombs of titania-based materials were successfully synthesized. It was found that the obtained materials not only show extremely high photocatalytic activities, but also possess high surface areas, a feature which can be rarely found in conventional photocatalysts.In the final year, we actually constructed modules using the obtained materials. Fibrous photocatalysts were packed in glass columns and were used as modules. The fiber morphology was adopted as higher irradiation efficiencies can be expected, as the transparency of fibers was generally higher than that of microhoneycombs. Air containing 100 ppm of toluene as the model VOC substance was used to test the performance of the modules. It was found that modules irradiated by UV lamps were able to remove toluene for a period longer than 1 week, even when the SV value exceeded 3000. Considering the high surface area of the microfibers, it is expected that similar performances can be achieved even when the modules are only periodically irradiated. Moreover, due to the unique morphology of the photocatalytic material, the modules only caused slight pressure drops. Therefore, it is expected that a highly efficient and compact photocatalytic unit can be constructed by using the modules obtained through this work.