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

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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.