Nozawa M, Tanigawa K, Hosomi M, Chikusa T, Kawada E
Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
Water Sci Technol. 2001;44(9):127-33.
Effective and compact deodorization systems have been required for the measure of small-scale emission sources of offensive odors usually found in urban areas. We have developed a sheet material with titanium dioxide (TiO2) photocatalyst supported on fiber activated carbon (FAC) for a compact deodorization system. In the deodorization system using the TiO2/FAC sheet and a ultraviolet lamp, malodorants can be collected on the TiO2/FAC sheet by adsorption and then decomposed by photocatalysis with UV-irradiation. In this study, we obtained basic information about the removal and the decomposition of malodorants in the photocatalytic deodorization system using the TiO2/FAC sheet. The malodorants used in this study were methyl mercaptan, ammonia, and hydrogen sulfide. In addition, two kinds of light sources, a black light bulb (BLB; dominant wavelength: 365 nm) and an ultraviolet germicidal lamp (UV2; dominant wavelength: 254 nm) were used to analyze the effect on removal and decomposition characteristics by different dominant wavelengths. The removal rates of malodorants from the gas phase were determined in the deodorization system in the presence or absence of the TiO2/FAC sheet and UV-irradiation in order to study each removal effect due to adsorption onto the TiO2/FAC sheet, direct photolysis by UV-irradiation, and photocatalytic decomposition. The effect of adsorption onto the TiO2 /FAC sheet was pronounced in this batch-type experiment. The effect of photocatalysis was observed from the removal rates of methyl mercaptan. The percent oxidation of ammonia to nitrate and that of methyl mercaptan to sulfate were examined by determining products, i.e. nitrate and sulfate ions, with purified water after the reaction. The formation of nitrate or sulfate was not observed without UV-irradiation using the BLB, while the reactions progressed in the presence of the TiO2/FAC sheet. When the UV2 lamp was used, the oxidation of methyl mercaptan to sulfate occurred without the TiO2/FAC sheet. This suggests that the decomposition characteristics of malodorants were dependent on the wavelength of the light source.
城市地区通常存在小规模恶臭排放源，因此需要高效紧凑的除臭系统。我们开发了一种以纤维活性炭（FAC）负载二氧化钛（TiO₂）光催化剂的片状材料，用于紧凑的除臭系统。在使用TiO₂/FAC片材和紫外线灯的除臭系统中，恶臭物质可通过吸附作用收集在TiO₂/FAC片材上，然后在紫外线照射下通过光催化作用分解。在本研究中，我们获得了关于使用TiO₂/FAC片材的光催化除臭系统中恶臭物质去除和分解的基础信息。本研究中使用的恶臭物质为甲硫醇、氨和硫化氢。此外，还使用了两种光源，即黑光灯（BLB；主峰波长：365nm）和紫外线杀菌灯（UV2；主峰波长：254nm），以分析不同主峰波长对去除和分解特性的影响。为了研究TiO₂/FAC片材吸附、紫外线直接光解和光催化分解对每种去除效果的影响，在有或没有TiO₂/FAC片材及紫外线照射的情况下，在除臭系统中测定了气相中恶臭物质的去除率。在这个间歇式实验中，TiO₂/FAC片材的吸附作用很明显。从甲硫醇的去除率中观察到了光催化作用。通过测定反应后纯水中的产物，即硝酸根离子和硫酸根离子，研究了氨氧化为硝酸盐以及甲硫醇氧化为硫酸盐的百分比。在使用BLB且无紫外线照射的情况下未观察到硝酸盐或硫酸盐的形成，而在有TiO₂/FAC片材的情况下反应得以进行。当使用UV2灯时，在没有TiO₂/FAC片材的情况下甲硫醇也能氧化为硫酸盐。这表明恶臭物质的分解特性取决于光源的波长。
