具降解丙酮、氨氣及甲醛空氣清淨裝置之研發

Abstract

隨著科技與網路的發展，人們待在室內的時間越來越長，也因此人們對於室內品質變得更加重視。本實驗目的為使用二氧化鈦混合活性碳塗佈於不同基材上，探討不同形式之光觸媒反應器在處理大環境之揮發性有機物質之降解效能。並使用電腦模擬的方式最佳化反應器結構，使流體更容易接觸光觸媒且同時提高污染物在反應器內的滯留時間。製作出一台結合去除空氣中之揮發性有機物質、捕抓懸浮粒子及殺菌效果的空氣清淨狀裝置。 實驗製作三種光觸媒純二氧化鈦 P25、二氧化鈦混合活性碳、MTA，並比較出降解效果最好的一種。實驗結果顯示在小空間之清淨裝置一中,三種光觸媒二氧化鈦 P25、二氧化鈦混合1g活性碳、MTA之殘留比率分別為2.3 × 10-3、0.5 × 10-3及6.7 × 10-3；置於725 L大環境採樣箱內的空氣清淨裝置二之殘留比率分別為0.8099、0.7950、0.8357 ；置於725 L大環境採樣箱內的空氣清淨裝置三之殘留比率分別為0.8093、0.7544、0.9484 。再比較混合1、2、3g活性碳之降解效能。實驗結果顯示混合3g活性碳時之降解程度最佳，因此選取二氧化鈦混合3g活性碳為後續實驗之光觸媒材料。 在反應器方面，使用清淨裝置四可得到最佳結果。進行丙酮降解實驗，清淨裝置四之殘留濃度為18.9 × 10-3 ppm；清淨裝置三為83.1 × 10-3 ppm。選用清淨裝置四為後續實驗之反應器。在降解氨氣的實驗中，實驗7小時後氨氣濃度從8.8 ppm下降至 0.1114 ppm。進行高濃度甲醛降解實驗，實驗160分鐘後，甲醛濃度從3.257 ppm下降至13.0 × 10-3 ppm。模擬真實室內甲醛污染情況，控制甲醛起始濃度在0.111 ppm，實驗四分鐘後，濃度下降至0.072 ppm。同時發現，二氧化鈦混合活性碳光觸媒擁有非常好的吸附能力，能吸附反應中產生的副產物。 本實驗也進行了初步的光觸媒再生實驗。實驗結果顯示1g的光觸媒材料在照光兩小時後之降解效能有提升的現象；在照光4小時後，光觸媒材料降解效能變得更好。光源及亮度對於光催化反應非常重要，光衰減的實驗結果顯示，實驗前光亮度平均值為4.02 mWcm-2，燈管連續開啟 72 小時後，光亮度之均值為4.00 mWcm-2。證明實驗所使用之紫外燈管有一定的耐用性，實驗中紫外光亮度並不會有明顯的衰減。測試反應器內裝置四支燈管，降解效能為最佳。在殺菌實驗中，結果顯示直接照射紫外光時之細菌存活率為零。 旋風筒反應器進行了光催化反應動力分析，結果顯示當光觸媒塗佈面積減半的時候反應速率為3.5 × 10-4

People stay indoor most of the time, optimizing the indoor air quality become more important. The purposes of this study are to investigate the photodegradation efficiency of TiO2 P25, TiO2 mixed active carbon and MTA in four photocatalytic reactors. Using CFD modeling to observe the air flow inside the cyclone and optimizing the structure to increase the opportunity of the pollutant to touch photocatalyst. Developing an air cleaner for photodegradation of VOCs, particulate matter captured and disinfection. The results show that the photodegradation rate of acetone in photocatalytic reactor l by using TiO2 P25, TiO2 mixed active carbon and MTA as photocatalyst are 2.3 × 10-3, 0.5 × 10-3, 6.7 × 10-3 , respectively. While, the photocatalytic reactor 2 in 725 L test chamber are 0.8099、0.7950、0.8357 ppm, respectively and for the photocatalytic reactor 3 are 0.8093、0.7544、0.9484 . Comparison the photodegradation rate of mixing 1, 2, 3g active carbon. The result shows that the photodegradation rate of using TiO2 mixed 3g actived carbon is the best. Cyclone photocatalytic reactor has the best photodegradation efficiency. The photodegradation rate of acetone in photocatalytic reactor 4 and 3 are 18.9 × 10-3 ppm and 83.1 × 10-3 , respectively. The concentration of ammonia in photocatalytic reactor 4 after UV-irradiation for 7hr decreases from 8.8 ppm to 0.1114 ppm. The cyclone photocatalytic reactor has high photodegradation efficiency of HCHO. The concentration of HCHO decreases from 3.257 ppm to 0.013 ppm after UV-irradiation for 160 min. For simulate a real situation of polluted environment, the initial concentration of HCHO has been controlled at 0.111ppm. The concentration of HCHO attained to a value of 0.072 ppm in 4 min. In addition, active carbon can adsorb the side products that are generated from the photocatalytic process. In regeneration experiment, 1g of photocatalyst after UV-irradiation for 2hr, the capability of photodegrade has been improved and UV-irradiation for 4hr has the best result. The UV lamps in this study won’t decay significantly after turn on 72hr. The intensity before 72hr is 4.02mWcm-2, after turn on for 72hr the intensity becomes to 4.00 mWcm-2. Four UV lamps are inserted inside the cyclone. After UV-irradiation, E.coli has a zero survival rate. In kinetic analysis, the reaction rate of photocatalyst coating area is half and full are 3.5 × 10-4