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  • 學位論文

室內空氣中甲醛的綠色化學分析方法及降解研究

Determination of Formaldehyde in Indoor Air by Green Analytical Method and Its Degradation Study

指導教授 : 凌永健
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摘要


人們於日常生活中因曝露於室內空氣污染,所引起的健康風險遠大於室外空氣。環保署於2005年提出「室內空氣品質建議值草案」,規定甲醛的建議濃度為0.1 ppmv。 空氣中甲醛檢測標準方法規定,採集之室內空氣樣品須帶回實驗室檢測,每個樣品在前處理過程中,會使用數毫升的含氯有機溶劑。本研究利用溶劑棒微萃取技術 (Solvent Bar Microextraction, SBME),取代現行標準方法使用的液-液萃取技術,成功達到避免廢棄物之產生和減少有機溶劑用量,符合綠色化學理念;本研究亦使用配有塗佈2,4-二硝基苯胼(2,4-dinitrophenyl hydrazine, DNPH)濾紙的攜帶型甲醛偵測器,現場實地偵測,10分鐘後即可測定甲醛濃度,達到現場實時測定之綠色化學理念。 本研究使用標準方法和甲醛偵測器方法,比對測定3處大量使用木製產品的新近裝修室內空氣中甲醛,濃度介於0.133~0.321 ppmv,皆高於建議值,相對差異百分比皆低於20%,其中一處在通風30分後,甲醛濃度從0.279 ppmv降為0.131 ppmv。說明此二方法的相匹配,及良好通風可以降低室內甲醛濃度。 本研究亦利用TiO2光觸媒降解甲醛。實驗結果顯示層接層(Layer-by-Layer)法塗佈光觸媒節省時間,均勻性佳、光穿透率高,可以達到90% 降解效率。TiO2光降解醛類(C1~C5)氣體效率佳,低碳數醛類的降解效率較佳;降解途徑為先被氧化成有機酸,再裂解為較低碳數的醛類,裂解反應的速率比氧化反應的速率慢。

並列摘要


The health risk from exposure to indoor air pollution is greater than from outdoor. To effectively promote indoor air quality control, the EPA has issued the draft of the Indoor Air Quality Control Act in 2005 and set the recommended value of indoor formaldehyde concentration as 0.1ppmv. The standard method for determining formaldehyde in air required the sample being brought back to laboratory for analysis and used several ml of chloroform per sample. We replaced the liquid-liquid extraction used in current standard method by solvent bar microextraction. The approach successfully prevented waste generation and reduced organic solvent use, fulfilling the principles of green chemistry. We also used a portable formaldehyde detecting instrument equipped with an 2,4-dinitrophenyl hydrazine (DNPH) –coated filter, which could determine formaldehyde concentration on-site in 10 min. We compared the analytical performance between the standard method and the portable method by determining the indoor formaldehyde concentrations in three newly renovated home/office/shops which used many wooden products. The values ranged from 0.133~0.321 ppmv and were all above the recommended values. The relative percent difference were all smaller than 20%,In one location, the formaldehyde concentration decreased from 0.279 ppmv to 0.131 ppmv after 30 min ventilation。The findings demonstrate the compatibility between these two methods and effective reduction of indoor formaldehyde could be achieved by sound ventilation. We also used TiO2 photocatalyst to degrade formaldehyde. The results show that TiO2 photocatalyst prepared by layer-by-layer method saved time, good uniformity, and high light transmission, which could achieve degradation efficiency of 90%. TiO2 could effectively degrade aldehydes (C1~C5). Low carbon aldehydes showed better efficiency. The aldehyde was converted to carboxylic acid first, then to aldehyde with lower carbon number. The rate of the later reaction (decomposition) is smaller than the former one (oxidization).

並列關鍵字

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參考文獻


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