奈米碳管產生空氣負離子裝置控制生物氣膠效率空間分布之研究

The spacial distribution of control efficiency of bioaerosol by negative air ions generated by carbon nanotube

陳彥潔(Yan-Jie Chen)

指導教授 ： 李慧梅

國立臺灣大學/工學院/環境工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.00631

摘要

本研究評估使用奈米碳管作為場發射材料產生空氣負離子在鼻下呼吸範圍中對生物氣膠的控制效能。在生物氣膠方面選擇大腸桿菌( Escherichia coli, E. coli )、枯草桿菌( B. subtilis )、酵母菌( C. famata )、青黴菌( P. citrinum )，鼻下呼吸範圍定義為以下巴為中心6 cm半徑之圓切面自面部前方0 cm至12 cm之圓柱空間。研究目的為模擬奈米碳管產生空氣負離子微型裝置佩帶在鼻下18 cm處，評估對鼻下呼吸範圍之生物氣膠的控制效果。首先探討空氣負離子在呼吸範圍中的分布狀況以及對四種生物氣膠的控制效率分佈，進而比較四種生物氣膠控制效率的差異，最後探討空氣負離子穩定度對生物氣膠控制效率的影響。
　　研究結果發現，空氣負離子在呼吸範圍中的濃度分佈在面部前方5 cm處最高，隨與空氣負離子產生源距離增加而衰減，由於面部會中和負電荷，故也會使空氣負離子濃度驟減。整體呼吸範圍中的空氣負離子濃度皆在3.02×105 ions/cm3以上。在生物氣膠控制效率方面，E. coli平均控制效率為25%∼44%，B. subtilis平均控制效率為26%∼39%，兩者皆在面部前方5∼12 cm之間有最佳控制效率；C. famata平均控效率為29%∼42%，在面部前方有最佳控制效率；P. citrinum平均控制效率為41%∼48%，是四種生物氣膠中控制效果最好的氣膠物種。整體而言，面部前方5∼12 cm之間有最佳控制效率。由四種生物氣膠之控制效率分佈可發現，粒徑大小與氣膠吸濕性會影響控制效率分佈。在靠近面部處，粒徑大的真菌氣膠控制效率會高於粒徑小的細菌氣膠；在空氣負離子以水合狀態存在時，吸濕性佳的E. coli氣膠控制效率會高於吸濕性較差的B. sutilis氣膠。此外，由改變空氣負離子實驗的結果得知，提升空氣負離子穩定度可有效增加對生物氣膠的控制效率。

關鍵字

生物氣膠 ； 空氣負離子 ； 奈米碳管 ； 呼吸範圍

並列摘要

The purpose of this study was to evaluate the distribution of control efficiency on bioaerosols in the breathing space by using negative air ions (NAIs) which was produced by carbon nanotubes (CNTs). The species of bioaerosol we used were Escherichia coli (E. coli), B. subtilis, C. famata and P. citrinum. The breathing space is defined as a circle surface in front of the mask from 0 to 12 cm. The center of the circle surface was the chin, and the diameter of the circle was 6 cm.
This study investigated the distribution of NAIs in the breath space. The results indicated that the highest NAIs concentration was distributed 5 cm far in front of the mask, and the NAIs concentration was decayed with the distance to the ionizer. The NAIs concentration also decayed on the mask surface due to electric neutralization. The ionizer can keep the NAIs concentration above 3.02×105 ions/cm3 in the breathing space.
This study investigated the distribution of control efficiency for four kinds of bioaerosols, and compared the difference of them. There was 25% to 44% average control efficiency for E. coli, and 26% to 39% average control efficiency for B. subtilis. The best control area for both of bacteria aerosols was 5 cm to 12cm in front of the mask. For fungal aerosol, there was 29% to 42% average control efficiency for C. famata, and the best control area was close to the mask. And P. citrinum had best control efficiency. There was 41% to 48% average control efficiency for P. citrinum.
According to the results, the diameter of bioaerosols and the hygroscopic growth of the aerosol were the factors influenced the control efficiency. The control efficiency of fungal aerosols with larger particle size (> 2 μm) was better than bacteria aerosols with smaller particle size (<1 μm). When the NAIs combined with H2O molecules, the control efficiency of E. coli aerosol was better than B. subtilis due to difference in hygroscopic characteristics. At the last, this study investigated the bioaerosols control efficiency in different stable level of NAIs. The results indicated that the control efficiency was increased with the stable NAIs concentration.

並列關鍵字

Bioaerosol ； Negative air ion ； Carbon nanotube ； Breathing space

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