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

• Main Authors: Yan-Jie Chen, 陳彥潔
• Other Authors: 李慧梅
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/42341531118637544933

碩士 === 國立臺灣大學 === 環境工程學研究所 === 97 === 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.