Germicidal Effects of Non-Thermal Plasma on Bioaerosols
| Autor: | Hui-Pin Lin, 林惠萍 |
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| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 It has been known that lots of air pollutants exist in the indoor environment. It also has been reported that these pollutants, particularly bioaerosols, can cause a serious illness on human respiratory system. Therefore, an innovative non-thermal dielectric barrier discharges (DBD) plasma system was used to test its feasibility of removing bioaerosols in the study. The sterilization efficacy of bioaerosols by DBD plasma system was evaluated based on different pivotal parameters including types of bioaerosols, plasma power inputs and frequencies, relative humidity (RH), and retention times. The results showed that the sterilization efficacy of bioaerosols was following the order: Yeast > S. aurcus > P. citrinum > B. subtilis. It found that the sterilization efficacy of fungi with either non spore-form or spore-form was greater than that of bacteria. With regard to the effect of power inputs and frequencies, the results concluded that high voltage and low frequency could achieve better sterilization efficiency in comparison with low voltage and high frequency. In addition, the results indicated that the higher efficacy was appeared at longer retention time. Finally, it also found that high RH significantly improved the sterilization efficacy of S. aurcus, Yeast, and P. citrinum. However, increasing RH has limited effect on B. subtilis. The electricial particles charged in non-thermal DBD plasma system was the main mechanism of sterilizing bioaerosols. With the deposition of the electricial particles on outer cell membrane, it generated the electrostatic tension to break down the cell. Another mechanism of sterilization was the production of the reactive species, such as O3 and OH∙. These reactive species could desconstruct cell membrane, and oxidize amino acids and DNA inside the cells. The optimal operating conditions of non-thermal DBD plasma system were controlled at retention time of 1.5 sec, input power with 10W, and power frequency of 60Hz in this study. For the four different bioaerosols, the sterilization efficacy were all greater than 90% regardless the effect of RH. This research demonstrated the potential of non-thermal DBD plasma system to break down bioaerosols, and this system could be applied to improve indoor air quality. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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