Ultrasonic humidifier use is a potential source of human exposure to inhalable particulates. This paper focused on the behavior of insoluble iron oxides particles, and aluminum oxide particles in ultrasonic humidifiers. 10 mg/L Fe oxide particles and 5 mg/L Al oxide suspension solutions were added into tap water, as fill water for ultrasonic humidifiers operated for 14 hours. Denser, heavier particles of approximate 1.5 um diameter of iron or aluminum oxides accumulated in the humidifier reservoir. Smaller, suspended metal oxide particles of 0.22-0.57 um diameter were emitted as aerosols from humidifiers. Soluble anions and cations in tap water were present in the aerosols emitted from humidifiers. The results indicate that if suspended particles and dissolved minerals are present in source water, they will be transported in aerosolized waters. / M. S. / Ultrasonic humidifiers are used widely globally. However, they may cause adverse human health effects, such as respiratory damage, and even deaths. Previous work focused on the effect of soluble constituents in the fill water on the emissions of aerosols. This paper demonstrated the fate and transport of insoluble mineral particles in the ultrasonic humidifiers. The particles used were iron oxides particles powder (micro iron oxide, and nano iron oxide), and aluminum oxide particles in suspension (nano size), which have different mean particle sizes. Results showed only very small portion of iron oxides particles transported into the aerosols, and a relatively much bigger portion of aluminum oxide particles transported into the aerosols, which may be contributed by their differences in density and form. In conclusion, denser and heavier particles settled to the bottom of the humidifiers, while smaller and suspended particles were emitted in the aerosols.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/99237 |
| Date | 10 January 2018 |
| Creators | Yao, Wenchuo |
| Contributors | Civil and Environmental Engineering, Dietrich, Andrea M., Marr, Linsey C., Gallagher, Daniel L. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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