10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Continuous Bioaerosol Sampling Using the Super-hydrophilic Silica Coated Wet-cyclone System
YUSUNG CHO, Ki Joon Heo, Byoung Uk Lee, Jae Hee Jung, Korea Institute of Science and Technology
Abstract Number: 1267 Working Group: Bioaerosols
Abstract Recently, increasing attention has been paid to the relationship between hazardous respirable bioaerosol and human health. Thus, there is growing need to develop the portable bioaerosol detector that can provide the real-time and continuous bioaerosol information. Recently, the bioaerosol analysis techniques based on micro-electromechanical systems (MEMS) have been studied for the miniaturization of the bioaerosol sensor with the accurate and rapid response of target aerosol.
The cyclone system has been used extensively to collect and concentrate airborne particles by the cyclonic action of the fluid in the cylinder. In the 1960's, the development of a wetted-wall cyclone (called wet-cyclone) having nearly continuous liquid flow was started as a means of sampling a large volume flow rate of air (about 1,000 L/min). In recent years, the wet-cyclone system has been developed for the real-time bioaerosol sampler. In this system, the target bioaerosol can be concentrated in a small amount of sampling water. However, the non-uniform and unstable water film condition in the wet-cyclone can yield the significant increase of the particle wall loss. This undesired situation is caused by the unstable momentum balance between air to the liquid stream, the rapid evaporation of the liquid, and the hydrophobic status of the wet-cyclone inner surfaces.
In this study, we applied the super-hydrophilic treatment to the inner wall of wet-cyclone by silica nanoparticle coating to make uniform and stable liquid film. The wettability of the coated surface was evaluated through the water contact angle measurement. Also, the durability test of coatings was conducted from the comparison of the contact angle before and after the sonication process. Finally, the performance of the super-hydrophilic coated wet-cyclone system was evaluated regarding particle collection efficiency and particle wall loss. The collection efficiency was defined as the aerosol to liquid transfer rate. In this test, we used the two types of test aerosol, standard polystyrene-latex particles (PSL) and S. epidermidis.
The hydrophilic performance of the polycarbonate surface is gradually increased with silica coating concentration. Additional annealing process of the sample in the dry oven can increase the binding property of the silica nanoparticle film and the substrate; thus its super-hydrophilic property can be maintained despite the 10-minute sonication environment. Finally, the aerosol to liquid transfer rate was increased ~45% to ~99.99% after the super-hydrophilic coating treatment on the inner wall of wet-cyclone.
This research was supported by the Ministry of Environment (2016000160008), the Ministry of Science and ICT (2015R1D1A1A09056879), and KIST Institutional Program, Republic of Korea.