Generation of Submicron Mass/Volume-Monodisperse Aerosols with a Nebulizer-Impactor-Electrostatic Classifier System

Abstract

A study was undertaken to investigate the mass size dispersion of particles classified according to their electrical mobilities. This is of primary concern in experiments that measure a concentration dependent property of the classified particles. Initially, the mass size distribution of particles produced by the 3-jet Collison, 6-jet Collison, and Misty-Ox nebulizers was measured. A 0-2 stage impactor was,placed after the nebulizers and the size mass distribution was measured again. The polydisperse particle stream was then used to generate "size classified" aerosol and the mass size distribution of the equal mobility particles was calculated and measured. It was found that without an impactor in line, the aerosol stream contained a significant mass fraction of multiply charged particles. When an impactor was inserted directly after the nebulizers, the multiply charged particles were effectively removed and the particles were nearly monodisperse.

Generation of Nanoparticles with a Nebulizer-Cyclone System

“…The number concentrations (∼10 6 particles/cc) of 40-60 nm particles produced with the nebulizer-cyclone generator are comparable or slightly greater than those found by other researchers using nebulizers and impactors (Niida 1988;Asgharian 1992). The number concentration found in this study is similar to nanoparticle generation by other methods (Veranth 2003;Chen 2007).…”

“…Smaller drop production would also facilitate more rapid drying at a lower relative humidity. Lastly, it would reduce the number of multiple-charged particles when producing monodispersed aerosols with a nebulizer and DMA combination (Asgharian et al 1992).…”

“…Several researchers have used an impactor to remove the largest airborne droplets produced by a nebulizer (May 1973;Asgharian et al 1992;Peters et al 1994). Impactors typically offer a sharp size separation but with solid particles can have issues with overloading, which changes their cutoff characteristics .…”

“…However, electrospray generators tend to easily clog, produce low particle output rates, and require that the sprayed solution have specific conductive properties. A differential mobility analyzer (DMA) may be used to size select a narrow range of particles produced with a nebulizer but results in a very low particle output rate (Asgharian et al 1992).…”