Residue Particles: Tips to Minimize a Potentially Problematic Artifact of Aerosol Generation

Justin S. Koczak, ANDREA J. TIWARI, Daniel R. Troolin, TSI Incorporated

     Abstract Number: 373
     Working Group: Exhibitor and Instrument Application Showcase

Abstract
Aerosol generation is a key feature of numerous experimental designs within aerosol research: atmospheric chemistry studies, exposure studies, and other research areas depend on the ability to generate aerosol particles of a desired composition and size distribution. In the case of generating aerosols from a liquid feed material, droplets are created and as the liquid evaporates from each droplet, dry aerosol particles result. This is often a very successful technique when using solutions (e.g., NaCl is dissolved in water, and the solution is aerosolized to create NaCl aerosol). In the case of suspensions such as Polystyrene Latex (PSL), two types of aerosol particles often result: the first is the desired suspended particle while the second is a residue particle, which forms from any typically undesired dissolved nonvolatile species that had been present in the bulk liquid (e.g., surfactants, impurities, stabilizers, etc.). If the residue particles are very different in size compared to the suspended particle size, their presence may not necessarily cause negative effects to the outcome of the experiment. If, however, the suspended particles are comparable in size to the residue, the similarity in size between the two particles types in the aerosol can inhibit accurate characterization of the desired aerosol. This is particularly challenging when examining smaller submicrometer aerosols (e.g., less than 20 nm) in applications such as colloid characterization, liquid purity monitoring, or instrument calibration. This Exhibitor Showcase will illustrate the formation of residue particles using different samples, and will demonstrate how proper selection of an aerosol generation technique can help to reduce the presence and therefore mitigate influence of residue particles.