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Volume 16, No. 1, January 2016, Pages 25-35 PDF(1.14 MB)  
doi: 10.4209/aaqr.2015.03.0170   

What are the Driving Factors Influencing the Size Distribution of Airborne Synthetic Clay Particles Emitted from a Jet Milling Process?

Ehsan Majd Faghihi1, Darren Martin2, Farhad Salimi3, Grant Edwards2, Congrong He1, Lidia Morawska1

1 International Laboratory for Air Quality and Health, Queensland University of Technology, GPO Box 2434, Brisbane QLD, 4001, Australia
2 Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane QLD, 4072, Australia
3 Menzies Research Institute, University of Tasmania, Hobart TAS, 7000, Australia


  • Emission characteristics of particles were infered by in-depth analysis of PNSD data.
    Contributions of different size ranges of particles to the emission were determined.
    PNSDs of emitted nanoparticles were analyzed using multi-lognormal fitting method.
    surface treatments and milling feed rate are both driving factors influencing PNSD.
    No general trend existed in PNSD variations due to surface treatment or feed rate.



In the field of workplace air quality, measuring and analyzing the size distribution of airborne particles to identify their sources and apportion their contribution has become widely accepted, however, the driving factors that influence this parameter, particularly for nanoparticles (< 100 nm), have not been thoroughly determined. Identification of driving factors, and in turn, general trends in size distribution of emitted particles would facilitate the prediction of nanoparticles’ emission behavior and significantly contribute to their exposure assessment. In this study, a comprehensive analysis of the particle number size distribution data, with a particular focus on the ultrafine size range of synthetic clay particles emitted from a jet milling machine was conducted using the multi-lognormal fitting method. The results showed relatively high contribution of nanoparticles to the emissions in many of the tested cases, and also, that both surface treatment and feed rate of the machine are significant factors influencing the size distribution of the emitted particles of this size. In particular, applying surface treatments and increasing the machine feed rate have the similar effect of reducing the size of the particles, however, no general trend was found in variations of size distribution across different surface treatments and feed rates. The findings of our study demonstrate that for this process and other activities, where no general trend is found in the size distribution of the emitted airborne particles due to dissimilar effects of the driving factors, each case must be treated separately in terms of workplace exposure assessment and regulations.



Keywords: Airborne particle emission; Size distribution; Workplace aerosol measurement.



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