Vikram Pratap1, S. Aditya Kiran1, Qijing Bian2, Jeffrey R. Pierce2, Philip K. Hopke1, Shunsuke Nakao This email address is being protected from spambots. You need JavaScript enabled to view it.1

1 Department of Chemical and Biomolecular Engineering, Clarkson University, Potsdam, NY 13676, USA
2 Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523, USA


Received: May 28, 2020
Revised: August 12, 2020
Accepted: September 29, 2020

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.


Download Citation: ||https://doi.org/10.4209/aaqr.2020.05.0268  


Cite this article:

Pratap, V., Kiran, S.A., Bian, Q., Pierce, J.R., Hopke, P.K. and Nakao, S. (2020). Observation of Vapor Wall Deposition in a Smog Chamber Using Size Evolution of Pure Organic Particles. Aerosol Air Qual. Res. https://doi.org/10.4209/aaqr.2020.05.0268


HIGHLIGHTS

  • Size distributions of pure particles can assess vapor wall deposition.
  • Temperature dependence of vapor pressure determines vapor wall deposition.
  • Slow evaporation of particles led to apparent lack of vapor wall deposition.
 

ABSTRACT 


Prior studies have shown that neglecting the vapor wall loss could lead to the underestimation of the secondary organic aerosol (SOA) yields in smog chamber experiments. The majority of the previous studies investigated vapor wall loss of a wide range of semi-volatile organic vapors at room temperatures using extensive chemical analysis. This study poses a question: Can vapor wall deposition in a smog chamber be observed only using physical measurements of aerosol properties? This study assesses the significance of vapor wall loss using only the size evolution of pure organic compound particles. To our knowledge, this technique is used for the first time in assessing the vapor wall loss of chemical species in chamber experiments. Dark experiments were conducted by injecting pure levoglucosan particles into an outdoor smog chamber at multiple ambient temperatures, ranging from -10oC to +15oC. Peak diameter analysis revealed levoglucosan particles shrunk by ~37% at 15oC and ~20% at 10oC experiments, whereas no shrinkage was observed at temperatures below 0°C suggesting significant vapor wall loss of levoglucosan at warmer temperatures (> 10oC). Two-Moment Aerosol Sectional (TOMAS) and additional simple kinetic model simulations suggest that the effects of temperature on vapor wall loss can primarily be explained by the change in saturation vapor pressure of the organic compound and that the lack of apparent vapor wall loss of levoglucosan below 0°C was due to kinetics, i.e., slow evaporation relative to the chamber experiment timescales. The same approach can be applied to other organic species to expand the range of volatility relevant to chamber experiments.


Keywords: Organic aerosol; Teflon chamber; Vapor wall loss; Levoglucosan; Low temperature.




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