Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions
Atmospheric aerosol particles are often partially or completely composed of inorganic salts, such as ammonium sulfate and sodium chloride, and therefore exhibit hygroscopic properties. Many inorganic salts have well-defined deliquescence and efflorescence points at which they take up and lose water,...
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2015-08-01
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doaj-79dc0c22e5884fbc9e3773474a821e5c2020-11-24T21:01:11ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242015-08-0115158975898610.5194/acp-15-8975-2015Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutionsM. A. Zawadowicz0S. R. Proud1S. S. Seppalainen2D. J. Cziczo3Massachusetts Institute of Technology, Cambridge, Massachusetts, USAMassachusetts Institute of Technology, Cambridge, Massachusetts, USAMassachusetts Institute of Technology, Cambridge, Massachusetts, USAMassachusetts Institute of Technology, Cambridge, Massachusetts, USAAtmospheric aerosol particles are often partially or completely composed of inorganic salts, such as ammonium sulfate and sodium chloride, and therefore exhibit hygroscopic properties. Many inorganic salts have well-defined deliquescence and efflorescence points at which they take up and lose water, respectively. Field measurements have shown that atmospheric aerosols are not typically pure inorganic salt, instead, they often also contain organic species. There is ample evidence from laboratory studies that suggests that mixed particles exist in a phase-separated state, with an aqueous inorganic core and organic shell. Although phase separation has not been measured in situ, there is no reason it would not also take place in the atmosphere. Here, we investigate the deliquescence and efflorescence points, phase separation and ability to exchange gas-phase components of mixed organic and inorganic aerosol using a flow tube coupled with FTIR (Fourier transform infrared) spectroscopy. Ammonium sulfate aerosol mixed with organic polyols with different O : C ratios, including 1,4-butanediol, glycerol, 1,2,6-hexanetriol, 1,2-hexanediol, and 1,5-pentanediol have been investigated. Those constituents correspond to materials found in the atmosphere in great abundance and, therefore, particles prepared in this study should mimic atmospheric mixed-phase aerosol particles. Some results of this study tend to be in agreement with previous microscopy experiments, but others, such as phase separation properties of 1,2,6-hexanetriol, do not agree with previous work. Because the particles studied in this experiment are of a smaller size than those used in microscopy studies, the discrepancies found could be a size-related effect.http://www.atmos-chem-phys.net/15/8975/2015/acp-15-8975-2015.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
M. A. Zawadowicz S. R. Proud S. S. Seppalainen D. J. Cziczo |
spellingShingle |
M. A. Zawadowicz S. R. Proud S. S. Seppalainen D. J. Cziczo Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions Atmospheric Chemistry and Physics |
author_facet |
M. A. Zawadowicz S. R. Proud S. S. Seppalainen D. J. Cziczo |
author_sort |
M. A. Zawadowicz |
title |
Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions |
title_short |
Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions |
title_full |
Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions |
title_fullStr |
Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions |
title_full_unstemmed |
Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions |
title_sort |
hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions |
publisher |
Copernicus Publications |
series |
Atmospheric Chemistry and Physics |
issn |
1680-7316 1680-7324 |
publishDate |
2015-08-01 |
description |
Atmospheric aerosol particles are often partially or completely composed of
inorganic salts, such as ammonium sulfate and sodium chloride, and therefore
exhibit hygroscopic properties. Many inorganic salts have well-defined
deliquescence and efflorescence points at which they take up and lose water,
respectively. Field measurements have shown that atmospheric aerosols are
not typically pure inorganic salt, instead, they often also contain organic
species. There is ample evidence from laboratory studies that suggests that
mixed particles exist in a phase-separated state, with an aqueous inorganic
core and organic shell. Although phase separation has not been measured in
situ, there is no reason it would not also take place in the atmosphere.
Here, we investigate the deliquescence and efflorescence points, phase
separation and ability to exchange gas-phase components of mixed organic and
inorganic aerosol using a flow tube coupled with FTIR (Fourier transform infrared) spectroscopy. Ammonium
sulfate aerosol mixed with organic polyols with different O : C ratios,
including 1,4-butanediol, glycerol, 1,2,6-hexanetriol, 1,2-hexanediol, and
1,5-pentanediol have been investigated. Those constituents correspond to
materials found in the atmosphere in great abundance and, therefore,
particles prepared in this study should mimic atmospheric mixed-phase
aerosol particles. Some results of this study tend to be in agreement with
previous microscopy experiments, but others, such as phase separation
properties of 1,2,6-hexanetriol, do not agree with previous work. Because
the particles studied in this experiment are of a smaller size than those
used in microscopy studies, the discrepancies found could be a size-related
effect. |
url |
http://www.atmos-chem-phys.net/15/8975/2015/acp-15-8975-2015.pdf |
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