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Surface Partitioning in Organic-Inorganic Mixtures Contributes to the Size-Dependence of the Phase-State of Atmospheric Nanoparticles

Werner, Josephina; Dalirian, Maryam; Walz, Marie Madeleine; Ekholm, Victor; Wideqvist, Ulla; Lowe, Samuel J.; Öhrwall, Gunnar LU ; Persson, Ingmar; Riipinen, Ilona and Björneholm, Olle LU (2016) In Environmental Science and Technology 50(14). p.7434-7442
Abstract

Atmospheric particulate matter is one of the main factors governing the Earth's radiative budget, but its exact effects on the global climate are still uncertain. Knowledge on the molecular-scale surface phenomena as well as interactions between atmospheric organic and inorganic compounds is necessary for understanding the role of airborne nanoparticles in the Earth system. In this work, surface composition of aqueous model systems containing succinic acid and sodium chloride or ammonium sulfate is determined using a novel approach combining X-ray photoelectron spectroscopy, surface tension measurements and thermodynamic modeling. It is shown that succinic acid molecules are accumulated in the surface, yielding a 10-fold surface... (More)

Atmospheric particulate matter is one of the main factors governing the Earth's radiative budget, but its exact effects on the global climate are still uncertain. Knowledge on the molecular-scale surface phenomena as well as interactions between atmospheric organic and inorganic compounds is necessary for understanding the role of airborne nanoparticles in the Earth system. In this work, surface composition of aqueous model systems containing succinic acid and sodium chloride or ammonium sulfate is determined using a novel approach combining X-ray photoelectron spectroscopy, surface tension measurements and thermodynamic modeling. It is shown that succinic acid molecules are accumulated in the surface, yielding a 10-fold surface concentration as compared with the bulk for saturated succinic acid solutions. Inorganic salts further enhance this enrichment due to competition for hydration in the bulk. The surface compositions for various mixtures are parametrized to yield generalizable results and used to explain changes in surface tension. The enhanced surface partitioning implies an increased maximum solubility of organic compounds in atmospheric nanoparticles. The results can explain observations of size-dependent phase-state of atmospheric nanoparticles, suggesting that these particles can display drastically different behavior than predicted by bulk properties only.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Environmental Science and Technology
volume
50
issue
14
pages
9 pages
publisher
The American Chemical Society
external identifiers
  • scopus:84978924101
  • wos:000380295700019
ISSN
0013-936X
DOI
10.1021/acs.est.6b00789
language
English
LU publication?
yes
id
9bd58391-1bc0-42ce-8076-933079302e4f
date added to LUP
2017-01-12 13:23:02
date last changed
2017-09-18 11:36:26
@article{9bd58391-1bc0-42ce-8076-933079302e4f,
  abstract     = {<p>Atmospheric particulate matter is one of the main factors governing the Earth's radiative budget, but its exact effects on the global climate are still uncertain. Knowledge on the molecular-scale surface phenomena as well as interactions between atmospheric organic and inorganic compounds is necessary for understanding the role of airborne nanoparticles in the Earth system. In this work, surface composition of aqueous model systems containing succinic acid and sodium chloride or ammonium sulfate is determined using a novel approach combining X-ray photoelectron spectroscopy, surface tension measurements and thermodynamic modeling. It is shown that succinic acid molecules are accumulated in the surface, yielding a 10-fold surface concentration as compared with the bulk for saturated succinic acid solutions. Inorganic salts further enhance this enrichment due to competition for hydration in the bulk. The surface compositions for various mixtures are parametrized to yield generalizable results and used to explain changes in surface tension. The enhanced surface partitioning implies an increased maximum solubility of organic compounds in atmospheric nanoparticles. The results can explain observations of size-dependent phase-state of atmospheric nanoparticles, suggesting that these particles can display drastically different behavior than predicted by bulk properties only.</p>},
  author       = {Werner, Josephina and Dalirian, Maryam and Walz, Marie Madeleine and Ekholm, Victor and Wideqvist, Ulla and Lowe, Samuel J. and Öhrwall, Gunnar and Persson, Ingmar and Riipinen, Ilona and Björneholm, Olle},
  issn         = {0013-936X},
  language     = {eng},
  month        = {07},
  number       = {14},
  pages        = {7434--7442},
  publisher    = {The American Chemical Society},
  series       = {Environmental Science and Technology},
  title        = {Surface Partitioning in Organic-Inorganic Mixtures Contributes to the Size-Dependence of the Phase-State of Atmospheric Nanoparticles},
  url          = {http://dx.doi.org/10.1021/acs.est.6b00789},
  volume       = {50},
  year         = {2016},
}