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| Titel |
The effect of low solubility organic acids on the hygroscopicity of sodium halide aerosols |
| VerfasserIn |
L. Miñambres, E. Méndez, M. N. Sánchez, F. Castaño, F. J. Basterretxea |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 20 ; Nr. 14, no. 20 (2014-10-29), S.11409-11425 |
| Datensatznummer |
250119128
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| Publikation (Nr.) |
 copernicus.org/acp-14-11409-2014.pdf |
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| Zusammenfassung |
| In order to accurately assess the influence of fatty acids on the
hygroscopic and other physicochemical properties of sea salt aerosols,
hexanoic, octanoic or lauric acid together with sodium halide salts (NaCl,
NaBr and NaI) have been chosen to be investigated in this study. The
hygroscopic properties of sodium halide sub-micrometre particles covered with
organic acids have been examined by Fourier-transform infrared spectroscopy
in an aerosol flow cell. Covered particles were generated by flowing
atomized sodium halide particles (either dry or aqueous) through a heated
oven containing the gaseous acid. The obtained results indicate that gaseous
organic acids easily nucleate onto dry and aqueous sodium halide particles.
On the other hand, scanning electron microscopy (SEM) images indicate that
lauric acid coating on NaCl particles makes them to aggregate in small
clusters. The hygroscopic behaviour of covered sodium halide particles in
deliquescence mode shows different features with the exchange of the halide
ion, whereas the organic surfactant has little effect in NaBr particles,
NaCl and NaI covered particles experience appreciable shifts in their
deliquescence relative humidities, with different trends observed for each
of the acids studied. In efflorescence mode, the overall effect of the
organic covering is to retard the loss of water in the particles. It has
been observed that the presence of gaseous water in heterogeneously
nucleated particles tends to displace the cover of hexanoic acid to
energetically stabilize the system. |
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