 |
| Titel |
Hygroscopic properties and cloud condensation nuclei activation of limonene-derived organosulfates and their mixtures with ammonium sulfate |
| VerfasserIn |
A. M. K. Hansen, J. Hong, T. Raatikainen, K. Kristensen, A. Ylisirniö, A. Virtanen, T. Petäjä, M. Glasius, N. L. Prisle |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 24 ; Nr. 15, no. 24 (2015-12-21), S.14071-14089 |
| Datensatznummer |
250120240
|
| Publikation (Nr.) |
 copernicus.org/acp-15-14071-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| Organosulfates have been observed as constituents of atmospheric aerosols in
a wide range of environments; however their hygroscopic properties remain
uncharacterised. Here, limonene-derived organosulfates with a molecular
weight of 250 Da (L-OS 250) were synthesised and used for simultaneous
measurements with a hygroscopicity tandem differential mobility analyser
(H-TDMA) and a cloud condensation nuclei counter (CCNC) to determine the
hygroscopicity parameter, κ, for pure L-OS 250 and mixtures of
L-OS 250 with ammonium sulfate (AS) over a wide range of humidity conditions.
The κ values derived from measurements with H-TDMA decreased with
increasing particle dry diameter for all
chemical compositions investigated, indicating that κH-TDMA
depends on particle diameter and/or
surface effects; however, it is not clear if this trend is statistically
significant. For pure L-OS 250, κ was found to increase with
increasing relative humidity, indicating dilution/solubility effects to be
significant. Discrepancies in κ between the sub- and supersaturated
measurements were observed for L-OS 250, whereas κ of AS and mixed
L-OS 250/AS were similar. This discrepancy was primarily ascribed to limited
dissolution of L-OS 250 at subsaturated conditions. In general, hygroscopic
growth factor, critical particle diameter and κ for the mixed
L-OS 250/AS particles converged towards the values of pure AS for mixtures
with ≥ 20 % w / w AS. Surface tension measurements of bulk
aqueous L-OS 250/AS solutions showed that L-OS 250 was indeed surface active,
as expected from its molecular structure, decreasing the surface tension of
solutions with 24 % from the pure water value at a L-OS 250 concentration
of 0.0025 mol L−1. Based on these surface tension measurements, we
present the first concentration-dependent parametrisation of surface tension
for aqueous L-OS 250, which was implemented to different process-level models
of L-OS 250 hygroscopicity and CCN activation. The values of κ
obtained from the measurements were compared with κ calculated
applying the volume additive Zdanovskii–Stokes–Robinson mixing rule, as
well as κ modelled from equilibrium Köhler theory with different
assumptions regarding L-OS 250 bulk-to-surface partitioning and aqueous
droplet surface tension. This study is to our knowledge the first to
investigate the hygroscopic properties and surface activity of L-OS 250;
hence it is an important first step towards understanding the atmospheric
impact of organosulfates. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|