 |
| Titel |
Novel methods for predicting gas–particle partitioning during the formation of secondary organic aerosol |
| VerfasserIn |
F. Wania, Y. D. Lei, C. Wang, J. P. D. Abbatt, K.-U. Goss |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 23 ; Nr. 14, no. 23 (2014-12-11), S.13189-13204 |
| Datensatznummer |
250119232
|
| Publikation (Nr.) |
 copernicus.org/acp-14-13189-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Several methods have been presented in the literature to predict an organic
chemical's equilibrium partitioning between the water insoluble organic
matter (WIOM) component of aerosol and the gas phase, Ki,WIOM,
as a function of temperature. They include (i) polyparameter linear free
energy relationships calibrated with empirical aerosol sorption data, as well
as (ii) the solvation models implemented in SPARC and (iii) the
quantum-chemical software COSMOtherm, which predict solvation equilibria from
molecular structure alone. We demonstrate that these methods can be used to
predict Ki,WIOM for large numbers of individual molecules
implicated in secondary organic aerosol (SOA) formation, including those with
multiple functional groups. Although very different in their theoretical
foundations, these methods give remarkably consistent results for the
products of the reaction of normal alkanes with OH, i.e. their partition
coefficients Ki,WIOM generally agree within one order of
magnitude over a range of more than ten orders of magnitude. This level of
agreement is much better than that achieved by different vapour pressure
estimation methods that are more commonly used in the SOA community. Also, in
contrast to the agreement between vapour pressure estimates, the agreement
between the Ki,WIOM estimates does not deteriorate with
increasing number of functional groups. Furthermore, these partitioning
coefficients Ki,WIOM predicted SOA mass yields in agreement
with those measured in chamber experiments of the oxidation of normal
alkanes. If a Ki,WIOM prediction method was based on one or
more surrogate molecules representing the solvation properties of the mixed
OM phase of SOA, the choice of those molecule(s) was found to have a
relatively minor effect on the predicted Ki,WIOM, as long as
the molecule(s) are not very polar. This suggests that a single surrogate
molecule, such as 1-octanol or a hypothetical SOA structure proposed by
Kalberer et al. (2004), may often be sufficient to represent the WIOM component of
the SOA phase, greatly simplifying the prediction. The presented methods
could substitute for vapour-pressure-based methods in studies such as the
explicit modelling of SOA formation from single precursor molecules in chamber
experiments. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|