Influence of Organic Compound Functionality on Aerosol Hygroscopicity: Dicarboxylic Acids, Alkyl-Substituents, Sugars and Amino Acids

Hygroscopicity data for 36 organic compounds including amino acids, organic acids, alcohols and sugars is determined using a Comparative Kinetics Electrodynamic Balance (CK-EDB). The CK-EDB employs an electric field to trap charged aqueous droplets in a temperature and relative humidity (RH) controlled chamber. The dual micro dispenser set up allows for sequential trapping of probe and sample droplets for accurate determination of droplet water activities from 0.45 to > 0.99. Here, we validate and benchmark the CK-EDB for the homologous series of straight chain dicarboxylic acids (oxalic – pimelic) with measurements in better agreement with UNIversal quasichemical Functional group Activity Coefficients (UNIFAC) predictions than the original data used to parametrise UNIFAC. Further, a series of increasingly complex organic compounds, with subtle changes to molecular structure and branching, are used to rigorously assess the accuracy of predictions by UNIFAC, which does not explicitly account for molecular structure. We show that the changes in hygroscopicity that result from increased branching and chain length are poorly represented by UNIFAC, with UNIFAC under-predicting hygroscopicity. Similarly, amino acid hygroscopicity is under-predicted by UNIFAC predictions, a consequence of the original data used in the parametrisation of the molecular subgroups. New hygroscopicity data are also reported for a selection of alcohols and sugars and show variable levels of agreement with predictions.

Creator(s) Rachael Miles, Grazia Rovelli, Jonathan Reid, Aleksandra Marsh, Alexander G Cowling
Publication date 12 Apr 2017
Language eng
Publisher University of Bristol
Licence Non-Commercial Government Licence for public sector information
DOI 10.5523/bris.3eoilb28zwoqr2jifjxj7cntex
Complete download (zip) http://data.bris.ac.uk/datasets/3eoilb28zwoqr2jifjxj7cntex/3eoilb28zwoqr2jifjxj7cntex.zip
Citation Rachael Miles, Grazia Rovelli, Jonathan Reid, Aleksandra Marsh, Alexander G Cowling (2017): Influence of Organic Compound Functionality on Aerosol Hygroscopicity: Dicarboxylic Acids, Alkyl-Substituents, Sugars and Amino Acids. https://doi.org/10.5523/bris.3eoilb28zwoqr2jifjxj7cntex
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