Hygroscopic properties of aminium sulfate aerosols

Rovelli, Grazia, Miles, Rachael E. H., Reid, Jonathan P. and Clegg, Simon L. (2017) Hygroscopic properties of aminium sulfate aerosols. Atmospheric Chemistry and Physics, 17 (6). pp. 4369-4385. ISSN 1680-7324

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Alkylaminium sulfates originate from the neutralisation reaction between short-chained amines and sulfuric acid and have been detected in atmospheric aerosol particles. Their physicochemical behaviour is less well characterised than their inorganic equivalent, ammonium sulfate, even though they play a role in atmospheric processes such as the nucleation and growth of new particles and cloud droplet formation. In this work, a comparative evaporation kinetics experimental technique using a cylindrical electrodynamic balance is applied to determine the hygroscopic properties of six short-chained alkylaminium sulfates, specifically mono-, di-, and tri-methylaminium sulfate and mono-, di-, and tri-ethyl aminium sulfate. This approach allows for the retrieval of a water-activity-dependent growth curve in less than 10 s, avoiding the uncertainties that can arise from the volatilisation of semi-volatile components. Measurements are made on particles > 5 µm in radius, avoiding the need to correct equilibrium measurements for droplet-surface curvature with assumed values of the droplet-surface tension. Variations in equilibrium solution droplet composition with varying water activity are reported over the range 0.5 to > 0.98, along with accurate parameterisations of solution density and refractive index. The uncertainties in water activities associated with the hygroscopicity measurements are typically < ±0.2 % at water activities > 0.9 and  ∼  ±1 % below 0.9, with maximum uncertainties in diameter growth factors of ±0.7 %. Comparison with previously reported measurements show deviation across the entire water activity range.

Item Type: Article
Faculty \ School: Faculty of Science > School of Environmental Sciences
UEA Research Groups: Faculty of Science > Research Groups > Climate, Ocean and Atmospheric Sciences (former - to 2017)
Faculty of Science > Research Groups > Marine and Atmospheric Sciences (former - to 2017)
Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
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Depositing User: Pure Connector
Date Deposited: 25 Apr 2017 05:09
Last Modified: 22 Oct 2022 02:35
URI: https://ueaeprints.uea.ac.uk/id/eprint/63292
DOI: 10.5194/acp-17-4369-2017

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