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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
16 Dec 2016
Review status
A revision of this discussion paper was accepted for the journal Atmospheric Chemistry and Physics (ACP) and is expected to appear here in due course.
Evaporation of sulphate aerosols at low relative humidity
Georgios Tsagkogeorgas1, Pontus Roldin2,3, Jonathan Duplissy2,4, Linda Rondo5, Jasmin Tröstl6, Jay G. Slowik6, Sebastian Ehrhart5,a, Alessandro Franchin2, Andreas Kürten5, Antonio Amorim7, Federico Bianchi2, Jasper Kirkby5,8, Tuukka Petäjä2, Urs Baltensperger6, Michael Boy2, Joachim Curtius5, Richard C. Flagan9, Markku Kulmala2,4, Neil M. Donahue10, and Frank Stratmann1 1Leibniz Institute for Tropospheric Research, 04318, Leipzig, Germany
2Department of Physics, University of Helsinki, P.O. Box 64, 00014, Helsinki, Finland
3Division of Nuclear Physics, Lund University, P.O. Box 118, 221 00, Lund, Sweden
4Helsinki Institute of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
5Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
6Paul Scherrer Institute, 5232, Villigen, Switzerland
7Fac. Ciencias & CENTRA, Universidade de Lisboa, Campo Grande, 1749 – 016, Lisboa, Portugal
8CERN, 1211, Geneva, Switzerland
9California Institute of Technology, Pasadena, CA 91125, USA
10Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA 15213, USA
anow at: Atmospheric Chemistry Department, Max Planck Institute for Chemistry, 55128, Mainz, Germany
Abstract. Here we explore the vapour pressure of sulphuric acid at very low relative humidity, where evaporation of sulphuric acid from particles can be important in the atmospheres of Earth and Venus. We performed experiments in the CLOUD chamber at CERN forming sulphuric acid particles via nucleation and then measuring evaporation versus temperature and relative humidity. We modelled the experiments with the ADCHAM model to constrain the thermodynamic properties governing the evaporation of sulphuric acid. ADCHAM includes a thermodynamics module coupled to an aerosol dynamics module. We derived the mole fractions and activity coefficients of H2SO4, HSO4, SO42− and SO3 in the particles and then simulated the condensation and evaporation of H2SO4 and SO3. We constrained the equilibrium constants for the dissociation of H2SO4 to HSO4 (KH2SO4) and the dehydration of H2SO4 to SO3 (xKSO3). Our results suggest that particle shrinkage is mainly governed by H2SO4 evaporation, however, we cannot dismiss a contribution from SO3 evaporation. We conclude that KH2SO4 = 2–4 ∙ 109 mol ∙ kg−1 at 288.8 ± 5 K and xKSO3 ≥ 1.4 ∙ 1010.

Citation: Tsagkogeorgas, G., Roldin, P., Duplissy, J., Rondo, L., Tröstl, J., Slowik, J. G., Ehrhart, S., Franchin, A., Kürten, A., Amorim, A., Bianchi, F., Kirkby, J., Petäjä, T., Baltensperger, U., Boy, M., Curtius, J., Flagan, R. C., Kulmala, M., Donahue, N. M., and Stratmann, F.: Evaporation of sulphate aerosols at low relative humidity, Atmos. Chem. Phys. Discuss.,, in review, 2016.
Georgios Tsagkogeorgas et al.
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
RC1: 'Referee Comment on acp-2016-1045', Anonymous Referee #1, 01 Mar 2017 Printer-friendly Version 
RC2: 'Review for acp-2016-1045', Anonymous Referee #2, 06 Mar 2017 Printer-friendly Version 
AC1: 'Author Comment on acp-2016-1045', Georgios Tsagkogeorgas, 15 Apr 2017 Printer-friendly Version Supplement 
Georgios Tsagkogeorgas et al.
Georgios Tsagkogeorgas et al.


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Short summary
The H2SO4 vapor pressure plays key role in Earth's and Venus' atmospheres. In regions where RH is low and stabilizing bases are scarce, H2SO4 can evaporate from particles; however, the H2SO4 vapour pressure at low RH is uncertain. To address this, we measured H2SO4 evaporation versus T and RH in the CLOUD chamber and constrained the equilibrium constants for dissociation and dehydration of H2SO4. This study is important for nucleation, particle growth and H2SO4 formation occurring in atmosphere.
The H2SO4 vapor pressure plays key role in Earth's and Venus' atmospheres. In regions where RH...