naa a22 4500 528786814 20180924065502.0 cr unu---uuuuu 180924s2008 xx s 000 0 eng 10.3929/ethz-b-000012570 doi 10.5194/acp-8-4559-2008 doi (ETHRESEARCH)oai:www.research-collection.ethz.ch:20.500.11850/12570 A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients [Elektronische Daten] [Andreas Zuend, Claudia Marcolli, Beiping P. Luo, Thomas Peter] Atmos. chem. phys. Open access ethresearch Tropospheric aerosols contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behaviour. By means of activity coefficients, non-ideal behaviour can be taken into account. We present here a thermodynamic model named AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) that is able to calculate activity coefficients covering inorganic, organic, and organic-inorganic interactions in aqueous solutions over a wide concentration range. This model is based on the activity coefficient model LIFAC by Yan et al. (1999) that we modified and reparametrised to better describe atmospherically relevant conditions and mixture compositions. Focusing on atmospheric applications we considered H+, Li+, Na+, K+, NH+4, Mg2+, Ca2+, Cl−, Br−, NO−3, HSO−4, and SO2−4 as cations and anions and a wide range of alcohols/polyols composed of the functional groups CHn and OH as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are well represented up to high ionic strength. Most notably, a semi-empirical middle-range parametrisation of direct organic-inorganic interactions in alcohol+water+salt solutions strongly improves the agreement between experimental and modelled activity coefficients. At room temperature, this novel thermodynamic model offers the possibility to compute equilibrium relative humidities, gas/particle partitioning and liquid-liquid phase separations with high accuracy. In further studies, other organic functional groups will be introduced. The model framework is not restricted to specific ions or organic compounds and is therefore also applicable for other research topics. Creative Commons Attribution 3.0 Unported http://creativecommons.org/licenses/by/3.0 ethresearch Zuend Andreas joint author Marcolli Claudia joint author Luo Beiping P. joint author Peter Thomas joint author Atmospheric Chemistry and Physics Munich : European Geophysical Society 8 (16), pp. 4559-4593 1680-7375 http://hdl.handle.net/20.500.11850/12570 text/html WWW-Backlink auf das Repository (Open access) 1 Journal Article ethresearch ETHRESEARCH 856 40 http://hdl.handle.net/20.500.11850/12570 text/html WWW-Backlink auf das Repository (Open access) ETHRESEARCH 700 1- Zuend Andreas joint author ETHRESEARCH 700 1- Marcolli Claudia joint author ETHRESEARCH 700 1- Luo Beiping P. joint author ETHRESEARCH 700 1- Peter Thomas joint author ETHRESEARCH 773 0- Atmospheric Chemistry and Physics Munich : European Geophysical Society 8 (16), pp. 4559-4593 1680-7375 BK010053 XK010053 XK010000 ETHRESEARCH ETHRESEARCH ETHRESEARCH Journal Article Open access