Prediction of Toxic Semi-Volatile Organic Gas-Particle Partitioning in the Atmosphere with the Use of Activity Coefficients

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9708533 Kamens The main objective of this research is to dramatically improve our ability to calculate the equilibrium partitioning of semi-volatile organic toxic compounds, which distribute between gas and aerosol phases. This will be done specifically for particles which have organic liquid layers, such as particles from diesel fuel, wood combustion, and secondary organic aerosols. The partitioning of compound classes which contain environmentally emitted or created organic acids, carbonyls, chlorinated organics, alkanes, polynuclear aromatic hydrocarbons, and cyclical siloxanes, will be investigated. The activity coefficients of the organics in given liquid particle mixtures will be calculated using the group contribution method. These activity coefficients will then be used along with vapor pressures and other aerosol properties to calculate equilibrium partitioning constants. Outdoor chamber measurements will be performed to provide gas-particle partitioning data. Since aerosol chemical composition and atmospheric humidity strongly influence activity coefficient predictions, initial experiments will be carried out with known aerosol compositions at constant humidities. Later experiments will investigate more complex particle systems.