AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Surface Tension Modeling of Multicomponent Atmospheric Aqueous Aerosols Using Competitive and Assisted Adsorption
HALLIE BOYER, Cari Dutcher, University of Minnesota
Abstract Number: 227 Working Group: Aerosol Chemistry
Abstract Surface properties of aqueous solutions are necessary for determining atmospheric aerosol particle interactions with the ambient, such as uptake of water vapor and radical species, as well as effects on their optical properties and morphology. In previous work (Boyer et al. JPC Lett., 2015; Wexler and Dutcher, JPC Lett., 2013), we used statistical mechanics to derive analytic expressions for surface tension of binary aqueous solutions, and reduced the number of free parameters down to zero to enable estimation of surface tension for systems where there are little or no data available. Here, the model approach is extended to multi-component aqueous solutions by identifying surface partition functions for solutes of varied molecular sizes. If solutes exhibit similar surface propensities, competitive adsorption between solute species is expected at the surface. Conversely, for solutes with opposite tendencies towards surface adsorption, we foresee assisted adsorption. We apply the model in ternary form to organic acids by considering their partial dissociation and to solute mixtures of organics (glycerol and ethanol) and electrolytes (NaCl and NH4NO3). Using binary model parameter values that were found to correlate strongly with solute physico-chemical properties, parameter free predictions for surface tension of aqueous systems of multiple solutes are presented. Excellent agreement has been found between the model predictions and experimental data obtained both from literature.