Volume Additivity of Nanoscale Aerosol Mixtures

SAMANTHA LI, Sarah Petters, University of California, Riverside

     Abstract Number: 687
     Working Group: Aerosol Physics

Abstract
Nanosized aerosols are subject to elevated internal pressure that can influence reaction rates, reaction mechanisms, and the viscosity of organic aerosols. Accurate models of interlinked physicochemical properties are essential for understanding and predicting aerosol formation and growth. Although results have shown that factors such as constriction, irregularity, or excess volume of mixing can introduce errors in particle diameter measurements, particle density estimates remain crude, and conservation of density is typically assumed. In this work, we present a multidimensional framework for predicting the role of surface tension and changing partial molar volume on aerosol uptake and growth processes. We incorporated measurements and interpolated datasets from chemical oceanography and atmospheric chemical thermodynamics and track mixing energy and growth-factor-dependent partial molar volumes. Activity models including an empirical model of thermochemical properties of seawater and the Extended Aerosol Inorganics Model (E-AIM) were used to determine energy of mixing. The Laplace equation was used to estimate internal pressure based on surface tension and water uptake. The compressibility of pseudo-binary aqueous mixtures was found to be dependent on the composition. We discuss recommendations for mass- and diameter-based metrics of particle growth. Results also vary as a function of the composition-dependent surface tension and composition-dependent particle growth by hygroscopic water uptake.