Determination of Activity Coefficients of Semi-Volatile Organic Aerosols Using the Integrated Volume Method

Abstract

We demonstrate the use of the Integrated Volume Method (IVM) to estimate activity coefficients of semi-volatile organic compounds pertinent to ambient/atmospheric aerosols in binary mixtures. We generate binary solution aerosols with different mole fractions of individual components; for each mixture, we measure total change in aerosol volume upon heating from 25• C to 35• C, with the aerosols being at equilibrium in both states. The change in aerosol volume, or in other words, the partitioning between the particle phase and the gas phase, is used to determine activity coefficients of the compounds as a function of their mole fraction in the mixture. We demonstrate this method using the following four model systems. System 1: adipic acid-pimelic acid, which illustrates polar organic-polar organic interactions. Nonideal behavior was observed with activity coefficients around three at infinite dilution. System 2: adipic acid-dioctyl sebacate, which illustrates polar organic-non-polar organic interactions. The compounds in this experiment did not form a solution. System 3: adipic acid-ammonium sulfate, which illustrates polar organic-inorganic interactions. The compounds in this experiment did not form a solution. System 4: adipic acid-ambient extracts, which illustrates the potential use of the method to study partitioning behavior of individual components in a complex matrix approximating that of real ambient aerosol. The measured activity coefficients of adipic acid were less than unity for the tested range of mixing ratios, indicating suppression of volatility of this compound in ambient organic matrix.

Determining Aerosol Volatility Parameters Using a “Dual Thermodenuder” System: Application to Laboratory-Generated Organic Aerosols

“…Parameter values reported in the literature for the tested acids vary widely, but our results are generally consistent with those from studies that allow for nonunity values of a. For example, our results suggest that a for these aerosols are of order 0.1, in agreement with results determined by Saleh et al (2009Saleh et al ( , 2012. Modeling results suggest that the addition of VRT-TD data provides tighter constraint on feasible DH vap and a values.…”

“…The kinetic method has been applied in several ways. For example, volatility tandem differential mobility analyzer (VT-DMA) studies (Bilde and Pandis 2001;Saleh et al 2009;Tao and McMurry 1989;Zhang et al 1993) measure the kinetics of mass transfer in a size-selected mono-disperse aerosol in a perturbed condition (e.g., heated environment) to estimate volatility parameters. Other works have used kinetic models to estimate both thermodynamic and kinetic parameters from observed evaporation in a TD (Cappa and Jimenez, 2010;Park et al 2013;Saleh et al 2011).…”

Toward the Determination of Joint Volatility-Hygroscopicity Distributions: Development and Response Characterization for Single-Component Aerosol

“…Results for succinic acid (Figure 7f) appear consistent with estimates of solid P o from various literature sources. Adjusting the accommodation/evaporation coefficient resulted in a significant change in the fitted parameters, placing it in agreement with the results of Saleh et al (2009). The model fitting for pimelic acid is not possible, since only points at one temperature set point were uninfluenced by insoluble cores and available for fitting (Figure 6f).…”

“…Note that (b) excludes the outlier value from Cappa et al (2007). Plotted literature data (letters) correspond to sources as follows: A (Bilde et al 2003), B (Booth et al 2009), C (Booth et al 2010), D (Booth et al 2011), E (Cappa et al 2007), F (Chattopadhyay et al 2001), G (Pope et al 2010), H (Riipinen et al 2007), I (Saleh et al 2009), J (Saleh et al 2010), K (Salo et al 2010), and L (Soonsin et al 2010). Kuwata et al (2012) 0 the limited volatilization observed.…”

Influence of the vapor wall loss on the degradation rate constants in chamber experiments of levoglucosan and other biomass burning markers

“…The particle mass accommodation coefficient α is generally poorly constrained, although, most authors have typically made use of a particle mass accommodation coefficient α between 0.1 and 1 (Saleh and Khlystov, 2009;May et al, 2012;Ye et al, 2016;Platt et al, 2017). In other works, Julin et al, (2014) and atmospheric chamber characteristics.…”