Growth Kinetics and Size Distribution Dynamics of Viscous Secondary Organic Aerosol

Zaveri, Rahul A.; Shilling, John E.; Zelenyuk, Alla; Liu, Jiumeng; Bell, David M.; D’Ambro, Emma L.; Gaston, Cassandra J.; Thornton, Joel A.; Laskin, Alexander; Lin, Peng; Wilson, Jacqueline; Easter, Richard C.; Wang, Jian; Bertram, Allan K.; Martin, Scot T.; Seinfeld, John H.; Worsnop, Douglas R.

doi:10.1021/acs.est.7b04623

Cited by 98 publications

(158 citation statements)

References 69 publications

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“…As particle‐phase diffusion limitations slow or halt the rate at which condensing vapors can diffuse through the particle, the condensing vapors can more easily evaporate. Reducing α accounts for this net reduction in the condensation rate, but it does not account for potential size‐dependent diffusion limitations (Zaveri et al, ). (We assume liquid particles in our primary cases, which will likely have accommodation coefficients at or close to unity; Julin et al, .)…”

Section: Methodsmentioning

confidence: 99%

More Than Emissions and Chemistry: Fire Size, Dilution, and Background Aerosol Also Greatly Influence Near‐Field Biomass Burning Aerosol Aging

et al. 2019

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Biomass burning emits particles (black carbon and primary organic aerosol) and precursor vapors to the atmosphere that chemically and physically age in the atmosphere. This theoretical study explores the relationships between fire size (determining the initial plume width and concentration), dilution rate, and entrainment of background aerosol on particle coagulation, organic aerosol (OA) evaporation, and secondary organic aerosol (SOA) condensation in smoke plumes. We examine the impacts of these processes on aged smoke OA mass, geometric mean diameter (Dg), peak lognormal modal width (σg), particle extinction (E), and cloud condensation nuclei (CCN) concentrations. In our simulations, aging OA mass is controlled by competition between OA evaporation and SOA condensation. Large, slowly diluting plumes evaporate little in our base set of simulations, which may allow for net increases in mass, E, CCN , and Dg from SOA condensation. Smaller, quickly diluting fire plumes lead to faster evaporation, which favors decreases in mass, E, CCN, and Dg. However, the SOA fraction of the smoke OA increases more rapidly in smaller fires due to faster primary organic aerosol evaporation leading to more SOA precursors. Net mass changes for smaller fires depend on background OA concentrations; increasing background aerosol concentrations decrease evaporation rates. Although coagulation does not change mass, it can decrease the number of particles in large/slowly diluting plumes, increasing Dg and E, and decreasing σg. While our conclusions are limited by being a theoretical study, we hope they help motivate future smoke‐plume analyses to consider the effects of fire size, meteorology, and background OA concentrations.

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Section: Methodsmentioning

confidence: 99%

More Than Emissions and Chemistry: Fire Size, Dilution, and Background Aerosol Also Greatly Influence Near‐Field Biomass Burning Aerosol Aging

et al. 2019

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“…2c). After C g and C s converge, they continue to decrease simultaneously while C p increases slowly, showing that the particle undergoes quasi-equilibrium growth (Shiraiwa and Zhang et al, 2012). For LVOC (C 0 = 0.1 µg m −3 ) condensation, τ eq is short (∼ 140 s) because a local thermodynamic equilibrium between the gas phase and the near-surface bulk is established relatively quickly (as mostly controlled by the condensation sink; Riipinen et al, 2011;Tröstl et al, 2016) due to very slow reevaporation of the LVOC.…”

Section: Impacts Of Volatility and Diffusivity On Equilibration Timesmentioning

confidence: 99%

Timescales of secondary organic aerosols to reach equilibrium at various temperatures and relative humidities

Liu

Shiraiwa

2019

Atmos. Chem. Phys.

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Secondary organic aerosols (SOA) account for a substantial fraction of air particulate matter, and SOA formation is often modeled assuming rapid establishment of gas-particle equilibrium. Here, we estimate the characteristic timescale for SOA to achieve gas-particle equilibrium under a wide range of temperatures and relative humidities using a state-of-the-art kinetic flux model. Equilibration timescales were calculated by varying particle phase state, size, mass loadings, and volatility of organic compounds in open and closed systems. Model simulations suggest that the equilibration timescale for semi-volatile compounds is on the order of seconds or minutes for most conditions in the planetary boundary layer, but it can be longer than 1 h if particles adopt glassy or amorphous solid states with high glass transition temperatures at low relative humidity. In the free troposphere with lower temperatures, it can be longer than hours or days, even at moderate or relatively high relative humidities due to kinetic limitations of bulk diffusion in highly viscous particles. The timescale of partitioning of low-volatile compounds into highly viscous particles is shorter compared to semi-volatile compounds in the closed system, as it is largely determined by condensation sink due to very slow re-evaporation with relatively quick establishment of local equilibrium between the gas phase and the near-surface bulk. The dependence of equilibration timescales on both volatility and bulk diffusivity provides critical insights into thermodynamic or kinetic treatments of SOA partitioning for accurate predictions of gas-and particle-phase concentrations of semi-volatile compounds in regional and global chemical transport models.

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“…The partitioning of semi-volatile compounds into viscous particles may result in kinetically limited growth in contrast to quasi-equilibrium growth (Perraud et al, 2012;Booth et al, 2014;Zaveri et al, 2014), which also affects the evolution of particle size distribution upon SOA growth Zaveri et al, 2018). Note that the equilibration timescale of SOA partitioning is determined by bulk diffusivity or viscosity, but is also affected by other factors such as volatility, accommodation coefficient, particle size, and mass loadings (Shiraiwa and Seinfeld, 2012;Mai et al, 2015;Liu et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Predicting the glass transition temperature and viscosity of secondary organic material using molecular composition

et al. 2018

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Abstract. Secondary organic aerosol (SOA) accounts for a large fraction of submicron particles in the atmosphere. SOA can occur in amorphous solid or semi-solid phase states depending on chemical composition, relative humidity (RH), and temperature. The phase transition between amorphous solid and semi-solid states occurs at the glass transition temperature (T g ). We have recently developed a method to estimate T g of pure compounds containing carbon, hydrogen, and oxygen atoms (CHO compounds) with molar mass less than 450 g mol −1 based on their molar mass and atomic O : C ratio. In this study, we refine and extend this method for CH and CHO compounds with molar mass up to ∼ 1100 g mol −1 using the number of carbon, hydrogen, and oxygen atoms. We predict viscosity from the T g -scaled Arrhenius plot of fragility (viscosity vs. T g /T ) as a function of the fragility parameter D. We compiled D values of organic compounds from the literature and found that D approaches a lower limit of ∼ 10 (±1.7) as the molar mass increases. We estimated the viscosity of α-pinene and isoprene SOA as a function of RH by accounting for the hygroscopic growth of SOA and applying the Gordon-Taylor mixing rule, reproducing previously published experimental measurements very well. Sensitivity studies were conducted to evaluate impacts of T g , D, the hygroscopicity parameter (κ), and the Gordon-Taylor constant on viscosity predictions. The viscosity of toluene SOA was predicted using the elemental composition obtained by high-resolution mass spectrometry (HRMS), resulting in a good agreement with the measured viscosity. We also estimated the viscosity of biomass burning particles using the chemical composition measured by HRMS with two different ionization techniques: electrospray ionization (ESI) and atmospheric pressure photoionization (APPI). Due to differences in detected organic compounds and signal intensity, predicted viscosities at low RH based on ESI and APPI measurements differ by 2-5 orders of magnitude. Complementary measurements of viscosity and chemical composition are desired to further constrain RH-dependent viscosity in future studies.

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Growth Kinetics and Size Distribution Dynamics of Viscous Secondary Organic Aerosol

Cited by 98 publications

References 69 publications

More Than Emissions and Chemistry: Fire Size, Dilution, and Background Aerosol Also Greatly Influence Near‐Field Biomass Burning Aerosol Aging

More Than Emissions and Chemistry: Fire Size, Dilution, and Background Aerosol Also Greatly Influence Near‐Field Biomass Burning Aerosol Aging

Timescales of secondary organic aerosols to reach equilibrium at various temperatures and relative humidities

Predicting the glass transition temperature and viscosity of secondary organic material using molecular composition

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