Multicomponent diffusion in atmospheric aerosol particles

Abstract

Condensed phase mass transport in single aerosol particles is investigated using a linear quadrupole electrodynamic balance (LQ-EDB) and the Maxwell–Stefan (MS) framework.

Morphology and Viscosity Changes after Reactive Uptake of Isoprene Epoxydiols in Submicrometer Phase Separated Particles with Secondary Organic Aerosol Formed from Different Volatile Organic Compounds

“…Additionally, different SOA particle sizes after IEPOX uptake (150, 200, and 250 nm from initially 150 nm particles) have been investigated, with phase separation and more particles with complex morphology being observed at larger particle sizes. , After IEPOX uptake, the larger particles were more viscous for α-pinene, β-caryophyllene, and isoprene SOA-coated sulfate particles, indicating particle size could play an important role in morphology, affecting subsequent heterogeneous reactions. Evidence accumulates that semisolid phases and individual particle properties can limit diffusion and heterogeneous reactions in organic–inorganic particles. − , In addition, unexpected properties of submicron aerosol, such as high acidity , and increased pressure, continue to paint an increasingly complicated picture of organic–inorganic particle behavior. This makes VOC- and size-dependent morphology and viscosity changes even more important to consider given their important role in overall aerosol mixing state, − as well as cloud condensation nuclei (CCN) and ice nucleating particle (INP) activity, ,, which are important in cloud formation. − …”

“…Organosulfates, − which are a key component of atmospheric SOA, have been shown to increase particle viscosity after incorporation of inorganic sulfate ions into organic species. , Modeling used to study SOA viscosities has continued to improve, leading to better predictions of viscosity for multicomponent mixtures and surrogate SOA mixtures derived from the oxidation of different VOC precursors. − Shiraiwa et al have related molecular weight to glass transition temperature ( T g ) and viscosity according to the number of different C, H, and O atoms and C–H and C–O bonds in a molecular formula or the molecular weight ( M ), oxygen-to-carbon ratio (O:C), and coefficients ( A – E ) (eq ): Despite significant progress in understanding OA viscosity, ,,− understanding the impacts on viscosity within individual submicron particles from different VOC precursors on reactive uptake is still limited. Recent research has shown the importance of interactions between the organic and inorganic components, such as increased propensity for semisolid aerosol due to ion–molecules interactions, , and that even in aqueous multicomponent mixtures, measured equilibration time scales can be slower than predicted by pure components using simple mixing rules …”

Non-Fickian diffusion in viscous aerosol particles

“…21 and 22 is solved using an adaptive grid finite-volume scheme. [36][37][38] For the adaptive grid part of the scheme, the spherical particle is divided into K shells where each shell has a thickness of ∆r = s(t)/K. Therefore, the time-dependent thickness of each shell is…”

Hygroscopicity of Microplastic and Mixed Microplastic Aqueous Ammonium Sulfate Systems

“…34,35 Aqueous inorganic aerosol, such as sea spray, reaches equilibrium with the surrounding air rapidly. However, the time required to reach equilibrium can be greatly extended when diffusion limitations exist (e.g., highly viscous particles 36,37 and particles coated in organic films 38,39 ). Changes in size and optical properties also lead to variation in the radiative forcing efficiency of the aerosol.…”

“…The uptake and loss of water as aerosol moves through air of varying relative humidity (RH) results in changes in size and optical properties. , Aqueous inorganic aerosol, such as sea spray, reaches equilibrium with the surrounding air rapidly. However, the time required to reach equilibrium can be greatly extended when diffusion limitations exist (e.g., highly viscous particles , and particles coated in organic films , ). Changes in size and optical properties also lead to variation in the radiative forcing efficiency of the aerosol. , Hygroscopic atmospheric particles that undergo efflorescence and deliquescence will have different water contents depending on the RH history of the particle .…”