Hygroscopicity of internally mixed ammonium sulfate and secondary organic aerosol particles formed at low and high relative humidity

Razafindrambinina, Patricia N.; Malek, Kotiba A.; Dawson, Joseph Nelson; DiMonte, Kristin; Raymond, Timothy M.; Dutcher, Dabrina D.; Freedman, Miriam Arak; Asa-Awuku, Akua

doi:10.1039/d1ea00069a

Cited by 4 publications

(3 citation statements)

References 93 publications

(266 reference statements)

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“…The subsaturated water uptake measurements were performed using a widely utilized H-TDMA setup. A detailed description of the H-TDMA operation has been provided in previous literature. ,− In brief, the generated aerosol stream (flow rate = 0.3 L min –1 ) was passed to a DMA (TSI 3082) where dry particle sizes (80, 100, 120, and 140 nm) were selected by an electrostatic classifier. These selected sizes provided us with sufficient concentration for a successful experiment.…”

Section: Methods and Materialsmentioning

confidence: 99%

The Role of Organic Vapor in the Water Uptake of Organic Aerosols

Malek,

Ferdousi-Rokib,

Rastogi

et al. 2024

ACS Earth Space Chem.

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Organic solvents are ubiquitous in the atmosphere and can readily form a coated layer around the particles. While their presence has been widely reported, their effects on cloud droplet formation have been poorly understood. This study elucidated the effect of a prominent organic solvent on the water uptake of organic aerosols under the relevant environmental conditions. Specifically, we investigated the water uptake efficiencies of aerosols obtained from three organic isomers of different solubilities, namely, phthalic acid (PTA; high solubility), isophthalic acid (IPTA; partial solubility), and terephthalic acid (TPTA; low solubility) in the presence of aqueous-phase and gas-phase ethanol (EtOH). Using laboratory-based measurements, the water uptake properties were investigated under supersaturated and subsaturated conditions by using a cloud condensation nuclei counter (CCNC) and a hygroscopicity tandem differential mobility analyzer (H-TDMA), respectively. Under supersaturated conditions (0.86%), the critical diameter (D d ) of each system was reported and compared relative to the pure compounds. Under a supersaturated environment, the presence of EtOH was shown to increase the water uptake efficiency of partial and low solubility particles, IPTA and TPTA, but not the water-soluble PTA particles. In supersaturated environments, the intrinsic solubility of aerosol particles governs its water uptake behavior. Since PTA exhibits a high-water solubility, the presence of EtOH exerted little to no influence on the dissolution of PTA particles. Hence, EtOH had no impact on the water uptake of PTA particles. This is signified by the minimal change in critical diameter (∼0.1−2 nm) between the PTA systems that contained EtOH compared with the pure PTA particles. Conversely, the addition of EtOH to IPTA and TPTA aerosols enhanced the dissolution of these partial/low-water solubility particles, as a result, increasing their water uptake affinity. The addition of ethanol to IPTA and TPTA particles resulted in a decrease in critical diameter by ∼6−8.2 and ∼16−20.1 nm, respectively. Our subsaturated results show that EtOH has the opposite effect relative to our supersaturated results. Under a subsaturated environment, the water uptake affinity of PTA particles was enhanced by the presence of EtOH and diminished for IPTA and TPTA particles. The water uptake of PTA was enhanced with the presence of aqueous ethanol (G f increased from ∼1.02 to ∼1.23), while IPTA and TPTA particles showed reduction in size (G f decreased from ∼1.01 to ∼0.95). This is attributed to the morphological properties of the particles supported by TEM images and shape factor measurements. Hence, atmospheric organic solvents can readily coat aerosol particles and play a major role in the water uptake properties under sub-and super-saturated conditions.

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Section: Methods and Materialsmentioning

confidence: 99%

The Role of Organic Vapor in the Water Uptake of Organic Aerosols

Malek,

Ferdousi-Rokib,

Rastogi

et al. 2024

ACS Earth Space Chem.

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“…Atmospheric aerosols consist of a mixture of organic and inorganic components. ,− Particle formation and atmospheric chemical processes commonly result in the formation of internally mixed organic–inorganic particles. ,, Such internally mixed systems can exist in different phase states depending on aerosol composition (type of organic and inorganic salts), average oxygen-to-carbon (O:C) ratio, and environmental conditions [temperature and relative humidity (RH)]. ,− An internal organic–inorganic mixture can also undergo liquid–liquid phase separation (LLPS). ,,− Hence, knowledge of the aerosol chemical composition and their subsequent mixtures can improve water uptake predictions and has been the focus of several studies (including but not limited to Hodas et al, Altaf et al, Razafindrambinina et al, Massoli et al, Vu et al, and Fofie et al).…”

Section: Introductionmentioning

confidence: 99%

“…14,21−25 An internal organic−inorganic mixture can also undergo liquid−liquid phase separation (LLPS). 14,21,26−29 Hence, knowledge of the aerosol chemical composition and their subsequent mixtures can improve water uptake predictions and has been the focus of several studies (including but not limited to Hodas et al, 30 Altaf et al, 13 Razafindrambinina et al, 31 Massoli et al, 32 Vu et al, 33 and Fofie et al 34 ).…”

Section: Introductionmentioning

confidence: 99%

Liquid–Liquid Phase Separation Can Drive Aerosol Droplet Growth in Supersaturated Regimes

Malek,

Gohil,

Olonimoyo

et al. 2023

ACS Environ. Au

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It is well known that atmospheric aerosol size and composition impact air quality, climate, and health. The aerosol composition is typically a mixture and consists of a wide range of organic and inorganic particles that interact with each other. Furthermore, water vapor is ubiquitous in the atmosphere, in indoor air, and within the human body’s respiratory system, and the presence of water can alter the aerosol morphology and propensity to form droplets. Specifically, aerosol mixtures can undergo liquid–liquid phase separation (LLPS) in the presence of water vapor. However, the experimental conditions for which LLPS impacts water uptake and the subsequent prediction of aerosol mixtures are poorly understood. To improve our understanding of aerosol mixtures and droplets, this study explores two ternary systems that undergo LLPS, namely, the 2MGA system (sucrose + ammonium sulfate + 2-methylglutaric acid) and the PEG1000 system (sucrose + ammonium sulfate + polyethylene glycol 1000). In this study, the ratio of species and the O:C ratios are systematically changed, and the hygroscopic properties of the resultant aerosol were investigated. Here, we show that the droplet activation above 100% RH of the 2MGA system was influenced by LLPS, while the droplet activation of the PEG1000 system was observed to be linearly additive regardless of chemical composition, O:C ratio, and LLPS. A theoretical model that accounts for LLPS with O:C ratios was developed and predicts the water uptake of internally mixed systems of different compositions and phase states. Hence, this study provides a computationally efficient algorithm to account for the LLPS and solubility parameterized by the O:C ratio for droplet activation at supersaturated relative humidity conditions and may thus be extended to mixed inorganic–organic aerosol populations with unspeciated organic composition found in the ambient environment.

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Effects of mixing state on water-uptake properties of ammonium sulfate – Organic mixtures

Razafindrambinina

Malek

DiMonte

et al. 2022

Aerosol Science and Technology

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Hygroscopicity of internally mixed ammonium sulfate and secondary organic aerosol particles formed at low and high relative humidity

Abstract: Volatile organic matter that is suspended in the atmosphere such as α-Pinene and β-caryophyllene undergoes aging processes, as well as chemical and photooxidation reactions to create secondary organic aerosol (SOA),...

Cited by 4 publications

References 93 publications

The Role of Organic Vapor in the Water Uptake of Organic Aerosols

The Role of Organic Vapor in the Water Uptake of Organic Aerosols

Liquid–Liquid Phase Separation Can Drive Aerosol Droplet Growth in Supersaturated Regimes

Effects of mixing state on water-uptake properties of ammonium sulfate – Organic mixtures

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