Efflorescence kinetics of aerosols comprising internally-mixed ammonium sulfate and water-soluble organic compounds

Xu, Yanming; Liu, Pai; Ma, Shuaishuai; Pei, Wenxiu; Pang, Shu-Feng; Zhang, Yunhong

doi:10.1016/j.atmosenv.2022.119007

Cited by 3 publications

(10 citation statements)

References 62 publications

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“…We first tested pure ammonium sulfate (AS) aerosols to validate the vacuum FTIR measurement results (Figure S5). The ERH range of AS measured (43%–35%) was consistent with previous studies (54% - 36%). ,,, …”

Section: Resultssupporting

confidence: 91%

“…When RH was close to the efflorescence point, AN droplets were in a supersaturated state. When RH decreased to 20%, the characteristic peak of NH 4 + red-shifted from 1431 to 1419 cm –1 , and the characteristic peak of NO 3 – blue-shifted from 1320 to 1343 cm –1 , which indicated the crystallization of AN microdroplets. ,, When the RH was less than 10%, neither the water peaks nor the peak shifts were observable, indicating that AN droplets completely lost water and crystallized.…”

Section: Resultsmentioning

confidence: 97%

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Role of WSOCs and pH on Ammonium Nitrate Aerosol Efflorescence: Insights into Secondary Aerosol Formation

Sun,

Hu,

Cao

et al. 2023

Environ. Sci. Technol.

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Efflorescence of ammonium nitrate (AN) aerosols significantly impacts atmospheric secondary aerosol formation, climate, and human health. We investigated the effect of representative water-soluble organic compounds (WSOCs) (sucralose (SUC), glycerol (GLY), and citric acid (CA) on AN:WSOC aerosol efflorescence using vacuum Fourier transform infrared spectroscopy. Combining efflorescence relative humidity (ERH) measurements, heterogeneous nucleation rates, and model predictions, we found that aerosol viscosity, correlating with molecular diffusion, effectively predicted ERH variations among the AN:WSOC aerosols. WSOCs with higher viscosity (SUC and CA) hindered efflorescence, while GLY with a lower viscosity showed a minor effect. At a low AN:CA molar ratio (10:1), CA promoted ERH, likely due to CA crystallization. Increasing the droplet pH inhibited AN:CA aerosol efflorescence. In contrast, for AN:SUC and AN:GLY aerosols, efflorescence is pH-insensitive. With the addition of trivial sulfate, AN:SUC droplets exhibited two-stage efflorescence, coinciding with ammonium sulfate and AN efflorescence. Given the atmospheric abundance, the morphology, phase, and mixing state of nitrate aerosols are significant for atmospheric chemistry and physics. Our results suggest that AN:WSOCs aerosols can exist in the amorphous phase in the atmosphere, with efflorescence behavior depending on the aerosol composition, viscosity, pH, and the cation and anion interactions in a complex manner.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 97%

Role of WSOCs and pH on Ammonium Nitrate Aerosol Efflorescence: Insights into Secondary Aerosol Formation

Sun,

Hu,

Cao

et al. 2023

Environ. Sci. Technol.

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“…NaCl is the major component of SSAs, 28 and H 2 A is dicarboxylic acid that constitutes the watersoluble organic component of atmospheric aerosols. 29 In aerosols, NaCl reacts with H 2 A, producing HCl and sodium oxalate (Na 2 A) 30,31 H A NaCl NaHA HCl Reaction R1.1 is driven by the degassing of volatile HCl from microdroplets (.R1.2) and is termed chloride depletion. 30 Although the chloride depletion phenomenon has been observed for decades, the dynamic evolution of aerosol pH during such a process is yet to be directly measured.…”

Section: −mentioning

confidence: 99%

“…Our target sample was microdroplets comprising a mixture of sodium chloride (NaCl) and oxalic acid (H 2 A; hereafter, A denotes C 2 O 4 2– ). NaCl is the major component of SSAs, and H 2 A is dicarboxylic acid that constitutes the water-soluble organic component of atmospheric aerosols . In aerosols, NaCl reacts with H 2 A, producing HCl and sodium oxalate (Na 2 A) , normalH 2 normalA false( normala normalq false) + normalN normala normalC normall false( normala normalq false) ⇌ normalN normala normalH normalA false( normala normalq false) + normalH normalC normall false( normala normalq false) normalH normalC normall false( normala normalq false) → normalH normalC normall false( normalg false) …”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spatiotemporally Resolved pH Measurement in Aerosol Microdroplets Undergoing Chloride Depletion: An Application of In Situ Raman Microspectrometry

et al. 2022

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Acidity is a defining property of atmospheric aerosols that profoundly affects environmental systems, human health, and climate. However, directly measuring the pH of aerosol microdroplets remains a challenge, especially when the microdroplets' composition is nonhomogeneous or dynamically evolving or both. As a result, a pH measurement technique with high spatiotemporal resolution is needed. Here, we report a spatiotemporally resolved pH measurement technique in microdroplets using spontaneous Raman spectroscopy. Our target sample was the microdroplets comprising sodium chloride and oxalic acid�laboratory surrogates of sea spray aerosols and watersoluble organic compounds, respectively. Our measurements show that the chloride depletion from the microdroplets caused a continuous increase in pH by ∼0.5 units in 2 hours. Meanwhile, the surface propensity of chloride anions triggers a stable pH gradient inside a single droplet, with the pH at the droplet surface lower than that at the core by ∼ 0.4 units. The uncertainties arising from the Raman detection limit (±0.08 pH units) and from the nonideal solution conditions (−0.06 pH units) are constrained. Our findings indicate that spontaneous Raman spectroscopy is a simple yet robust technique for precise pH measurement in aerosols with high spatiotemporal resolution.

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Influence of the Neutralization Degree on the Ice Nucleation Ability of Ammoniated Sulfate Particles

Bertozzi,

Wagner,

Höhler

et al. 2024

JGR Atmospheres

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Previous laboratory measurements suggest that ammonium sulfate crystals (AS, (NH4)2SO4) are efficient ice‐nucleating particles under cirrus conditions. Sulfate particles not completely neutralized by ammonium are less well studied and include two other solids, ammonium bisulfate (AHS, NH4HSO4) and letovicite (LET, (NH4)3H(SO4)2). In this work, we have obtained the first comprehensive data set for the heterogeneous ice nucleation ability of crystallized particles in the AS–LET–AHS system as a function of their degree of neutralization at a temperature of about 220 K. Quantitative data on nucleation onsets, ice‐active fractions, and ice nucleation active surface site densities were derived from expansion cooling experiments in a large cloud chamber and measurements with two continuous flow diffusion chambers. We found a strong dependence of the efficiency and the mode of heterogenous ice nucleation on the degree of neutralization. Ice formation for AS, mixed AS/LET, and LET crystals occurred by the deposition nucleation or pore condensation and freezing mode. The lowest nucleation onset was observed for AS, where 0.1% of the particles became ice‐active at an ice saturation ratio of 1.25. This threshold gradually increased to 1.35 for LET, and abruptly further to 1.45 for mixed LET/AHS crystals, which partially deliquesced and induced ice formation via immersion freezing. Pure AHS crystals did not form due to the inhibition of efflorescence. Our data allow for a more sophisticated treatment of ice formation in the AS–LET–AHS system in future model simulations, which have so far only considered the available data for AS alone.

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Efflorescence kinetics of aerosols comprising internally-mixed ammonium sulfate and water-soluble organic compounds

Cited by 3 publications

References 62 publications

Role of WSOCs and pH on Ammonium Nitrate Aerosol Efflorescence: Insights into Secondary Aerosol Formation

Role of WSOCs and pH on Ammonium Nitrate Aerosol Efflorescence: Insights into Secondary Aerosol Formation

Spatiotemporally Resolved pH Measurement in Aerosol Microdroplets Undergoing Chloride Depletion: An Application of In Situ Raman Microspectrometry

Influence of the Neutralization Degree on the Ice Nucleation Ability of Ammoniated Sulfate Particles

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