scholarly journals Microscopic Evidence for Phase Separation of Organic Species and Inorganic Salts in Fine Ambient Aerosol Particles

2021 ◽  
Vol 55 (4) ◽  
pp. 2234-2242
Author(s):  
Weijun Li ◽  
Lei Liu ◽  
Jian Zhang ◽  
Liang Xu ◽  
Yuanyuan Wang ◽  
...  
Keyword(s):  
Phase Separation ◽  
Aerosol Particles ◽  
Inorganic Salts ◽  
Ambient Aerosol ◽  
Organic Species ◽  
Microscopic Evidence

scholarly journals Liquid–liquid phase separation in particles containing organics mixed with ammonium sulfate, ammonium bisulfate, ammonium nitrate or sodium chloride

2013 ◽  
Vol 13 (23) ◽  
pp. 11723-11734 ◽  
Author(s):  
Y. You ◽  
L. Renbaum-Wolff ◽  
A. K. Bertram
Keyword(s):  
Phase Separation ◽  
Sodium Chloride ◽  
Liquid Phase ◽  
Relative Humidity ◽  
Ammonium Sulfate ◽  
Inorganic Salt ◽  
Liquid Phase Separation ◽  
Inorganic Salts ◽  
Organic Species ◽  
Liquid Liquid Phase Separation

Abstract. As the relative humidity varies from high to low values in the atmosphere, particles containing organic species and inorganic salts may undergo liquid–liquid phase separation. The majority of the laboratory work on this subject has used ammonium sulfate as the inorganic salt. In the following we studied liquid–liquid phase separation in particles containing organics mixed with the following salts: ammonium sulfate, ammonium bisulfate, ammonium nitrate and sodium chloride. In each experiment one organic was mixed with one inorganic salt and the liquid–liquid phase separation relative humidity (SRH) was determined. Since we studied 23 different organics mixed with four different salts, a total of 92 different particle types were investigated. Out of the 92 types, 49 underwent liquid–liquid phase separation. For all the inorganic salts, liquid–liquid phase separation was never observed when the oxygen-to-carbon elemental ratio (O : C) &amp;geq; 0.8 and was always observed for O : C < 0.5. For 0.5 &amp;leq; O : C < 0.8, the results depended on the salt type. Out of the 23 organic species investigated, the SRH of 20 organics followed the trend: (NH4)2SO4 &amp;geq; NH4HSO4 &amp;geq; NaCl &amp;geq; NH4NO3. This trend is consistent with previous salting out studies and the Hofmeister series. Based on the range of O : C values found in the atmosphere and the current results, liquid–liquid phase separation is likely a frequent occurrence in both marine and non-marine environments.

scholarly journals Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions

2015 ◽  
Vol 15 (15) ◽  
pp. 8975-8986 ◽  
Author(s):  
M. A. Zawadowicz ◽  
S. R. Proud ◽  
S. S. Seppalainen ◽  
D. J. Cziczo
Keyword(s):  
Phase Separation ◽  
Ammonium Sulfate ◽  
Atmospheric Aerosols ◽  
Aerosol Particles ◽  
Field Measurements ◽  
Inorganic Salts ◽  
Ample Evidence ◽  
Hygroscopic Properties ◽  
Inorganic Aerosol

Abstract. Atmospheric aerosol particles are often partially or completely composed of inorganic salts, such as ammonium sulfate and sodium chloride, and therefore exhibit hygroscopic properties. Many inorganic salts have well-defined deliquescence and efflorescence points at which they take up and lose water, respectively. Field measurements have shown that atmospheric aerosols are not typically pure inorganic salt, instead, they often also contain organic species. There is ample evidence from laboratory studies that suggests that mixed particles exist in a phase-separated state, with an aqueous inorganic core and organic shell. Although phase separation has not been measured in situ, there is no reason it would not also take place in the atmosphere. Here, we investigate the deliquescence and efflorescence points, phase separation and ability to exchange gas-phase components of mixed organic and inorganic aerosol using a flow tube coupled with FTIR (Fourier transform infrared) spectroscopy. Ammonium sulfate aerosol mixed with organic polyols with different O : C ratios, including 1,4-butanediol, glycerol, 1,2,6-hexanetriol, 1,2-hexanediol, and 1,5-pentanediol have been investigated. Those constituents correspond to materials found in the atmosphere in great abundance and, therefore, particles prepared in this study should mimic atmospheric mixed-phase aerosol particles. Some results of this study tend to be in agreement with previous microscopy experiments, but others, such as phase separation properties of 1,2,6-hexanetriol, do not agree with previous work. Because the particles studied in this experiment are of a smaller size than those used in microscopy studies, the discrepancies found could be a size-related effect.

scholarly journals Liquid-liquid phase separation in organic particles containing one and two organic species: importance of the average O:C

2018 ◽  
Author(s):  
Mijung Song ◽  
Suhan Ham ◽  
Ryan J. Andrews ◽  
Yuan You ◽  
Allan K. Bertram
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Cloud Condensation Nuclei ◽  
Experimental Studies ◽  
Liquid Phase Separation ◽  
Inorganic Salts ◽  
Organic Species ◽  
Organic Particles ◽  
Almost All ◽  
Liquid Liquid Phase Separation

Abstract. Recently, experimental studies have shown that liquid-liquid phase separation (LLPS) can occur in organic particles free of inorganic salts. Most of these studies used organic particles consisting of secondary organic materials generated in environmental chambers. To gain additional insight into LLPS in organic particles free of inorganic salts, we studied LLPS in organic particles consisting of one and two commercially available organic species. For particles containing one organic species, three out of the six particle types investigated underwent LLPS. In these cases, LLPS was observed when the O:C was ≤ 0.44 and the RH was between ~ 97 and ~ 100 %. The mechanism of phase separation was likely nucleation and growth. For particles containing two organic species, thirteen out of the fifteen particle types investigated underwent LLPS. In these cases, LLPS was observed when the O:C was ≤ 0.58 and mostly when the RH was between ~ 90 and ~ 100 % RH. The mechanism of phase separation was likely spinodal decomposition. In almost all cases when LLPS was observed (for both one-component and two-component particles), the highest RH at which two liquids was observed was 100 ± 2.0 %, which has important implications for the cloud condensation nuclei (CCN) properties of these particles. These combined results provide additional evidence that LLPS needs to be considered when predicting the CCN properties of organic particles in the atmosphere.

scholarly journals Hygroscopic and phase separation properties of ammonium sulfate/organic/water ternary solutions

2015 ◽  
Vol 15 (5) ◽  
pp. 6537-6566 ◽  
Author(s):  
M. A. Zawadowicz ◽  
S. R. Proud ◽  
S. S. Seppalainen ◽  
D. J. Cziczo
Keyword(s):  
Phase Separation ◽  
Ammonium Sulfate ◽  
Atmospheric Aerosols ◽  
Inorganic Salt ◽  
Aerosol Particles ◽  
Field Measurements ◽  
Inorganic Salts ◽  
Ample Evidence ◽  
Hygroscopic Properties ◽  
Inorganic Aerosol

Abstract. Atmospheric aerosol particles are often partially or completely composed of inorganic salts, such as ammonium sulfate and sodium chloride, and therefore exhibit hygroscopic properties. Many inorganic salts have well-defined deliquescence and efflorescence points at which they take up and lose water, respectively. Deliquescence and efflorescence of simple inorganic salt particles have been investigated by a variety of methods, such as IR spectroscopy, tandem mobility analysis and electrodynamic balance. Field measurements have shown that atmospheric aerosols are not typically pure inorganic salt, instead they often also contain organic species. There is ample evidence from laboratory studies that suggests that mixed particles exist in a phase-separated state, with an aqueous inorganic core and organic shell. Although phase separation has not been measured in situ, there is no reason it would not also take place in the atmosphere. Many recent studies have focused on microscopy techniques that require deposition of the aerosol on a glass slide, possibly changing its surface properties. Here, we investigate the deliquescence and efflorescence points, phase separation and ability to exchange gas-phase components of mixed organic and inorganic aerosol using a flow tube coupled with FTIR spectroscopy. Ammonium sulfate aerosol mixed with organic polyols with different O : C ratios, including 1,4-butanediol, glycerol, 1,2,6-hexanetriol, 1,2-hexanediol, and 1,5-pentanediol have been investigated. Those constituents correspond to materials found in the atmosphere in great abundance, and therefore, particles prepared in this study should mimic atmospheric mixed phase aerosol particles. The results of this study tend to be in agreement with previous microscopy experiments, with several key differences, which possibly reveal a size-dependent effect on phase separation in organic/inorganic aerosol particles.

scholarly journals Liquid–liquid phase separation in organic particles containing one and two organic species: importance of the average O : C

2018 ◽  
Vol 18 (16) ◽  
pp. 12075-12084 ◽  
Author(s):  
Mijung Song ◽  
Suhan Ham ◽  
Ryan J. Andrews ◽  
Yuan You ◽  
Allan K. Bertram
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Cloud Condensation Nuclei ◽  
Experimental Studies ◽  
Liquid Phase Separation ◽  
Inorganic Salts ◽  
Organic Species ◽  
Organic Particles ◽  
Almost All ◽  
Liquid Liquid Phase Separation

Abstract. Recently, experimental studies have shown that liquid–liquid phase separation (LLPS) can occur in organic particles free of inorganic salts. Most of these studies used organic particles consisting of secondary organic materials generated in environmental chambers. To gain additional insight into LLPS in organic particles free of inorganic salts, we studied LLPS in organic particles consisting of one and two commercially available organic species. For particles containing one organic species, three out of the six particle types investigated underwent LLPS. In these cases, LLPS was observed when the O : C was  ≤ 0.44 (but not always) and the relative humidity (RH) was between  ∼ 97 % and  ∼ 100 %. The mechanism of phase separation was likely nucleation and growth. For particles containing two organic species, 13 out of the 15 particle types investigated underwent LLPS. In these cases, LLPS was observed when the O : C was  ≤ 0.58 (but not always) and mostly when the RH was between  ∼ 90 % RH and  ∼ 100 % RH. The mechanism of phase separation was likely spinodal decomposition. In almost all cases when LLPS was observed (for both one-component and two-component particles), the highest RH at which two liquids was observed was 100±2.0 %, which has important implications for the cloud condensation nuclei (CCN) properties of these particles. These combined results provide additional evidence that LLPS needs to be considered when predicting the CCN properties of organic particles in the atmosphere.

First Quantification of Imidazoles in Ambient Aerosol Particles: Potential Photosensitizers, Brown Carbon Constituents, and Hazardous Components

2016 ◽  
Vol 50 (3) ◽  
pp. 1166-1173 ◽  
Author(s):  
Monique Teich ◽  
Dominik van Pinxteren ◽  
Simonas Kecorius ◽  
Zhibin Wang ◽  
Hartmut Herrmann
Keyword(s):  
Aerosol Particles ◽  
Brown Carbon ◽  
Ambient Aerosol
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