Liquid−Liquid Phase Separation in Mixed Organic/Inorganic Aerosol Particles

Ciobanu, V. Gabriela; Marcolli, Claudia; Krieger, Ulrich K.; Weers, U.; Peter, Thomas

doi:10.1021/jp905054d

Cited by 183 publications

(373 citation statements)

References 49 publications

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“…The schlieren developed into small droplets that coalesced to form an inner phase within the particle. Ciobanu et al (2009) have also observed spinodal decomposition for LLPS of PEG-400/AS/H 2 O particles. At 71.9 % RH, inner and outer phases together with satellite inclusions can be clearly discriminated in the liquid droplet.…”

Section: Llps Features Of C5/as/h 2 O C6/as/h 2 O and C7/as/h 2 O Drmentioning

confidence: 72%

“…The most prominent feature in the reference spectrum of crystalline AS is the symmetric stretching vibration of SO 2− 4 at ∼975 cm −1 (Zhang and Chan, 2002;Ling and Chan, 2008;Ciobanu et al, 2009). The band of the stretching vibration of NH + 4 at around 3130 cm −1 (Ciobanu et al, 2009;Yeung et al, 2009) is also distinguished. The C6 and C7 references reveal C-H stretching vibrations at 2880-2984 and 2875-2990 cm −1 , respectively, and several peaks between 700 and 1670 cm −1 .…”

Section: Chemical Compositions Of the Different Phasesmentioning

confidence: 97%

“…Strong reduction of N 2 O 5 hydrolysis rates have also been observed for sulfuric acid and seasalt aerosols that were coated with organic surfactants (Thornton and Abbatt, 2005;McNeill et al, 2006;. Ciobanu et al (2009) used optical microscopy and microRaman spectroscopy to investigate LLPS of micrometersized droplets consisting of poly(ethylene glycol)-400 (PEG-400)/AS/water. The resulting morphology was an aqueous AS inner phase surrounded by a mainly PEG-400 containing outer phase.…”

Section: Song Et Al: Liquid-liquid Phase Separation and Morphologymentioning

confidence: 99%

“…Previous studies on phase transitions of single aerosol particles have mostly been performed with one organic substance in the presence of AS (Parsons et al, 2006;Ling and Chan, 2008;Ciobanu et al, 2009;Yeung et al, 2009;Bertram et al, 2011). Studies on more complex organic mixtures are needed to obtain insight into the phase transitions of organic/inorganic aerosols considering atmospheric aerosol composition.…”

Section: Song Et Al: Liquid-liquid Phase Separation and Morphologymentioning

confidence: 99%

“…3a, the inner phase and the satellite inclusions consist of a concentrated aqueous AS solution containing only small amounts of organics. On the other hand, spectrum (a4) acquired from the outer phase of C6/AS/H 2 O shows well discernable signals of the dicarboxylic acids and the AS and water bands appear only as weak features, establishing the outer phase as highly concentrated aqueous dicarboxylic acid solution with AS as a minor component (see also Ciobanu et al, 2009;Smith et al, 2011).…”

Section: Chemical Compositions Of the Different Phasesmentioning

confidence: 99%

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Liquid-liquid phase separation and morphology of internally mixed dicarboxylic acids/ammonium sulfate/water particles

et al. 2012

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Abstract. Knowledge of the physical state and morphology of internally mixed organic/inorganic aerosol particles is still largely uncertain. To obtain more detailed information on liquid-liquid phase separation (LLPS) and morphology of the particles, we investigated complex mixtures of atmospherically relevant dicarboxylic acids containing 5, 6, and 7 carbon atoms (C5, C6 and C7) having oxygen-to-carbon atomic ratios (O:C) of 0.80, 0.67, and 0.57, respectively, mixed with ammonium sulfate (AS). With micrometer-sized particles of C5/AS/H 2 O, C6/AS/H 2 O and C7/AS/H 2 O as model systems deposited on a hydrophobically coated substrate, laboratory experiments were conducted for various organic-to-inorganic dry mass ratios (OIR) using optical microscopy and Raman spectroscopy. When exposed to cycles of relative humidity (RH), each system showed significantly different phase transitions. While the C5/AS/H 2 O particles showed no LLPS with OIR = 2:1, 1:1 and 1:4 down to 20 % RH, the C6/AS/H 2 O and C7/AS/H 2 O particles exhibit LLPS upon drying at RH 50 to 85 % and ∼90 %, respectively, via spinodal decomposition, growth of a second phase from the particle surface or nucleation-and-growth mechanisms depending on the OIR. This suggests that LLPS commonly occurs within the range of O:C < 0.7 in tropospheric organic/inorganic aerosols. To support the comparison and interpretation of the experimentally observed phase transitions, thermodynamic equilibrium calculations were performed with the AIOMFAC model. For the C7/AS/H 2 O and C6/AS/H 2 O systems, the calculated phase diagrams agree well with the observations while for the C5/AS/H 2 O system LLPS is predicted by the model at RH below 60 % and higher AS concentration, but was not observed in the experiments.Both core-shell structures and partially engulfed structures were observed for the investigated particles, suggesting that such morphologies might also exist in tropospheric aerosols.

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Section: Llps Features Of C5/as/h 2 O C6/as/h 2 O and C7/as/h 2 O Drmentioning

confidence: 72%

Section: Chemical Compositions Of the Different Phasesmentioning

confidence: 97%

Section: Song Et Al: Liquid-liquid Phase Separation and Morphologymentioning

confidence: 99%

Section: Song Et Al: Liquid-liquid Phase Separation and Morphologymentioning

confidence: 99%

Section: Chemical Compositions Of the Different Phasesmentioning

confidence: 99%

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Liquid-liquid phase separation and morphology of internally mixed dicarboxylic acids/ammonium sulfate/water particles

et al. 2012

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Redistribution of black carbon in aerosol particles undergoing liquid‐liquid phase separation

Brunamonti

Krieger

Marcolli

et al. 2015

Geophysical Research Letters

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Atmospheric black carbon (BC) is a major anthropogenic greenhouse agent, yet substantial uncertainties obstruct understanding its radiative forcing. Particularly debated is the extent of the absorption enhancement by internally compared to externally mixed BC, which critically depends on the interior morphology of the BC-containing particles. Here we suggest that a currently unaccounted morphology, optically very different from the customary core-shell and volume-mixing assumptions, likely occurs in aerosol particles undergoing liquid-liquid phase separation (LLPS). Using Raman spectroscopy on micrometer-sized droplets, we show that LLPS of an organic/inorganic model system drives redistribution of BC into the outer (organic) phase of the host particle. This results in an inverted core-shell structure, in which a transparent aqueous core is surrounded by a BC-containing absorbing shell. Based on Mie theory calculations, we estimate that such a redistribution can increase the absorption efficiency of internally mixed BC aerosols by up to 25% compared to the core-shell approximation.

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Observational constraints on glyoxal production from isoprene oxidation and its contribution to organic aerosol over the Southeast United States

Mao

Min

et al. 2016

JGR Atmospheres

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We use a 0‐D photochemical box model and a 3‐D global chemistry‐climate model, combined with observations from the NOAA Southeast Nexus (SENEX) aircraft campaign, to understand the sources and sinks of glyoxal over the Southeast United States. Box model simulations suggest a large difference in glyoxal production among three isoprene oxidation mechanisms (AM3ST, AM3B, and Master Chemical Mechanism (MCM) v3.3.1). These mechanisms are then implemented into a 3‐D global chemistry‐climate model. Comparison with field observations shows that the average vertical profile of glyoxal is best reproduced by AM3ST with an effective reactive uptake coefficient γglyx of 2 × 10−3 and AM3B without heterogeneous loss of glyoxal. The two mechanisms lead to 0–0.8 µg m−3 secondary organic aerosol (SOA) from glyoxal in the boundary layer of the Southeast U.S. in summer. We consider this to be the lower limit for the contribution of glyoxal to SOA, as other sources of glyoxal other than isoprene are not included in our model. In addition, we find that AM3B shows better agreement on both formaldehyde and the correlation between glyoxal and formaldehyde (RGF = [GLYX]/[HCHO]), resulting from the suppression of δ‐isoprene peroxy radicals. We also find that MCM v3.3.1 may underestimate glyoxal production from isoprene oxidation, in part due to an underestimated yield from the reaction of isoprene epoxydiol (IEPOX) peroxy radicals with HO2. Our work highlights that the gas‐phase production of glyoxal represents a large uncertainty in quantifying its contribution to SOA.

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Liquid−Liquid Phase Separation in Mixed Organic/Inorganic Aerosol Particles

Cited by 183 publications

References 49 publications

Liquid-liquid phase separation and morphology of internally mixed dicarboxylic acids/ammonium sulfate/water particles

Liquid-liquid phase separation and morphology of internally mixed dicarboxylic acids/ammonium sulfate/water particles

Redistribution of black carbon in aerosol particles undergoing liquid‐liquid phase separation

Observational constraints on glyoxal production from isoprene oxidation and its contribution to organic aerosol over the Southeast United States

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