Role of the Aerosol Phase State in Ammonia/Amines Exchange Reactions

Chan, Lap P.; Chan, Chak Keung

doi:10.1021/es4004685

Cited by 53 publications

(110 citation statements)

References 42 publications

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“…Even for large droplets, where size-dependent effects are not important for phase state, pure dimethylaminium sulfate does not form a solid phase, even at < 3 % RH. However, the exposure of such an amorphous liquid droplet to ammonia results in the formation of a solid phase which contains ammonium and aminium and is resistant to further exchange (Chan and Chan, 2013). If a phase transition does occur for the mixed ammonium-dimethylaminium-sulfate nanoparticles in the present study, the molar concentrations of the species present in the smaller, purely liquid particles would be higher than those in the liquid phase of the slightly larger mixed-phase particles.…”

Section: Particle-phase Base : Acid Ratiosmentioning

confidence: 66%

“…For example, steric effects that favor the presence of ammonia over DMA may be important at these small sizes. Thermodynamic calculations and previous experimental studies on larger particles suggest aqueous mixtures of aminium and ammonium sulfates with base : acid ratios from 2 : 1 to 1 : 1 are the stable composition at the RH of the CLOUD chamber experiments (Chan and Chan, 2013;Sauerwein et al, 2015). However, there were unfortunately no direct observations on the phase and water content of the nanoparticles in these experiments.…”

Section: Particle-phase Dimethylaminium-ammonium Ratiosmentioning

confidence: 81%

“…In addition, a given salt may only have certain stable configurations when dried. A dimethylamine sulfate droplet was shown to go from a 2 : 1 solution to a 1.5 : 1 DMAH + : SO 2− 4 ratio particle when dried (Chan and Chan, 2013). Ouyang et al (2015) showed a tendency for dried DMA : H 2 SO 4 nanoclusters to reach a consistent density of 1.567 g cm −3 , independent of the bulk composition of the initial electrospray solution.…”

Section: Post-cloud7 Calibrationsmentioning

confidence: 99%

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Unexpectedly acidic nanoparticles formed in dimethylamine–ammonia–sulfuric-acid nucleation experiments at CLOUD

et al. 2016

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Abstract. New particle formation driven by acid-base chemistry was initiated in the CLOUD chamber at CERN by introducing atmospherically relevant levels of gas-phase sulfuric acid and dimethylamine (DMA). Ammonia was also present in the chamber as a gas-phase contaminant from earlier experiments. The composition of particles with volume median diameters (VMDs) as small as 10 nm was measured by the Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS). Particulate ammonium-to-dimethylaminium ratios were higher than the gas-phase ammonia-to-DMA ratios, suggesting preferential uptake of ammonia over DMA for the collected 10-30 nm VMD particles. This behavior is not consistent with present nanoparticle physicochemical models, which predict a higher dimethylaminium fraction when NH 3 and DMA are present at similar gas-phase concentrations. Despite the presence in the gas phase of at least 100 times higher base concentrations than sulfuric acid, the recently formed particles always had measured base : acid ratios lower than 1 : 1. The lowest base fractions were found in particles below 15 nm VMD, with a strong size-dependent composition gradient. The reasons for the very acidic composition remain uncertain, but a plausible explanation is thatPublished by Copernicus Publications on behalf of the European Geosciences Union. 13602 M. J. Lawler et al.: Acidic nanoparticles at CLOUD the particles did not reach thermodynamic equilibrium with respect to the bases due to rapid heterogeneous conversion of SO 2 to sulfate. These results indicate that sulfuric acid does not require stabilization by ammonium or dimethylaminium as acid-base pairs in particles as small as 10 nm.

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Section: Particle-phase Base : Acid Ratiosmentioning

confidence: 66%

Section: Particle-phase Dimethylaminium-ammonium Ratiosmentioning

confidence: 81%

Section: Post-cloud7 Calibrationsmentioning

confidence: 99%

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Unexpectedly acidic nanoparticles formed in dimethylamine–ammonia–sulfuric-acid nucleation experiments at CLOUD

et al. 2016

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“…The resulting alkyl-ammonium (aminium) salts -including sulfates, nitrates (Pratt et al 2009), and carboxylates (Smith et al 2010) -can promote particle growth and cloud droplet formation. Re-volatilization of amines from the particle phase has been observed for aminium nitrates (Murphy et al 2007), as well as for certain secondary and tertiary aminium sulfates (Chan and Chan 2013).…”

Section: ¡3mentioning

confidence: 97%

Water Activities and Osmotic Coefficients of Aqueous Solutions of Five Alkylaminium Sulfates and Their Mixtures with H₂SO₄at 25^oC

Sauerwein

Clegg

Chan

2015

Aerosol Science and Technology

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Alkylaminium sulfates are frequently detected in ambient aerosols, and are believed to be important in the nucleation of new particles in the atmosphere, despite the comparatively low gas phase concentrations of amines. In this study, water activities and osmotic coefficients have been measured, using a chilled mirror dew point technique, of aqueous mixtures of sulfuric acid and the following alkylaminium sulfates: methylaminium, ethylaminium, dimethylaminium, diethylaminium, and trimethylaminium sulfate. The samples were prepared by mixing solutions of the five corresponding amines and aqueous sulfuric acid and determining the exact aminium to sulfate molar ratios by ion chromatography. The results were correlated using an extended Zdanovskii-StokesRobinson equation to enable concentration/water activity relationships to be calculated over the entire composition range from pure aqueous sulfuric acid to pure aqueous aminium sulfate. Water activities and osmotic coefficients for aminium:sulfate ratios of 1:1 (the bisulfate salts) and lower showed great similarity with ammonium bisulfate, but osmotic coefficients for the 2:1 ratio (the aminium sulfates) were significantly larger (and water activities lower) than for ammonium sulfate. These results differ from those obtained in Clegg et al.'s (2013) study. The relative values of the osmotic coefficients, in concentrated solutions, suggest that the numbers of methyl or ethyl groups in the aminium ion may have a stronger lowering effect on water activity than the alkyl chain length.

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“…A comparison of ATOFMS data sets obtained in Cork, Paris, Zurich, Dunkirk and Corsica (ADRIMED and SAF-MED) found this ion only in the latter two data sets (Healy et al, 2015 − 2 ) were found in the average negative mass spectra of EC-TMA and OC-TMA; however only 0.3 and 18 % of these particles actually produced negative mass spectra and K-TMA particles produced none. Alkylaminium sulfate particles have been shown to readily absorb water at low relative humidities (< 45 %) (Chan and Chan, 2013;Hu et al, 2014), and particle-bound water has been shown to suppress negative ion formation in mass spectrometers (Neubauer et al, 1997(Neubauer et al, , 1998. The proportion of amine particles with negative mass spectra is low in contrast to other particle classes which produced signals in up to 100 % of their negative mass spectra (K-EC-SO x , K-SO xOxalate).…”

Section: Regionally Transported Combustionmentioning

confidence: 99%

Sources and mixing state of summertime background aerosol in the north-western Mediterranean basin

et al. 2017

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Abstract. An aerosol time-of-flight mass spectrometer (ATOFMS) was employed to provide real-time single particle mixing state and thereby source information for aerosols impacting the western Mediterranean basin during the ChArMEx-ADRIMED and SAF-MED campaigns in summer 2013. The ATOFMS measurements were made at a ground-based remote site on the northern tip of Corsica.Twenty-seven distinct ATOFMS particle classes were identified and subsequently grouped into eight general categories: EC-rich (elemental carbon), K-rich, Na-rich, amines, OC-rich (organic carbon), V-rich, Fe-rich and Carich particles. Mass concentrations were reconstructed for the ATOFMS particle classes and found to be in good agreement with other co-located quantitative measurements (PM 1 , black carbon (BC), organic carbon, sulfate mass and ammonium mass). Total ATOFMS reconstructed mass (PM 2.5 ) accounted for 70-90 % of measured PM 10 mass and was comprised of regionally transported fossil fuel (EC-rich) and biomass burning (K-rich) particles. The accumulation of these transported particles was favoured by repeated and extended periods of air mass stagnation over the western Mediterranean during the sampling campaigns. The single particle mass spectra proved to be valuable source markers, allowing the identification of fossil fuel and biomass burning combustion sources, and was therefore highly complementary to quantitative measurements made by Particle into Liquid Sampler ion chromatography (PILS-IC) and an aerosol chemical speciation monitor (ACSM), which have demonstrated that PM 1 and PM 10 were comprised predominantly of sulfate, ammonium and OC. Good temporal agreement was observed between ATOFMS EC-rich and K-rich particle mass concentrations and combined mass concentrations of BC, sulfate, ammonium and low volatility oxygenated organic aerosol (LV-OOA). This combined information suggests that combustion of fossil fuels and biomass produced primary EC-and OC-containing particles, which then accumulated ammonium, sulfate and alkylamines during regional transport.Three other sources were also identified: local biomass burning, marine and shipping. Local combustion particlesPublished by Copernicus Publications on behalf of the European Geosciences Union. (emitted in Corsica) contributed little to PM 2.5 particle number and mass concentrations but were easily distinguished from regional combustion particles. Marine emissions comprised fresh and aged sea salt: the former was detected mostly during a 5-day event during which it accounted for 50-80 % of sea salt aerosol mass, while the latter was detected throughout the sampling period. Dust was not efficiently detected by the ATOFMS, and support measurements showed that it was mainly in the PM 2.5-10 fraction. Shipping particles, identified using markers for heavy fuel oil combustion, were associated with regional emissions and represented only a small fraction of PM 2.5 particle number and mass concentration at the site.

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Role of the Aerosol Phase State in Ammonia/Amines Exchange Reactions

Cited by 53 publications

References 42 publications

Unexpectedly acidic nanoparticles formed in dimethylamine–ammonia–sulfuric-acid nucleation experiments at CLOUD

Unexpectedly acidic nanoparticles formed in dimethylamine–ammonia–sulfuric-acid nucleation experiments at CLOUD

Water Activities and Osmotic Coefficients of Aqueous Solutions of Five Alkylaminium Sulfates and Their Mixtures with H₂SO₄at 25^oC

Sources and mixing state of summertime background aerosol in the north-western Mediterranean basin

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Role of the Aerosol Phase State in Ammonia/Amines Exchange Reactions

Cited by 53 publications

References 42 publications

Unexpectedly acidic nanoparticles formed in dimethylamine–ammonia–sulfuric-acid nucleation experiments at CLOUD

Unexpectedly acidic nanoparticles formed in dimethylamine–ammonia–sulfuric-acid nucleation experiments at CLOUD

Water Activities and Osmotic Coefficients of Aqueous Solutions of Five Alkylaminium Sulfates and Their Mixtures with H2SO4at 25oC

Sources and mixing state of summertime background aerosol in the north-western Mediterranean basin

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Water Activities and Osmotic Coefficients of Aqueous Solutions of Five Alkylaminium Sulfates and Their Mixtures with H₂SO₄at 25^oC