Heterogeneous Reactions of Linoleic Acid and Linolenic Acid Particles with Ozone:  Reaction Pathways and Changes in Particle Mass, Hygroscopicity, and Morphology

Lee, Alex K. Y.; Chan, Chak K.

doi:10.1021/jp071812l

Cited by 50 publications

(80 citation statements)

References 49 publications

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“…From this perspective it is surprising that under dry conditions, the hygroscopic growth factors would not respond more significantly to ozonolysis. Also in a recent study by Lee and Chan (2007b) on ozonolysis of linoleic and linolenic acids under dry conditions, the mass growth factors hardly increased compared to oleic acid ozonolysis mentioned above. One aspect may certainly be the fact that the most hygroscopic products expected from AR ozonolysis, MA and GA, may undergo significant evaporation (Kumar et al, 2003;Koehler et al, 2006;Rissmann et al, 2007).…”

Section: Resultsmentioning

confidence: 92%

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Changes of fatty acid aerosol hygroscopicity induced by ozonolysis under humid conditions

et al. 2008

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Abstract. Unsaturated fatty acids are important constituents of the organic fraction of atmospheric aerosols originating from biogenic or combustion sources. Oxidative processing of these may change their interaction with water and thus affect their effect on climate. The ozonolysis of oleic and arachidonic acid aerosol particles was studied under humid conditions in a flow reactor at ozone exposures close to atmospheric levels, at concentrations between 0.5 and 2 ppm. While oleic acid is a widely used proxy for such studies, arachidonic acid represents polyunsaturated fatty acids, which may decompose into hygroscopic products. The hygroscopic (diameter) growth factor at 93% relative humidity (RH) of the oxidized arachidonic particles increased up to 1.09 with increasing RH during the ozonolysis. In contrast, the growth factor of oleic acid was very low (1.03 at 93% RH) and was almost invariant to the ozonolysis conditions, so that oleic acid is not a good model to observe oxidation induced changes of hygroscopicity under atmospheric conditions. We show for arachidonic acid particles that the hygroscopic changes induced by humidity during ozonolysis are accompanied by about a doubling of the ratio of carboxylic acid protons to aliphatic protons. We suggest that, under humid conditions, the reaction of water with the Criegee intermediates might open a pathway for the formation of smaller acids that lead to more significant changes in hygroscopicity. Thus the effect of water to provide a competing pathway during ozonolysis observed in this study should be motivation to include water, which is ubiquitously present in and around atmospheric particles, in future studies related to aerosol particle aging.

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Section: Resultsmentioning

confidence: 92%

“…Depending on the matrix, these reactions can continue and lead to high-molecular weight compounds or further to oligomers. In addition to these processes, for polyunsaturated fatty acids, autoxidation processes could also contribute, especially at low ozone concentrations and over long time scales (Lee and Chan, 2007b).…”

Section: Resultsmentioning

confidence: 99%

Changes of fatty acid aerosol hygroscopicity induced by ozonolysis under humid conditions

et al. 2008

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“…EDB has been used extensively for directly measuring particle mass changes during water uptake (Peng et al 2001) and chemical reactions (Lee and Chan 2007;Chan and Chan 2011). In brief, a single droplet was charged as it passed through the induction plate mounted at the top entrance of the EDB.…”

Section: Edb Equilibrium Mass and Hygroscopic Measurementsmentioning

confidence: 99%

“…In particular, an inclusion of solid lauric acid of about 7 wt% reduced the O 3 uptake coefficient of oleic acid by an order of magnitude (Knopf et al 2005). Moreover, the high level of O 3 (ppm level) commonly used in laboratory studies may also complicate the analysis (Lee and Chan 2007).…”

Section: Introductionmentioning

confidence: 99%

Roles of the Phase State and Water Content in Ozonolysis of Internal Mixtures of Maleic Acid and Ammonium Sulfate Particles

Chan

2012

Aerosol Science and Technology

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The ozonolysis of maleic acid/ammonium sulfate (MA/AS, 30/70 wt%) internal mixtures was investigated at various relative humidities (RHs) (80%, 55%, 30%, and <5%) and physical states (aqueous and crystalline solid). Complementary laboratory techniques-an electrodynamic balance coupled with in situ Raman spectroscopy and a reaction flow cell coupled with offline ion chromatography (IC)-were employed to probe the mass changes, spectroscopic changes, product identities, and post-reaction hygroscopic changes in ozone-processed MA/AS mixed particles. The rate of ozonolysis was highly dependent on the physical state and the water content of the particles. Crystalline solid particles underwent negligible changes even after exposure to 10-ppm ozone for six days. Aqueous particles reacted much faster and the rate was related to the RH during reaction. It took 23 h to reduce MA to 50% of its initial mass at 80% RH, whereas it took 87 h to do the same at 55% RH or lower. We believe that the salting-out of ozone in concentrated droplets at 55% RH may have contributed to the reduced ozonolysis rate. The molar conversion of MA to glyoxylic acid was about unity in both the 55% RH and the 80% RH experiments. Exposed particles may have formed amorphous solids when dried and their hygroscopicity was different from that of the corresponding parent particles. Early deliquescence of reacted particles was observed, suggesting the strong influence of aging on aerosol hygroscopicity.

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“…Raman studies have been carried out to probe the phase state (Bertram et al, 2011), hygroscopic properties (Yeung et al, 2009) and heterogeneous reactivity (Lee and Chan, 2007) of laboratory-generated atmospherically relevant particles at…”

Section: Introductionmentioning

confidence: 99%

Electrospray surface-enhanced Raman spectroscopy (ES-SERS) for probing surface chemical compositions of atmospherically relevant particles

Gen

Chan

2017

Atmos. Chem. Phys.

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Abstract. We present electrospray surface-enhanced Raman spectroscopy (ES-SERS) as a new approach to measuring the surface chemical compositions of atmospherically relevant particles. The surface-sensitive SERS is realized by electrospraying Ag nanoparticle aerosols over analyte particles. Spectral features at v(SO Enhanced spectra of the solid AS and AS / SA particles revealed the formation of surface-adsorbed water on their surfaces at 60 % relative humidity. These observations of surface aqueous sulfate and adsorbed water demonstrate a possible role of surface-adsorbed water in facilitating the dissolution of sulfate from the bulk phase into its water layer(s). Submicron ambient aerosol particles collected in Hong Kong exhibited non-enhanced features of black carbon and enhanced features of sulfate and organic matter (carbonyl group), indicating an enrichment of sulfate and organic matter on the particle surface.

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Heterogeneous Reactions of Linoleic Acid and Linolenic Acid Particles with Ozone: Reaction Pathways and Changes in Particle Mass, Hygroscopicity, and Morphology

Cited by 50 publications

References 49 publications

Changes of fatty acid aerosol hygroscopicity induced by ozonolysis under humid conditions

Changes of fatty acid aerosol hygroscopicity induced by ozonolysis under humid conditions

Roles of the Phase State and Water Content in Ozonolysis of Internal Mixtures of Maleic Acid and Ammonium Sulfate Particles

Electrospray surface-enhanced Raman spectroscopy (ES-SERS) for probing surface chemical compositions of atmospherically relevant particles

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