The mass accommodation coefficient of ozone on an aqueous surface

Müller, B.; Heal, Mathew R.

doi:10.1039/b202491h

Cited by 33 publications

(62 citation statements)

References 19 publications

(31 reference statements)

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“…These results have been obtained using textbook [ Seinfeld and Pandis , 1998] values for the various constants (rate constants, disassociation constants, Henry's Law coefficients, and diffusivities at 298 K). The value of the accommodation coefficients for SO 2 was taken to be 0.2 and for ozone the value was 0.04, in keeping with that suggested by Müller and Heal [2002]. It must be stressed that the values of [S(IV)] S and [O 3 ] S shown by the solid lines in Figure 2 are the values at the surface of the droplet However, because of the high concentration of S(IV) and the speed of the reaction at high pH, the O 3 concentration within the interior of the droplet can be severely depleted; that is, Q can become very small at high pH, whereas the fractional decrease in [S(IV)] caused by the reaction with O 3 is negligible.…”

Section: Discussionsupporting

confidence: 81%

Oxidation of S(IV) in sea‐salt aerosol at high pH: Ozone versus aerobic reaction

Hoppel

Caffrey

2005

J. Geophys. Res.

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[1] The oxidation of dissolved SO 2 (as S(IV)) by dissolved O 3 is known to increase rapidly with pH and is generally thought to be the mechanism responsible for the oxidation of S(IV) in sea-salt aerosol at high pH. Recently, Hoppel et al. (2001) have shown that an aerobic reaction studied by Zhang and Millero (1991) increases even more rapidly with pH than O 3 oxidation and exceeds that of O 3 at pH of about 7.5 to 8.5, depending on the ambient SO 2 concentrations. At high pH, both of these oxidation mechanisms proceed so rapidly that the actual rate is constrained by both gas-phase and aqueous-phase transport processes. A method of analysis is developed to calculate the transport-limited reaction rates for both of these mechanisms in sea-salt aerosol. Even when the unconstrained O 3 -S(IV) rate is faster than the aerobic mechanism, aqueousphase transport limitations on ozone can slow the constrained O 3 -S(IV) rate to the degree that it is slower than the aerobic reaction. In general, the O 3 -S(IV) rate is favored over the aerobic mechanism at low SO 2 and high O 3 concentrations, whereas the aerobic mechanism is favored at high SO 2 concentrations. The analysis indicates that the O 3 -S(IV) mechanism is more important in the remote regions where the SO 2 concentration can be extremely low. When the SO 2 concentration approaches 1 ppb or greater the aerobic mechanism is likely to be more important.Citation: Hoppel, W. A., and P. F. Caffrey (2005), Oxidation of S(IV) in sea-salt aerosol at high pH: Ozone versus aerobic reaction,

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Section: Discussionsupporting

confidence: 81%

Oxidation of S(IV) in sea‐salt aerosol at high pH: Ozone versus aerobic reaction

Hoppel

Caffrey

2005

J. Geophys. Res.

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“…The coefficient k mt accounts for the gas and interfacial mass transport limitations. R p is the radius of the droplet or aerosol particle, M O 3 is the molar mass of O 3 and α is the mass accommodation coefficient (4.0×10 −2 , Müller and Heal, 2002). In Eq.…”

Section: Chemistrymentioning

confidence: 99%

Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

et al. 2016

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Abstract. The growth of aerosol due to the aqueous phase oxidation of sulfur dioxide by ozone was measured in laboratory-generated clouds created in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN). Experiments were performed at 10 and − 10 • C, on acidic (sulfuric acid) and on partially to fully neutralised (ammonium sulfate) seed aerosol. Clouds were generated by performing an adiabatic expansion -pressurising the chamber to 220 hPa above atmospheric pressure, and then rapidly releasing the excess pressure, resulting in a cooling, condensation of water on the aerosol and a cloud lifetime of approximately 6 min. A model was developed to compare the observed aerosol growth with that predicted using oxidation rate constants previously measured in bulk solutions. The model captured the measured aerosol growth very well for experiments performed at 10 and −10 • C, indicating that, in contrast to some previous studies, the oxidation rates of SO 2 in a dispersed aqueous system can be well represented by using accepted rate constants, based on bulk measurements. To the best of our knowledge, these are the first laboratory-based measurements of aqueous phase oxidation in a dispersed, supercooled population of droplets. The measurements are therefore important in confirming that the extrapolation of currently accepted reaction rate constants to temperatures below 0 • C is correct.

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“…O 3 is reported to have variable mass accommodation coefficients (10 Ϫ3 -10 Ϫ2 ) on a pure air-water interface. 22,23 Similarly, PAHs also show small mass accommodation coefficients. 9,10 However, the presence of a PAH at the interface may increase the PAH-O 3 interaction at the airwater interface of a fog droplet.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous Oxidation by Ozone of Naphthalene Adsorbed at the Air-Water Interface of Micron-Size Water Droplets

Raja

Valsaraj

2005

Journal of the Air & Waste Management Association

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The mass transfer of naphthalene vapor to water droplets in air was studied in the presence of ozone (O 3 ) in the gas phase. A falling droplet reactor with water droplets of diameters 55, 91, and 182 m was used for the study. O 3 reacted with naphthalene at the air-water interface, thereby decreasing the mass transfer resistance and increasing the rate of uptake of naphthalene into the droplet. A Langmuir-Hinshelwood reaction mechanism at the air-water interface satisfactorily described the surface reaction. The first-order surface reaction rate constant, k s , increased with decreasing droplet size. Three organic intermediates were identified in the aqueous phase as a result of ozonation of naphthalene at the surface of the droplet indicating both peroxidic and nonperoxidic routes for ozonation. The presence of an organic carbon surrogate (fulvic acid) increased both the partition constant of naphthalene and the surface reaction rate of O 3 . The heterogeneous oxidation of naphthalene by O 3 on the droplet was 15 times faster than the homogeneous oxidation by O 3 in the bulk air phase, whereas it was only 0.08 times the homogeneous gas-phase oxidation by hydroxyl radicals under atmospheric conditions.

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The mass accommodation coefficient of ozone on an aqueous surface

Cited by 33 publications

References 19 publications

Oxidation of S(IV) in sea‐salt aerosol at high pH: Ozone versus aerobic reaction

Oxidation of S(IV) in sea‐salt aerosol at high pH: Ozone versus aerobic reaction

Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

Heterogeneous Oxidation by Ozone of Naphthalene Adsorbed at the Air-Water Interface of Micron-Size Water Droplets

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