Ozone Interaction with Polycyclic Aromatic Hydrocarbons and Soot in Atmospheric Processes:  Theoretical Density Functional Study by Molecular and Periodic Methodologies

Maranzana, Andrea; Serra, Giovanni; Giordana, Anna; Tonachini, Glauco; Gianluca, Barco; Causa, Mariella

doi:10.1021/jp053672q

Cited by 31 publications

(38 citation statements)

References 37 publications

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“…7. This value appears to be unreasonably small since the the self-diffusion constant of squalane has been measured to be 3×10 35 . Currently, we cannot rule out this possibility and further study on reaction products in the thin shell layer may provide the necessary clue.…”

Section: B Ozone Transmission Through Reactive Shellmentioning

confidence: 96%

The Reactive–Diffusive Length of OH and Ozone in Model Organic Aerosols

Lee

Wilson

2016

J. Phys. Chem. A

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A key step in the heterogeneous oxidation of atmospheric aerosols is the reaction of ozone (O3) and hydroxyl radicals (OH) at the gas-particle interface. The formation of reaction products and free radical intermediates and their spatial distribution inside the particle is a sensitive function of the length over which these oxidants diffuse prior to reaction. The reactive-diffusive length of OH and ozone at organic aerosol interfaces is determined by observing the change in the effective uptake coefficient for size-selected model aerosols comprising a reactive core and a thin nanometer-sized (0-12 nm) organic shell. The core and shell materials are selected so that they are immiscible and adopt an assumed core-shell configuration. The results indicate a reactive-diffusive length of 1.4 nm for hydroxyl (OH) radicals in squalane and 1.0 nm for ozone in squalene. Measurements for a purely diffusive system allow for an estimate for diffusion constant (1.6 × 10(-6) cm(2)/s) of ozone in squalane to be determined. The reactive-diffusive length offers a simple first order estimate of how shielding of aerosols by immiscible layers can alter estimates of oxidative lifetimes of aerosols in the atmosphere.

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Section: B Ozone Transmission Through Reactive Shellmentioning

confidence: 96%

The Reactive–Diffusive Length of OH and Ozone in Model Organic Aerosols

Lee

Wilson

2016

J. Phys. Chem. A

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“…A large number of experimental (Perraudin et al 2007;McCabe and Abbatt 2008;Bedjanian and Nguyen 2010;Shiraiwa et al 2011) and theoretical chemistry studies (Maranzana et al 2005;Giordana et al 2008) investigated the reactivity of ozone with soot particles and with PAHs deposited on different substrates. From these studies, the reactivity of O 3 with soot can be explained by a multi-step mechanism starting with (1) the physisorption of O 3 on the surface, which then undergoes dissociation to form a chemisorbed oxygen atom bound to the aromatic ring, and (2) the release of O 2 in the gas phase.…”

Section: Maturity Of Sootmentioning

confidence: 99%

“…Ketones and aldehydes have been identified as the main final products of the reaction leading to a local increase of the polarity of the surface, which enhances the uptake of water molecules. In particular, Maranzana et al, (Maranzana et al 2005;Giordana et al 2008) concluded from density function theory calculations that the energy barrier controlling the ozonization of internal positions is too high to be a viable option in atmospheric processes, and that it would be only possible for large graphene-like structures or very large concentration of O 3 and only after the reaction of the border positions. Therefore, the assumption that reactions with ozone takes place more favorably where the C-H bonds are abundant seems to be reasonable.…”

Section: Maturity Of Sootmentioning

confidence: 99%

Cloud condensation nuclei from the activation with ozone of soot particles sampled from a kerosene diffusion flame

Grimonprez

Faccinetto

Batut

et al. 2018

Aerosol Science and Technology

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Due to the exponential increase in aircraft traffic in recent decades, the role of soot particles emitted by aircraft engines on the radiative forcing needs to be addressed, and especially their interaction with clouds has to be better understood and quantified. In this work, we investigate the hygroscopic properties of fresh and aged soot sampled on line in a kerosene flame. The activated fraction (F a) of size selected soot is measured by means of a variable supersaturation condensation nucleus counter at several heights above the burner (HAB), thereby probing soot particles with different residence times in the flame, i.e., different degrees of maturity. In order to simulate atmospheric aging, the activity of soot as cloud condensation nuclei is measured as a function of ozone exposure. We show that fresh soot is hydrophobic (F a $0), while F a increases when soot is exposed to ozone. The measurements depend on the HAB at which soot particles are sampled showing that activation of soot particles is related to their chemical composition. This study brings new results on the link between atmospheric aging of soot and its hygroscopic properties, which is of great interest for understanding the role of soot in the cloud formation.

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“…The dissociated products are molecular oxygen such as a chemisorbed oxygen atom bound to the delocalized p-electrons of an aromatic surface. [49][50][51] The chemical equations of the multi-step L-H mechanism can be described as follows:…”

Section: Effect Of Humidity-induced Viscosity/diffusivity Changesmentioning

confidence: 99%

Kinetic limitations in gas-particle reactions arising from slow diffusion in secondary organic aerosol

et al. 2013

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The potential for aerosol physical properties, such as phase, morphology and viscosity/ diffusivity, to affect particle reactivity remains highly uncertain. We report here a study of the effect of bulk diffusivity of polycyclic aromatic hydrocarbons (PAHs) in secondary organic aerosol (SOA) on the kinetics of the heterogeneous reaction of particle-borne benzo[a]pyrene (BaP) with ozone. The experiments were performed by coating BaP-ammonium sulfate particles with multilayers of SOA formed from ozonolysis of alpha-pinene, and by subsequently investigating the kinetics of BaP loss via reaction with excess ozone using an aerosol flow tube coupled to an Aerodyne Aerosol Mass Spectrometer (AMS). All reactions exhibit pseudo-first order kinetics and are empirically well described by a Langmuir-Hinshelwood (L-H) mechanism. The results show that under dry conditions (RH < 5%) diffusion through the SOA coating can lead to significant mass transfer constraints on the kinetics, with behavior between that previously observed by our group for solid and liquid organic coats. The reactivity of BaP was enhanced at -50% relative humidity (RH) suggesting that water uptake lowers the viscosity of the SOA, hence lifting the mass transfer constraint to some degree. The kinetics for -70% RH were similar to results obtained without SOA coats, indicating that the SOA had sufficiently low viscosity and was sufficiently liquid-like that reactants could rapidly diffuse through the coat. A kinetic multi-layer model for aerosol surface and bulk chemistry was applied to simulate the kinetics, yielding estimates for the diffusion coefficients (in cm2 s(-1)) for BaP in alpha-pinene SOA of 2 x 10(-14), 8 x 10(-14) and > 1 x 10(-12) for dry (RH < 5%), 50% RH and 70% RH conditions, respectively. These results clearly indicate that slow diffusion of reactants through SOA coats under specific conditions can provide shielding from gas-phase oxidants, enabling the long-range atmospheric transport of toxic trace species, such as PAHs and persistent organic pollutants.

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Ozone Interaction with Polycyclic Aromatic Hydrocarbons and Soot in Atmospheric Processes: Theoretical Density Functional Study by Molecular and Periodic Methodologies

Cited by 31 publications

References 37 publications

The Reactive–Diffusive Length of OH and Ozone in Model Organic Aerosols

The Reactive–Diffusive Length of OH and Ozone in Model Organic Aerosols

Cloud condensation nuclei from the activation with ozone of soot particles sampled from a kerosene diffusion flame

Kinetic limitations in gas-particle reactions arising from slow diffusion in secondary organic aerosol

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