Photochemistry of Atmospheric Particles

Navea, Juan G.; Grassian, Vicki H.

doi:10.1016/b978-0-12-409547-2.13210-x

Cited by 8 publications

(21 citation statements)

References 70 publications

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“…Both energy gaps are smaller than the cutoff for solar radiation in the troposphere and our solar simulator under experimental conditions (290 nm). [33][34][35]66 Thus, photoirradiation of the batch reactor can induce redox reactions initiated by electrons in the conduction band (e cb − ) and the concomitant hole in the valence band (h vb + ), as described in reactions 8 and 9…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Iron and nitrite quantification started at a t = 0 min, defined as the moment of FA loading into the acid solution. After t = 0 min, the suspension aliquots were colorimetrically analyzed for dissolved iron and nitrite ion content . As reported in a previous work, dissolved iron speciation was quantified using 1,10-phenanthroline, which selectively forms an orange complex with Fe 2+ with an absorbance band at 510 nm .…”

Section: Methodsmentioning

confidence: 99%

“…After t = 0 min, the suspension aliquots were colorimetrically analyzed for dissolved iron and nitrite ion content. 33 As reported in a previous work, dissolved iron speciation was quantified using 1,10-phenanthroline, which selectively forms an orange complex with Fe 2+ with an absorbance band at 510 nm. 18 Total dissolved iron was quantified in the same samples by adding hydroxylamine to reduce all Fe 3+ to Fe 2+ prior to phenanthroline complexation.…”

Section: ■ Experimental Sectionmentioning

confidence: 98%

“…As an oxidizing acid, HNO 3 can impact the speciation of iron, while daytime conditions have shown to drive surface reactions of HNO 3 on semiconductors and chromophores present in these atmospheric aerosols. 33 In fact, recent studies in our research group suggest that HNO 3 heterogeneous photochemistry on metal oxides, common components of combustion particles, can lead to nitrous acid formation and the renoxification of the atmosphere. 34−36 However, little is known about the rate and yields of these reactions in the acidic deliquescent layer around FA particles during atmospheric transport.…”

Section: ■ Introductionmentioning

confidence: 98%

“…For mineral dust, the rate of iron dissolution depends not only on the pH but also on the mineralogy of the particles, the solar flux, and the identity of the acid. ,, One important atmospheric acid is nitric acid (HNO 3 ), primarily generated from nitrogen oxide atmospheric reactions. As an oxidizing acid, HNO 3 can impact the speciation of iron, while daytime conditions have shown to drive surface reactions of HNO 3 on semiconductors and chromophores present in these atmospheric aerosols . In fact, recent studies in our research group suggest that HNO 3 heterogeneous photochemistry on metal oxides, common components of combustion particles, can lead to nitrous acid formation and the renoxification of the atmosphere. − However, little is known about the rate and yields of these reactions in the acidic deliquescent layer around FA particles during atmospheric transport.…”

Section: Introductionmentioning

confidence: 99%

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Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Kim

Xiao

Karchere-Sun

et al. 2020

ACS Earth Space Chem.

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Atmospheric combustion particles, such as fly ash emitted from coal-fired power plants, are a potential source of atmospheric iron, with significant implications in climate and global biogeochemical cycles. While the iron content and speciation of fly ash depend closely on the source region and combustion process, few studies have been carried out comparing the atmospheric processing of fly ash produced from coal-fired power plants in different regions. In this study, we present an investigation of iron dissolution in acidic aqueous solutions: HNO 3 and HCl at pH 1 and pH 2 under daytime and nighttime conditions for three fly ash samples from three different sources: United States (USFA), Central Europe (EUFA), and India fly ash (INFA). Iron mobility and speciation depend on the source region and the combustion efficiency that generates fly ash. In HCl suspensions, proton-promoted mechanisms lead to larger fractions of aqueous-phase iron leached from fly ash particles, with poorly combusted samples providing significant fractions of Fe 2+ . In HNO 3 suspensions, a surface-mediated redox reaction suppresses the mobility of Fe 2+ , leading to the formation of nitrites. In the presence of solar radiation, previously unrecognized pathways of atmospheric processing enhance the formation Fe 2+ and nitrous acid from combustion particles. The information provided herein could be significant to increase our understanding of the effects of combustion particles in the atmospheric chemical balance regarding iron and nitrites.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 98%

Section: ■ Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Kim

Xiao

Karchere-Sun

et al. 2020

ACS Earth Space Chem.

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Particle formation and surface processes on atmospheric aerosols: A review of applied quantum chemical calculations

Leonardi

Ricker

Gale

et al. 2020

Int J of Quantum Chemistry

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Aerosols significantly influence atmospheric processes such as cloud nucleation, heterogeneous chemistry, and heavy-metal transport in the troposphere. The chemical and physical complexity of atmospheric aerosols results in large uncertainties in their climate and health effects. In this article, we review recent advances in scientific understanding of aerosol processes achieved by the application of quantum chemical calculations. In particular, we emphasize recent work in two areas: new particle formation and heterogeneous processes. Details in quantum chemical methods are provided, elaborating on computational models for prenucleation, secondary organic aerosol formation, and aerosol interface phenomena. Modeling of relative humidity effects, aerosol surfaces, and chemical kinetics of reaction pathways is discussed. Because of their relevance, quantum chemical calculations and field and laboratory experiments are compared. In addition to describing the atmospheric relevance of the computational models, this article also presents future challenges in quantum chemical calculations applied to aerosols.

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Effects of Coadsorbed Water on the Heterogeneous Photochemistry of Nitrates Adsorbed on TiO₂

et al. 2018

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Nitric acid, a well-known sink of NO gases in the atmosphere, has been found to be photoactive while adsorbed on tropospheric particles. When adsorbed onto semiconductive metal oxides, nitrate's photochemical degradation can be interpreted as a photocatalytic process. Yet, the photolysis of nitrate ions on the surface of aerosols can also be initiated by changes in the symmetry of the ion upon adsorption. In this study, we use quantum chemistry to model the vibrational spectra of adsorbed nitrate on TiO, a semiconductor component of atmospheric aerosols, and determine the kinetics of the heterogeneous photochemical degradation of nitrate under simulated solar light. Frequencies and geometry calculations suggest that the symmetry of chemisorbed nitrate ion depends strongly on coadsorbed water, with water changing the reactive surface of TiO. Upon irradiation, surface nitrate undergoes photolysis to yield nitrogen-containing gaseous products including NO, NO, HONO, and NO, in proportions that depend on relative humidity (RH). In addition, the heterogeneous photochemistry rate constant decreases an order of magnitude, from (5.7 ± 0.1) × 10 s on a dry surface to (7.1 ± 0.8) × 10 s when nitrate is coadsorbed with water above monolayer coverage. Little is known about the roles of coadsorbed water on the heterogeneous photochemistry of nitrates on TiO, along with its impact on the chemical balance of the atmosphere. This work discusses the roles of water in the photolysis of surface nitrates on TiO and the concomitant renoxification of the atmosphere.

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Photochemistry of Atmospheric Particles

Cited by 8 publications

References 70 publications

Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Particle formation and surface processes on atmospheric aerosols: A review of applied quantum chemical calculations

Effects of Coadsorbed Water on the Heterogeneous Photochemistry of Nitrates Adsorbed on TiO₂

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Photochemistry of Atmospheric Particles

Cited by 8 publications

References 70 publications

Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Particle formation and surface processes on atmospheric aerosols: A review of applied quantum chemical calculations

Effects of Coadsorbed Water on the Heterogeneous Photochemistry of Nitrates Adsorbed on TiO2

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Product

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Effects of Coadsorbed Water on the Heterogeneous Photochemistry of Nitrates Adsorbed on TiO₂