Adsorption and Transport of Gas-Phase Naphthalene on Micron-Size Fog Droplets in Air

Raja, Suresh; Valsaraj, Kalliat T.

doi:10.1021/es034591f

Cited by 24 publications

(52 citation statements)

References 33 publications

(41 reference statements)

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“…9 In this work, a diluted aromatic hydrocarbon vapor stream in helium along with O 3 gas was fed into the falling droplet reactor. To study the kinetics and uptake in the droplet flow tube apparatus, the whole experimental apparatus was traced with heating coils and controlled by temperature controllers obtained from Omega Engineering Inc.…”

Section: Experimental Apparatusmentioning

confidence: 99%

“…9,10 As fresh droplets traversed the reactor, the PAH vapors were incorporated into the droplets. The PAH concentration increased with droplet/gas contact time and decreased droplet radius.…”

Section: Introductionmentioning

confidence: 99%

“…These experiments showed that the partitioning of PAHs between the gas and a water droplet was larger for small droplets. 9,10 This was attributed to increased partitioning of compounds to the air-water interface through adsorption. As a consequence, the equilibrium at the airwater interface required a modified partition constant given by:…”

Section: Introductionmentioning

confidence: 99%

“…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. 21 In the natural atmosphere, the primary oxidants are the hydroxyl radical, O 3 , and the nitrate radical.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Experimental Apparatusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…These compounds could be able to start photochemical and photosensitized reactions upon radiation absorption. Polycyclic Aromatic Hydrocarbons (PAHs) constitute one of the most widespread classes of organic pollutants in water, soil and atmosphere [2][3][4][5][6][7] , and received particular attention due to their mutagenic effects 8 . The PAH nitroderivatives also cause concern for their direct mutagenicity.…”

Section: Introductionmentioning

confidence: 99%

Photochemistry of 1-Nitronaphthalene: A Potential Source of Singlet Oxygen and Radical Species in Atmospheric Waters

et al. 2010

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Abstract1-Nitronaphthalene (1NN) was used as a model of nitro-PAHs to investigate photosensitized reactions in aqueous solution in the presence of oxygen and halides. Laser Flash Photolysis (LFP) was employed to investigate electron transfer between halide anions and the triplet state of 1NN, leading to the formation of dihalogen radical anions (X 2 •-) in solution. The experiments were performed in the absence or presence of oxygen, showing a bimolecular quenching rate constant for the triplet state of 1NN ( 3 1NN) by oxygen of (1.95 ± 0.05) × 10 9 M -1 s -1 . The decay of 3 1NN was observed to strongly depend on the pH of the medium. At pH > 2, 3 1NN decayed with a pseudo-first order rate constant close to 6.0 × 10 5 s -1 . The rate constant was markedly enhanced at lower pHs, reaching 2.0 × 10 6 s -1 at pH ~ 0.1, which suggests formation of the protonated triplet state ( 3 1NNH + ) at low pHs. Furthermore, we showed that the photoreactions of 3 1NN in the presence of oxygen are potential sources of HO 2 • , 1 O 2 and possibly • OH in aqueous media. In Milli-Q water (pH ~ 6.5) and in the presence of halide anions the quenching rate constant of 3 1NN was evaluated to be (2.9 ± 0.4) × 10 4 M -1 s -1 for chloride, (7.5 ± 0.2) × 10 8 M -1 s -1 for bromide, and (1.1 ± 0.1) × 10 10 M -1 s -1 for iodide. Also in this case a pH-dependent reactivity was evidenced, and the quenching rate constant was (7.7 ± 1.2) × 10 5 M -1 s -1 with chloride at pH 1.1.

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Monitoring of Fogwater Chemistry in the Gulf Coast Urban Industrial Corridor: Baton Rouge (Louisiana)

Raja

Ravikrishna

Kommalapati

et al. 2005

Environ Monit Assess

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Seventeen fog events were sampled in Baton Rouge, Louisiana during 2002-2004 as part of characterizing wet deposition by fogwater in the heavily industrialized corridor along the Louisiana Gulf Coast in the United States. These samples were analyzed for chemical characteristics such as pH, conductivity, total organic and inorganic carbon, total metals and the principal ion concentrations. The dominant ionic species in all samples were NH4+, NO3-, Cl- and SO4(2-). The pH of the fogwater sampled had a mean value of 6.7 with two cases of acidic pH of 4.7. Rainwater and fogwater pH were similar in this region. The acidity of fogwater was a result of NO3- but partly offset by high NH4+. The measured gaseous SO2 accounted for a small percentage of the observed sulfate concentration, indicating additional gas-to-particle conversion of SO2 to sulfate in fogwater. The gaseous NOx accounted for most of the dissolved nitrate and nitrite concentration in fogwater. The high chloride concentration was attributable to the degradation of chlorinated organics in the atmosphere. The metal composition was traced directly to soil-derived aerosol precursors in the air. The major metals observed in fogwater were Na, K, Ca, Fe, Al, Mg and Zn. Of these Na, K, Ca and Mg were predominant with mean concentrations > 100 microM. Al, Fe and Zn were present in the samples, at mean concentrations < 100 microM. Small concentrations of Mn (7.8 microM), Cu (2 microM), Pb (0.07 microM) and As (0.32 microM) were also observed in the fogwaters, and these were shown to result from particulates (PM2.5) in the atmosphere. The contribution to both ions and metals from the marine sources in the Louisiana Gulf Coast was minimal. The concentrations of all principal ionic species and metals in fogwater were 1-2 orders of magnitude larger than in rainwater. Several linear alkane organic compounds were observed in the fogwater, representing the contributions from petroleum products at concentrations far exceeding their aqueous solubility. A pesticide (atrazine) was also observed in fogwater, representing the contribution from the agricultural activities nearby.

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Adsorption and Transport of Gas-Phase Naphthalene on Micron-Size Fog Droplets in Air

Cited by 24 publications

References 33 publications

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

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

Photochemistry of 1-Nitronaphthalene: A Potential Source of Singlet Oxygen and Radical Species in Atmospheric Waters

Monitoring of Fogwater Chemistry in the Gulf Coast Urban Industrial Corridor: Baton Rouge (Louisiana)

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