Effect of Acids on Water Vapor Uptake by Pyrogenic Silica

Bogdan, Anatoli; Kulmala, Markku

doi:10.1006/jcis.1997.4920

Cited by 11 publications

(17 citation statements)

References 20 publications

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“…For example, the water film thickness on the powder surface upon exposure to the vapors over a 5-10 wt.% (0.8-1.7 M) aqueous solution of HNO 3 was about twice that upon exposure to water vapor alone, 37 and the mass of water adsorbed from the vapor over a 45 wt.% (9 M) HNO 3 solution per gram of SiO 2 was reported to be about a factor of five larger than the mass adsorbed on exposure to water vapor alone at the same RH. 38 Quartz is primarily silica so that the Bogdan et al results should be comparable to our quartz data; indeed, the data in Fig. 6 show a significant increase in water uptake on quartz at 80% RH.…”

supporting

confidence: 86%

“…Bogdan and coworkers [37][38][39] have reported enhancement of water uptake on silica powders due to HNO 3 . For example, the water film thickness on the powder surface upon exposure to the vapors over a 5-10 wt.% (0.8-1.7 M) aqueous solution of HNO 3 was about twice that upon exposure to water vapor alone, 37 and the mass of water adsorbed from the vapor over a 45 wt.% (9 M) HNO 3 solution per gram of SiO 2 was reported to be about a factor of five larger than the mass adsorbed on exposure to water vapor alone at the same RH.…”

mentioning

confidence: 99%

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Interactions of gaseous nitric acid with surfaces of environmental interest

Dubowski

Sumner

Menke

et al. 2004

Phys. Chem. Chem. Phys.

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Gaseous nitric acid removal by surfaces in experimental systems and in the atmospheric boundary layer is rapid. However, neither the form of HNO 3 on surfaces nor its impact on the properties of the thin surface film are known. We report here studies of surfaces that have been exposed at room temperature (295 AE 2 K) to gaseous mixtures of water vapor with HNO 3 at concentrations from 46 ppb to 4 Â 10 3 ppm. The surfaces were probed using a combination of Fourier transform infrared spectrometry (FTIR), non-contact atomic force microscopy (AFM), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS). Exposure of borosilicate glass, quartz, and thin Teflon films to mixtures of gaseous HNO 3 and water vapor leads to the subsequent uptake of much larger amounts of water than occurs on the corresponding unexposed surfaces. Infrared spectra show evidence for the formation of nitric acid-water complexes on the surface that leads to this enhanced water uptake. On borosilicate glass, exposure to the nitric acid-water vapor mixture results in surface segregation of the trace metal oxides and their nitrates formed from reaction with HNO 3 . The majority of these oxides can be removed by rinsing with water; however, smaller, segregated regions of ZnO remain on the surface. The implications for heterogeneous reactions in thin films on surfaces in laboratory systems and in the atmosphere are discussed.

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confidence: 86%

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confidence: 99%

Interactions of gaseous nitric acid with surfaces of environmental interest

Dubowski

Sumner

Menke

et al. 2004

Phys. Chem. Chem. Phys.

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“…However, with respect to the kinetics in the thin films, even a factor of five increase in water uptake measured for silica powders 134 does not reconcile the large discrepancies in the measured rates of HONO production compared to that calculated for reaction in a bulk aqueous layer on the surface.…”

mentioning

confidence: 70%

The heterogeneous hydrolysis of NO2 in laboratory systems and in outdoor and indoor atmospheres: An integrated mechanism

Finlayson-Pitts

Wingen

Sumner

et al. 2002

Phys. Chem. Chem. Phys.

627

767

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The heterogeneous reaction of NO 2 with water on the surface of laboratory systems has been known for decades to generate HONO, a major source of OH that drives the formation of ozone and other air pollutants in urban areas and possibly in snowpacks. Previous studies have shown that the reaction is first order in NO 2 and in water vapor, and the formation of a complex between NO 2 and water at the air-water interface has been hypothesized as being the key step in the mechanism. We report data from long path FTIR studies in borosilicate glass reaction chambers of the loss of gaseous NO 2 and the formation of the products HONO, NO and N 2 O. Further FTIR studies were carried out to measure species generated on the surface during the reaction, including HNO 3 , N 2 O 4 and NO 2 + . We propose a new reaction mechanism in which we hypothesize that the symmetric form of the NO 2 dimer, N 2 O 4 , is taken up on the surface and isomerizes to the asymmetric form, ONONO 2 . The latter autoionizes to NO + NO 3 À , and it is this intermediate that reacts with water to generate HONO and surface-adsorbed HNO 3 . Nitric oxide is then generated by secondary reactions of HONO on the highly acidic surface. This new mechanism is discussed in the context of our experimental data and those of previous studies, as well as the chemistry of such intermediates as NO + and NO 2 + that is known to occur in solution. Implications for the formation of HONO both outdoors and indoors in real and simulated polluted atmospheres, as well as on airborne particles and in snowpacks, are discussed. A key aspect of this chemistry is that in the atmospheric boundary layer where human exposure occurs and many measurements of HONO and related atmospheric constituents such as ozone are made, a major substrate for this heterogeneous chemistry is the surface of buildings, roads, soils, vegetation and other materials. This area of reactions in thin films on surfaces (SURFACE ¼ Surfaces, Urban and Remote: Films As a Chemical Environment) has received relatively little attention compared to reactions in the gas and liquid phases, but in fact may be quite important in the chemistry of the boundary layer in urban areas.

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“…The independence of the properties of vicinal water on the specific nature of the surface was termed as the paradoxical effect. Bogdan and Kulmala [67] spectroscopy. Braun and Drost-Hansen [68] measured the heat capacity of water on silica and found it to be 25-30% greater than that at bulk.…”

Section: Characteristics Of Water On Silica Surfacementioning

confidence: 99%