DRIFTS and Knudsen cell study of the heterogeneous reactivity of SO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; and NO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; on mineral dust

Ullerstam, Maria; Johnson, Matthew S.; Vogt, Rainer; Ljungström, Evert

doi:10.5194/acp-3-2043-2003

Cited by 136 publications

(117 citation statements)

References 38 publications

(55 reference statements)

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“…Therefore, accessible active sites also decreased with time. Previous research has found that γ obs depends on sample mass due to the diffusion of reactant gas into the underlying layers of the multilayer powder sample 2010b, c;Ullerstam et al, 2003;Underwood et al, 2000 and2001). Some studies have found, however, that uptake coefficient is unrelated to sample mass (Qiu et al, 2011;Seisel et al, 2005).…”

Section: Kinetics Of Ma Uptake Onto Ammonium Saltsmentioning

confidence: 90%

“…Prior to the experiments, the reactor chamber was passivated with amines for 90 min until a steady state QMS signal was established as the samples were isolated from the gas by the sample cover. The observed uptake coefficients (γ obs ) were calculated with a Knudsen cell equation (Tabor et al, 1994;Ullerstam et al 2003;Underwood et al, 2000).…”

Section: Uptake Experimentsmentioning

confidence: 99%

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Differences in the reactivity of ammonium salts with methylamine

et al. 2012

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Abstract. The heterogeneous uptake of methylamine (MA) onto (NH 4 ) 2 SO 4 , NH 4 HSO 4 , NH 4 NO 3 and NH 4 Cl was investigated using a Knudsen cell reactor coupled to a quadrupole mass spectrometer, in situ Raman spectrometer and theoretical calculations. Exchange reactions were observed between MA and NH 4 NO 3 , (NH 4 ) 2 SO 4 , and NH 4 Cl were observed at 298 K. Simple acid-base reaction for MA was found taking place on NH 4 HSO 4 . CH 3 NH 3 NO 3 and CH 3 NH 3 Cl are not stable at low pressure and have higher dissociation vapor pressure than methylammonium sulfate. The observed uptake coefficients of MA on (NH 4 ) 2 SO 4 , NH 4 HSO 4 , NH 4 NO 3 and NH 4 Cl at 298 K were measured to be 6.30±1.03×10 −3 , 1.78±0.36×10 −2 , 8.79±1.99×10 −3 and 2.29±0.28×10 −3 , respectively. A linear free energy relationship was found for the heterogeneous reactions between MA and NH 4 Cl, (NH 4 ) 2 SO 4 and NH 4 NO 3 . Namely, the natural logarithm of uptake coefficients of MA on these ammonium salts is linearly related to the electrostatic potential of the H atom in the NH + 4 group.

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Section: Kinetics Of Ma Uptake Onto Ammonium Saltsmentioning

confidence: 90%

Section: Uptake Experimentsmentioning

confidence: 99%

Differences in the reactivity of ammonium salts with methylamine

et al. 2012

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“…26 For steady-state uptake, the uptake coefficient can be calculated using the Knudsen cell equation: [26][27][28][29] where A h is the effective area of the escape aperture (m 2 ), A s is the geometric area of the sample holder (m 2 ); I 0 and I are the mass spectral intensities with the sample holder closed and open, respectively. As for the multilayer powder sample, the linear mass dependent (LMD) region of the observed uptake coefficient has been reported by different groups in various reaction systems, and has been ascribed to the diffusion of reactant molecules into the underlying layers of multilayer powder samples.…”

Section: The Effect Of Temperature On the Heterogeneousmentioning

confidence: 99%

“…As for the multilayer powder sample, the linear mass dependent (LMD) region of the observed uptake coefficient has been reported by different groups in various reaction systems, and has been ascribed to the diffusion of reactant molecules into the underlying layers of multilayer powder samples. [29][30][31][32][33] Therefore, the true uptake coefficients, γ t , can be calculated from where "slope" is the slope of the plot of γ versus sample mass in the linear regime (kg -1 ), A s is the geometric area (m 2 ) of the sample holder, and S BET is the specific surface area of the particle sample (m 2 ‚kg -1 ). 34 As shown in Figure 3, there was a strong linear dependence of uptake coefficients at the initial time γ(Ini) and at steady state γ(SS) versus sample mass.…”

Section: The Effect Of Temperature On the Heterogeneousmentioning

confidence: 99%

Temperature Dependence of the Heterogeneous Reaction of Carbonyl Sulfide on Magnesium Oxide

2008

J. Phys. Chem. A

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The experimental determination of rate constants for atmospheric reactions and how these rate constants vary with temperature remain a crucially important part of atmosphere science. In this study, the temperature dependence of the heterogeneous reaction of carbonyl sulfide (COS) on magnesium oxide (MgO) has been investigated using a Knudsen cell reactor and a temperature-programmed reaction apparatus. We found that the adsorption and the heterogeneous reaction are sensitive to temperature. The initial uptake coefficients (γ t (Ini)) of COS on MgO decrease from 1.07 ( 0.71 × 10 -6 to 4.84 ( 0.60 × 10 -7 with the increasing of temperature from 228 to 300 K, and the steady state uptake coefficients (γ t (SS)) increase from 5.31 ( 0.06 × 10 -8 to 1.68 ( 0.41 × 10 -7 with the increasing of temperature from 240 to 300 K. The desorption rate constants (k des ) were also found to increase slightly with the enhancement of temperature. The empirical formula between the uptake coefficients, desorption rate constants and temperature described in the form of Arrhenius expression were obtained. The activation energies for the heterogeneous reaction and desorption of COS on MgO were measured to be 11.02 ( 0.34 kJ‚mol -1 and 6.30 ( 0.81 kJ‚mol -1 , respectively. The results demonstrate that the initial uptake of COS on MgO is mainly contributed by an adsorption process and the steady state uptake is due to a catalytic reaction. The environmental implication was also discussed.

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“…[28][29][30][31][32][33][34] Diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) is a powerful technique for following the chemistry of solid particles in real time under laboratory conditions. [35][36][37][38] It has the advantage of relatively strong signals due to the macroscopic amounts of sample used, but the matrix used must be infrared transparent. DRIFTS is not normally applicable to liquids where interface and bulk liquid phase reactions are important.…”

Section: Introductionmentioning

confidence: 99%

A new approach to studying aqueous reactions using diffuse reflectance infrared Fourier transform spectrometry: application to the uptake and oxidation of SO2 on OH-processed model sea salt aerosol

Shaka

Robertson

Finlayson-Pitts

2007

Phys. Chem. Chem. Phys.

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A new approach to studying aqueous reactions using diffuse reflectance infrared Fourier transform spectrometry: application to the uptake and oxidation of SO2 on OH-processed model sea salt aerosol. Diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) is a powerful technique for analyzing solid powders and for following their reactions in real time. We demonstrate that it can also be applied to studying the uptake and reactions of gases in liquid films. Within the DRIFTS cell, a 10% (w/w) mixture of MgCl 2 Á 6H 2 O in NaCl was equilibrated with air at 50% RH, which is above the deliquescence point of the magnesium salt but below that of NaCl. This mixture of NaCl coated with an aqueous magnesium chloride solution was then reacted with gas phase OH to generate hydroxide ions via a previously identified interface reaction. This treatment, hereafter referred to as OH-processing, was sufficient to convert some of the magnesium chloride to Mg(OH) 2 and Mg 2 (OH) 3 Cl Á 4H 2 O, making the aqueous film basic and providing a reservoir of alkalinity. Subsequent addition of SO 2 to the basic processed mixture resulted in its uptake and conversion to sulfite which was measured by FTIR. The sulfite was simultaneously oxidized to sulfate by HOCl/OCl À that was formed in the initial OH-processing of the salt. Further uptake and oxidation of SO 2 in the aqueous film took place when the salt was subsequently exposed to O 3 . These studies demonstrate that DRIFTS can be used to study the chemistry in liquid films in real time, and are consistent with the hypothesis that the reaction of gaseous OH with chloride ions generates alkalinity that enhances the uptake and oxidation of SO 2 under these laboratory conditions.

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DRIFTS and Knudsen cell study of the heterogeneous reactivity of SO<sub>2</sub> and NO<sub>2</sub> on mineral dust

Cited by 136 publications

References 38 publications

Differences in the reactivity of ammonium salts with methylamine

Differences in the reactivity of ammonium salts with methylamine

Temperature Dependence of the Heterogeneous Reaction of Carbonyl Sulfide on Magnesium Oxide

A new approach to studying aqueous reactions using diffuse reflectance infrared Fourier transform spectrometry: application to the uptake and oxidation of SO2 on OH-processed model sea salt aerosol

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