scholarly journals Kinetics and mechanism of the uptake of N<sub>2</sub>O<sub>5</sub> on mineral dust at 298 K

2005 ◽  
Vol 5 (12) ◽  
pp. 3423-3432 ◽  
Author(s):  
S. Seisel ◽  
C. Börensen ◽  
R. Vogt ◽  
R. Zellner
Keyword(s):  
Mineral Dust ◽  
Heterogeneous Reaction ◽  
Recent Model ◽  
Saharan Dust ◽  
Uptake Coefficient ◽  
Model Calculations ◽  
Upper Limits ◽  
Uptake Rates ◽  
Hydrolysis Of ◽  
Dust Surface

Abstract. The heterogeneous reaction of N2O5 with mineral (Saharan) dust has been studied at T=298 K using a combination of Knudsen and DRIFTS cells for kinetic and product investigations, respectively. The initial uptake coefficient has been determined to be γ=(8.0±0.3)·10−2. This uptake slowly saturates into a steady state uptake of γ=(1.3±0.3)·10−2 suggesting that reaction of N2O5 with the mineral dust surface and hydrolysis of N2O5 on the surface take place simultaneously. Both uptake coefficients have been calculated on the basis of the geometric (projected) surface area of the sample and must therefore be regarded as upper limits. In addition, the product investigations show that N2O5 is irreversibly taken up to form nitrate on the surface. Recent model calculations suggest that the uptake rates of N2O5 on Saharan dust which we measured may be large enough to influence the photo-oxidant budget of the atmosphere.

scholarly journals Kinetics and mechanism of the uptake of N<sub>2</sub>O<sub>5</sub> on mineral dust at 298 K

2005 ◽  
Vol 5 (4) ◽  
pp. 5645-5667
Author(s):  
S. Seisel ◽  
C. Börensen ◽  
R. Vogt ◽  
R. Zellner
Keyword(s):  
Steady State ◽  
Mineral Dust ◽  
Heterogeneous Reaction ◽  
Kinetics And Mechanism ◽  
Saharan Dust ◽  
Uptake Coefficient ◽  
Uptake Rates ◽  
Hydrolysis Of ◽  
Dust Surface ◽  
Initial Uptake

Abstract. The heterogeneous reaction of N2O5 with mineral (Saharan) dust has been studied at T=298 K using a combination of Knudsen and DRIFTS cell for kinetic and product investigations, respectively. The initial uptake coefficient has been determined to be γ=(8.0±0.3)·10−2. This uptake slowly saturates into a steady state uptake of γ=(1.3±0.3)10−2 suggesting that reaction of N2O5 with the mineral dust surface and hydrolysis of N2O5 on the surface take place simultaneously. Moreover, the product investigations suggest that N2O5 is irreversibly taken up forming nitrate on the surface. The uptake rates of N2O5 on Saharan dust are large enough to influence the photo-oxidant budget of the atmosphere.

scholarly journals Ozone decomposition on Saharan dust: an experimental investigation

2002 ◽  
Vol 2 (6) ◽  
pp. 1809-1845 ◽  
Author(s):  
F. Hanisch ◽  
J. N. Crowley
Keyword(s):  
Experimental Investigation ◽  
Heterogeneous Reaction ◽  
Exposure Period ◽  
Saharan Dust ◽  
Ozone Decomposition ◽  
Uptake Coefficient ◽  
Conversion Efficiencies ◽  
Dust Surface ◽  
Very High ◽  
Initial Uptake

Abstract. The heterogeneous reaction between O3 and authentic Saharan dust surfaces was investigated in a Knudsen reactor at approx 296 K. O3 was destroyed on the dust surface and O2 was formed with conversion efficiencies of 1.0 and 1.3 molecules O2 per O3 molecule destroyed for unheated and heated samples, respectively. No O3 desorbed from exposed dust samples, showing that the uptake was irreversible. The uptake coefficients for the irreversible destruction of O3 on (unheated) Saharan dust surfaces depended on the O3 concentration and varied between 3.5 x10-4 and 5.5 x10-6 for the initial uptake coefficient (g0 approx 3 x10-5 at 30 ppbv O3 STP) and between 4.8 x10-5 and 2.2 x10-6 for the steady-state uptake coefficient (gss approx 7 x10-6 at 30 ppbv O3 STP). At very high O3 concentrations the surface was deactivated, and O3 uptake ceased after a certain exposure period. Sample re-activation (i.e. de-passivation) was found to occur over periods of hours, after exposure to O3 had ceased, suggesting that re-activation processes play a role both in the laboratory and in the atmosphere.

scholarly journals Ozone decomposition on Saharan dust: an experimental investigation

2003 ◽  
Vol 3 (1) ◽  
pp. 119-130 ◽  
Author(s):  
F. Hanisch ◽  
J. N. Crowley
Keyword(s):  
Experimental Investigation ◽  
Heterogeneous Reaction ◽  
Exposure Period ◽  
Saharan Dust ◽  
Ozone Decomposition ◽  
Uptake Coefficient ◽  
Conversion Efficiencies ◽  
Dust Surface ◽  
Very High ◽  
Initial Uptake

Abstract. The heterogeneous reaction between O3 and authentic Saharan dust surfaces was investigated in a Knudsen reactor at approx 296 K. O3 was destroyed on the dust surface and O2 was formed with conversion efficiencies of 1.0 and 1.3 molecules O2 per O3 molecule destroyed for unheated and heated samples, respectively. No O3 desorbed from exposed dust samples, showing that the uptake was irreversible. The uptake coefficients for the irreversible destruction of O3 on (unheated) Saharan dust surfaces depended on the O3 concentration and varied between 3.5 x 10-4 and 5.5 x 10-6 for the initial uptake coefficient (g0 approx 3 x 10-5 at 30 ppbv O3 STP) and between 4.8 x 10-5 and 2.2 x 10-6 for the steady-state uptake coefficient (gss approx 7 x10-6 at 30 ppbv O3 STP). At very high O3 concentrations the surface was deactivated, and O3 uptake ceased after a certain exposure period. Sample re-activation (i.e. de-passivation) was found to occur over periods of hours, after exposure to O3 had ceased, suggesting that re-activation processes play a role both in the laboratory and in the atmosphere.

scholarly journals Uptake of NO<sub>3</sub> and N<sub>2</sub>O<sub>5</sub> to Saharan dust, ambient urban aerosol and soot: a relative rate study

2010 ◽  
Vol 10 (6) ◽  
pp. 2965-2974 ◽  
Author(s):  
M. J. Tang ◽  
J. Thieser ◽  
G. Schuster ◽  
J. N. Crowley
Keyword(s):  
Mineral Dust ◽  
Relative Rate ◽  
Simultaneous Detection ◽  
Saharan Dust ◽  
Uptake Coefficient ◽  
Ambient Aerosols ◽  
Mixing Ratios ◽  
A Value ◽  
Rate Study ◽  
Absolute Basis

Abstract. The uptake of NO3 and N2O5 to Saharan dust, ambient aerosols and soot was investigated using a novel and simple relative rate method with simultaneous detection of both NO3 and N2O5. The use of cavity ring down spectroscopy to detect both trace gases enabled the measurements to be carried out at low mixing ratios (<500 pptv or 1×1010 molecule cm−3). The uptake coefficient ratio, γ(NO3)/γ(N2O5), was determined to be 0.9±0.4 for Saharan dust, independent of relative humidity, NO3 or N2O5 mixing ratio and exposure time. Ambient (urban) aerosols showed a very limited capacity to take up N2O5 but were reactive towards NO3 with γ(NO3)/γ(N2O5)>15. A value of γ(NO3)/γ(N2O5)~1.5–3 was obtained when using candle generated soot. The relative rate obtained for Saharan dust can be placed on an absolute basis using our recently determined value of γ(N2O5)=1×10−2 to give γ(NO3)=9×10−3, which is significantly smaller than the single previous value. With the present uptake coefficient, reaction of NO3 with mineral dust will generally not contribute significantly to its NO3 loss in the boundary atmosphere or to the nitration of mineral dust.

scholarly journals Study of the heterogeneous reaction of O<sub>3</sub> with CH<sub>3</sub>SCH<sub>3</sub> using the wetted-wall flowtube technique

2003 ◽  
Vol 3 (5) ◽  
pp. 1665-1673 ◽  
Author(s):  
M. Barcellos da Rosa ◽  
W. Behnke ◽  
C. Zetzsch
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Transport Model ◽  
Heterogeneous Reaction ◽  
Surface Film ◽  
Pure Water ◽  
Order Rate Constant ◽  
Uv Spectrophotometry ◽  
Uptake Coefficient ◽  
Model Calculations

Abstract. This work presents the heterogeneous kinetics of the reaction of CH3SCH3 (dimethyl sulphide, DMS) with O3 (ozone) in aqueous solutions of different ionic strengths (0, 0.1 and 1.0M NaCl) using the wetted-wall flowtube (WWFT) technique. Henry's law coefficients of DMS on pure water and on different concentrations of NaCl (0.1M - 4.0M) in the WWFT from UV spectrophotometric measurements of DMS in the gas phase, using a numerical transport model of phase exchange, were determined to be H ±s (M atm-1) = 2.16±0.5 at 274.4 K, 1.47±0.3 at 283.4 K, 0.72±0.2 at 291 K, 0.57±0.1 at 303.4 K and 0.33±0.1 at 313.4 K on water, on 1.0M NaCl to be H = 1.57±0.4 at 275.7 K, 0.8±0.2 at 291 K and on 4.0M NaCl to be H = 0.44±0.1 at 275.7 K and 0.16±0.04 at 291 K, showing a significant effect of ionic strength, m, on the solubility of DMS according to the equation ln (H/M atm-1) = 4061 T-1 - 0.052 m2 - 50.9 m T-1 - 14.0. At concentrations of DMS(liq) above 50 mM, UV spectrophotometry of both O3(gas) and DMS(gas) enables us to observe simultaneously the reactive uptake of O3 on DMS solution and the gas-liquid equilibration of DMS along the WWFT. The uptake coefficient, g (gamma), of O3 on aqueous solutions of DMS, varying between 1 and 15·10-6, showed a square root-dependence on the aqueous DMS concentration (as expected for diffusive penetration into the surface film, where the reaction takes place in aqueous solution). The uptake coefficient was smaller on NaCl solution in accord with the lower solubility of O3. The heterogeneous reaction of O3(gas) with DMS(liq) was evaluated from the observations of the second order rate constant (kII) for the homogeneous aqueous reaction O3(liq) + DMS(liq) using a numerical model of radial diffusion and reactive penetration, leading to kII ± D kII (in units of 108 M-1 s-1) = 4.1±1.2 at 291.0 K, 2.15±0.65 at 283.4 K and 1.8±0.5 at 274.4 K. Aside from the expected influence on solubility and aqueous-phase diffusion coefficient of both gases there was no significant effect of ionic strength on kII, that was determined for 0.1M NaCl, leading to kII ± D kII (108 M-1 s-1) = 3.2±1.0 at 288 K, 1.7±0.5 at 282 K and 1.3±0.4 at 276 K, and for 1.0M NaCl, leading to 3.2±1.0 at 288 K, 1.3±0.4 at 282 K and 1.2±0.4 at 276 K, where the error limits are estimated from the output of the model calculations, taking the variability of individual runs at various DMS levels into account.

scholarly journals Uptake of NO<sub>3</sub> and N<sub>2</sub>O<sub>5</sub> to Saharan dust, ambient urban aerosol and soot: a relative rate study

2010 ◽  
Vol 10 (1) ◽  
pp. 391-415
Author(s):  
M. J. Tang ◽  
J. Thieser ◽  
G. Schuster ◽  
J. N. Crowley
Keyword(s):  
Mineral Dust ◽  
Relative Rate ◽  
Simultaneous Detection ◽  
Saharan Dust ◽  
Uptake Coefficient ◽  
Ambient Aerosols ◽  
Mixing Ratios ◽  
A Value ◽  
Rate Study ◽  
Absolute Basis

Abstract. The uptake of NO3 and N2O5 to Saharan dust, ambient aerosols and soot was investigated using a novel and simple relative rate method with simultaneous detection of both NO3 and N2O5. The use of cavity ring down spectroscopy to detect both trace gases enabled the measurements to be carried out at low mixing ratios (<500 pptv or 1×1010 molecule cm-3). The uptake coefficient ratio, γ(3)/γ(N2O5), was determined to be 0.9±0.4 for Saharan dust, independent of relative humidity, NO3 or N2O5 mixing ratio and exposure time. Ambient (urban) aerosols showed a very limited capacity to take up N2O5 but were reactive towards 3 with γ(NO3)/γ(N2O5)>15. A value of γ(NO3)/γ(N2O5)≈1.5–3 was obtained when using candle generated soot. The relative rate obtained for Saharan dust can be placed on an absolute basis using our recently determined value of γ(N2O5)=1×10−2 to give γ(NO3)=9×10-3, which is significantly smaller than the single previous value. With the present uptake coefficient, reaction of NO3 with mineral dust will generally not contribute significantly to its NO3 loss in the boundary atmosphere or to the nitration of mineral dust.

scholarly journals The heterogeneous chemical kinetics of N<sub>2</sub>O<sub>5</sub> on CaCO<sub>3</sub> and other atmospheric mineral dust surrogates

2006 ◽  
Vol 6 (5) ◽  
pp. 1373-1388 ◽  
Author(s):  
F. Karagulian ◽  
C. Santschi ◽  
M. J. Rossi
Keyword(s):  
Gas Phase ◽  
Mineral Dust ◽  
Dust Sample ◽  
Saharan Dust ◽  
Molecular Flow ◽  
Flow Conditions ◽  
Powder Samples ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Limiting Values

Abstract. Uptake experiments of N2O5 on several mineral dust powder samples were carried out under continuous molecular flow conditions at 298±2 K. At [N2O5]0=(4.0±1.0)×1011 cm−3 we have found γss values ranging from (3.5±1.1)×10−2 for CaCO3 to (0.20±0.05) for Saharan Dust with γss decreasing as [N2O5]0 increased. The uptake coefficients reported in this work are to be regarded as upper limiting values owing to the fact that they are based on the geometric (projected) surface area of the mineral dust sample. We have observed delayed production of HNO3 upon uptake of N2O5 for every investigated sample owing to hydrolysis of N2O5 with surface-adsorbed H2O. Arizona Test Dust and Kaolinite turned out to be the samples that generated the largest amount of gas phase HNO3 with respect to N2O5 taken up. In contrast, the yield of HNO3 for Saharan Dust and CaCO3 is lower. On CaCO3 the disappearance of N2O5 was also accompanied by the formation of CO2. For CaCO3 sample masses ranging from 0.33 to 2.0 g, the yield of CO2 was approximately 42–50% with respect to the total number of N2O5 molecules taken up. The reaction of N2O5 with mineral dust and the subsequent production of gas phase HNO3 lead to a decrease in [NOx] which may have a significant effect on global ozone.

scholarly journals The interaction of N<sub>2</sub>O<sub>5</sub> with mineral dust: aerosol flow tube and Knudsen reactor studies

2007 ◽  
Vol 7 (5) ◽  
pp. 13291-13343
Author(s):  
C. Wagner ◽  
F. Hanisch ◽  
N. Holmes ◽  
H. de Coninck ◽  
G. Schuster ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Reasonable Agreement ◽  
Flow Reactor ◽  
Mineral Dust ◽  
Saharan Dust ◽  
Flow Tube ◽  
Aerosol Flow ◽  
A Value ◽  
Upper Limits ◽  
Efficient Uptake

Abstract. The interaction of mineral dust with N2O5 was investigated using both airborne mineral aerosol (using an aerosol flow reactor with variable relative humidity) and bulk samples (using a Knudsen reactor at zero humidity). Both authentic (Saharan, SDCV) and synthetic dust samples (Arizona test dust, ATD and calcite, CaCO3) were used to derive reactive uptake coefficients (γ). The aerosol experiments (Saharan dust only) indicated efficient uptake, with e.g. a value of γ (SDCV)=(1.3±0.2)×10−2 obtained at zero relative humidity. The values of γ obtained for bulk substrates in the Knudsen reactor studies are upper limits due to assumptions of available surface area, but were in reasonable agreement with the AFT measurements, with: γ(SDCV)=(3.7±1.2)×10−2, γ(ATD)=(2.2±0.8)×10−2 and γ(CaCO3)=(5±2)×10−2. The errors quoted are statistical only. The results are compared to literature values and assessed in terms of their impact on atmospheric N2O5.

scholarly journals Heterogeneous reaction of peroxyacetic acid and hydrogen peroxide on ambient aerosol particles under dry and humid conditions: kinetics, mechanism and implications

2015 ◽  
Vol 15 (4) ◽  
pp. 5713-5750
Author(s):  
Q. Q. Wu ◽  
L. B. Huang ◽  
H. Liang ◽  
Y. Zhao ◽  
D. Huang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Mineral Dust ◽  
Heterogeneous Reaction ◽  
Fine Particulate Matter ◽  
Organic Peroxides ◽  
Peroxyacetic Acid ◽  
Uptake Coefficient ◽  
Secondary Aerosols ◽  
Main Components ◽  
Haze Days

Abstract. Hydrogen peroxide (H2O2) and organic peroxides play important roles in the cycle of oxidants and the formation of secondary aerosols in the atmosphere. Recent field observations suggest that peroxyacetic acid (PAA, CH3C(O)OOH) is one of the most important organic peroxides in the atmosphere, whose budget is potentially related to the aerosols. Here we present the first laboratory measurements of the uptake coefficient of gaseous PAA and H2O2 onto the ambient fine particulate matter (PM2.5) as a function of relative humidity (RH) at 298 K. The results show that the PM2.5, which was collected in an urban area, can take up PAA and H2O2 at the uptake coefficient (γ) of 10−4, and both γPAA and γH2O2 increase with increasing RH. However, γPAA is more sensitive to the RH variation than is γH2O2, which indicates that the enhanced uptake of peroxide compounds on PM2.5 under humid conditions is dominated by chemical processes rather than dissolution. Considering that mineral dust is one of the main components of PM2.5, we also determined the uptake coefficients of gaseous PAA and H2O2 on authentic Asian Dust Storm (ADS) and Arizona Test Dust (ATD) particles. Compared to ambient PM2.5, ADS shows a similar γ value and RH dependence in its uptake coefficient for PAA and H2O2, while ATD gives a negative dependence on RH. The present study indicates that in addition to the mineral dust in PM2.5, other components (e.g., inorganic soluble salts) are also important to the uptake of peroxide compounds. When the heterogeneous reaction of PAA on PM2.5 is considered, its atmospheric lifetime is estimated to be 3.3 h on haze days and 7.6 h on non-haze days, values which agree well with the field observed result.

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