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

2008 ◽  
Vol 8 (1) ◽  
pp. 91-109 ◽  
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 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 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 The uptake of SO<sub>2</sub> on Saharan dust: a flow tube study

2005 ◽  
Vol 5 (10) ◽  
pp. 2679-2689 ◽  
Author(s):  
J. W. Adams ◽  
D. Rodriguez ◽  
R. A. Cox
Keyword(s):  
Gas Phase ◽  
Mineral Dust ◽  
Unit Area ◽  
Surface Reactivity ◽  
Saharan Dust ◽  
Bet Surface Area ◽  
Flow Tube ◽  
Wall Flow ◽  
Phase Water ◽  
Initial Uptake

Abstract. The uptake of SO2 onto Saharan mineral dust from the Cape Verde Islands was investigated using a coated wall flow tube coupled to a mass spectrometer. The rate of loss of SO2 to the dust coating was measured and uptake coefficients were determined using the measured BET surface area of the sample. The uptake of SO2, with an initial concentration between (2-40)x1010molecule cm-3 (0.62-12 µTorr), was found to be strongly time dependent over the first few hundred seconds of an experiment, with an initial uptake γ0,BET of (6.6±0.8)x10-5 (298 K), declining at longer times. The amount of SO2 adsorbed on the dust samples was measured over a range of SO2 concentrations and mineral dust loadings. The uptake of SO2 was found to be up to 98% irreversible over the timescale of these investigations. Experiments were also performed at 258 K, at a relative humidity of 27% and at 298 K in the presence of ozone. The initial uptake and the amount of SO2 taken up per unit area of BET dust surface was the same within error, irrespective of the conditions used; however the presence of ozone reduced the amount of SO2 released back into the gas-phase per unit area once exposure of the surface ended. Multiple uptakes to the same surface revealed a loss of surface reactivity, which did not return if the samples were exposed to gas-phase water, or left under vacuum overnight. A mechanism which accounts for the observed uptake behaviour is proposed and numerically modelled, allowing quantitative estimates of the rate and amount of SO2 removal in the atmosphere to be estimated. Removal of SO2 by mineral dust is predicted to be significant at high dust loadings.

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 Heterogeneous reaction of N<sub>2</sub>O<sub>5</sub> with illite and Arizona test dust particles

2014 ◽  
Vol 14 (1) ◽  
pp. 245-254 ◽  
Author(s):  
M. J. Tang ◽  
G. Schuster ◽  
J. N. Crowley
Keyword(s):  
Relative Humidity ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Heterogeneous Reaction ◽  
Thermal Dissociation ◽  
Dust Particles ◽  
Mineral Surfaces ◽  
Uptake Coefficient ◽  
Flow Tube ◽  
Aerosol Flow

Abstract. The heterogeneous reaction of N2O5 with airborne illite and Arizona test dust (ATD) particles was investigated at room temperature and at different relative humidities using an atmospheric pressure aerosol flow tube. N2O5 at concentrations in the range 8 to 24 × 1012 molecule cm−3 was monitored using thermal-dissociation cavity ring-down spectroscopy at 662 nm. At zero relative humidity a large uptake coefficient of N2O5 to illite was obtained, γ(N2O5) = 0.09, which decreased to 0.04 as relative humidity was increased to 67%. In contrast, the uptake coefficient derived for ATD is much lower (~0.006) and displays a weaker (if any) dependence on relative humidity (0–67%). Potential explanations are given for the significant differences between the uptake behaviour for ATD and illite and the results are compared with uptake coefficients for N2O5 on other mineral surfaces.

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 The uptake of SO<sub>2</sub> on Saharan dust: a flow tube study

2005 ◽  
Vol 5 (3) ◽  
pp. 2643-2676 ◽  
Author(s):  
J. W. Adams ◽  
D. Rodriguez ◽  
R. A. Cox
Keyword(s):  
Gas Phase ◽  
Mineral Dust ◽  
Unit Area ◽  
Surface Reactivity ◽  
Saharan Dust ◽  
Bet Surface Area ◽  
Flow Tube ◽  
Wall Flow ◽  
Phase Water ◽  
Initial Uptake

Abstract. The uptake of SO2 onto Saharan mineral dust from the Cape Verde Islands was investigated using a coated wall flow tube coupled to a mass spectrometer. The rate of loss of SO2 to the dust coating was measured and uptake coefficients were determined using the measured BET surface area of the sample. The uptake of SO2, with an initial concentration between (2–40)×1010 molecule cm-3 (0.62–12 µTorr), was found to be strongly time dependent over the first few hundred seconds of an experiment, with an initial uptake γ0,BET of (6.6±0.8)×10-5 (298 K), declining at longer times. The amount of SO2 adsorbed on the dust samples was measured over a range of SO2 concentrations and mineral dust loadings. The uptake of SO2 was found to be up to 98% irreversible over the timescale of these investigations. Experiments were also performed at 258 K, at a relative humidity of 27% and at 298 K in the presence of ozone. The initial uptake and the amount of SO2 taken up per unit area of BET dust surface was the same within error, irrespective of the conditions used; however the presence of ozone reduced the amount of SO2 released back into the gas-phase per unit area once exposure of the surface ended. Multiple uptakes to the same surface revealed a loss of surface reactivity, which did not return if the samples were exposed to gas-phase water, or left under vacuum overnight. A mechanism which accounts for the observed uptake behaviour is proposed and numerically modelled, allowing quantitative estimates of the rate and amount of SO2 removal in the atmosphere to be estimated. Removal of SO2 by mineral dust is predicted to be significant at high dust loadings.

scholarly journals Reactive uptake coefficients for heterogeneous reaction of N<sub>2</sub>O<sub>5</sub> with submicron aerosols of NaCl and natural sea salt

2004 ◽  
Vol 4 (5) ◽  
pp. 1381-1388 ◽  
Author(s):  
D. J. Stewart ◽  
P. T. Griffiths ◽  
R. A. Cox
Keyword(s):  
Relative Humidity ◽  
Flow Reactor ◽  
Heterogeneous Reaction ◽  
Sea Salt ◽  
Uptake Coefficient ◽  
A Value ◽  
Reactive Uptake Coefficient ◽  
Uptake Coefficients ◽  
Kinetics Of Uptake ◽  
Kinetics Of

Abstract. The kinetics of uptake of gaseous N2O5 on submicron aerosols containing NaCl and natural sea salt have been investigated in a flow reactor as a function of relative humidity (RH) in the range 30-80% at 295±2K and a total pressure of 1bar. The measured uptake coefficients, γ, were larger on the aerosols containing sea salt compared to those of pure NaCl, and in both cases increased with increasing RH. These observations are explained in terms of the variation in the size of the salt droplets, which leads to a limitation in the uptake rate into small particles. After correction for this effect the uptake coefficients are independent of relative humidity, and agree with those measured previously on larger droplets. A value of γ=0.025 is recommended for the reactive uptake coefficient for N2O5 on deliquesced sea salt droplets at 298K and RH>40%.

scholarly journals Reactive uptake coefficients for heterogeneous reaction of N<sub>2</sub>O<sub>5</sub> with submicron aerosols of NaCl and natural sea salt

2004 ◽  
Vol 4 (1) ◽  
pp. 569-590 ◽  
Author(s):  
D. J. Stewart ◽  
R. A. Cox
Keyword(s):  
Relative Humidity ◽  
Flow Reactor ◽  
Heterogeneous Reaction ◽  
Sea Salt ◽  
Uptake Coefficient ◽  
A Value ◽  
Reactive Uptake Coefficient ◽  
Uptake Coefficients ◽  
Kinetics Of Uptake ◽  
Kinetics Of

Abstract. The kinetics of uptake of gaseous N2O5 on submicron aerosols containing NaCl and natural sea salt has been investigated in a flow reactor as a function of relative humidity (RH) in the range 30-80% at 295+/-2 K and a total pressure of 1 bar. The measured uptake coefficients, γ, were larger on the aerosols containing sea salt compared to those of pure NaCl, and in both cases increased with increasing RH. These observations are explained in terms of the variation in water content and hence size of the salt droplets, which leads to a limitation in the uptake rate into small particles. After correction for this effect the uptake coefficients are independent of relative humidity, and agree with those measured previously on larger droplets. A value of γ=0.025 is recommended for the reactive uptake coefficient for N2O5 on deliquesced sea salt droplets at 298 K and RH>40%.

High-Throughput Synthesis of Lignin Particles (∼30 nm to ∼2 μm) via Aerosol Flow Reactor: Size Fractionation and Utilization in Pickering Emulsions

2016 ◽  
Vol 8 (35) ◽  
pp. 23302-23310 ◽  
Author(s):  
Mariko Ago ◽  
Siqi Huan ◽  
Maryam Borghei ◽  
Janne Raula ◽  
Esko I. Kauppinen ◽  
...  
Keyword(s):  
High Throughput ◽  
Flow Reactor ◽  
Pickering Emulsions ◽  
Size Fractionation ◽  
Aerosol Flow
Sign in / Sign up

Export Citation Format

Share Document