Module 6.1 - Aromatic Compounds, Carbonyls and Acids - OCR ...
Gas-Particle Partitioning of Carbonyls in Simulation Chamber Studies of Secondary ... · 2019. 1....
Transcript of Gas-Particle Partitioning of Carbonyls in Simulation Chamber Studies of Secondary ... · 2019. 1....
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Gas-Particle Partitioning of Carbonyls inSimulation Chamber Studies of
Secondary Organic Aerosol Formation
John Wenger, Robert Healy, Kristina Kuprovskyte, Shouming Zhou
Department of Chemistry and Environmental Research InstituteUniversity College Cork
Ireland
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Gas/Particle Partitioning
• Many organic compounds partition between gas and particle phase
• Kp=[particle phase]/[gas phase][aerosol]
VOC
Gas phase products
oxidized
KpOrganic aerosol
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Denuder-Filter Sampling
Particle phase
Gas phase
Air Flow
Denuder tube coated with XAD-4 resin
Filter
Sorbent
Typically used for non-polar organic compounds
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• Aim: to apply denuder-filter sampling to studies of SOA formation
• Secondary organic fraction represents up to 70% of the organic fraction of fine aerosols
• Composition of SOA ?
• Formation mechanisms ?
• Main species contributing to SOA ?
Secondary Organic Aerosol (SOA)
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Biogenic Precursors of SOA
Seinfeld & Pankow, Annu. Rev. Phys. Chem. 2003. 54:121–40
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Anthropogenic Precursors of SOA
Seinfeld & Pankow, Annu. Rev. Phys. Chem. 2003. 54:121–40
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SOA Formation
Emission ofVolatile Organic
Compounds
SOA PrecursorsAlkanes (>C7)
AromaticsAlkenes (>C6)
~100 compounds
High volatility productsCarbonyls
Low volatility productsMultifunctional oxygenates
Reaction withOH, O3, NO3 Gas-particle
Partitioning
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Derivatization of oxygenated organics
Yu et al. ES&T 1998, 32, 2357-2370
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FF
F
F F
O N
N O
F
F
F
F
F
MW = 448
Fragment mass = 181
Glyoxal derivatizedfragments here
More than one isomer possible- (multiple peaks)
O
Oglyoxal derivatizes
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Example: OH + Limonene SOA
Jaoui et al., ES&T, 2006, 40, 3819-3828
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Denuder-Filter Sampling at UCC
• 5-channel glass denuder
• Coated with XAD-4 resin
• Denuder and filter doped with pentafluorobenzyl hydroxyl amine (PFBHA) to convert polar carbonyls to oximes
Denuder Tube(gas collection)
Filter pack (particle collection)
Air flow
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Trapping Efficiency Tests• Range of carbonyls introduced to chamber (10 - 200 ppbv)
To pump To pump
Denuder tube coated withXAD-4 and PFBHA
Sampling ports
Impinger system
PFBHA in H2O
6000 L FEP Teflon chamber
Trapping efficiency =100*(1-Cout/Cin)
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XAD-4 vs XAD-4/PFBHABenzaldehyde
0
20
40
60
80
100
120
10 20 30 40 50
Time (min)
Trap
ping
Effi
cien
cy (%
) XAD-4
XAD-4 +PFBHA
O
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XAD-4 vs XAD-4/PFBHAMethylglyoxal
0
20
40
60
80
100
120
10 20 30 40 50
Time (min)
Trap
ping
Effi
cien
cy (%
) XAD-4
XAD-4 +PFBHA
O
O
Temime et al., ES&T, 2007, 41, 6514-6520
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Atmospheric Simulation Chamber at UCC
• FEP foil (6000 litres)• Dry purified air• Atmospheric P and T• Humidity control
• on-line GC• NOx and O3 analysers• denuder – filter, GC-MS• Particle Sizer and counter
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p-xylene photo-oxidation experiment
• Aerosol mass yield=3.84%
0
100
200
300
400
500
600
700
800
-30 70 170 270 370 470
Time (min)
ppbv
0
50
100
150
200
250
300
350
400
450
ugm
-3
Lights OffLights On
NO NO2
Aerosol mass
O3
p-xylene/5
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p-xylene photo-oxidation
OH
O
O
O
O
O
O
O
O
O
OH additionH-abstraction
ringcleavage
OH addition
O
O
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GC-MS Analysis of p-xylene extracts (filter)
1
2
3
4
5
6
7
8
Reconstructed ion chromatogram (m/z 181) of a filter extract from XYL_NOx_11: glyoxal 2: methylglyoxal 3: oxopropanedial 4: 2,3-dioxobutanal 5: 3-hexene-2,5-dione6: 2-hydroxy-3-oxobutanal 7: 2,3-dioxobutanal 8: oxopropanedial.
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Denuder-Filter vs Filter Alone
0
10000
20000
30000
40000
50000
60000
70000
80000
glyoxal methylglyoxal hexenedione p-tolualdehyde
GC
-MS
resp
onse
Denuder FilterFilter alone
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GC-MS Analysis of p-xylene extracts (filter)
XYL_NOx_1 XYL_NOx_2
Relative humidity (%) <5 24
glyoxal 3.88 ± 0.26 4.37 ± 0.70
methylglyoxal 3.72 ± 0.12 3.47 ± 0.74
oxopropanedial 0.66 ± 0.06 0.79 ± 0.14
2,3-dioxobutanal 5.22 ± 0.11 6.19 ± 0.57
2-hydroxy-3-oxobutanal 0.38 ± 0.04 0.31 ± 0.03
p-tolualdehyde not observed 0.84
3-hexene-2,5-dione 2.06 ± 0.28 2.44 ± 0.34
Total identified 15.92 ± 0.87 18.41 ± 2.52
% Contribution to SOA mass
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Gas/Particle Partitioning Values
• Kp calculated both theoretically:
610760
×°×××××
=Lomom
omltheoretica PMW
TRfKpγ
• MWom= Average molecular weight of organic species in particles (=120)
• fom= fraction of particle that is organic (= 1)• γom = Activity coefficient (assumed =1)• Po
L = sub-cooled vapour pressure
Pankow,Atmos Environ,1994
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Gas/Particle Partitioning Values
• Kp calculated both theoretically:
• and experimentally:
][exp aerosolCC
Kpgas
particle
×=
610760
×°×××××
=Lomom
omltheoretica PMW
TRfKpγPankow,
Atmos Environ,1994
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Gas/Particle Partitioning Values
• Glyoxal and methylglyoxal Kp several orders of magnitude higher than expected
p-tolualdehyde Hexenedione Glyoxal Methylglyoxal
Kptheoretical 3.2x10-07 1.3x10-06 9.8x10-10 2.0x10-09
Kpexperimental 4.3x10-06 3.8x10-05 4.2x10-05 3.3x10-05
Kpexp/theory 13 29 43238 16963
(vapour pressures from SPARC on line calculator- University of Georgia)
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Experiments at PSI Chamber
Healy et al., ACP, 2008, 8, 3215-3230
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Denuder-Filter Configurations
• Setup 2 allows for the trapping efficiency of the tube to be tested for each experiment
Tube 1
Tube 2
FilterTube 1
Filter
Tube 2
AIR
FLOW
Setup 1(Typical)
Setup 2(Gas-phase breakthrough)
AIR
FLOW
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Gas phase
Particle phase
Gas phase breakthrough
glyoxal Methylglyoxal
Denuder vs Filter Extracts
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Photooxidation of Isoprene
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O
methacrolein
O
methyl vinyl ketoneO
Oglyoxal
O
O
methylglyoxal
OHO
glycolaldehyde
O
HO
hydroxyacetone
OHO
C4 hydroxycarbonyl
O
C5 carbonyl
Photooxidation products
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Gas/Particle Partitioning Values
• methacrolein, methylvinylketone not detected in particle phase
• Glyoxal and methylglyoxal Kp several orders of magnitude higher than expected
glycolaldehyde Hydroxyacetone Glyoxal Methylglyoxal
Kptheoretical 3.6x10-07 7.2x10-07 9.8x10-10 2.0x10-09
Kpexperimental 2.2x10-05 1.5x10-05 4.4x10-05 6.7x10-06
Kpexp/theory 59 20 45538 3476
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Photooxidation of 1,3,5-TMB
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Gas/Particle Partitioning Values
2-methyl-4-oxo-2-pentenal Methylglyoxal
Kptheoretical 9.3x10-07 2.0x10-09
Kpexperimental 1.8x10-04
*1.3x10-04
1.2x10-05
*2.0x10-05
Kpexp/theory 190 6256
*Obtained using PTR-MS with denuder and heated inlet to vapourize SOA;Hellen et al, ES&T, (2008), 42, 7347-7353.
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SOA Formation mechanisms
Emission ofVolatile Organic
Compounds
SOA PrecursorsAlkanes (>C7)
AromaticsAlkenes (>C6)
~100 compounds
High volatility productsCarbonyls
Low volatility productsMultifunctional oxygenates
Reaction withOH, O3, NO3 Gas-particle
Partitioning
Kp exp ≈ Kp calc
Kp exp >> Kp calc
HeterogeneousReactions*
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Acid-catalyzed Oligomerization-uptake of glyoxal to particles
Liggio et al.,ES&T, 2005, 39, 1532-1541
O
H
OH
OH
H
OH
OH
H
OH
OH
OH
HOOH
OH
H
HOOH
OH
H
OOH
H2O
H+
H2O
- H+
H
HOOH
+
HO
OH
OH
O
H
OH
OH
OH
- H+
HO
OH
OH
O
OH
OH
OH
H+
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Conclusions• Small dicarbonyls (glyoxal and methyl glyoxal)
partition to the particle phase much more than expected from vapour pressure calculations. Consistent with oligomerization hypothesis (in chambers at least!).
• Monofunctional carbonyl compounds much less likely to undergo reactive uptake
• Models that incorporate Kp for oxidation products should use compound-specific values (Johnson et al., 2005, 2006; Jenkin et al., 2004).
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Future Directions
• On-tube derivatization of acids/phenols
• Further chamber experiments on oxygenated aromatics, PAHs and BVOCs
• What happens in the real atmosphere?
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36
Sampling site
500 m
N
City centre
Tivoli Docks
50 m
Sampling point
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Denuder-filter sampling
To pump
Quartz fibre filters (2)(PFBHA-treated)
Annular denuder(XAD-4 coated & PFBHA-treated)
(KI-coated denuder)
Cyclone(PM2.5 fraction)
Inlet
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GC-MS data (denuder & filter extracts) after sampling for 24 hr 23-24th September 2008
* Impurities or column peaks
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Carbonyls at Tivoli Docks
Sampling for 24 hours at 16.7 L/min. Weather conditions dry, mainly cloudy, lightwind from SW
Gas phase conc. Particle phase conc.
Detection limit for standard
ng/m3 (ppbv) ng/m3 ngMVK 1087 (0.38) * 3.5Methacrolein 380 (0.13) * 1.0Glycolaldehyde 1006 (0.48) * 4.0Hexanal 409 (0.10) 2.0Heptanal 144 (0.03) 2.0Benzaldehyde 263 (0.06) 2.0p-Tolualdehyde 55 (0.01) 0.6Nonanal 404 (0.07) 5.0Decanal 343 (0.05) 5.0Glyoxal 77 (0.03) ? 0.6Methylglyoxal 69 (0.02) ? 0.3Dimethylglyoxal 102 (0.03) ? 0.6
3,5-dimethylbenzaldehyde 73 (0.01) 0.6
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First studies on SOA formation from naphthalene
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Odum yield curves
SOA mass concentration (M0)
0 100 200 300 400 500
SOA
yie
ld (Y
)
0.00
0.05
0.10
0.15
0.20
0.25
RH=0%, HC/NOx=1.0-2.2
RH=0%, HC/NOx=3.0-4.4
RH=25%, HC/NOx=1.0-1.8
RH=50%, HC/NOx=1.0-1.8
HONO as OH source
∑∑==
⎟⎠⎞
⎜⎝⎛
×+×
==n
1i i0
ii0
n
1ii
KM1KαMYY
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Aerosol yield parameters
One compound model
Two compounds model
a K a1 K1 a2 K2
RH=0, HC/NOx=1.0-1.8
0.1636 0.0113 0.1477 0.013 1 3.19E-5
RH=0, HC/NOx=3.0-4.4
0.2198 0.0125 0.2198 0.0125 3.52E-7 1.32E-8
RH=25, HC/NOx=1.0-1.8
0.2324 0.0081 0.2324 0.0081 3.65E-5 1.22E-6
RH=50, HC/NOx=1.0-1.8
0.2548 0.0095 0.2548 0.0095 1.96E-7 6.44E-9
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Acknowledgements
• Robert Healy, Shouming Zhou
• Kristina Kuprovskyte, Ashley Allshire
• Brice Temime (now in Marseille)
• Josef Dommen, Axel Metzger et al. (PSI)
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XAD-4 vs XAD-4/PFBHA2,6-dimethylbenzoquinone
0
20
40
60
80
100
120
10 20 30 40 50
Time (min)
Trap
ping
Effi
cien
cy (%
) XAD-4
XAD-4 +PFBHA
O
O
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Glyoxal trimer dissolved in solvent mix vs dissolved in methanol
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Kp calculations
• MWom= Average molecular weight of organic species in particles (=120)
• fom= fraction of particle that is organic (= 1)• γom = Activity coefficient (assumed =1)• Po
L = sub-cooled vapour pressure • Adsorption to particle surface not considered
for Kp values
610760
×°×××××
=Lomom
omltheoretica PMW
TRfKpγ
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Polymerization reactions in aromatics-SOApolymer-”backbone”
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Gas-phase Carbonyl yields for p-xylene
methylglyoxal 35%methylbutenedial 3%
Glyoxal 30%Hexenedione 5%
P-tolualdehyde 10%
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Minimize Artefacts
• Direct filter sampling is prone to artefacts• Adsorption of gases to filter - Positive artefact• Desorption of semi-volatiles – Negative artefact• Denuder-filter sampling minimizes artefacts• Mainly used for non-polar organic compounds
that partition between both gas and particle phases, e.g. PAHs