1www.cert.ucr.edu

Role of Glyoxal in SOA Formation from Aromatic Hydrocarbons

SHUNSUKE NAKAO, Yingdi Liu, Ping Tang, Chia-Li Chen, David Cocker

AAAR 2011Orlando, FLOct.6 (Thu)

10E.5

2

Role of glyoxal in aromatic SOA formation

SOA: Secondary Organic Aerosol

3

SOA formation from glyoxal – Cloud and fog processing

• Aqueous oxidation (Tan et al., 2009)

• Evaporating droplet (Leoffler et al., 2006; De Haan et al., 2009)

– “Missing sink” uptake onto aerosol• 15% of SOA formation in Mexico city (Volkamer et al., 2007)

– Uptake onto wet (NH4)2SO4 • SO4

2- enhances Henry’s law constant (Ip et al., 2009)

• Catalytic effect of NH4+ on oligomerization (Nozière et al., 2009)

• Chamber studies (Jang and Kamens, 2001; Kroll et al., 2005; Liggio et al., 2005; Galloway et al., 2009, 2011; Volkamer et al., 2009)

– Uptake onto organic seed• Fulvic acid, humic acid sodium salt, amino acids, carboxylic acids

(Corrigan et al., 2008; Volkamer et al., 2009; De Haan et al., 2009)

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SOA formation from aromatics

Glyoxal inferred to play a major role in aromatic-SOA

• Glyoxal significant product: 8~24% from toluene (with NOx, Calvert et al., 2002)

• Oligomer formation (Kalberer et al., 2004)

• Water effect: Cocker et al., 2001 no effect (RH2~50%) Edney et al., 2000 no effect (RH 52~70%) Zhou et al., 2011 2~3 fold increase (RH 10~90%, ascribed to glyoxal)

This study: synthesized glyoxal, added glyoxal into aromatic-SOA system, and evaluated its impact

Kalberer et al., Science, 2004RH 40~50%

Experimental • Glyoxal synthesis - Heating glyoxal trimer dihydrate / P2O5 mixture under vacuum (Galloway et al., 2009, ACP)

• Gas Phase Analysis

Glyoxal, NO2 – CEAS

(Cavity Enhanced Absorption Spectrometer)

GC-FID – hydrocarbon

O3, NOX analyzer

• Particle Phase Analysis

SMPS – volume concentration and size distribution (Scanning Mobility Particle Sizer)

V/H-TDMA –volatility/hygroscopicity (Volatility/hygroscopicity Tandem Differential Mobility Analyzer)

HR-ToF-AMS – bulk chemical composition (Aerodyne High Resolution Time-of-Flight Mass Spectrometer)

Dual SMPS

Blacklights

Dual teflon reactor

APMTDMA

PTRMSAMS

Glyoxal uptake onto wet (NH4)2SO4

Glyoxal uptake confirmed(reversible oligomerization, Galloway et al., 2009; wall-reservoir, Loza et al., 2010)

RH~65%RunID: EPA1369A

50

40

30

20

10

0

Gly

oxal

(pp

b)

86420

Uptake time (hour)

0.6

0.5

0.4

0.3

0.2

0.1

0.0

Organic/S

ulfate

500

400

300

200

100

0

Perfluorohexane (ppb)

Glyoxal Org/sulfate Tracer

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Glyoxal and SOA formation from toluene/NOx photooxidation

Solid line: model prediction by SAPRC11(Poster 5E.8)

NO: 42 ppbRH 40%RunID: EPA1503A

100

80

60

40

20

0

To

lue

ne (

ppb

)

1086420Hours after lights on

30

25

20

15

10

5

0

Glyoxal (p

pb)

50

40

30

20

10

0

Vo

lume

conce

ntration (

m3/cm

3)

Toluene Volume Glyoxal Glyoxal - model

0.10

0.08

0.06

0.04

0.02

0.00

Tol

uene

(pp

m)

1086420Hours after lights on

100

80

60

40

20

0

PM

Volum

e concentration (m

3/cm3)

Effect of additional glyoxal on toluene SOA formation

Kinetic effect

Additional 80ppb glyoxal

NOx: ~40ppbRH ~70%

+ glyoxal

+ H2O2

9

140

120

100

80

60

40

20

0

Gly

oxal

(pp

b)

121086420

Hours after lights on

100

80

60

40

20

0

PM

volume (

m3/cm

3)

Glyoxal Volume (suspended) Volume (wall-corrected)

No glyoxal uptake onto “aromatic-SOA seed”

No contribution from glyoxal during/after SOA formation

Shaded area: dark

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Glyoxal oligomer

Vol

ume

Fra

ctio

n R

emai

ning

16014012010080604020

Decanedioic acid Hexanedioic acid

Thermodenuder vaporization profiles

Glyoxal oligomer & aromatic SOA low volatile (<<10-8 Pa)

Aromatic SOA

~10-6~10-5

Pa~10-7

~10-8

Faulhaber et al., AMT, 2009

Residence time: ~15 sec

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Volatility evolution1.0

0.8

0.6

0.4

0.2

0.0

Vol

ume

Fra

ctio

n R

emai

ning

@10

0C

121086420Hours after lights on

Toluene + NOx (humid) Toluene + NOx + glyoxal (humid)

Toluene + NOx + H2O2 (humid)

12

100

80

60

40

20

0

Pa

rtic

le v

olum

e (m

3 /cm

3 )

250200150100500

Hydrocarbon reacted (g/m3)

non-seeded non-seeded non-seeded

Toluene + NOx (RH~70%)

Non-seeded vs (NH4)2SO4 seed

(NH4)2SO4 seed (NH4)2SO4 seed (NH4)2SO4 seed (NH4)2SO4 seed

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2-tert-butylphenol(BP)

• Tert-butyl AMS fragment (C4H9+)

tracer for BP SOA

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Enhanced SOA formation by glyoxal without glyoxal oligomerization

Higher SOA without decrease in C4H9 fraction

2t-BP (100ppb) + H2O2 (250ppb) RH 51%Added glyoxal ~ 1ppm

12

8

4

0

Vo

lum

e c

on

cen

tra

tion

(m

3/c

m3)

121086420Hours after lights on

0.20

0.15

0.10

0.05

0.00

fC4 H

9

add glyoxal Vol

C4H9+

Conclusion

• The role of glyoxal in this chamber study was observed to be a radical source; insignificant contribution of reactive uptake was observed.

• Glyoxal uptake onto “SOA seed” needs to be evaluated

• Glyoxal reactive uptake onto wet (NH4)2SO4 confirmed

• No significant glyoxal uptake onto toluene SOA was observed

- Addition of glyoxal/H2O2 resulted in same PM formation and PM volatility

- Addition of glyoxal after PM formation (dark, SOA seed) did not form SOA

- Presence of (NH4)2SO4 seeds did not impact SOA yield significantly

- Addition of glyoxal did not alter fC4H9 of 2-tert-BP SOA

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Acknowledgements

• Graduate advisor: Dr. David Cocker• Current/former students: Christopher Clark, Ping Tang,

Xiaochen Tang, Dr. Quentin Malloy, Dr. Li Qi, Dr. Kei Sato

• Undergraduate student: Sarah Bates• Support staff: Kurt Bumiller, Chuck Bufalino• Glyoxal synthesis: Dr. Melissa Galloway, Dr. Arthur Chan• Funding sources: NSF, W.M. Keck Foundation, and

University of California, Transportation Center