Research needs in indoor surface chemistry - National ...
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Research needs in
indoor surface chemistry
Hugo Destaillats
Lawrence Berkeley National Laboratory
Indoor Environment Group
Emerging Science on Indoor Chemistry and Implications:
An Information-Gathering Workshop
The National Academy of Sciences, Engineering, and Medicine
April 5, 2021
How do we study surfaces?
Molecular and structural approach Partitioning and exposure
Anatase (101)
Nylon fibers TiO2 nanotubes
• 2D or 3D, small domains • 3D, large reservoir
• Known chemical composition • Partially known chemical composition
• Structure defined at the molecular level • Not defined at the molecular level
2
Main questions
1. Definitions: What are indoor surfaces? What are good model indoor surfaces?
2. Partitioning: We need to better understand how surfaces act as pollutant sinks,
reservoirs and secondary sources
3. Surface chemistry: What is unique, different and/or relevant about it?
4. Occupant exposures: What is the role of surfaces in mediating exposures to
harmful chemicals? How can we assess the risks?
5. Practical applications: Can we remove pollution from surfaces?
Can indoor surfaces be engineered to improve IAQ?
3
Recent review articles on indoor surface chemistry
Workshop: Molecular Insights into Chemical Reactions on Indoor Surfaces
Ann Arbor MI, May 8th 2018
(Sloan Foundation’s Chemistry of Indoor Environments Program)
4
Model indoor materials for surface chemistry studies
Material Category Model System Chemical Formulas Chemical Structure
O O
Glass Inorganic Silicon Dioxide SiO2 Si
Quicklime (Cement) CaO
Concrete Inorganic Ca2+ O2-
Limestone (Aggregate) CaCO3
Drywall
Inorganic Gypsum CaSO4·2H2O
core
Polyethylene
Fabric Organic terephthalate [C10H8O4]n
(PET, polyester)
Ault et al.,
Carpet Organic Nylon (e.g. Nylon 6) [NH(CH2)5CO]n Chem, 2020
Wood/
Organic Cellulose [C6H10O5]n
cotton
Synthetic Rubber
Latex- Mixed [CH3COOCH=CH2]n
(e.g. Co-Polymer of
Painted Inorganic/ and
Vinyl Acetate and
Drywall Organic [CH2CHCOO(CH2)3CH3]n
Butyl Acrylate)
5
Adsorption of limonene on hydroxylated silica (RH = 0)
Infrared spectroscopy Atomistic molecular dynamics simulations
Fang et al., Chem. Sci., 2019 6
Adsorption of limonene on hydroxylated silica (RH ≠ 0)
IR spectroscopy
Tools to better understand
the molecular basis of:
• Fugacity and partitioning
• Surface chemistry
MD simulations
Increasing water on surface
Frank et al., J. Phys. Chem. A, 2020 7
Indoor surfaces are coated with adventitious layers, dust, skin cells
Surface nicotine in homes, cars and hotels SVOC deposition on surfaces Desquamation
Non-smoking Smoking Smoking
with ban
Nicotine on surfaces (µg/m2)
[summary of multiple studies]
Quintana et al., Nic. Tob. Res., 2013
Nicotine in house dust (µg/g)
Nr. samples % det. median
Smokers 5 100 7.8
Non-smokers 20 95 0.51
Whitehead et al., Chem. Res. Toxicol., 2015 Wan et al., ES&T Lett., 2020 Weschler, Indoor
Air, 2016 8
Indoor ozone chemistry: surfaces play a major role
Surface removal rates are typically higher than air exchange Surface deposition vs. gas phase reaction
chamber inlet
chamber air
use of household cleaner
Weschler, Indoor Air, 2000 Singer et al, Atmos. Environ., 2006
9
Ozone deposition: reactivity and byproducts
O3 reacts with materials, releasing O3 reacts with
secondary byproducts adsorbed and
deposited
compounds,
Fabric
wall releasing
panel
Bio-based
secondary
tile byproducts
Clay
tile
Linoleum- Fiberglass
like tile ceiling tile 6-methyl-5-hepten
-2-one (6-MHO)
Hardwood Clay- 4-oxopentanal
Recycled composite based (4-OPA)
carpet floor paint
Lamble et al., Atmos. Environ., 2011
Lamble et al, Atmos. Environ. 2011 Liu et al, PNAS 2021
10What are the mechanisms of ozone’s reactive deposition?
Criegee reaction: Ozone + alkene What mechanisms can describe the
reaction of ozone with other species?
Arata et al, ES&T 2019
Hoigné and Bader,
• Oxidation of linear and terminal alkenes leads to formation of Water Res. 1977
(& others)
VOCs, with increasing yields at higher RH
• O3 decomposes
in aqueous medium,
Wylie and Abbatt, ES&T 2020 with formation of
reactive radicals, peroxides.
• Oxidation of endocyclic double bond is less likely to produce • Possible reaction with adsorbed
small volatile fragments and secondary aerosols, due to the species and substrate materials.
lower volatility and increased polarity of byproducts
• Greater potential for exposure via dermal uptake and ingestion
11Chemistry of nitrogenated species on indoor surfaces
Flow tube reactor experiments Kitchen soiling is most reactive
2 NO2 + H2O surface HONO + HNO3
• Process catalyzed by grime
collected on glass substrates
placed in a home for 4 weeks
• Enhanced conversion with near UV
irradiation (photosensitized by
organics on surface films)
NO2 uptake and HONO yield increased with RH
• HONO is precursor of OH radicals, and can
react with other indoor species
Liu et al, ES&T 2020 12Nitrosation of amines adsorbed to indoor surfaces
Amine nitrosation by HONO
HONO + H+ ⇌ NO+ + H2O
• Postulated through
formation of NO+,
H
H H
a strong electrophile.
NO+ +
N
H H2O H
HONO
O +NH O N
N CH3 CH3
2 +
H3O CH3 N O
• In diluted aqueous
N N
(b)
NNK solution, NO+ (aq) forms
Nicotine
at low pH
H H H H O H
C O
NO+
.+ + C
N (b) N (a) H
+
N
H H2O NH2 H HONO N H
N O
• Do we have such acidic
N N H2C (c) (a) N CH3 N CH3
H3O+ N CH3
conditions on the
CH3
H NNA
+
surface?
HONO (NO +) H H H H
(c)
• What other mechanisms
H H
H H H
+
N H2O +
NH2 HONO N
NO+ N CH2 N H3O+ N
N O can catalyze NO+
+ HCHO
NNN formation?
Sleiman et al, PNAS 2010
13Exposure: harm metrics only available for some compounds and routes
NNK INDOOR DUST INDOOR SURFACES
1000 1000
California homes Casino US homes Chamber
100 100 S N/S Terrycloth
NNK (ng m-2)
No Significant (n.d.)
NNK (ng g-1)
S S
S
Risk Level (NSRL) 10
S
10
Polyester
• Cal OEHHA’s NSRL for
NNK: 14 ng/day 1 N/S 1
(Prop. 65)
NNK conc.
• NSRLs are defined as 0.1 above which 0.1
the daily level posing Whitehead Matt et al Matt et al NSRL is Thomas Thomas
Thomas Bahl BahlBahl
2018 exceeded 2014 2014 2014 2014
et al 2014
a 10-5 lifetime risk of et al 2015 2017 et al 2014
cancer
• Assuming an adult dust ingestion rate of • No equivalent “yardstick” to
• Cancer potency assess exposure risk
derived from rodents 30 mg/day (US EPA), the NNK
exposed via drinking concentration above which NSRL is • Walls ≠ fabrics ≠ other surfs.
water exceeded (24-h exposure) is ≈ 0.5 ng/mg
14Remediation: can we remove pollution from surfaces?
• Smoke from 6 cigarettes, 100
A) O3 and PM number concentration
150 PAHs ■ Chamber blank ■ 14-h post smoking ■ After 1-h ozonation
2000 NICOTINE
Chamber O₃ blank
settled for 14 hours Start and end of
ozone generation Ozone concentration
THS
Concentration (µg/g fabric)
10 Particle number
• Ozone generator (300 mg h-1) 1500 THS post-ozonation
Particle concentration (#/cm3)
operated for a 1-h period 100
1
Ozone (ppb)
•
1000
Samples: VOCs, PM, SVOCs on particles
and adsorbed to indoor surfaces 50 0.1
500
THS settled overnight
ND ND ND ND
0.01
NAP 2-MN 1-MN FLN PHEN ANT FLNT PYR CHR B[a]A nicotine
OZONE 0 0
-2 -1 0 1 2 3 4
O3 generator ON O3 generator OFF ULTRAFINE PARTICLES
B) PM size and number distribution
Time (h)
200
400
Chamber blank THS settled THS settled 1h
300
+ furnishings overnight overnight O3 injection THS Ozonation
150
Particle concentration (dN/dlogDp)
200
175 mg O3
Particle diameter (nm)
reacted
O₃ (ppb)
THS Tang et al,
100 with smoke 100
90 Environ. Res. 2021
80
70
60
50
50
40
30
background
0
20
0 0.5 1 1.5 2 2.5
-2 -1 0 1 2 3 4
Time (h) Time (h) 15Engineered surfaces can improve indoor environmental quality
• Indoor surfaces can be modified for air TiO2-coated quartz fiber air cleaning filters
cleaning purposes
120 m2/g
• Passive (e.g., walls) and active applications
• Reactive and/or adsorptive approaches
1 mm 20 µm 500 nm
Can air cleaners remove pathogens?
1.8
1.6
1.4
1.2
Benzene
Css / C0
1 Toluene
0.8 o-Xylene
Undecane
0.6
1-Butanol
0.4
Formaldehyde
0.2
Acetaldehyde
0
20 40 60 80 100 120 140
• PCO developed for aircraft cabin air cleaning Residence time (ms)
• Removes VOCs and inactivates pathogens 1 0.8 Face velocity (m s-1) 0.4 0.2
900 750 Recirculation flow (m3 h-1) 300 150
Gorvel et al., Clean Soil Air Water, 2014 Destaillats et al., Applied Catalysis B: Environmental, 2012
16Acknowledgement
LBNL / UC Berkeley colleagues (current and former)
Brett Xiaochen Lara Marion Randy Mohamad Jennifer Bill Tom Bill Charlie
Singer Tang Gundel Russell Maddalena Sleiman Logue Fisk Kirchstetter Nazaroff Weschler
California Consortium on Thirdhand Smoke: thirdhandsmoke.org
Alfred P. Sloan Foundation
17You can also read
