The Effect of Metal Salts on Quantification of
Elemental and Organic Carbon in Diesel Exhaust
Particles using Thermal-Optical Evolved Gas Analysis
By
Y. Wang, A. Chung*, S. E. Paulson
Department of Atmospheric and Oceanic Sciences, University of California at Los
Angeles, Los Angeles, California 90095-1565
[*] now at: AMEC Geomatrix, Inc. Newport Beach, CA 92663
Correspondence to: S. E. Paulson ([email protected])
This supplemental material contains 1 Table and 7 Figures
Table S1: Mole fractions of metal salts and their hydratesa.
mole fraction of salt
Fe2(SO4)3
CuSO4
Na2SO4
MnCl2
MgCl2
FeCl3
FeCl2
CaCl2
CuCl2
NaCl
KCl
CuCl
ZnCl2
0.27
0.53
0.96
0.13
0.48
0.84
0.48
0.00
0.21
1.00
1.00
1.00
1.00
mole fraction of hydrate
Fe2(SO4)3·5H2O
CuSO4·5H2O
Na2SO4·10H2O
MnCl2·4H2O
MgCl2·6H2O
FeCl3·6H2O
FeCl2·4H2O
CaCl2·6H2O
CuCl2·2H2O
0.73
0.47
0.04
0.87
0.52
0.16
0.52
1.00
0.79
a: Inferred from a comparison of the ICP and SMPS measurements. The excess volume measured with the SMPS,
corrected for the known density of the salt and its most common hydrate, was assumed to be due to water in the
hydrate. From this the mole fractions of the two forms were inferred.
67±2
72±5
91±5
89±2
96±2
86±4
81±8
101±4
89±4
106±3
80±4
-3
dN/dlogDp (cm )
94±2
97±2
Dp (nm)
Figure S1: Number size distributions of metal salts in the chamber during the sampling period.
250
TCestimated = 0.998 ×TCmeasured -0.516
(R2=0.88, p<.0001)
TC_estimated (µg)
200
CaCl2
CuCl
CuCl2
CuSO4
Fe2(SO4)3
FeCl2
FeCl3
KCl
MgCl2
MnCl2
Na2SO4
NaCl
ZnCl2
150
100
50
0
0
50
100
150
200
250
TC_measured (µg)
Figure S2: The relationship between measured total carbon (TC) by TOEGA and estimated TC for
metal-loaded diesel samples. Estimated TC was calculated from the BC concentration measured by
optical transmissometer and linear relationship between TC and BC, TC (µg)= 1.78 ×BC(µg) - 21.97,
derived from diesel reference samples.
Fraction of Carbon Conversion
1.0
0.9
0.8
Na2SO4
KCl
NaCl
MgCl2
CaCl2
0.7
CuCl2
FeCl2
MnCl2
FeCl3
CuSO4
CuCl
Fe2(SO4)3
ZnCl2
0.6
Diesel
0.5
600 700 800 900
600 700 800 900
Temperature (ºC)
600 700 800 900
Figure S3: Average carbon conversion profiles of diesel and metal-loaded diesel samples in the
He/O2-phase of TOEGA. All the metal catalysts lower the temperature at which >60% conversion
(oxidation) of diesel carbon was achieved.
ΔT0.8 (°C)
Metal to Carbon Ratio
Figure S4: Reduction of T0.8 (temperature when 80% carbon evolves from filter) as a function of
metal to carbon ratio for metal-loaded diesel compared to diesel reference samples. The effect of
metal catalysts on the soot oxidation temperature is mostly independent on the metal loading.
14
(a)
12
Char (%)
10
y = 0.04x - 1.47
R2 = 0.92
8
6
4
2
0
0
100
200
300
Total Carbon (µg)
400
600
(b)
Split time (sec)
500
400
300
y = 0.56x + 336
2
R = 0.52
200
100
0
0
100
200
300
Total Carbon (µg)
400
100
200
300
Total Carbon (µg)
400
1.60
(c)
1.40
EC/OC
1.20
1.00
0.80
0.60
0.40
0.20
0.00
0
Figure S5: The relationship between char (a), OC-EC split time (b), EC/OC ratio (c), and total carbon
content for diesel control samples.
Δ char (%)
Metal to Carbon Ratio
Figure S6: Percent increase of char as a function of metal to carbon ratio for metal-loaded diesel
compared to diesel reference samples. The values have been adjusted for the effect of TC. The y axis
represents ([char]metal-loaded diesel sample-[char]diesel reference sample with matched TC loading)/[char]diesel reference sample with
matched TC loading ×100. Char: the percent reduction of laser transmittance through the filter during the
inert heating phase of TOEGA.
Δ split time (sec)
Metal to Carbon Ratio
Figure S7: Change of OC-EC split time as a function of metal to carbon ratio for metal-loaded diesel
compared to diesel reference samples. The values have been adjusted for the effect of TC on OC-EC
split time.