Supporting information
Comprehensive characterization and environmental risk assessment of
End-of-Life automotive catalytic converters to arrange a sustainable
roadmap for future recycling practices
Nazanin Bahaloo-Horeh, Seyyed Mohammad Mousavi
Biotechnology Group, Chemical Engineering Department, Tarbiat Modares University, Tehran, Iran
Corresponding author: Seyyed Mohammad Mousavi
Email address: [email protected]
Tel.: +98-21-82884917, Fax: +98-21-82884931
Postal address: Iran, Tehran, Jalal Ale Ahmad, Nasr, P.O. Box: 14115-111.
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Text S-1: Chemical digestion procedure
Chemical digestion was done with a mixture of acids, including HCl, HNO3, HClO4, and HF
(HF was applied to digest the metals bounded to silicate materials (Nemati et al., 2011)). In
this regard, 0.25 g of powder was weight, and subjected to an acid mixture in a Teflon
beaker. Then, the sample was heated at 220 °C using a hot box for 4 h for complete digestion.
Next, the digest was filtered and the metal content of the solution was evaluated by ICP-MS.
Besides, the PGMs content was analyzed by the fire assay method.
Concerning the complexity of the SACCs powder, the sampling and measurements were
applied in triplicates to check the accuracy, reliability, and reproducibility of the experiments.
Text S-2: CHNS analysis
For CHNS analysis, 1 mg of the SACCs powder was combusted in a CHNS analyzer under
the O2 stream in a furnace with a temperature of 980 °C. Bypassing the produced combustion
gasses including CO2, H2O, SO2, and NO2 through the column, their concentrations were
calculated. The helium and acetanilide were applied as a carrier gas and standard,
respectively.
Text S-3: BET analysis
Before running BET analysis (Belsorp-mini, BEL Japan Inc.), the SACCs powder was
degassed for 5 h at 150 °C, followed by cooling to room temperature. The BET method in the
relative pressure domain from 0 to 1 was utilized to determine specific surface areas. The
pore size distribution of SACCs powder was specified by the Brunauere-Joynere-Hallenda
(BJH) approach.
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Text S-4: Determination of isoelectric point
The fine SACCs powder (0.1 g) was suspended in 100 mL solution of 0.01 M NaCl as the
base electrolyte, and then, the suspension was agitated to reach chemical equilibrium. NaOH
and HCl were used for adjusting the pH over the range of 2–8 with the concentrations of 1.0
M and 0.1 M in order to change the pH value to a large and small extent, respectively.
Text S-5: TCLP, WET, and SPLP protocol
TCLP protocol
For the TCLP test, two different leaching extraction fluids were applied, based on the
buffering capacity and alkalinity of the waste. To define a proper extraction fluid, the pH of
the sample was determined by adding 5 g of sample to 96.5 mL of deionized water and then
shaking intensely for 5 min. If the pH of the solid waste was<5, the extraction fluid #1 (64.3
mL of 1 N NaOH and 5.7 mL of acetic acid made up to 1 L with deionized water) with a pH
of about 4.93± 0.05 was applied, and if the pH of the solid waste was >5, 3.5 mL of 1 N HCl
was added to the sample and heated to 50 °C for 10 min. After cooling, the pH was measured.
If the pH is <5.0, the extraction fluid #1 was applied, and if the pH is >5.0, the extraction
fluid #2 (5.7 mL of acetic acid made up to 1 L with deionized water) with a pH of about
2.88± 0.05 was adopted.
In the case of SACCs powder, after the addition of 3.5 mL of 1 N HCl, the pH of SACCs
powder in deionized water became under a pH of 5; thus, the proper extraction fluid for the
TCLP test was extraction fluid #1. The SACCs powder was mixed with leaching extraction
fluid at a liquid to solid (L/S) ratio of 20:1 (mL/g) and then agitated for 18 h. Next, the
extract was centrifuged, filtered, and analyzed for metal concentration by ICP-AES.
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It should be noted that acetic acid applied in TCLP demonstrates the organic acids generated
through the biological decomposition of waste in landfills (Priya and Hait, 2019). Albeit
TCLP demonstrates to be very useful, it has been stated that this leaching test is unsuccessful
in predicting the leaching of metals from some waste with alkaline nature (González and
Barnes, 2002; Hira et al., 2018).
WET protocol
For the WET procedure, 0.2 M sodium citrate as an extraction solution at pH 5.0 was used.
The SACCs powder was mixed with leaching extraction solution at an L/S ratio of 10:1
(mL/g) and then agitated for 48 h. The leachates were then centrifuged, filtered, and analyzed
for metal concentration by ICP-AES. Albeit WET exhibits to be very beneficial, it is a
lengthy step in the determination of metals leaching from waste (González and Barnes, 2002;
Hira et al., 2018).
SPLP protocol
For the SPLP, a mix of sulfuric acid/nitric acid (60/40 wt%) as an extraction solution was
used with a proper dilution with deionized water to make pH 4.20 ± 0.05. The SACCs
powder was mixed with leaching extraction solution at an L/S ratio of 20:1 (mL/g) and then
agitated for 18 h. The leachates were then centrifuged, filtered, and analyzed for metal
concentration by ICP-AES (Hira et al., 2018). It should be noted that the SPLP is applied for
the assessment of waste leachability in inert landfills, including no high biodegradable
substance (Jang and Townsend, 2003).
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(a) (b)
(c)
Fig. S1. BSE image and corresponding EDX analysis of the SACCs powder.
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050010001500200025003000350040000
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40
60
80
100
120
Wave numbers (cm-1)
Tra
nsm
ittan
ce (%
)
3422.071634.64
958.26909.44
1181.94
675.85
769.58
578.19
448.55
483.40
614.89
Fig. S2. FTIR spectra of SACCs powder.
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Fig. S3. Microphotographs of the SACCs powder surface.
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0.4 4 400
20
40
60
80
100
Particle size (μm)
Cum
ulat
ive
dist
ribu
tion
(%)
Fig. S4. The particle size distribution of the SACCs after crushing and milling.
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Table S1
The water solubility of oxide and hydroxide forms of major metals presented in SACCs (Green and
Perry, 2007).
Name Form Solubility in 100 partsCold water Hot water
Al Al(OH)3 0.000104 InsolubleAl2O3 Insoluble Insoluble
Ba Ba(OH)2 1.67 101.4BaO 1.5 90.8
Ca Ca(OH)2 0.185 0.077CaO Forms Ca(OH)2 -
Fe Fe(OH)3 Insoluble InsolubleFe2O3 Insoluble -Fe(OH)2 0.00067 -FeO Insoluble Insoluble
Mg Mg(OH)2 0.0009 -MgO 0.00062 -
Mn Mn(OH)2 0.002 InsolubleMnO Insoluble InsolubleMn2O3 Insoluble InsolubleMnO2 Insoluble Insoluble
K KOH 97 178K2O Forms KOH Very soluble
Na NaOH 42 347Na2O Forms NaOH -
Sr Sr(OH)2 0.41 21.83SrO Forms Sr(OH)2 -
Zn Zn(OH)2 0.00052 -ZnO 0.00042 -
As As2O3 1.21 2.93Pb PbO 0.0068 -Zr ZrO2 Insoluble InsolubleSi SiO2 Insoluble InsolubleTi TiO2 Insoluble Insoluble
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Table S2
Chemical composition of the SACCs powder using XRF analysis.
Component Al2O3 SiO2 MgO Zr Ce P2O5 MnO Ba Fe2O3 Zn CaO La Pd TiO2 Nd Sr Na2O Hf In K2O SO3 L.O.I
Content (wt
%)40.04
31.6
18.80 4.51
4.1
32.11 1.35 1.29 1.01 0.67 0.66
0.6
20.53 0.46 0.40 0.28 0.26
0.1
60.09 0.08 0.06 0.87
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100
Table S3
The content of typical main elements (wt%) loading in SACCs reported in different studies.
Al Si Zr Ce Nd La Ti Mn Zn Fe Mg Ba Ca K Na Hf Pt Pd Rh Ref.
27.1
4n.a. n.a. n.a. n.a. n.a. n.a. n.a.
0.17
1
0.58
14.18
1.82
4
0.05
7n.a. n.a.
n.a
.
0.200
90.4534 0.0637 (Karim and Ting, 2020)
n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a.n.a
.0.18 0.12 0.016 (Upadhyay et al., 2013)
n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a.n.a
.0.379 0.0582 0.239 (Harjanto et al., 2006)
n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a.n.a
.
0.081
8
0.0516
7
0.0213
8(Chen and Huang, 2006)
20.2
7n.a.
1.46
7
6.15
3n.a. n.a. n.a. n.a. n.a. n.a
5.89
3
1.15
5n.a. n.a. n.a. n.a
0.230
0n.a 0.0530 (Kim et al., 2000)
28.3 0.133.49
6
7.96
4n.a. n.a.
0.06
3
0.03
1n.a.
1.50
0
0.04
5n.a.
0.04
7
0.00
8
0.15
5
n.a
.
0.067
91.1510 0.0702 (Šebek et al., 2011)
17.6
2
19.2
6
0.00
6
0.00
3n.a. n.a.
0.28
1
0.00
2n.a.
0.33
5
4.79
4n.a.
0.03
20.02
0.09
5
n.a
.
0.397
5- - (Šebek et al., 2011)
23.0
0
15.6
0n.a. 0.61 n.a. n.a. n.a. n.a. n.a. n.a. 5.50 0.50 0.12 n.a. n.a.
n.a
.0.097 <0.001 0.008
(Rumpold and Antrekowitsch,
2012)
16.2
09.00 n.a. 2.50 n.a. n.a. n.a. n.a. n.a. n.a. 6.10 0.49 0.65 n.a. n.a.
n.a
.0.110 <0.001 0.024
(Rumpold and Antrekowitsch,
2012)
n.a n.a n.a n.a n.a n.a n.a n.a0.02
5
0.23
7n.a n.a
0.13
2n.a. n.a. n.a n.a. 0.0441 0.0131 (Nogueira et al., 2014)
30.9 16.6 1.2 3.82 n.a. n.a. n.a. n.a. n.a. n.a. 7.68 n.a. n.a. n.a. n.a. n.a n.a. 0.1698 0.0242 (Chen et al., 2015)
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101
102
7 6 .
17.7
1
30.5
82.74 2.21 n.a. n.a. n.a. n.a. n.a. n.a. 3.12 n.a. n.a. n.a. n.a.
n.a
.
0.070
00.2835 0.0118 (Morcali et al., 2015)
25.7 10.7 10.5 2.7 0.6 0.8 0.7 n.a. n.a. n.a. 4.1 1.7 n.a. n.a. n.a. 0.5 0.010 n.a. 0.010 (Eskina et al., 2016)
22.5 n.a. 15.1 6.03 n.a. 3.37 n.a. n.a. 0.09 0.25 2.61 n.a. n.a. n.a. n.a.n.a
.0.77 1.52 0.34 (Firmansyah et al., 2019)
27.5
88.69 5.74 5.31
0.6
70.33 n.a. 2.82 n.a. n.a. 2.72 n.a. 0.51 n.a. n.a.
n.a
.n.a. n.a. n.a. (Zhao et al., 2019)
16.811.0
02.73 2.23 n.a.
0.23
2
0.31
7n.a.
0.28
1
0.71
35.23 n.a. 0.33 n.a. n.a.
n.a
.
0.095
80.167 0.0318 (Spooren and Atia, 2020)
20.0
0
16.1
61.48 5.53 n.a. n.a. 0.27 n.a. 0.2
0.62
65.55 n.a. 0.57 n.a. n.a.
n.a
.0.069 0.045 0.016 (Shin et al., 2015)
n.a.: not analyzed
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