Document KRBraX1zM9EdgDNNmLvQwJynN
Supporting Information of
Mechanistic Investigations of Thermal Decomposition of Perfluoroalkyl Ether Carboxylic Acids and Short-chain Perfluoroalkyl Carboxylic Acids
Ali Alinezhada,+, Heng Shaob,+, Katerina Litvanovac, Runze Suna, Alena Kubatovac, Wen Zhangd, Yang Lib,*, Feng Xiaoa,* a Department of Civil and Environmental Engineering, The University of Missouri, Columbia,
Missouri 65211, USA b Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory
of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China c Department of Chemistry, The University of North Dakota, Grand Forks, North Dakota 58202, USA d John A. Reif, Jr. Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA
+: The authors contributed equally to this work and share first authorship. *Corresponding authors
Number of pages: 22 Number of tables: 8 Number of figures: 10
S1
Contents
UPLC-QToF-MS/MS method.........................................................................................................3 HRPIS experiments .........................................................................................................................3 Determination of extraction efficiency ............................................................................................3 TDPyrGCMS method ................................................................................................................4 DFT calculations..............................................................................................................................4 Possible PFBA thermal decomposition pathways ...........................................................................5 Table S1. PFAS chemicals used in this study..................................................................................6 Table S2. BDEs of HFPO-DA.........................................................................................................7 Table S3. BDEs of HFPO-TA. ........................................................................................................8 Table S4. BDEs of HFPO-TeA. ......................................................................................................9 Table S5. BDEs of PFMeUPA. .....................................................................................................11 Table S6. BDEs of PFMPA. ..........................................................................................................11 Table S7. BDEs of PFBA. .............................................................................................................12 Table S8. BDEs of PFPeA.............................................................................................................12 Figure S1. Thermal decomposition of a mixture of HPFO-DA, PFCAs, and PFSAs pre-adsorbed on (a) a single-use resin and (b, c) GAC. ......................................................................................14 Figure S2. Apparent yield of F from PFCAs and PFECAs ...........................................................15 Figure S3. TDPyrGCMS chromatograms of HFPO-DA at 200500 oC. ................................15 Figure S4. TDPyrGCMS chromatogram and spectrum of HFPO-DA at 200 oC. ...................16 Figure S5. TDPyrGCMS chromatogram and spectrum of HFPO-DA at 300 oC. ...................17 Figure S6. TDPyrGCMS chromatogram and spectrum of HFPO-DA at 500 oC. ...................18 Figure S7. TDPyrGCMS chromatogram and spectrum of PFBA heated at 200 oC. ...............19 Figure S8. TDPyrGCMS chromatogram of PFBA heated at 300 oC. .....................................20 Figure S9. TDPyrGCMS chromatogram of PFPeA heated at 200 oC. ....................................20 Figure S10. TDPyrGCMS chromatogram of PFPeA heated at 300 oC. ..................................21
S2
UPLC-QToF-MS/MS method.
PFAS and polar thermal decomposition products were analyzed on a Waters Acquity UPLC coupled with a Waters QToF-MS/MS (Synapt G2-S, Waters Corporation, Milford, MA, USA). Chromatography was performed using a Waters Acquity UPLC BEH Shield RP18 column (100 2.1 mm; 130 ; 1.7 m) with a Waters Acquity UPLC BEH Shield RP18 VanGuard precolumn (5 2.1 mm; 130 ; 1.7 m). The mobile phase consisted of eluent A (2 mM ammonium formate in OptimaTM water; LC/MS grade) and eluent B (2 mM ammonium formate in OptimaTM methanol; LC/MS grade). The elution started at 20% B for 0.5 min and then was linearly increased to 85% B in 5 min, further increased to 98% B in 0.1 min and kept isocratic for 1.5 min. At 7.1 min, the A/B ratio changed back to the initial value of 80/20 over 0.1 min to reequilibrate the column for another 1.3 min. Analytes were eluted using a Waters Acquity UPLC pump with a well-plate autosampler maintained at 8 oC. The flow rate was maintained at 0.45 mL/min, and the column temperature was 55 oC.
Mass spectrometry analysis was performed using the Synapt G2-S QToF-MS with an ESI source in a negative or positive ion mode. MS operating conditions were as follows: cone voltage, 20 V; capillary voltage, 1.8 kV; source temperature, 110 C; desolvation temperature, 350 C; cone gas flow rate, 10 L/h; and desolvation gas flow, 1,000 L/h. The analyzer was operated with an extended dynamic range at 10,000 resolution (fwhm at m/z 554) with an acquisition time of 0.1s. The Synapt G2-S ToF MSE mode was used to collect data with the T-wave element alternated between low (MS) and high (MSE) energy states in which the transfer T-wave element voltage ranged from 10-25 V. Leucine enkephalin (400 pg/L) was infused at a rate of 10 L/min for mass correction. MassLynx V4.1 software (Waters) was used for instrument control, acquisition, and mass analysis. The structural information of the degradation products was obtained by the stateof-the-art MSE function that allows the simultaneous acquisition of both MS and MS/MS fragmentation during a single chromatographic run.1, 2
Quantification of all target PFAAs was made using extracted ion currents (10 ppm mass window). It was based on their m/z values and UPLC retention times relative to six-point external calibration standard curves.
HRPIS experiments The identification of thermal decomposition products of PFAS was conducted in two major steps.2 In brief, high-resolution precursor ion scans were performed after aligning MS and MS/MS extracted ion chromatograms generated from UPLC-ESI-ToF-MSE data using the MassLynx V4.1 software. The parent MS and characteristic MS/MS spectra aligned with characteristic fragment ions were then examined and candidate PFAS parent compounds were identified by HRPIS2 with a mass error tolerance of 10 ppm.
Determination of extraction efficiency We previously compared the different approaches for extracting PFAS from spent GAC.3 In these experiments, GAC particles (0.07 g) in pre-cleaned polypropylene vials were spiked with a known volume of 1 103 mol/L PFAS stock solution in methanol. Then 10-mL methanol amended with 100 mmol/L NH4Ac was added to the tubes to extract PFAS from GAC. The liquid phase was sampled and microfiltered (0.45 m nylon filter; Thermo ScientificTM Target2TM). The concentration of PFAS in the filtrate was determined and the mass was calculated to determine the recovery by comparing it with the spiked mass. The recovery rate varies from 79.2% to 111.8%3
S3
for most of the PFAS investigated. Without the addition of NH4Ac, the recovery is largely below 70%.
TDPyrGCMS method The Frontier 3030D pyrolyzer, including an optional autosampler, is installed on top of the GC. This system allows for multiple-step heating, including TD at 300 oC (evolution of intact low MW compounds) and Pyr, typically at temperatures above 350 oC (evolution of thermal breakdown products of high MW species or thermally stable species). Following the different TDPyr steps, the gaseous products were concentrated in a cryogenic trapping system, introduced on the GC column, and analyzed by GCMS. A Frontier 30-m Ultra Alloy capillary column (30 m; Frontier Labs Inc., Japan) was used with an inner diameter of 0.25 mm and a 5% diphenyldimethyl polysiloxane stationary phase with 0.25 m film thickness. The MS analysis was performed with electron ionization in the mass range of 35-850 m/z. Ultra-pure helium (99.999%) was used as the carrier gas with a constant flow rate of 1.1 mL/min. A known mass of PFAS chemical was placed in the Pyr furnace and heated at a rate of 400 oC /min from 50 oC to 200 oC to analyze thermal decomposition products generated at 200 oC. The temperature was maintained at 200 oC for 30 sec before sampling for GCMS analysis. After sampling, the Pyr furnace temperature was increased from 200 oC to 300 oC at a rate of 400 oC /min and kept at 300 oC for 30 sec before sampling for GCMS analysis of gaseous products generated at 300 oC. To analyze Analyses at different temperatures were performed on each of the PFAS samples (see below). Two blank samples were prepared with clean, empty cups and analyzed before PFAS samples. If the baseline of the second blank was not clean, a third blank was prepared and analyzed. No perfluorinated species were found in blank samples. We were able to analyze HFPO-DA, PFBA, and PFPeA by TDPyrGCMS. Not that the analysis of one PFAS sample using TDPyrGCMS by a commercial laboratory can cost $3,000$5,000.
DFT calculations
A supercomputer (Intel Platinum 48 Core, Beijing Super Cloud Computing Center) was
used to perform high-throughput DFT calculations of BDEs, also known as bond enthalpy, in
PFECAs, short-chain PFCAs, and the unsaturated PFCA (i.e., PFMeUPA). A state-of-the-art M06-
2X method4 at a 3-zeta basis set of Def2-TZVP was employed using the state-of-the-art Gaussian
16 program.5 The M06-2X method was chosen for the structural optimization, frequency analysis,
and single-point energy calculation with 3-zeta basis set of Def2-TZVP at 298.15K in the gas
phase.4 Gaussian's input and output files were edited and viewed by GaussView 6. The Gibbs free
energy, G(T), and bond dissociation enthalpies (BDE) were calculated by Eq (S1) and (S2):
G(T) = (EE + GFE) 627.5094
(S1)
BDE = G(T) product - G(T) reactant
(S2)
where EE represents the electronic energy of PFAS (Hartree, an unit of energy in the Hartree
atomic units system); GFE, the thermal correction to G(T) (Hartree); G(T) product, represents the
total Gibbs free energy of all products in each reaction (kcal/mol); and G(T) reactant, the total Gibbs
free energy of the reactant in each reaction (kcal/mol). BDEs for all bonds in HFPO-DA, HFPO-
TA, HFPO-TeA, PFBA, PFPeA, PFMPA, and PFMeUPA were calculated. Based on experimental
S4
data on intermediates (e.g., PFPrA from HFPO-DA), the reaction with the lowest BDE value was regarded as the most favorable thermal degradation pathway.
Possible PFBA thermal decomposition pathways
( ( ) )
{ ( ){ PFBA
Kcal +F
CF3 CF2 + CF2 COOH 65.4mol CF3 COOH (TFA)
Kcal +F
CF3 + CF2 CF2 COOH 75.4mol CF3 CF2 COOH (PFPrA)
/
Kcal
CF3 CF2 CF2 + COOH 72.0mol
F
CF3 CF2 = CF2 (perfluoropropene)
CF2
+COOH
CF3 CF2
CF3 CF2 COOH (PFPrA)
(S3)
S5
PFECAs (perfluoroalkyl ether
carboxylic acids) Perfluoro-2-methyl-3-
oxahexanoic acid
Perfluoro-2,5-dimethyl3,6-dioxanonanoic acid
Table S1. PFAS chemicals used in this study.
Acronyms Purity CAS #
Structure
HFPODA
HFPOTA
97% 97%
1325213-6
1325214-7
F F FO
F
O OH
FF F F
FFF
FFF
F FF
FO
FF O O OH
F F FF F
FFF
SMILES
OC(=O)C(F)(OC(F)(F)C(F )(F)C(F)(F)F)C(F)(F)F
OC(=O)C(F)(OC(F)(F)C(F )(OC(F)(F)C(F)(F)C(F)(F) F)C(F)(F)F)C(F)(F)F
Pefluoro-2,5,8-trimethyl3,6,9-trioxadecanoic acid
HFPOTeA
95%
6529416-8
FFF
F F FF F
FO
F
O O O OH
FF F F
FF F
FFF
FFF
OC(=O)C(F)(OC(F)(F)C(F )(OC(F)(F)C(F)(OC(F)(F) C(F)(F)C(F)(F)F)C(F)(F)F )C(F)(F)F)C(F)(F)F
Perfluoro-3methoxypropanoic acid
PFMPA
95% 377-73-1
FF F F O
FO
OH
FF
OC(=O)C(F)(F)C(F)(F)OC (F)(F)F
Perfluoro-3,6dioxaheptanoic acid
PFO2Hp A
98%
15177258-6
FF F F O F O O OH
F FF F
OC(=O)C(F)(F)OC(F)(F)C (F)(F)OC(F)(F)F
PFCAs
Perfluorobutyric acid (C4)
perfluoropentanoic acid (C5)
Perfluoroheptanoic acid (C6)
Perfluorooctanoic acid (C8)
Perfluorononanoic acid (C9)
Perfluorodecanoic acid (C10)
Perfluoroundecanoic acid (C11)
Unsaturated PFCA
Acronyms PFBA
PFPeA PFHpA PFOA PFNA PFDA PFUnDA Acronyms
Purity 99.5
97% 97% 95% 97% 98% 95% Purity
CAS # 375-22-4
2706-903
375-85-9
335-67-1
375-95-1
335-76-2
2058-948
CAS #
4-
PFMeUP 97% 103229-
(trifluoromethyl)hexafluoro
A
89-6
pent-2-enoic acid
PFSAs
Acronym Purity CAS #
s
Perfluorobutanesulfonic PFBS 98.0% 29420-
acid potassium salt (C4)
49-3
Perfluorohexanesulfonic PFHxS 98.0 3871-99-
acid potassium salt (C6)
%
6
Perfluorooctanesulfonic PFOS 98.0 2795-39-
acid potassium salt (C8)
%
3
All PFAS chemicals were purchased from SigmaAldrich.
Structure (C4)
OC(=O)C(F)(F)C(F)(F)C( F)(F)F
Structure
FFFF
F
OH
FFFF O
Structure
SMILES C(=C(/C(C(F)(F)F)(C(F)(F )F)F)\F)(\C(=O)O)/F
SMILES
C(C(C(F)(F)S(=O)(=O)[O-])(
(C4) F)F)(C(F)(F)F)(F)F.[K+]
S6
PFAS HFPO-DA
Table S2. BDEs of HFPO-DA.
Sequence
G(T)
CF3-CF2-CF2-O-CF(CF3)-COOH CF3-CF2-CF2
O-CF(CF3)-COOH CF3-CF2-CF2-O CF(CF3)-COOH
CF3-CF2-CF2-O-CF(CF3) COOH
CF3 CF2-CF2-O-CF(CF3)-COOH
CF3-CF2 CF2-O-CF(CF3)-COOH CF3-CF2-CF2-O-CF()-COOH
CF3 CF3-CF2-CF2-O-CF(CF3)-CO
OH
F
CF2-CF2-CF2-O-CF(CF3)-COOH CF3-CF()-CF2-O-CF(CF3)-COOH CF3-CF2-CF()-O-CF(CF3)-COOH CF3-CF2-CF2-O-C()(CF3)-COOH CF3-CF2-CF2-O-CF(CF2())-COOH
CF3-CF2-CF2-O-CF(CF3)-COO H
PFBA:CF3-CF2-CF2-COOH CF2
CF3-CF2 PFPrA:CF3-CF2-COOH
CF3-CF2-OH CF3-CF2-O CF3-COF CF3-CF2-CO CF3-CH2-CO
CH2 CF3-CH2-COOH TFA:CF3-COOH CF3-CF2-CF2-O-CF=CF2
-1553.312539 -813.233055 -739.952607 -888.451761 -664.74252 -1364.093419 -189.105688 -337.614015 -1215.575725 -575.426334 -977.764859 -1215.58953 -337.612099 -1477.41267 -75.74036 -99.748541 -1453.382954 -1453.393842 -1453.390428 -1453.409519 -1453.380619 -1552.632638 -0.508793 -1002.453442 -237.740076 -575.426332 -764.650124 -651.327167 -650.646133 -550.8659 -688.747647 -490.243044 -39.123645 -566.140985 -526.842746 -1264.243824
BDE (Kcal/mol)
79.6
74.2
71.2
77.1
76.1
69.6
100.1
113.6 106.8 108.9 96.9 115.1 107.4 -72.0 41.8 -74.1 -100.7 108.1 1.3 101.7 15.8 1.3 18.6 109.6 63.4
S7
PFAS HFPO-TA
Table S3. BDEs of HFPO-TA.
Sequence
G(T)
CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)COOH
CF3-CF2-CF2 O-CF(CF3)-CF2-O-CF(CF3)-COOH
CF3-CF2-CF2-O CF(CF3)-CF2-O-CF(CF3)-COOH
CF3-CF2-CF2-O-CF(CF3)-CF2 O-CF(CF3)-COOH
CF3-CF2-CF2-O-CF(CF3)-CF2-O CF(CF3)-COOH
CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3) COOH CF3
CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-COOH CF3-CF2
CF2-O-CF(CF3)-CF2-O-CF(CF3)-COOH CF3-CF2-CF2-O-CF(CF3) CF2-O-CF(CF3)-COOH
CF3-CF2-CF2-O-CF()-CF2-O-CF(CF3)-COOH CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF()-COOH CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CO
OH F CF2-CF2-CF2-O-CF(CF3))-CF2-O-CF(CF3)COOH CF3-CF()-CF2-O-CF(CF3))-CF2-O-CF(CF3)COOH CF3-CF2-CF()-O-CF(CF3))-CF2-O-CF(CF3)COOH CF3-CF2-CF2-O-C()(CF3))-CF2-O-CF(CF3)COOH CF3-CF2-CF2-O-CF(CF2())-CF2-O-CF(CF3)COOH CF3-CF2-CF2-O-CF(CF3)-CF()-O-CF(CF3)COOH CF3-CF2-CF2-O-CF(CF3)-CF2-O-C()(CF3))COOH CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF2())COOH CF3-CF2-CF2-O-CF(CF3))-CF2-O-CF(CF3)COO H
-2341.964749
-813.233055 -1528.606552 -888.451761 -1453.388777 -1601.890257 -739.954354 -1677.10784 -664.736712 -2152.750138 -189.105688 -337.614015 -2004.228208 -575.426334 -1766.417313 -1364.088423 -977.759719 -2004.237566 -2004.241153 -2266.069485
-75.74036 -99.748541
-2242.034955
-2242.044995
-2242.045754
-2242.054898
-2242.037578
-2242.043057
-2242.060282
-2242.033061
-2341.289742
-0.508793
BDE (Kcal/mol)
78.5 77.9 75.4 75.4 68.4 76.9 76.0 73.2 71.0 68.8 97.2
113.7
107.4 107.0 101.2 112.1 108.7 97.8 114.9
104.3
S8
PFAS
HFPOTeA
Table S4. BDEs of HFPO-TeA.
Sequence
G(T)
CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2O-CF(CF3)-COOH CF3-CF2-CF2
O-CF(CF3)-CF2-O-CF(CF3)-CF2-O-CF(CF3)COOH
CF3-CF2-CF2-O CF(CF3)-CF2-O-CF(CF3)-CF2-O-CF(CF3)-
COOH
CF3-CF2-CF2-O-CF(CF3)-CF2 O-CF(CF3)-CF2-O-CF(CF3)-COOH
CF3-CF2-CF2-O-CF(CF3)-CF2-O CF(CF3)-CF2-O-CF(CF3)-COOH CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2
O-CF(CF3)-COOH CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2-
O
CF(CF3)-COOH CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2-
O-CF(CF3) COOH
CF3 CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2-O-
CF(CF3)-COOH CF3-CF2
CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2-OCF(CF3)-COOH
CF3-CF2-CF2-O-CF(CF3) CF2-O-CF(CF3)-CF2-O-CF(CF3)-COOH CF3-CF2-CF2-O-CF()-CF2-O-CF(CF3)-CF2-O-
CF(CF3)-COOH CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)
CF2-O-CF(CF3)-COOH CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF()-CF2-O-
CF(CF3)-COOH CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2-
O-CF()-COOH
CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2O-CF(CF3)-CO OH
F
CF2-CF2-CF2-O-CF(CF3))-CF2-O-CF(CF3)-CF2O-CF(CF3)-COOH
-3130.620629 -813.233055 -2317.264657 -888.451761 -2242.045307 -1601.890257 -1528.606559 -1677.10784 -1453.388766 -2390.546803 -739.954354 -2465.764497 -664.736712 -2941.406309 -189.105688 -337.614015 -2792.88427 -575.426334 -2555.075269 -1364.088424 -1766.419561 -2792.895628 -2152.746618 -977.759727 -2792.894759
-2792.89898
-3054.725719 -75.74036 -99.748541
-3030.691078
BDE (Kcal/mol)
77.1
77.5 77.7 77.8 75.0 74.9
68.2
76.8
74.7 70.7 69.6 71.7 70.2 67.5 97.0
113.6
S9
CF3-CF()-CF2-O-CF(CF3))-CF2-O-CF(CF3)CF2-O-CF(CF3)-COOH
CF3-CF2-CF()-O-CF(CF3))-CF2-O-CF(CF3)CF2-O-CF(CF3)-COOH
CF3-CF2-CF2-O-C()(CF3))-CF2-O-CF(CF3)CF2-O-CF(CF3)-COOH
CF3-CF2-CF2-O-CF(CF2())-CF2-O-CF(CF3)CF2-O-CF(CF3)-COOH
CF3-CF2-CF2-O-CF(CF3)-CF()-O-CF(CF3)-CF2O-CF(CF3)-COOH
CF3-CF2-CF2-O-CF(CF3)-CF2-O-C()(CF3)-CF2O-CF(CF3)-COOH
CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF2())CF2-O-CF(CF3)-COOH
CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF()O-CF(CF3)-COOH
CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2O-C()(CF3)-COOH
CF3-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2O-CF(CF2())-COOH
CF3-CF2-CF2-O-CF(CF3))-CF2-O-CF(CF3)-CF2O-CF(CF3)-COO H
-3030.70118 -3030.703336 -3030.713093 -3030.695099 -3030.702729 -3030.711961 -3030.695904 -3030.694184 -3030.716696 -3030.689959 -3129.945458
-0.508793
107.2 105.9 99.8 111.1 106.3 100.5 110.6 111.6 97.5 114.3
104.4
S10
PFAS PFMeUPA
PFAS PFMPA
Table S5. BDEs of PFMeUPA.
Sequence
G(T)
F3C-CF(CF3)-CF=CF-COOH F3C
F3C-CF()-CF=CF-COOH F3C-C(F)(CF3) CF=CF-COOH
F3C-CF(CF3)-CF CF-COOH
F3C-CF(CF3)-CF=CF COOH
F3C-CF(CF3)-CF=CF-CO OH
F
F2C()-CF(CF3)-CF=CF-COOH F3C-C(CF3)()-CF=CF-COOH F3C-CF(CF3)-C()=CF-COOH F3C-CF(CF3)-CF=C()-COOH F3C-CF(CF3)-CF=CF-COO
H
-1278.332983 -337.614015 -940.625237 -813.24455 -464.958501 -951.134437 -326.999959 -1089.086052 -189.105688 -1202.435888 -75.74036 -99.748541 -1178.404586 -1178.450607 -1178.416649 -1178.414004 -1277.655641 -0.508793
BDE (Kcal/mol)
58.8
81.5
124.6
88.6
98.4
112.9 84.0 105.3 107.0 105.8
Table S6. BDEs of PFMPA.
Sequence
F3C-O-CF2-CF2-COOH F3C
O-CF2-CF2-COOH F3C-O
CF2-CF2-COOH F3C-O-C(F2) CF2-COOH
F3C-O-CF2-C(F2) COOH
F3C-O-CF2-CF2-CO OH F
F2C()-O-CF2-CF2-COOH F3C-O-CF()-CF2-COOH F3C-O-CF2-CF()-COOH F3C-O-CF2-CF2-COO()
H
G(T)
-1077.697526 -337.614015 -739.937232 -412.837209 -664.718096 -650.663558 -426.92295 -888.473636 -189.105688 -1001.798102 -75.74036 -99.748541 -977.76497 -977.77539 -977.790429 -1077.018232 -0.508793
BDE (Kcal/mol)
91.8 89.2 69.7 74.2 99.8
115.5 108.9 99.5 107.0
S11
PFAS PFBA PFAS PFPeA
Table S7. BDEs of PFBA.
Sequence
PFBA:CF3-CF2-CF2-COOH CF3-CF2-CF2 COOH CF3
CF2-CF2-COOH CF3-CF2
CF2-COOH F
CF2-CF2-CF2-COOH CF3-CF()-CF2-COOH CF3-CF2-CF()-COOH
H CF3-CF2-CF2-COO CF3-CF2-CF2-CO
OH
G(T)
-1002.453442 -813.233055 -189.105688 -337.614015 -664.719353 -575.426334 -426.922951 -99.748541 -902.523309 -902.53657 -902.549616 -0.508793 -1001.774246 -926.554975 -75.74036
BDE (Kcal/mol)
72.0
75.4
65.4
114.0 105.6 97.4 106.9
99.2
Table S8. BDEs of PFPeA.
Sequence
CF3-CF2-CF2-CF2-COOH CF3-CF2-CF2-CF2 COOH CF3
CF2-CF2-CF2-COOH CF3-CF2
CF2-CF2-COOH CF3-CF2-CF2 CF2-COOH
CF3-CF2-CF2-CF2-CO OH F
CF2()-CF2-CF2-CF2-COOH CF3-CF()-CF2-CF2-COOH CF3-CF2-CF()-CF2-COOH CF3-CF2-CF2-CF()-COOH CF3-CF2-CF2-CF2--COO
H CF3-CF2-CF=CF2
CF2 CF3-CF2-CF2 PFBA: CF3-CF2-CF2-COOH CF3-CF=CF2
G(T)
-1240.258555 -1051.037884 -189.105688 -337.614015 -902.525015 -575.426334 -664.719353 -813.233475 -426.922951 -1164.359065
-75.74036 -99.748541 -1140.329073 -1140.342679 -1140.343539 -1140.354964 -1239.579189 -0.508793 -951.209463 -237.740076 -813.233055 -1002.453442 -713.402379
BDE (Kcal/mol)
72.2
75.0
70.8
64.1
99.9
113.5 105.0 104.5 97.3 107.0 50.1 40.6 -72.0 51.5
S12
CF3-CF2 PFPrA: CF3-CF2-COOH
CF2=CF2 CF3
TFA: CF3-COOH
-575.426332 -764.650124 -475.573578 -337.614015 -526.842746
41.8 -74.1 65.4 45.3 -77.2
S13
Figures
PFECAs HFPO-DA
FF
O F
F
O
OH
F F
FF
FF
F
HFPO-TA(H)
F
FF
F F
FF
O F
O
F
O
OH
F F FF F
FF
F
HFPO-TeA (H)
F
FF
F F FF F
O F
F
O
O
O
OH
F F
FF
FF F
FF
FF
F
F
PFMPA (H)
F F
FF
O
FO
OH
FF
F F
FF
O
PFO2HpA (H) F O O OH
F FF F
PFCAs PFBA (C4)
FF O
F
OH
F F
FF
PFPeA (C5) PFHpA (C6) PFOA (C8) PFNA (C9) PFDA (C10) PFUnDA (C11)
Degradation (%)
Degradation (%)
(a) on AmberChrom 1x8 (single-use AIX resin) in N2 (formerly known as Dowex 1x8)
100 80 60 40 20 0 -20 100 150 200 250 300 350 400 450 500 550 Thermal treatment temperature (oC)
(b) on FILTRASORB 200 (GAC) in N2
100 80 60 40 20 0 100 200 300 400 500 600 700 800 Thermal treatment temperature (oC)
Unsaturated PFCA F F F
F
PFMeUPA (C5) F
OH
FF F FO
PFSAs PFBS (C4)
F FF F
F
O
F
S O- K+
F F FO
PFHxS (C6) PFOS (C8)
Degradation (%)
(c) on FILTRASORB 200 (GAC) in air
100 80 60 40 20 0 100 150 200 250 300 350 400 450 500 550 Thermal treatment temperature (oC)
Figure S1. Thermal decomposition of a mixture of HPFO-DA, PFCAs, and PFSAs pre-adsorbed
on (a) a single-use resin and (b, c) GAC.3 Thermal treatment was conducted at different
temperatures for 30 min. In selected experiments, a high (H) initial mass of a mixture of PFECAs
(e.g., PFMPA (H)) was directly added to the resin to estimate the maximum percentage removal
of PFCEAs upon heating.
S14
Apparent Yield of F (mol %)
40 (a) 35 30 Heated 25 at 200 oC 20 15 10
5 0
Apparent Yield of F (mol %)
40 (b) 35 30 25 20 15 10
5 0
200
250 Temperature (oC)
PFBA HFPO-DA
300
PFBA PFPrA HFPO-DA HFPO-TeA HFPO-TA
Figure S2. Apparent yield of F from PFCAs and PFECAs (initial mass: 1.2 mol) heated for 30 min at different temperatures with the presence of GAC (0.1 g) to mimic the regeneration process (<300 oC) of PFAS-laden GAC.
Abundance
1000000 900000 800000 700000 600000 500000 400000 300000 200000 100000
Heated from 50 to 200 C at 400 oC/min, and then at 200 C for 30 sec.
T ime --> Abundance
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
950000 900000 850000 800000 750000 700000 650000 600000 550000 500000 450000 400000 350000 300000 250000 200000 150000 100000
50000
T ime -->
Heated from 300 to 500 C at 400 oC/min, and then at 500 C for 30 sec.
2.00
4.00
6.00
8.00
10.00 12.00 14.00 16.00
Abundance
950000 900000 850000 800000 750000 700000 650000 600000 550000 500000 450000 400000 350000 300000 250000 200000 150000 100000
50000
T ime -->
Heated from 200 to 300 C at 400 oC/min, and then at 300 C for 30 sec.
2.00
4.00
6.00
8.00 10.00 12.00 14.00 16.00
Figure S3. TDPyrGCMS chromatograms of HFPO-DA at 200500 oC.
S15
Figure S4. TDPyrGCMS chromatogram and spectrum of HFPO-DA at 200 oC. S16
Figure S5. TDPyrGCMS chromatogram and spectrum of HFPO-DA at 300 oC. S17
Figure S6. TDPyrGCMS chromatogram and spectrum of HFPO-DA at 500 oC. S18
TIC: 07_05122022_PFBA -1-40g-50-200C.D\data.ms
Propene, hexafluoro-, 81% CHS water Methylene chloride, 98% CHS
PFBA, 95% CHS
Abundance
200000 190000 180000 170000 160000 150000 140000 130000 120000 110000 100000
90000 80000 70000 60000 50000 40000 30000 20000
Heated from 50 to 200 C at 400 oC/min, and then at 200 C for 30 sec.
T ime -->
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
Scan 303 (1.951 min): 07_05122022_PFBA-1-40g-50-200C.D\data.ms
Abundance 16000
F
F
C3F5+
131.0
F C+ F
F
14000 12000
28.0
F F C+
CF3+ F 69.0
10000
8000 6000 4000 2000
0 m/z--> 0
F
F
F
F
F C2F4 F C+ 100 150
C2F3+ F 81
119
279.5
464.4
515.7
50
100
150
200
250
300
350
400
450
500
Figure S7. TDPyrGCMS chromatogram and spectrum of PFBA heated at 200 oC.
S19
Figure S8. TDPyrGCMS chromatogram of PFBA heated at 300 oC.
Figure S9. TDPyrGCMS chromatogram of PFPeA heated at 200 oC. S20
Figure S10. TDPyrGCMS chromatogram of PFPeA heated at 300 oC. S21
References cited in the Supporting Information:
1.
Waters., An overview of the principles of MSE, the engine that drives MS performance.
In Waters Corporation: Milford, MA, 2011; pp 1-6.
2.
Xiao, F.; Golovko, S. A.; Golovko, M. Y., Identification of novel non-ionic, cationic,
zwitterionic, and anionic polyfluoroalkyl substances using UPLC-TOF-MS(E) high-resolution parent ion
search. Anal Chim Acta 2017, 988, 41-49. doi:10.1016/j.aca.2017.08.016
3.
Xiao, F.; Sasi, P. C.; Yao, B.; Kubatova, A.; Golovko, S. A.; Golovko, M. Y.; Soli, D.,
Thermal stability and decomposition of perfluoroalkyl substances on spent granular activated carbon.
Environ Sci Tech Let 2020, 7(5), 343-350. doi:10.1021/acs.estlett.0c00114
4.
Zhao, Y.; Truhlar, D. G., The M06 suite of density functionals for main group
thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition
elements: two new functionals and systematic testing of four M06-class functionals and 12 other
functionals. Theoretical Chemistry Accounts 2008, 120(1), 215-241. doi:10.1007/s00214-007-0310-x
5.
Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman,
J. R.; Scalmani, G.; Barone, V.; Petersson, G. A.; Nakatsuji, H.; Li, X.; Caricato, M.; Marenich, A. V.;
Bloino, J.; Janesko, B. G.; Gomperts, R.; Mennucci, B.; Hratchian, H. P.; Ortiz, J. V.; Izmaylov, A. F.;
Sonnenberg, J. L.; Williams; Ding, F.; Lipparini, F.; Egidi, F.; Goings, J.; Peng, B.; Petrone, A.;
Henderson, T.; Ranasinghe, D.; Zakrzewski, V. G.; Gao, J.; Rega, N.; Zheng, G.; Liang, W.; Hada, M.;
Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,
H.; Vreven, T.; Throssell, K.; Montgomery Jr., J. A.; Peralta, J. E.; Ogliaro, F.; Bearpark, M. J.; Heyd, J.
J.; Brothers, E. N.; Kudin, K. N.; Staroverov, V. N.; Keith, T. A.; Kobayashi, R.; Normand, J.;
Raghavachari, K.; Rendell, A. P.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Millam, J. M.;
Klene, M.; Adamo, C.; Cammi, R.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Farkas, O.; Foresman,
J. B.; Fox, D. J. Gaussian 16 Rev. A.03, Wallingford, CT, 2016.
S22