1. Chemical Oxidation of Poly- and Perfluoroalkyl Substances in AFFF-Impacted Groundwater
Thomas Bruton, David Sedlak
Department of Civil and Environmental Engineering
University of California at Berkeley

2. Poly- and Perfluoroalkyl Substances (PFAS)
Contain perfluoroalkyl functional group: CnF2n+1 – R
Chemical and thermal stability
Hydrophobic and lipophobic
Applications:
textile stain and soil repellents
grease-proof food packaging
non-stick cookware
chemicals manufacturing
aqueous film–forming foam (AFFF)
used to extinguish fires involving
flammable liquids 2

3. Poly- and Perfluoroalkyl Substances (PFAS)
Perfluoroalkyl acids (PFAAs)
Perfluorinated carboxylic acids (PFCAs)
Perfluorinated sulfonic acids (PFSAs)
Polyfluoroalkyl substances
Fluorotelomer-based compounds
Perfluoroalkane sulfonamido derivatives
Polymers
After Buck, et al., Int. Env. Ass. Mgmnt, 2011 3

4. Poly- and Perfluoroalkyl Substances (PFAS)
Perfluoroalkyl acids (PFAAs)
Perfluorinated carboxylic acids (PFCAs)
Perfluorinated sulfonic acids (PFSAs)
Polyfluoroalkyl substances
Fluorotelomer-based compounds
Perfluoroalkane sulfonamido derivatives
Polymers
Perfluorinated carboxylic acids (PFCAs)
After Buck, et al., Int. Env. Ass. Mgmnt, 2011 4

5. Poly- and Perfluoroalkyl Substances (PFAS)
Perfluoroalkyl acids (PFAAs)
Perfluorinated carboxylic acids (PFCAs)
Perfluorinated sulfonic acids (PFSAs)
Polyfluoroalkyl substances
Fluorotelomer-based compounds
Perfluoroalkane sulfonamido derivatives
Polymers
Perfluorinated sulfonic acids (PFSAs)
After Buck, et al., Int. Env. Ass. Mgmnt, 2011 5

6. Poly- and Perfluoroalkyl Substances (PFAS)
Perfluoroalkyl acids (PFAAs)
Perfluorinated carboxylic acids (PFCAs)
Perfluorinated sulfonic acids (PFSAs)
Polyfluoroalkyl substances
Fluorotelomer-based compounds
Perfluoroalkane sulfonamido derivatives
Polymers
Fluorotelomer-based compounds
Perfluoroalkane sulfonamido derivatives
After Buck, et al., Int. Env. Ass. Mgmnt, 2011 6

7. PFOA and PFOS Persistent Bioaccumulative Toxic
developmental effects
cancer
liver damage
immune system effects
thyroid effects
U.S. EPA Lifetime Health Advisory
70 ppt combined (May 2016) 7

8. EPA UCMR3 (Unregulated Contaminant Monitoring Rule):
PFBS, PFHxS, PFOS, PFHpA, PFOA, PFNA
Sources include:
manufacturing facilities
wastewater treatment plants
landfills
aqueous film-forming foam
Image: EWG 8

9. PFAS in Groundwater: Treatment Options
Air stripping
Bioremediation
Ion exchange
Pump and treat + adsorption to granular activated carbon
effective for long-chain compounds
In situ chemical oxidation (ISCO)?
Siegrist (2011)
Siegrist (2011) 9

10. ISCO for PFAS Remediation
Fe/Mn oxides .
H2O2 HO
Pham et al. (2012) Wat. Res. 46: . 2-
Fe/Mn oxides -
S2O8
SO4
heat
Liu et al. (2014) ES&T, 48:
Siegrist (2011)
Siegrist (2011) 10

11. Oxidation of PFOA Fenton’s Reagent UV/S2O82- 11
Mitchell et al., ES&T Letters, 2014, 117−121
Hori et al., ES&T, 2005, 39, 11

12. Total Oxidizable Precursor (TOP) Analysis
Dilute
Sample
pH >12
0.15 M NaOH
0.06 M K2S2O8 . -
SO4 -
85˚C OH 2-
SO4 . HO
Houtz and Sedlak ES&T, 2012, 46, 9342−9349 12

13. Transformation During TOP Assay
HO
Houtz and Sedlak ES&T, 2012, 46, 9342−9349 13

14. Example: Conversion of AFFF
Before Oxidation
After Oxidation
No carboxylates detected
Houtz et al. ES&T, 2013, 46: 14

15. PFOA + HO 15

16. PFOA + HO 15

17. H2O2 Treatment of PFCAs (Fenton)
Conditions:
1.0 M H2O2
0.05 mM Fe(ClO4)3
pH = 3.5
control 16

18. H2O2 Treatment of PFCAs (Fenton)
Conditions:
1.0 M H2O2
0.05 mM Fe(ClO4)3
pH = 3.5
control 16

19. H2O2 Treatment of PFCAs (Fenton)
Conditions:
1.0 M H2O2
0.05 mM Fe(ClO4)3
pH = 3.5
control
w/shaking
no shaking 16

20. S2O82- Treatment of PFOA: Effect of pH
Conditions:
[S2O82-]0 = 50 mM, [MnO4-]0 = 1 mM, unbuffered DI H2O, T = 20 ± 2o C 17

21. S2O82- Treatment of PFOA: Effect of pH
Conditions:
[S2O82-]0 = 50 mM, [MnO4-]0 = 1 mM, unbuffered DI H2O, T = 20 ± 2o C
Generation of transformation products starts when pH drops below ~ 3.4 17

22. S2O82- Treatment of PFCAs: Effect of pH (Buffered)
Conditions:
pH 8 borate (50 mM) or pH 3 H2SO4 in DI H2O, T = 60o C or 85o C
pH 8
pH 3
Unbuffered
(pH < 3)
Persulfate consumed, mM 18

23. S2O82- Treatment of PFCAs: in Deionized Water
Conditions:
[S2O82-]0 = 50 mM,
unbuffered (pH < 3) MQ H2O,
T = 85o C
Control
75% 19

24. S2O82- Treatment of PFCAs: Effect of Sediments
Conditions:
[S2O82-]0 = 50 mM x 2, unbuffered (pH < 3) DI H2O, 200 g/L aquifer sediments, T = 85o C
32%
63% 20

25. S2O82- Treatment of PFCAs: Summary
Persulfate dose
100 mM
50 mM
Matrix
Sediment slurry
DI H2O 21

26. 8

27. S2O82- Treatment of Ansul AFFF
Conditions:
[S2O82-]0 = 50 mM,
unbuffered (pH < 3) MQ H2O,
T = 85o C
Lodyne (6:2 FtTAoS) … 23

28. S2O82- Treatment of 3M AFFF 24 Conditions: [S2O82-]0 = 50 mM,
unbuffered (pH < 3) MQ H2O
T = 85o C
Sulfonates 24

29. S2O82- Treatment of 3M AFFF 25 … Conditions: [S2O82-]0 = 50 mM,
unbuffered (pH < 3) MQ H2O
T = 85o C
Carboxylates … 25

30. Summary Fenton - PFOA loss due to sorption, not oxidation Persulfate
- conversion of precursors to PFCAs
- degradation of PFCAs
- pH, sediment
- not effective for PFSAs
Research Needs
- mechanistic explanation
- pilot/demonstration-scale 26

31. Thanks to 27 Jennifer Field Chris Higgins Lisa Alvarez-Cohen
Erika Houtz
Katie Harding-Marjanovic
Shan Yi 27