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

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

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

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

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

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

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

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

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

ISCO for PFAS Remediation Fe/Mn oxides . H2O2 HO Pham et al. (2012) Wat. Res. 46: 6454-6462 . 2- Fe/Mn oxides - S2O8 SO4 heat Liu et al. (2014) ES&T, 48: 10330-10336 Siegrist (2011) Siegrist (2011) 10

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, 2383-2388 11

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

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

Example: Conversion of AFFF Before Oxidation After Oxidation No carboxylates detected Houtz et al. ES&T, 2013, 46: 9342-9349. 14

PFOA + HO 15

PFOA + HO 15

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

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

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

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

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

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

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

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

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

8

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

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

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

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

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