The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306

June 24, 2019

Sheila Holman
Assistant Secretary for the Environment
1601 Mail Service Center
Raleigh, NC 27699-1601
sheila.holman@ncdenr.gov
Re:

Submission of Site Associated PFAS Fate and Transport Study Pursuant to Consent
Order Paragraph 27

Dear Ms. Holman,
Enclosed, please find a PDF copy of the Site Associated PFAS Fate and Transport Study for the
Chemours Fayetteville Works. This document presents an evaluation the fate and transport of
PFAS associated with the Site in the environment using the best currently available data andinformation. The evaluation includes a description of physical and chemical mechanisms andcompound properties that will influence fate and transport in the environment. The evaluation alsopresents available empirical data about hexafluoropropylene oxide dimer acid (HFPO-DA)
physical properties and fate and transport characteristics. This document meets the requirementsof Paragraph 27 of the Consent Order dated February 25, 2019. Geosyntec Consultants of NC, PC
has been approved as the third-party consultant by NCDEQ as required under Paragraph 27 of theConsent Order.
As always, if you have any questions or need any additional information concerning this report, or
the Consent Order implementation generally, please contact me at Brian.D.Long@chemours.com.
Sincerely,

Brian D. Long
Plant Manager
Chemours – Fayetteville Works

Enclosure
Site Associated PFAS Fate and Transport Study ReportCc:
William F. Lane, DEQ
Francisco Benzoni, NC DOJ
Michael Abraczinskas, DAQ
Michael Scott, DWM
Linda Culpepper, DWRDavid C. Shelton, Chemours
John F. Savarese, WLRK
Kemp Burdette, CFRW
Geoff Gisler, SELC

2

SITE ASSOCIATED PFASFATE AND TRANSPORT STUDYCHEMOURS FAYETTEVILLE WORKS
Prepared for

The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306
Prepared by
Geosyntec Consultants of NC, P.C.
2501 Blue Ridge Road, Suite 430
Raleigh, NC 27607
Project TR0795
June 2019

TABLE OF CONTENTS
1.

INTRODUCTION ....................................................................................................................1

2.

PFAS CHEMISTRY .................................................................................................................2
2.1

3.

ENVIRONMENTAL PROCESSES INFLUENCING PFAS FATE AND TRANSPORT .....5
3.1

3.2

3.3
4.

Physical Transport Processes ..........................................................................................5
3.1.1 Advection ............................................................................................................5
3.1.2 Diffusion ..............................................................................................................6
Chemical Processes .........................................................................................................6
3.2.1 Volatilization and Influence of Dissolution ........................................................7
3.2.2 Partitioning between Environmental Media ........................................................7
3.2.3 Potential PFAS Transformation in the Environment ........................................10
Summary of Site Associated PFAS Fate and Transport Pathways ...............................11

PFAS CHARACTERISTICS INFLUENCING FATE AND TRANSPORT ........................12
4.1
4.2
4.3
4.4
4.5

5.

Site Associated PFAS ......................................................................................................2

Isomer type ....................................................................................................................12
Fluorination ...................................................................................................................12
Presence and number of ether bonds .............................................................................12
Chain length ..................................................................................................................13
Number and type of functional groups ..........................................................................13

EMPIRICAL FATE AND TRANSPORT DATA ..................................................................14
5.1
5.2

HFPO-DA Empirical Data ............................................................................................14
Liquid Chromatography Retention Times .....................................................................14

6.

DISCUSSION AND SUMMARY .........................................................................................15

7.

REFERENCES .......................................................................................................................16
LIST OF TABLES

Table 1:

Classification of Site Associated PFAS

Table 2:

Empirically Measured Data for hexafluoropropylene oxide dimer acid (HFPO-DA)

Table 3:Site Associated PFAS Liquid Chromatography Elution Times

Fate and Transport of Site Associated PFASi

June 2019

ACRONYMS AND ABBREVIATIONSC

Carbon°C

degrees celsius

CAS

Chemical Abstracts Service

Chemours

The Chemours Company FC, LLC

COConsent Order

DEQ

North Carolina Department of Environmental Quality

DuPontE.I. du Pont de Nemours and Company

E1

Heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether

Geosyntec

Geosyntec Consultants of NC, PC

HFPO

Hexafluoropropylene oxide

HFPO-DA

Hexafluoropropylene oxide dimer acidLC

Liquid chromatograph

NCDEQ

North Carolina Department of Environmental Quality

Pa

Pascals

PAH

Polycyclic aromatic hydrocarbons

PCB

Polychlorinated biphenyl

PFAS

Per- and polyfluoroalkyl substances

PFOA

Perfluorooctanoic acid

PFOS

Perfluorooctanesulfonic acidpKa

Negative logarithm of the acid dissociation constant

PVF

Polyvinyl fluoride

USEPA

United States Environmental Protection Agency

Fate and Transport of Site Associated PFAS

ii

June 2019

1.

INTRODUCTION

This document has been prepared by Geosyntec Consultants of NC P.C. (Geosyntec) for The
Chemours Company FC, LLC (Chemours) to address requirements specified in Paragraph 27 of
the Consent Order (CO) between Chemours and the North Carolina Department of Environmental
Quality (NCDEQ) with the Cape Fear River Watch as intervenor. Geosyntec has been approvedby NCDEQ to prepare this document, which analyzes the fate and transport of per- andpolyfluoroalkyl substances (PFAS) originating from Chemours Fayetteville Works (the Site; theFacility). Specifically, Paragraph 27 of the CO states:
Chemours shall fund development by a third party contractor(s) of a study, basedon the best available data and information, analyzing the fate and transport ofidentified PFAS originating from the Facility in air, surface water andgroundwater. Chemours’ contractor(s) shall (i) be approved by DEQ, and (ii)submit the completed study to DEQ for review by June 30, 2019.
The objective of this report is to evaluate the fate and transport of PFAS associated with the Sitein the environment using the best currently available data and information. Based on available
data, this report presents a qualitative description of the fate and transport of these PFAS, including
a description of physical and chemical mechanisms and compound properties that will influence
fate and transport in the environment. At present, only a qualitative description is possible since
published measured fate and transport properties are scarce for PFAS associated with the Site. The
remainder of this report is organized as follows:1.

Introduction. This section describes the purpose and overview of this document.

2.

PFAS Chemistry. This section presents an overview of PFAS chemical structures
and then introduces Site Associated PFAS and their chemical characteristics.

3.

Environmental Processes Influencing PFAS Fate and Transport. This section
reviews the currently known physical and chemical mechanisms that control PFAS
fate and transport in the environment.

4.

PFAS Characteristics Influencing Fate and Transport. This section describes
how chemical characteristics of Site Associated PFAS are expected to influence
their fate and transport in the environment.

5.

Empirical Fate and Transport Data. This section presents the available empirical
data at the time of publication of this report for the PFAS related to the Site.

6.

Discussion and Summary. This section summarizes earlier sections of thisdocument.

Fate and Transport of Site Associated PFAS

1June 2019

2.

PFAS CHEMISTRYPFAS is a term used for a group of man-made carbon-based chemicals composed of a fully or
partially fluorinated chain of carbon atoms (referred to as a “tail”) and a nonfluorinated, polarfunctional group (referred to as a “head”) at one end of the carbon chain. Numerous variations offluorinated tails and functional groups exist, including for Site Associated PFAS (Table 1).
The term “PFAS” is most correctly used when referring to a perfluoroalkyl and polyfluoroalkyl
chemicals (Mueller and Yingling, 2018a). When many fluorine atoms are bonded to the carbon
atoms of the tail, the prefix “poly” is used in the name of the chemical compound. When all
potential fluorination locations on the carbon tail are fluorinated, i.e. there are no hydrogen-carbon
bonds, the prefix “per” is used in the name of the compound. The properties of per- andpolyfluoroalkyl substances are sufficiently similar that they are considered jointly and referred toas PFAS (Mueller and Yingling, 2018a).
In general, fluorination of the carbon chain renders it hydrophobic (i.e., unlikely to associate withwater molecules) and lipophobic (i.e., unlikely to associate with nonpolar carbon-based
molecules), while the polar head group is hydrophilic (i.e., likely to associate with watermolecules). In other words, the fluorinated tail does not have strong affinity for either polar or nonpolar phases while the head group does have affinity for polar phases (Mueller and Yingling,
2018b). These primary characteristics (fluorinated tail and polar functional group) control muchof the environmental properties of PFAS. Specific variations in chain length, molecular weight,
head group, and other structural features of PFAS also influence transport, toxicity, and reactivity
in the environment (Ahrens et al., 2011).
2.1

Site Associated PFAS

Chemours manufactures per- and polyfluoroalkyl ether compounds and polymers at the Site. The
Site is located within a 2,177-acre property approximately 15 miles southeast of the city of
Fayetteville in North Carolina. The Site was originally purchased by E.I. du Pont de Nemours andCompany (DuPont) in 1970 for production of nylon strapping and elastomeric tape. Presently
Chemours is the Site owner with leased tenants DuPont and Kuraray. The Site has five
manufacturing areas:Area 1- Chemours Monomers IXM;

Area 2- Chemours Polymer Processing Aid;



Area 3 - Kuraray Butacite®;

Area 4 - Kuraray SentryGlas®; andArea 5 - DuPont Company polyvinyl fluoride (PVF) resin manufacturing unit.

In addition to the manufacturing operations, Chemours operates two natural-gas-fired boilers anda wastewater treatment plant for the treatment of process wastewaters from the Kuraray andFate and Transport of Site Associated PFAS

2June 2019

DuPont manufacturing facilities and sanitary wastewaters from all three facilities. At present all
Chemours process wastewater is sent offsite for disposal.
PFAS from the Site have been identified by non-targeted mass spectrometry analyses performedby Chemours, the United States Environmental Protection Agency (USEPA), and researchers
within the University of North Carolina System. Non-targeted mass spectrometry is a specialized
technique used to identify unknown compounds, particularly when analytical standards of thesecompounds may not exist. These non-targeted studies identified perfluorinated ether compounds.
The term “ether” refers to compounds with an ether bond. An ether bond is two carbon atoms
linked by oxygen atom; this bond can also be referred to as “ether linkages”. These ether
compounds have been detected in environmental samples of soil, groundwater, surface water andrainwater (Sun et al., 2016; Hopkins et al., 2018; McCord and Strynar, 2019). To date, Chemours
has identified 24 PFAS associated with the Site in water and soil-based samples. In this document
these 24 PFAS are referred to as the “Site Associated PFAS” and they are presented in Table 1.
Analytical standards have been developed for these compounds to allow for quantitative
measurement in certain Site media (groundwater, surface water and rainwater). The analyticalmethod developed to quantify these Site Associated PFAS is referred to as "Table 3+". Currently
two commercial analytical laboratories can analyze samples using this method. Eurofins
TestAmerica Sacramento and Eurofins Lancaster can quantitate 20 of these compounds. Presently
a second method is being developed to quantitate the remaining 4 compounds (MTP, MMF, DFSA,
and PPF Acid).
Consistent with work published by McCord and Strynar (2019), Chemours has identified chemical
formulas, although not structures, for an additional 22 PFAS through non-targeted analysis ofwastewater samples collected prior to June 21, 2017 the date when Chemours began diverting
certain process wastewaters for offsite disposal. As part of Consent Order Paragraph 11a,
Chemours is performing non-targeted analysis on samples of stormwater and process water as
described in the PFAS Non-Targeted Analysis and Methods Development Plan (Chemours, 2019)
to identify PFAS potentially present in these samples which are in addition to the 24 PFAS thathave had their structures identified and standards synthesized. Chemours will then develop
analytical standards and methods for any newly identified PFAS compounds as part of Paragraph
11a efforts.
Site Associated PFAS described in this document are those detected in soil, groundwater, surface
water and rainwater samples. Some Site Associated PFAS compounds have been transported
offsite via aerial transport and deposition. These compounds can then be transferred to water andtransported to groundwater. Two additional perfluorinated compounds, Hexafluoropropyleneoxide (HFPO) and Heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether (E1), have been detected in air
samples collected to measure concentrations of PFAS in air emissions; these compounds have notbeen detected in water or soil based samples. Upon emission to air, HFPO and E1 become
dispersed in the global atmosphere (Yarwood, 2018a; Yarwood, 2018b). They are transformed
after reaction with atmospheric hydroxyl radicals (Yarwood, 2018a; Yarwood, 2018b). Other perFate and Transport of Site Associated PFAS

3

June 2019and polyfluorinated compounds have been potentially emitted to air but have not been quantified
to date in air samples. HFPO and E1 are not associated with water and hence have not been detectedin non-targeted analyses of groundwater, surface waters, or process waters by Chemours or otherresearchers.
The current group of 24 Site Associated PFAS that have been detected in soil or water samples are
the focus of this Fate and Transport study. The 24 Site Associated PFAS differ from each otherbased on the following properties:

Degree of fluorination

Isomer type

Functional groups

Chain lengthPresence of ether groups.

These attributes and chemical structures are shown in Table 1, and the anticipated relative effectthat each attribute will have on the compounds fate and transport in the environment is describedin Section 4.
The Site Associated PFAS that has been studied most to date is hexafluoropropylene oxide dimeracid (HFPO-DA; CAS 13252-13-6). HFPO-DA is one of a group of related chemicals. When either
hexafluoropropylene oxide dimer acid fluoride (“HFPO-DA fluoride”, CAS 2062-98-8) or
hexafluoropropylene oxide dimer acid ammonium salt (CAS 62037-80-3) enter water, HFPO-DA
is formed (Hogue, 2018). HFPO-DA fluoride is manufactured from HFPO (CAS 428-59-1) incontrolled conditions (Hogue, 2018). The same is true for the formation of HFPO-DA ammonium
salt from HFPO-DA fluoride. Because of the rapid reaction that transforms HFPO-DA fluoride
and HFPO-DA ammonium salt to HFPO-DA, HFPO-DA is the chemical with environmental
relevance. Accordingly, because the Table 3+ method and the McCord and Strynar (2019) methods
are designed for liquid samples, they measured HFPO-DA, not HFPO-DA ammonium salt.
Consequently, HFPO-DA is the only one of these related chemicals to be considered as a Site
Associated PFAS in this report.
HFPO-DA is the only Site Associated PFAS for which environmentally relevant experimental data
exist. These results are presented in this document and summarized in Section 5.1 and Table 2.

Fate and Transport of Site Associated PFAS

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June 2019

3.

ENVIRONMENTAL PROCESSES INFLUENCING PFAS FATE AND
TRANSPORTThe environmental fate and transport of Site Associated PFAS will result from a combination ofphysical and chemical factors and processes acting on individual PFAS. Physical processes involvethe mixing and transport of environmental media and chemicals within media while chemical
processes include interactions between compounds and environmental media or changes in thecompounds themselves. This section describes the physical and chemical factors and processes
that influence fate and transport.
3.1

Physical Transport Processes

Physical processes involve the movement of compounds in response to environmental gradients(e.g., pressure or chemical gradients). Advection and diffusion are the two physical processes thatwill affect Site Associated PFAS.
3.1.1

Advection

Advection in environmental fluids induces turbulence and consequent dispersion that can mix
chemicals into the flowing fluid. Advection of PFAS can occur in air, groundwater and surface
water. To the extent that Site Associated PFAS volatilize, become airborne associated toparticulates or dissolve (discussed below), they will be subject to advection.
Historically some Site Associated PFAS have been emitted to the atmosphere. Transport ofcompounds via air will be affected by local meteorology, precipitation, terrain and surface
characteristics. Additionally, source-specific parameters such as buoyancy, flow rate, exhaust
temperature, release height, etc. also influence fate and transport of a compound in the atmosphere.
Air transport also includes the airborne transport of particles that contain Site Associated PFAS.
These may originate from the land surface, from dust accumulation on industrial areas, or fromparticulate emissions that are part of industrial processes. Literature studies have documented
airborne PFAS accumulating to measurable levels on soil surface and in surface water through dry
or wet atmospheric deposition (Dreyer et al., 2010; Taniyasu, Yamashita et al. 2013, Rankin et al.,2016).
Site Associated PFAS are expected to be soluble in water (see Section 3.2.1), so compounds thatenter surface water or groundwater will be transported via advection. Dispersion in porous media
will cause PFAS concentrations to become distributed along the direction of flow andperpendicular to flow direction. Sorption to either aquifer material or air-water interfaces willretard groundwater transport. Advection in surface waters will also transport Site Associated
PFAS. Surface waters transport particles in both stormwater runoff and stream flow, and so surface
water transport of Site Associated PFAS will include both dissolved and particulate PFAS species.
When compounds sorb to organic and inorganic particles and those particles are immobile in calm

Fate and Transport of Site Associated PFAS

5June 2019

water (either as a stream bed or as a suspended load that settles), this may result in retardation
during surface water transport.
3.1.2

Diffusion

Diffusion transports chemicals through fluids (e.g. air and water) in response to concentration
gradients. Where advection is negligible, diffusion can be the primary mechanism of masstransport in environmental media. Effective diffusion, the amount of diffusion that occurs ingroundwater, is controlled by temperature, porosity, permeability, soil grain tortuosity, molecularsize of chemical compounds, and intermolecular interactions. It can be inhibited by interactions
between molecules and particles (i.e., aquifer material). Although diffusion coefficients for Site
Associated PFAS are not presently known, diffusion is expected to be of minor importance for thetransport of these chemicals because the groundwater, surface water, and air are not static in thevicinity of the Site and so advection is expected to be the dominant transport mechanism overdiffusion.
One scenario in which diffusion may be relevant is back diffusion. This occurs following multiple
separate processes. First, concentrations of chemicals in groundwater of low-permeability aquifer
formations (e.g., a clay formation) slowly increase due to diffusion of chemicals contained ingroundwater in neighboring, higher-permeability formations (e.g., a sand formation or surface
water). Over time the concentrations in the higher permeability formations decreases (e.g., due toa discontinuation of contamination and ongoing groundwater advection or due to treatment). When
this occurs, the higher concentrations of compounds are in the low-permeability formation, anddiffusion will occur to achieve equilibrium. This process is referred to as “back diffusion”. This
process can result a long-term, low-level source for chemicals to the groundwater in the permeableaquifer formation and thus potentially result in continued detections in the environment. Rates ofback diffusion for Site Associated PFAS will depend not only on presently unknown diffusivities
but also on the aquifer and clay soil properties of the Site.
3.2

Chemical Processes

Chemical processes involve interactions between chemical compounds and environmental media.
Chemical processes can alter transport of chemicals, including PFAS, in environmental media bytransferring them between media with different transport velocities. For example, if a chemicalload is introduced to surface water and a fraction of that load reacts with sediment particles, thendownstream transport of the total introduced load will be retarded. Conversely, chemical reactions
can result in mobilization of sediment-associated chemicals into more mobile phases (e.g., wateror air). The following subsections describe specific processes that are expected to influence Site
Associated PFAS.

Fate and Transport of Site Associated PFAS

6June 2019

3.2.1Volatilization and Influence of Dissolution

Volatilization is the process by which liquids become gases and can influence fate and transport
in groundwater, surface water and air. Volatilization of most carbon-based compounds occurs at
the liquid-to-gas transition phase. Dissolution is the process by which a compound forms achemical bond with a solvent (e.g., water) such that it behaves as though it is part of the solvent.
In environmental media, dissolution of a compound in water hinders the volatilization of thatcompound. Nonpolar and light compounds are highly volatile, whereas heavier and polar
compounds are less volatile because of their propensities to bond with each other and with water.
Polarity also facilitates dissolution in water. The volatility of a compound in liquid form can be
described by its vapor pressure, and the solubility of a compound describes its likelihood of
dissolving. Generally, PFAS vapor pressures are low and water solubilities are high. Most PFAS
have negatively charged head groups, so they are likely to be relatively mobile in the subsurface
due to the affinity of the head group for water molecules (Mueller and Yingling, 2018b).
All Site Associated PFAS contain at least one polar head group. Many Site Associated PFAS also
contain additional polar head groups or one or more ether bonds, yet some of them are also shortchain compounds. These two characteristics are likely to offset one another, with increased polarity
decreasing volatility while decreased chain length increasing volatility. For example, the vapor
pressure of HFPO-DA, which contains a six-member chain with one ether (i.e., oxygen) linkage
and a carboxylic acid head group, is 133 Pascals (Pa) at 25°C (DuPont, 2011). This indicates alower volatility than the linear six-carbon perfluorohexanoic acid (vapor pressure = 264 Pa at
25°C; National Center for Biotechnology Information, 2019) yet a higher volatility than the linear
eight-carbon perfluorooctanoic acid (vapor pressure = 70 Pa at 25°C; EPA, 2017). The Site
Associated PFAS have a chain length range (carbon and oxygen atoms) of 3-11 atoms with a wide
range of structural variation that includes ether linakages, polar head groups, and double bonds,
all of which will decrease volatilization of these PFAS when in pure liquid form (Table 1). Vapor
pressures and solubilities for Site Associated PFAS other than HFPO-DA have not been measured,
but they are expected to span a range of values due to the variation of chain length and otherstructural features. Most Site Associated PFAS are ethers, which are expected to be less volatileand more soluble than non-ether PFAS of equivalent chain length due to the polar oxygen atoms
included in their structures.
3.2.2

Partitioning between Environmental Media

After compounds enter the environment in a given medium (e.g., surface water), chemicalinteractions will result in their total mass being divided between the environmental media (e.g.,water, soils, sediments, air). This process is called partitioning. Partitioning can influence fate andtransport in groundwater and surface water. One of the most important partitioning processes issorption, which is the association of atoms or molecules with the surfaces of environmental media(e.g., air, particles, or organic carbon). Most often, sorption refers to the chemical “sticking” orassociation of low-concentration chemicals to the particles that make up sediment (including
Fate and Transport of Site Associated PFAS

7

June 2019

suspended sediment in surface waters) or soil. Sorption retards transport when dissolved atoms or
molecules become attached to sediment particles that are less mobile than water. In the subsurface,organic carbon in aquifer material is generally not mobile, so sorption will retard transport.
Similarly, in surface waters, sediment in river beds moves downstream more slowly than the waterin rivers, so sorption here also retards transport. This section examines the effect of partitioning
through four different processes that are particularly relevant to PFAS:
Sorption to Organic Carbon,

Electrostatic Interactions,

Air-Water Interface Partitioning, andFormation of Micelles.

Sorption to Organic Carbon
Like many elements and chemical compounds, PFAS can sorb to particles and porous media (i.e.,
suspended solids and soils). In the natural environment, many particles and porous media containorganic carbon. Generally, clay and silt particles tend to be high in organic carbon, whereas sandgrains are lower in organic carbon content. Particulate organic carbon (i.e., biomass) can comprisea substantial fraction of the particulate mass in many natural settings. Consequently, partitioningof low-concentration compounds, especially carbon-based compounds, in the environment isfrequently controlled by sorption to organic carbon.
The tails of PFAS are made primarily of carbon atoms. They tend to be nonpolar, and so they tend
to sorb to organic carbons in soil and sediment (Higgins and Luthy 2006, Guelfo and Higgins,2013). Because PFAS tails are also lipophobic, sorption to organic carbon tends to be weaker thanthat of alkanes or well-studied organic contaminants (e.g., PAHs, PCBs). The sorption andretardation of PFAS will increase with increasing fluorinated tail length. For a given soil, sediment,or organic carbon type, the structure of the PFAS tail affects its interactions with organic carbon
molecules. Branched isomers tend to have lower sorption affinity than linear isomers of equal
chain length (Kärrman et al., 2011).
The coefficient that describes the partitioning to organic carbon (referred to as “KOC”) of HFPODA has been measured as 12.0 L kg-1 for soil and as 12.6 L kg-1 for sludge (Bloxham, 2008). These
measurements were performed by dissolving HFPO-DA ammonium salt into a methanol-water
solution. Since HFPO-DA ammonium salt separates into HFPO-DA and an ammonium ion upon
contact with water, the results reported by this study for HFPO-DA ammonium salt are taken to
represent partitioning coefficients of HFPO-DA. These values are multiple orders of magnitude
lower than other common carbon-based contaminants like polycyclic aromatic hydrocarbons(PAHs) and polychlorinated biphenyls (PCBs). While the sorption of HFPO-DA to environmental
media is low, sorption to Granular Activated Carbon (GAC) will still occur to a much greater

Fate and Transport of Site Associated PFAS

8

June 2019degree than environmental media due to the high surface area of GAC relative to that of naturalorganic carbon.
No empirical partitioning data exist for other Site Associated PFAS outside of HFPO-DA. As withvolatilization, the range of chain lengths of the Site Associated PFAS suggests a potential rangeof sorption affinities to organic carbon. In general, compared to other well studied PFAS (e.g.,
perfluorooctanoic acid [PFOA] and perfluorooctanesulfonate [PFOS]), the Site Associated PFAS
are likely to have lower affinities to organic carbon. Site Associated PFAS have ether bonds and,for 5 of the 24 compounds, two charged head groups. Both of these features increase the polarityof the compounds and are likely to result in reduced sorption to organic carbon relative to nonether PFAS, given similar geochemical settings.

Electrostatic Interactions
Electrostatic interactions determine sorption of polar or charged chemicals to charged surfaces.
Site Associated PFAS are expected to have negatively charged head groups, and therefore
electrostatic sorption to soil and sediment particles is possible through ion exchange withnegatively charged ions on particle surfaces (Higgins and Luthy 2006). However, sorption to
charged particle surfaces in common soils and sediments is expected to be negligible relative tosorption to particulate organic carbon (Higgins and Luthy 2006).

Air-Water Interface Partitioning
In addition to sorption, many PFAS partition to air-water interfaces when the hydrophobic tail ofcarbon atoms of PFAS associates with the air-water interface of the subsurface unsaturated zone
or an above-ground water surface and the polar head group bonds to water (Brusseau et al., 2019;
Krafft and Riess 2015). This partitioning has been observed to retard subsurface transport byapproximately 50% in a model system with 20% air saturation (Brusseau, 2018). Other studies
indicate that the unsaturated zone can be a subsurface reservoir of PFAS (Weber et al., 2017).
Partitioning of PFAS at the air water interface will be dependent on PFAS concentration andstructure, the type of soils in the vadose zone and the degree of water saturation. Longer-chain
length PFAS are expected to accumulate at air-water interfaces more than shorter-chain length
PFAS (Brusseau et al., 2019). For Site Associated PFAS, adsorption to air-water interfaces may
be a retardation mechanism for subsurface transport. At present, experimental data do not exist toassess the potential degree of retardation from this effect.

Formation of micelles
At elevated concentrations, PFAS form micelles in water. Micelles are aggregations of individual
molecules (Yu et al., 2009; Du et al., 2014). Micelles represent an association of PFAS moleculeswith other PFAS molecules rather than surfaces or interfaces. In micelles, which are generally
spherical, the hydrophilic head groups of PFAS interact with surrounding water molecules and thehydrophobic portions interact with each other on the inside of the sphere. Micelle formation

Fate and Transport of Site Associated PFAS

9June 2019confounds the partitioning interactions described above. The branched geometries and ether bondsof Site Associated PFAS are expected to reduce the likelihood of micelle formation by providing
steric and electrostatic barriers to the association of the PFAS tails, but no empirical information
is currently available to quantify these effects in most Site Associated PFAS. The exception is
HFPO-DA: critical micelle concentration for HFPO-DA has been reported to vary between 0.135
and 0.2 moles per liter (approximately 40 to 70 grams per liter; Table 2). These concentrations are
significantly higher than observed in any groundwater or surface water sample.
3.2.3

Potential PFAS Transformation in the Environment

Current literature reviews indicate that transformation of most PFAS in the environment is
negligible. An important observed environmental transformation of PFAS has been the hydrolysis
of some polyfluorinated precursors to form perfluorinated compounds (Mueller and Yingling,2018) and the biotic degradation of trifluoroacetate (e.g., Visscher et al., 1994). Components ofSite Associated PFAS which may be amenable to transformation reactions that degrade the tailsof these compounds are ether bonds present in 21 of 24 Site Associated PFAS, and carbonhydrogen bonds present in 5 of 24 Site Associated PFAS. (e.g., Weber et al., 2017). With one
exception, no data exist to document their transformation in surface water or groundwater. The
one exception is HFPO-DA, which has been documented to persist in the environment (TheNetherlands, 2019). This is consistent with research showing that perfluoroether chains areresistant to abiotic and biotic degradation under environmentally relevant conditions, similar to theperfluoroalkyl chains (Wang et al., 2015).

Fate and Transport of Site Associated PFAS

10June 2019

3.3

Summary of Site Associated PFAS Fate and Transport Pathways

The anticipated relevance of the different factors and processes described above on a transport
pathway basis are summarized below.
Anticipated Relevance of Fate and Transport Processes and Mechanisms for Site Associated PFAS
Fate and Transport
Process or Mechanism

Air

Groundwater

Surface
Water

Physical – Advection







Physical – Diffusion
Chemical – Volatilization and Dissolution
Chemical – Sorption to Organic Carbon / Particles
Chemical – Electrostatic Interactions
Chemical – Partitioning to Air-Water Interfaces
Chemical – Formation of Micelles

‐‐


‐‐
‐‐
‐‐




‐‐

‐‐

‐‐


‐‐

‐‐

Chemical –Transformation

‐‐

‐‐

‐‐

Legend Process expected to have influence on fate and transport Process expected to have minimal influence on fate and transport
-- Process expected to have negligible influence on fate and transport

Fate and Transport of Site Associated PFAS

11

June 20194.

PFAS CHARACTERISTICS INFLUENCING FATE AND TRANSPORT

The discussion above of the physical and chemical processes that are expected to control PFAS
fate and transport in the environment reveals common themes across environmental media andchemical processes. This section discusses the anticipated effects of the defining chemical
characteristics of the Site Associated PFAS on their fate and transport.
4.1

Isomer type

Isomers are chemicals with identical formulas but distinct structures. The concept of varying
chemical structure is important in the Site Associated PFAS because some have a single chain ofcarbon and oxygen atoms in the tail whereas others have branched tails (Table 1). The existenceof branching in a compound can be determined visually by starting at the head group andexamining each atom of the chain, for example in Table 1 compare PFO5DA a linear compound
to Hydro-EVE Acid a branched compound. Branching occurs when a given carbon atom has morethan two carbon or oxygen atoms bonded to it and additional examination is required to determine
which atom is part of the chain and which is a smaller “branch” to the chain. In the 12 branched
Site Associated PFAS, all branches consist of a single carbon atom with three fluorine atoms
bonded to it.
Linear and branched PFAS differ in their partitioning behavior to particles. Isomerization also
results in significant differences in biochemical reactions and bioaccumulation (Mueller andYingling 2018b). For compounds with similar chain lengths and functional groups, branchedisomers sorb less than linear isomers in sediment (Houde et al., 2008; Chen et al., 2015) andmunicipal sludge (Filipovic and Berger, 2015). These studies suggest that the branched Site
Associated PFAS may be more mobile in surface water and groundwater than similar linear Site
Associated PFAS.
4.2

Fluorination

All Site Associated PFAS are fluorinated. However, 6 of the 24 compounds are considered
polyfluorinated – not perfluorinated – because a hydrogen atom occupies one of the bonding
locations that could hold a fluorine. Consequently, not all Site Associated PFAS are fluorinated tothe same degree. Perfluorinated compounds tend to have higher sorption affinities to particulateorganic carbon than polyfluorinated compounds (Xiao et al., 2017).
4.3

Presence and number of ether bonds

The presence of oxygen atoms in the tails of Site Associated PFAS distinguishes the Site
Associated PFAS from the majority of PFAS studied in the publicly available literature. Empiricalstudies of the effect of ether bonds on the partitioning behavior of PFAS in the environment has
not been conducted. Nonetheless, treatability studies using powdered activated carbon showed that
replacing a carbon (and its two bonded fluorine atoms) in the tail of a PFAS with an ether oxygen

Fate and Transport of Site Associated PFAS

12June 2019decreases the sorption affinity of that compound (Sun et al., 2016). This suggests that PFAS tails
with ether oxygens have increased tail polarity and decreased affinity for nonpolar organic carbon
compared to a PFAS with the same tail length but only with carbon atoms in the tail.
4.4

Chain length

Shorter-chain, linear PFAS without ether linkages have lower partitioning affinities to organiccarbon than similar compounds with longer chains. This implies that shorter-chained PFAS may
be transported from in groundwater at a faster rate (Sepulvado et al., 2011). It is expected in theenvironment that perfluorinated and polyfluorinated ether compounds of varying chain length will
exhibit the same trends of greater mobility with short chains and less mobility with longer chains.
4.5

Number and type of functional groups

The number and type of functional groups in PFAS may affect partitioning affinity and micelleformation due to the differing electrostatic and hydrophobic interactions and strengths of theseinteractions. Site Associated PFAS that have one or two sulfonic and/or carboxylic head groups
are expected to exist in deprotonated form at natural pH based on reported pKa values for HFPODA (Table 2). PFAS with two head groups (any combination of carboxylic or sulfonic acids) arereferred to as diprotic compounds and will likely experience less sorption to organic carbon andare expected to be more mobile in the environment.

Fate and Transport of Site Associated PFAS

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June 2019

5.

EMPIRICAL FATE AND TRANSPORT DATA

As mentioned in Section 3, to date, empirical data exist that describe the environmental behavior
of HFPO-DA but not for other Site Associated PFAS. This section consolidates information fromthese studies and also presents chromatographic retention time data for Site Associated PFAS.
5.1

HFPO-DA Empirical Data

Laboratory measurements of several HFPO-DA physicochemical properties were performed in2008 and 2011 by DuPont (Bloxham, 2008; DuPont, 2011). Some of these measurements refer to
HFPO-DA ammonium salt as a starting material. The HFPO-DA ammonium salt dissociates to
HFPO-DA and an ammonium ion in water, therefore the results from these experiments are
considered to be descriptive of HFPO-DA. Additionally, several experimental studies are
summarized by The Netherlands (2019). The results of these measurements are presented in Table
2. The primary observations from these data are as follows:

The coefficients that describe partitioning of HFPO-DA between water and the organic
fractions of soil and sludge (i.e., KOC values) have been estimated at 12.0 and 12.6 L/kg,
respectively;

HFPO-DA has a pKa between 2.45 and 2.84. This indicates that it will be deprontonatedat environmental pH;

HFPO-DA and HFPO-DA ammonium salt are completely soluble in water.

These observations are consistent with the expected effects of structural properties on HFPO-DA
fate and transport that are described in Section 0.
5.2

Liquid Chromatography Retention Times

Site Associated PFAS retention time data from a liquid chromatograph (LC) experiment performedby the Chemours Fluoroproducts analytical group are presented in Table 3. Retention times
presented are the time required for the Site Associated PFAS to travel through an LC column witha hydrophobic stationary phase. The mobile phase is the solvent in which the PFAS were dissolved
and which carried the PFAS through the LC column. Compounds that interact less strongly withthe column material pass through the column more quickly. LC retention times provide anindication of relative anticipated environmental mobility between Site Associated PFAS.
The distribution of retention times suggests that Site Associated PFAS may exhibit differential
mobility in soil and sediment depending on the compound. Given sufficient organic carbon to act
as a sorbent, some of the PFAS compounds will migrate more rapidly through the environment
while others will be subject to more sorption and retardation along transport pathways.

Fate and Transport of Site Associated PFAS

14

June 20196.

DISCUSSION AND SUMMARY

The PFAS associated with the Chemours Fayetteville Works Site are characterized primarily by
the presence of ether bonds, i.e. two carbons connected by an oxygen atom. Currently, the Sitessociated PFAS have limited publicly available, peer-reviewed literature describing their fate andtransport. The understanding of anticipated fate and transport of Site Associated PFAS presented
in this report was based on combining A) peer-reviewed studies for other PFAS chemicals that are
generally linear, perfluorinated, and lacking ether bonds with B) the studies that describe how
different PFAS chemical features may affect their environmental fate and transport.
Given the diversity in Site Associated PFAS chain length, head groups, number of ether bonds,
isomer type and fluorination, the Site Associated PFAS will span a range of mobilities inenvironmental media. Generally, Site Associated PFAS are expected to be mobile in theenvironment given the presence of charged head groups and ether bonds, but they will experiencesome retardation. For some Site Associated PFAS, mobility may be enhanced relative to straightchain, non-ether PFAS by their branched structure and the presence of two charged head groups.
The mobility of the Site Associated PFAS will be retarded by various chemical processes but will
likely have lower retardation than long-chain PFAS without ether bonds or other well-studiedcarbon-based chemicals like PAHs and PCBs. Chemical processes expected to have the mostimpact on mobility are sorption to organic carbon and, in the unsaturated soil zone, preferential
partitioning to the air water interface.

Fate and Transport of Site Associated PFAS

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June 2019

7.

REFERENCES

Ahrens, L., L. W. Y. Yeung, S. Taniyasu, P. K. S. Lam and N. Yamashita (2011). "Partitioning of
perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS) and perfluorooctane sulfonamide(PFOSA) between water and sediment." Chemosphere, 85(5): 731-737.
Bloxham, P. A. (2008). Estimation of the Adsorption Coefficient (Koc) ofHFPO Dimer
Acid Ammonium Salt on Soil and Sludge. Newark, Delaware, USA, DuPont de Nemours andCompany.
Brusseau, M. L. (2018). "Assessing the potential contributions of additional retention processes to
PFAS retardation in the subsurface." Science of The Total Environment 613-614: 176-185.
Brusseau, M. L., N. Yan, S. Van Glubt, Y. Wang, W. Chen, Y. Lyu, B. Dungan, K. C. Carroll and
F. O. Holguin (2019). "Comprehensive retention model for PFAS transport in subsurface systems."
Water Research 148: 41-50.
Chemours (2019). "PFAS Non-Targetted Analysis and Methods Development Plan Process and
Non-Process Wastewater and Stormwater" January 30, 2019
Chen, X., L. Zhu, X. Pan, S. Fang, Y. Zhang and L. Yang (2015). "Isomeric specific partitioning
behaviors of perfluoroalkyl substances in water dissolved phase, suspended particulate matters andsediments in Liao River Basin and Taihu Lake, China." Water Res 80: 235-244.
Dreyer, A., V. Matthias, I. Weinberg and R. Ebinghaus (2010). "Wet deposition of poly-andperfluorinated compounds in Northern Germany." Environmental Pollution 158(5): 1221-1227.
Du, Z., S. Deng, Y. Bei, Q. Huang, B. Wang, J. Huang and G. Yu (2014). "Adsorption behavior
and mechanism of perfluorinated compounds on various adsorbents—A review." Journal ofHazardous Materials 274: 443-454.
DuPont (2011). Discussion of Results: FRD903 Physical and Chemical Data and FRD902 Physicaland Chemical Data. DuPont Document PM-W-726.
EPA (2017). Technical Fact Sheet - Perfluorooctane sulfonate (PFOS) and Perfluorooctanoic Acid
(PFOA).
Accessed
onlineat:https://www.epa.gov/sites/production/files/201712/documents/ffrrofactsheet_contaminants_pfos_pfoa_11-20-17_508_0.pdf.
Eurofins (2019). "Client Specific: Table 3 Compounds by Direct Injection Using LC/MS/MS." TPFAS-WI201 27, Rev 2. April 12, 2019.

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Filipovic, M. and U. Berger (2015). "Are perfluoroalkyl acids in waste water treatment plant
effluents the result of primary emissions from the technosphere or of environmental recirculation?"
Chemosphere 129: 74-80.
Guelfo, J. L. and C. P. Higgins (2013). "Subsurface Transport Potential of Perfluoroalkyl Acids at
Aqueous Film-Forming Foam (AFFF)-Impacted Sites." Environmental Science & Technology
47(9): 4164-4171.
Higgins, C. P. and R. G. Luthy (2006). "Sorption of Perfluorinated Surfactants on Sediments."
Environmental Science & Technology 40(23): 7251-7256.
Hogue, C. (2018). "Confronting Fluoroethers." Chemical and Engineering News 12 February
2018, 28-34.
Hopkins, Z. R., M. Sun, J. C. DeWitt, and D. R. U. Knappe (2018). "Recently detected drinking
water contaminants: GenX and other per- and polyfluoroalkyl ether acids." Journal of theAmerican Water Works Association 110(7): 13-28.
Houde, M., G. Czub, J. M. Small, S. Backus, X. Wang, M. Alaee and D. C. G. Muir (2008).
"Fractionation and Bioaccumulation of Perfluorooctane Sulfonate (PFOS) Isomers in a Lake
Ontario Food Web." Environmental Science & Technology 42(24): 9397-9403.
Krafft, M. P. and J. G. Riess (2015). "Selected physicochemical aspects of poly- andperfluoroalkylated substances relevant to performance, environment and sustainability-part one."(1879-1298 (Electronic)).
Kärrman, A., K. Elgh-Dalgren, C. Lafossas and T. Møskeland (2011). "Environmental levels anddistribution of structural isomers of perfluoroalkyl acids after aqueous fire-fighting foam (AFFF)
contamination." Environmental Chemistry 8(4): 372-380.
McCord, J. and M. Strynar (2019). "Identification of per- and polyfluoroalkyl substances in theCape Fear River by high resolution mass spectrometry and nontargeted screening." Environ Sci
Technol 53(9): 4717-4727.
Mueller, R. and V. Yingling (2018a). "Naming Conventions and Physical and Chemical Properties
of Per- and Polyfluoroalkyl Substances (PFAS)". Interstate Technology Regulatory Council.
Mueller, R. and V. Yingling (2018b). "Environmental Fate and Transport for Per- andPolyfluoroalkyl Substances". Interstate Technology Regulatory Council.

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National Center for Biotechnology Information (2019). PubChem: Perfluorohexanoic Acid
(Compound). Accessed online at https://pubchem.ncbi.nlm.nih.gov//#query=Perfluorohexanoicacid/.
Rankin, K., S. A. Mabury, T. M. Jenkins and J. W. Washington (2016). "A North American andglobal survey of perfluoroalkyl substances in surface soils: Distribution patterns and mode ofoccurrence." Chemosphere 161: 333-341.
Sepulvado, J. G., A. C. Blaine, L. S. Hundal and C. P. Higgins (2011). "Occurrence and Fate of
Perfluorochemicals in Soil Following the Land Application of Municipal Biosolids."
Environmental Science & Technology 45(19): 8106-8112.
Sun, M., E. Arevalo, M. Strynar, A. Lindstrom, M. Richardson, B. Kearns, A. Pickett, C. Smith
and D. R. Knappe (2016). "Legacy and emerging perfluoroalkyl substances are important drinking
water contaminants in the Cape Fear River Watershed of North Carolina." Environmental science& technology letters 3(12): 415-419.
Taniyasu, S., N. Yamashita, H.-B. Moon, K. Y. Kwok, P. K. Lam, Y. Horii, G. Petrick and K.
Kannan (2013). "Does wet precipitation represent local and regional atmospheric transportation
by perfluorinated alkyl substances?" Environment international 55: 25-32.
TestAmerica (2019). "Title: Determination of Table 3 Compounds by LC/MS/MS Chemours
Fluoroproducts" SOP No. WS-LC-0031, Rev 2.1 April 03, 2019.
The Netherlands (2019). "Annex XV Report: Proposal for identification of a substance of very
high concern on the basis of the criteria set out in REACH Article 57." March 2019. Accessed
online at https://echa.europa.eu/documents/10162/ef1b1606-b234-2ce5-e159-2ab89d61bfbc.
Visscher, P. T., C. W. Culbertson and R. S. Oremland (1994). "Degradation of trifluoroacetate inoxic and anoxic sediments." Nature 369(6483): 729-731.
Wang, Z., I. T. Cousins, M. Scheringer and K. Hungerbuehler (2015). "Hazard assessment offluorinated alternatives to long-chain perfluoroalkyl acids (PFAAs) and their precursors: Statusquo, ongoing challenges and possible solutions." Environment International 75: 172-179.
Weber, A. K., L. B. Barber, D. R. LeBlanc, E. M. Sunderland and C. D. Vecitis (2017).
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Xiao, X., B. A. Ulrich, B. Chen and C. P. Higgins (2017). "Sorption of Poly- and Perfluoroalkyl
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Biochars and Activated Carbon." Environmental Science & Technology 51(11): 6342-6351.
Yarwood, G. 2018a. Atmospheric lifetime and degradation products of CF3CHF-O-CF2CF2CF3(E1). Memorandum to Joel Goss, Arnold & Porter, 30 March 2018.
Yarwood, G. 2018b. Atmospheric lifetime and degradation products of hexafluoropropylene oxide(HFPO). Memorandum to Joel Goss, Arnold & Porter, 3 April 2018.
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Fate and Transport of Site Associated PFAS

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TABLES

Fate and Transport of Site Associated PFAS

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Geosyntec Consultantsof NC P.C.

TABLE 1
CLASSIFICATION OF SITE ASSOCIATED PFAS
Chemours Fayetteville Works, North Carolina

Common Name

Chemical NameCAS #FormulaDegree ofFluorination

Ether
Bonds

Isomertype

Functional GroupsaR-C=Caa R-CO2Hb R-SO3Hc

Diproticd

Structure

PFAS without ether linkages

PPF Acid

Perfluoropropionic acid422-64-0

C3HF5O2Per

0

Linear

--



--

--

MMF

Difluoromalonic acid1514-85-8

C 3H2F 2O4

Per0

Linear

--



--



DFSA

Difluoro-sulfo-acetic acid422-67-3

C 2H2F 2O5S

Per

0Linear

--







Per- and polyfluoroalkyl ether carboxylic acids (PFECAs)

HFPO-DA

Hexafluoropropyleneoxide dimer acid13252-13-6

C6HF11O3

Per

1

Branched

--



--

--

PFECA-G

Perfluoro-4-isopropoxybutanoic
acid

801212-59-9

C7H1F13O1

Per

1

Branched

--



--

--

MTP

Perfluoro-2-methoxypropanoic
acid93449-21-9

C4H4F 4O3

Poly

1

Linear

--



--

--

Page 1 of 4

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TABLE 1
CLASSIFICATION OF SITE ASSOCIATED PFAS
Chemours Fayetteville Works, North Carolina

Functional GroupsaR-C=Caa R-CO2Hb R-SO3Hc

Diproticd

--



--

--

Branched

--



--

--

1

Linear

--



--

--

Per

2

Linear

--



--

--

C5HF9O4Per

2

Linear

--



--

--

39492-89-2

C5HF9O5Per

3Linear

--



--

--

39492-90-5

C6HF11O6

Per

4

Linear

--



--

--

Common Name

Chemical NameCAS #FormulaDegree ofFluorination

Ether
Bonds

Isomertype

PMPA

Perfluoromethoxypropyl
carboxylic acid

13140-29-9

C4HF7O3

Per

1

Branched

PEPA

Perfluoroethoxypropyl
carboxylic acid267239-61-2

C5HF9O3Per1

PFMOAA

Perfluoro-2-methoxyacetic acid674-13-5

C3HF5O3Per

PFO2HxA

Perfluoro(3,5-dioxahexanoic) acid39492-88-1

C4HF7O4PFECA B

Perfluoro-3,6-dioxaheptanoic
acid

151772-58-6

PFO3OA

Perfluoro(3,5,7-trioxaoctanoic)
acid

PFO4DA

Perfluoro(3,5,7,9-tetraoxadecanoic)
acid

Page 2 of 4

Structure

June 2019

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TABLE 1
CLASSIFICATION OF SITE ASSOCIATED PFAS
Chemours Fayetteville Works, North Carolina

Functional GroupsaR-C=Caa R-CO2Hb R-SO3Hc

Diproticd

--



--

--

Branched

--



--

--

2

Branched





--

--

1

Branched

--



--



Common Name

Chemical NameCAS #FormulaDegree ofFluorination

Ether
Bonds

Isomertype

PFO5DA

Perfluoro-3,5,7,9,11pentaoxadodecanoic acid39492-91-6

C7HF13O7

Per

5

LinearHydro-EVE
Acid

Perfluoroethoxsypropanoic
acid773804-62-9

C8H2F14O4

Poly

2

EVE Acid

Perfluoroethoxypropionicacid

69087-46-3

C8HF13O4

Per

R-EVE

R-EVE

N/A

C8H2F12O5

Per

Structure

Per- and polyfluoroalkyl ether sulfonic acids (PFESAs)

PES

Perfluoroethoxyethanesulfonicacid

113507-82-7

C4HF9O4S

Per

1Linear

--

--



--

NVHOS

Perfluoroethoxysulfonicacid1132933-86-8

C 4H2F 8O4S

Poly

1

Linear

--

--



--

Byproduct 6

Byproduct 6

N/A

C6H2F12O4S

Poly

1

Branched

--

--



--

Page 3 of 4

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TABLE 1
CLASSIFICATION OF SITE ASSOCIATED PFAS
Chemours Fayetteville Works, North Carolina

Functional GroupsaR-C=Caa R-CO2Hb R-SO3Hc

Common Name

Chemical NameCAS #FormulaDegree ofFluorination

Ether
Bonds

Isomertype

Byproduct 2

Byproduct 2749836-20-2

C7H2F14O5S

Poly

2

Branched

--

--



--

PFESA-BP1

Byproduct 1

29311-67-9

C7HF13O5S

Per

2

Branched



--



--

Diproticd

Structure

Per- and polyfluoroalkyl ether sulfonic and carboxylic acids (PFES-CAs)

Byproduct 4

Byproduct 4

N/A

C7H2F12O6S

Per

1

Branched

--







Byproduct 5

Byproduct 5

N/A

C7H3F11O7S

Poly

2

Branched

--







Notes:
Carbon double bond functional groupb
Carboxylic acid functional groupc
Sulfonic acid functional groupdCompound with two acid functional groupsaPage 4 of 4

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TABLE 2EMPIRICALLY MEASURED DATA FOR HEXAFLUOROPROPYLENE OXIDE DIMER ACID (HFPO-DA)
Chemours Fayetteville Works, North Carolina

Parameter

Abbreviation

Organic carbon
partitioning
coefficient

Log Koc

Acid dissociation
constant

pKa

Value

Unit

Notes
Measured for HFPO-DA
ammonium salt in soil.
Measured for HFPO-DA
ammonium salt in sludge.

1.08
1.1
2.84 ± 0.021

1

2

2.45

3
-1

Density

1.683

kg L

Vapor pressure

306

Pa

Solubility in water
Viscosity
Surface tension
Critical micelleconcentration

fully soluble
4.39
59.4

mm s
-1
mN m

0.135 - 0.2

M

CMC

Reference

19.9°C

325°C; sources agree within 1%

2, 3

2 -1

2
3

References:
1- Bloxham, P.A. 2008. Trade secret documented in Study Number DuPont-17568-1675.
2- The Netherlands. 2019. Annex XV Report: Proposal for identification of a substance of very high concern on the basis of thecriteria set out in REACH Article 57. Accessed online at https://echa.europa.eu/documents/10162/ef1b1606-b234-2ce5-e1592ab89d61bfbc. Experiments noted in this reference generally used an acid form with a purity of 98%.
3- DuPont. 2011. Discussion of Results: FRD903 Physical and Chemical Data and FRD902 Physical and Chemical Data. DuPont
Document PM-W-726.
Notes:°C - celsius

mN m-1 - millinewtons per meter% - percent

mm - millimeterskg L-1 - kilograms per liter
Pa - pascals

mm s-1 - millimeters per second

M - moles per liter

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TABLE 3
SITE ASSOCIATED PFAS LIQUID CHROMATOGRAPHY ELUTION TIMES
Chemours Fayetteville Works, North Carolina

Common Namea
DFSA
MMF
MTP
PPF Acid
PFMOAA
R-EVE
Byproduct 4
Byproduct 5PMPA
PFO2HxANVHOSPEPAPFECA B
PFO3OAHFPO-DAPESPECA GPFO4DA
Hydro-EVE Acid
EVE Acid
Byproduct 6
Byproduct 2
Byproduct 1
PFO5DAaCAS #422-67-3
1514-85-893449-21-9
422-64-0
674-13-5
N/A
N/A
N/A
13140-29-939492-88-1
1132933-86-8
267239-61-2
151772-58-6
39492-89-2
13252-13-6
113507-82-7
801212-59-939492-90-5
773804-62-9
69087-46-3
N/A
749836-20-2
29311-67-939492-91-6

Retention Time (min)
0.268
0.271
0.37
0.394
0.437
0.42
0.509
0.51
0.662
1.046
1.655
1.702
3.027
3.298
3.386
3.388
3.702
3.794
3.825
3.825
3.951
4.072
4.084
4.085

Please see Table 1 for details about each chemical.

Method:Elution times were provided by the Chemours Fluoroproducts Analytical Group. Elution times are basedon liquid samples analyzed by liquid chromatography--tandem mass spectrometry (LC-MS/MS) utilizing
the Multiple Reaction Monitoring method. Liquid chromatography was performed on an Agilent 1290
Infinity II LC with 6570 Triple Quad MS instrument with an Agilent InfinityLab Poroshell 120 EC-C18(2.1 x 50 mm, 2.7 µm) analytical column, an Agilent Infinity Lab Poroshell 120 EC-C18 (2.1 x 5 mm,
2.7 µm) as the guard column, a Restek Ultra Aqueous C18 (4.6 x 50 mm, 5 µm) as the trapping column,
and an Agilent Zorbax Eclipse Plus C18 (4.6 x 50 mm, 3.5 µm) as the delay column. Initial eluent
conditions were 85% mobile phase A (2 mM Ammonium Acetate in 5:95 Acetonitrile: Water) and 15%
of mobile phase B (Acetonitrile) for the first 1 mins. Then mobile phase B is ramped up to 90% at 5 mins,
and held for 1.40 mins. Then Mobile phase B is ramped down again to the initial state at 6.50 mins.

June 2019