Perfluorinated Chemicals (PFCs) E-Book

Nicholas P. Cheremisinoff

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 382

Veröffentlichungsjahr: 2016

Beschreibung

This new volume provides a timely study on the environmental challenges from a specific class of perfluorinated chemical compounds (PFCs) that are now being recognized as a worldwide health threat. Recent studies report that levels of classes of PFCs known as polyfluoroalkyl and perfluoroalkyl (PFASs) exceed federally recommended safety levels in public drinking-water supplies for 6 million people in the United States and that as many as 100 million people could be at risk from exposure to these chemicals. These chemicals occur globally in wildlife and humans. Both PFCAs and PFSAs have been produced for more than 50 years, but have only become of interest to regulators and environmentalists since the late 1990s. Recent advances in analytical methodology has enabled widespread detection in the environment and humans at trace levels. These toxic chemicals have been found in outdoor and indoor air, surface and drinking water, house dust, animal tissue, human blood serum, and human breast milk. Of great concern to communities is the presence of these compounds in a number of drinking water supplies in the U.S. and other countries. This new volume provides a timely explanation of the chemicals, provides a detailed review of the regulations both in the US and European Community, explains the health risk literature, and then explores in great detail available treatment technologies. The volume is a must for public water supply facilities, industrial operations that have historically used these chemicals and face legacy pollution issues, policy makers and the general public.

Leseprobe

Contents

Cover

Title page

Copyright page

Preface

About the Author

Abbreviations and Acronyms

Useful Conversion Factors

Chapter 1: What Fluoropolymers Are

1.1 Introduction

1.2 Evolution of Fluoropolymers and the Markets

1.3 PFAS Compounds

1.4 Terminology

References

Chapter 2: Definitions, Uses, and Evolution of PFCs

2.1 Perfluorinated Chemicals (PFCs) Of Interest

2.2 The PFC Family

2.3 PFOS

2.4 PFOA

2.5 Fluorotelomers

References

Chapter 3: Fire Fighting Foams

3.1 What AFFFs Are

3.2 Environmental Impacts

References

Chapter 4: Health Risk Studies

4.1 General

4.2 PFOA

4.3 PFOS

4.4 EFSA – EU Food and Safety Authority Findings

References

Chapter 5: Overview of the Environmental Concerns

5.1 Where It All Began

5.2 Emerging Contaminants of Concern

5.3 PFOS

5.4 PFOA

References

Chapter 6: The Supply Chain and Pathways to Contamination

6.1 Losses Along the Supply Chain and End of Life

6.2 Consumer Articles

6.3 Consumer Exposure to PFOS And PFOA

References

Chapter 7: Standards, Advisories, and Restrictions

7.1 Extent of Groundwater Contamination in the United States

7.2 The U.S. Water Quality Standards

7.3 Remedial Guidelines

7.4 Standards in Other Countries

References

Chapter 8: Overview of Water Treatment Technology Options

8.1 Technology Options

8.2 Case Studies, Literature, and Technologies

Reference

Chapter 9: Adsorption Technology

9.1 Overview

9.2 Activated Carbon and Other Carbonaceous Adsorbents

9.3 Zeolites

9.4 Polymeric Adsorbents

9.5 Oxidic Adsorbents

9.6 Adsorption Theory Basics and Isotherms

9.7 Adsorption of PFOA

9.8 Hardware and Operational Considerations

9.9 Backwashing

9.10 Permitting

9.11 Spent Carbon Management

9.12 Recommended References

References

Chapter 10: Case Studies

10.1 PFOA in Southern New Hampshire

10.2 Former Wurtsmith Air Force Base

10.3 Dupont Washington Works in West Virginia

10.4 PFC Contamination in Minnesota

References

Index

End User License Agreement

Guide

Cover

Copyright

Contents

Begin Reading

List of Tables

Chapter 1

Table 1.1 Important Commercial Fluoropolymers.

Table 1.2 Examples of PFASs. Highlighted chemicals are in Biomonitoring Studies.

Chapter 2

Table 2.1 Timeline of PFOA Perfluorinated Chemicals as reported by the Fluoride Action Network Project. (http://www.fluoridealert.org/wp-content/pesticides/effect.pfos.class.timeline.htm)

Table 2.2 Common derivatives and their chemical formulas.

Chapter 4

Table 4.1 PFOA Health risk literature studies.

Table 4.2 PFOS Health risk literature studies.

Chapter 5

Table 5.1 3M reported properties of PFOS.

Table 5.2 Chemical and physical properties of PFOA (EPA (2016)).

Chapter 6

Table 6.1 Major products and industry sector uses of PFOS.

Table 6.2 Literature reported concentrations of PFOS for different articles. (Source: UNEP, 2012).

Table 6.3 Comparison of total amount of PFCA in a typical American home. Source: Guo, Z., X. Liu,

et al.

(2009).

Chapter 7

Table 7.1 Number of Public Water Supplies with reported PFAS detections above minimum detection level and maximum reported measurement (ppt) for each state. (Source, UCMR 3).

Table 7.2 UCMR-3 reported PFOS/PFOA levels reported in public water supplies by state.

Table 7.3 April 2016 UCMR3 Data Summary (Note, total number of detections is 4,864.)

Table 7.4 PFAAs in EPA Method 537. Compounds in bold typeface are included in the UCMR3 Assessment Monitoring list. (Source: Sanchez,

et al.

)

Table 7.5 Drinking water guidelines for PFOA and PFOS.

Table 7.6 Administrative guidelines in μg/L.

Chapter 9

Table 9.1 Level of Effectiveness of GAC. (Source EPA

a

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Scrivener Publishing 100 Cummings Center, Suite 541J Beverly, MA 01915-6106

Publishers at Scrivener Martin Scrivener ([email protected]) Phillip Carmical ([email protected])

Perfluorinated Chemicals (PFCs)

Contaminants of Concern

Nicholas P. Cheremisinoff

Copyright © 2017 by Scrivener Publishing LLC. All rights reserved.

Co-published by John Wiley & Sons, Inc. Hoboken, New Jersey, and Scrivener Publishing LLC, Beverly, Massachusetts. Published simultaneously in Canada.

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Preface

This volume provides a primer on the environmental challenges created by perfluorinated compounds (PFCs). PFCs have been documented to occur globally in wildlife and humans. The most commonly studied PFC classes are the perfluorinated sulfonates (PFSAs) and the perfluorinated carboxylates (PFCAs). The most commonly detected classes of these compounds in the environment are perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). These compounds are bioaccumulative and very persistent to abiotic and biotic degradation. Compounds like PFOS are known as persistent organic pollutants (POPs) under the Stockholm Convention. Both PFCAs and PFSAs have been produced for more than 50 years, but have only become of interest to regulators and environmentalists since the late 1990s. Renewed and increasing interests in these compounds are due to the recent advances in analytical methodology that has enabled their widespread detection in the environment and humans at trace levels. PFCs have been found in outdoor and indoor air, surface and drinking water, household dust, animal tissue, human blood serum, and human breast milk. Because of the high persistence of PFOS and PFOA, the two compounds accumulate in the environment; concentrations in humans and environmental media are now believed to be at levels of great concern. Of acute concern to communities is the presence of these compounds in a number of drinking water supplies in the US, Canada, and throughout Europe and other continents.

For more than five decades these chemical compounds have been widely used as processing aids and surfactants in the manufacturing of fluoropolymers, which have gone into the making of a multitude of consumer-oriented commercial products. Fluoropolymers such as polytetrafluoroethylene (PTFE) are films (e.g., on nonstick cookware) or membranes (e.g., in outerwear) and are characterized by a fluorocarbon chain within the polymer backbone. Residual PFCA is present in fluoropolymer films and membranes used in manufacturing many different consumer articles. These chemicals are present as reaction impurities in various consumer products containing fluorinated polymers, which are added to products to make them stain, soil, water, and grease resistant.

Fluorinated polymers comprise a hydrocarbon backbone (e.g., polyesters, polyurethanes, polyethers) with perfluorinated side-chains. Consumer products treated with fluorinated polymers include clothing and textiles, carpets, leather, paper, and cardboard. PFSAs and related compounds have often been incorporated into fluorinated polymers used in making protective coatings for carpets and apparel, paper coatings approved for food contact, insecticide formulations, and surfactants, as, for example, in firefighting foams. Many articles in general use by consumers have found their way to municipal landfills at the end of their life cycle where years of leaching into the subsurface has resulted in contaminated groundwater. Facilities like airports, military bases, refineries, shipping ports, oil terminals, and many industrial complexes have for decades relied on and stockpiled aqueous firefighting foams, which contain PFAS compounds. These facilities have performed countless firefighting training drills, plus in some instances, responded to fire incidents in which the spent foams were then washed on to land, into surface waters, and into sewers which impacted public water treatment plants.

In 2001, the principal manufacturer of PFOS and related compounds with a chain length of eight carbon atoms ceased its manufacturing, leaving only small producers in Europe and Asia. In 2006, the USEPA began working with eight major leading companies in the per- and polyfluoroalkyl substances (PFASs) industry to join in a global stewardship program to commit to achieve, no later than 2010, a 95 percent reduction (as measured from a year 2000 baseline) in facility emissions to all media of perfluorooctanoic acid (PFOA), precursor chemicals that can break down to PFOA, and related higher homologue chemicals and product content levels of these chemicals; and further, to commit to working toward the elimination of these chemicals from emissions and products by 2015. Participating companies include Arkema, Asahi, BASF Corporation (successor to Ciba), Clariant, Daikin, 3M/Dyneon, DuPont, and Solvay Solexis. While these phase-out programs have largely been on track, the persistence of these chemical compounds in the environment from more than five decades of use continues to provide an open pathway to human exposure, particularly through the ingestion of contaminated water supplies. Furthermore, the chemical compounds, which have been touted as environmentally friendly replacements for PFAS (known as telomers), are now proving to be just as controversial as they also bioaccumulate, in some instances actually breakdown to PFOS/PFOA related chemicals when in the environment, and have few and incomplete health risk studies which support claims that the products are of “green” chemistry. PFAS are so stable in the environment that, in fact, the only way these man-made chemical compounds can be effectively destroyed is by high temperature incineration at thousands of degrees Celsius. The general population (consumers) continues to be exposed to PFOS and PFOA from the use of various PFC-containing products and the intake of contaminated food, environmental media, and house dust. In fact, comprehensive assessment of consumer exposure to PFOS and PFOA, including all relevant pathways, is missing from the scientific arsenal, thus placing the public at indeterminate levels of risk.

The USEPA and other international regulatory and health agencies are concerned about these long-chain PFCs because they are now found worldwide in the environment, wildlife, and in humans. Many or all of these chemical compounds bioaccumulate in wildlife and humans, are extremely persistent in the environment, and many are toxic to laboratory animals and wildlife, producing reproductive, developmental, and systemic effects in laboratory test animals. The USEPA anticipates that continued exposure could increase body burdens to levels that would result in adverse outcomes. The agency has already concluded that PFOA is a “likely human carcinogen.” It further points to numerous studies which document the prevalence of PFOA in the human environment and in bodily tissues, including studies that report the presence of PFOA in infants’ umbilical cord blood.

According to the Agency for Toxic Substances and Disease Registry, PFAS accumulates and remains in the human body, and the amount reduces very slowly over time. Scientists and medical professionals are concerned about the effects of these chemicals on human health and the lack of comprehensive health risk studies. The studies that have been conducted for humans have shown that certain PFAS may be associated with developmental delays in the fetus and child, including possible changes in growth, learning, and behavior; decreased fertility and changes to the body’s natural hormones; increased cholesterol; changes to the immune system; increased uric acid levels; changes in liver enzymes; and prostate, kidney, and testicular cancer.

In preparing this volume, the author examined more than 36,000 well sampling results from public water supplies across the United States. The analysis identifies many states and counties that are potentially at risk from exposure to these chemicals through endangered public water supplies. The study presented in this volume further accentuates a recently published study by the Harvard T.H. Chan School of Public Health, which reports levels of PFAS that exceed federally recommended safety levels in public drinking-water supplies for 6 million people in the United States, and that up to 100 million people could potentially be at risk. In Europe, the problem may be even more acute as guidelines for drinking water quality are less restrictive than in the United States, and certainly there remain many other parts of the world where PFAS chemicals continue to be produced and used while no enforceable drinking water standards exist. Groundwater contamination by these chemicals is a worldwide problem. This volume covers the EU as well as US drinking water quality advisories and recommended limits.

The volume further explores options for groundwater treatment. Unfortunately, the only technology currently applicable is carbon adsorption. While this water treatment technology has been around for decades, its adaptation to remediating water supplies that are impacted by PFAS compounds is still evolving. Each application poses significant technical and engineering challenges due to the presence of other contaminants and the levels of cleanup that are now being imposed to achieve quality that is considered low risk from exposure. The technology thus far has proven costly and has shown mixed results in certain operations. The volume explores the design criteria and steps that are taken to evaluate this technology for applications to public water supplies.

PFAS in the environment and especially in drinking water supplies represents a worldwide problem. It is fair to state that these chemicals may very well represent the chemical industry’s tobacco. It is a well-known historical fact that the tobacco industry understood and concealed the addictive nature and harmful effects of smoking from the public in order to reap untold fortunes. The chemical industry most certainly faces the very same scrutiny and public scorn because considerable evidence is now emerging that some chemical providers understood how dangerous these chemicals are but failed to warn of the consequences of their use. Placing this in perspective, a mere handful of chemical manufacturers created, developed, and distributed a broad spectrum of end-user market applications and products which incorporated these chemical ingredients whose consequence is only now being understood to have foreboding impacts to natural resource damages and worldwide public safety.

There are vast numbers of publications and articles which are in the public domain and available through the WWW on this subject. Yet the literature is fragmented, and even confusing and misleading. There does not appear to be a single source or even a handful of publications which provide a comprehensive overview of the issues surrounding these contaminants in straightforward language. The chemistry of these surfactants is sophisticated, complex, and in a number of instances, being hidden from the public. The fate and transport of these chemicals is incomplete and not fully defined. There is a noticeable lack of comprehensive health risk studies which should be of great concern to national and local governments. Further, there should be focused attention given to historical exposure issues to communities that are the result of legacy pollution — an area of concern that seems to receive little attention in the media and in state of the art reviews. To this end, the author prepared this volume for a broad spectrum of readers. It is intended as a primer — for the public at large, for public water providers that are now faced with monitoring these chemical contaminants and may be facing costly remedies, for environmental engineers who are now consulting and working to remedy legacy contamination problems stemming from the use and disposal of products and wastes containing PFAS, and for environmental policy makers who need to be much more versed in the public health risk issues and do require more than a cursory background to understand the pathways of exposure and their consequences to public risks.

There are ten chapters to this volume: Chapter 1 provides an overview of fluoropolymers and PFCs; Chapter 2 covers historical uses and evolution of PFCs; Chapter 3 discusses the use of these chemicals in firefighting foams; Chapter 4 covers health risk studies; Chapter 5 provides an overview of environmental concerns; Chapter 6 discusses supply chain and pathways of exposure to these chemicals in manufacturing and consumer products; Chapter 7 summarizes drinking water and other standards; Chapter 8 provides an overview of water treatment technology options; Chapter 9 covers adsorption technologies which are currently viewed as the preferred water treatment technology; and finally, Chapter 10 provides some cases studies.

The author wishes to thank Mohit Dayal of No-Pollution Enterprises for reviewing and editing the volume and Scrivener Publishing for its fine production of this book.

Nicholas P. Cheremisinoff, Ph.D.

About the Author

Nicholas P. Cheremisinoff earned his BSc, MSc and Ph.D. degrees in chemical engineering from Clarkson College of Technology (Clarkson University). His career spans more than 40 years internationally addressing pollution management, energy efficiency, and environmental policymaking. He has led and participated in hundreds of pollution prevention and environmental audits and pilot demonstrations; training programs on modern process design practices and plant safety; environmental management, product quality, waste minimization and energy efficiency programs; and has assisted in developing remediation plans for both public and private sector clients as well as for large infrastructure investments supported by the World Bank, the U.S. Trade & Development Agency, and the U.S. Agency for International Development. He has been proffered and approved in US state and federal courts to offer expert opinions on personal injury, toxic torts, and third-party property damage litigation matters arising from environmental issues. He holds multiple positions including serving as Principal of the environmental consulting firm No-Pollution Enterprises, serves part-time as the Director of Clean Technologies and Pollution Prevention Projects for PERI (Princeton Energy Resources International, LLC, Rockville, MD), and is a member of the Board of Directors of ThermoChem Recovery International, Inc. Dr. Cheremisinoff has contributed extensively to the industrial press as author, co-author, or editor of more than 150 technical reference books.

Abbreviations and Acronyms

AAL

annual ambient air limit

ACT

accelerated column test

AFFF

aqueous film-forming foams

ANSI

American National Standards Institute

AOC

articles of commerce or Areas of Concern

APFN

ammonium perfluoronanoate

APFO

ammonim perfluooctanoate

AR-AFFF

alcohol-resistant aqueous film-forming foams

AR-FFFP

alcohol-resistant film-forming fluoroprotein foams

ASTM

American Society for Testing and Materials

AWWA

American Water Works Association Standard

BAFs

bioaccumulation factors

BAT

best available technologies

BCFK

bioconcentration factor

BCF

bioconcentration factor

BDST

bed depth service time

BEP

best environmental practices

BOD

biological oxygen demand

BRAC

Base Realignment and Closure

BTEX

benzene, toluene, ethyl benzene, and p-xylene

BWS

black walnut shells

CAS

Chemical Abstract Service

CASRN

Chemical Abstracts Registration Number

CBI

Confidential Business Information

CCD

charge-coupled device (technology for capturing digital images)

CCL

contaminant candidate list

COD

chemical oxygen demand

CTFE

Chlorotrifluoroethylene

DoD

Department of Defense

EFSA

EU Food and Safety Authority

ETFE

ethylene tetrafluoroethylene

EtFOSA

N

-ethyl perfluorooctane sulfonamide (sulfluramid)

EtFOSE

N

-ethyl perfluorooctane sulfonamidoethanol

EtFOSEA

N

-ethyl perfluorooctane sulfonamidoethyl acrylate

EtFOSEP

di[

N

-ethyl perfluorooctane sulfonamidoethyl] phosphate

EU

European Union

FC-53

Potassium1,1,2,2-tetrafluoro-2-(perfluorohexyloxy)ethane sulfonate/perfluoro[hexyl ethyl ether sulfonate]

FC-53B

Potassium2-(6-chloro-1 , 1 , 2 , 2 , 3 , 3 , 4 , 4 , 5 , 5 , 6 , 6-dodecafluorohexyloxy)-1,1,2,2-tetrafluoroethane sulfonate

FC-248

PFOS tetraethyl ammonium salt

FEVE

fluoroethylenevinylether

FFFC

firefighting foam coalition

FFFP

film-forming fluoroprotein foams

FTOH

fluorotelomer alcohol or fluorotelomer olefin

FOIA

Freedom of Information Act

GAC

granular activated carbon

g/mol

grams per mole

HA

health advisory

HBV

Health Based Value

HMW

high molecular weight

HPMC

high pressure water minicolumn

HRLs

Health Risk Limits

IARC

International Agency for Research on Cancer

IRIS

Integrated Risk Information System

IRP

Installation Restoration Program

K

ow

octanol-water partition co-efficient

K

oc

organic carbon-water partitioning coefficient

LOAEL

lowest observed adverse effect level

LoCfPA

List of Chemicals for Priority Action

LMW

low molecular weight

MDH

Minnesota Department of Health

MDL

minimum detection limit

MeFOSA

N

-methyl perfluorooctane sulfonamide

MeFOSE

N

-methyl perfluorooctane sulfonamidoethanol

MeFOSEA

N

-methyl perfluorooctane sulfonamidoethyl acrylate

MPCA

Minnesota Pollution Control Agency

MTZ

mass transfer zone

MSDS

Material Safety Data Sheet

NCOD

National Contaminant Occurrence Database

N-Et FOSE

N-ethyl Fluorooctylsulfonamidoethanol

NHDES

New Hampshire Department of Environmental Services

NIP

national implementation plan

N-Me FOSE

N-methyl Fluorooctylsulfonamidoethanol

NOAEL

no observed adverse effect level

NHANES

National Health and Nutrition Examination Survey

NSF

National Science Foundation

OECD

Organization for Economic Co-operation and Development

PAHs

polyaromatic hydrocarbons

PAC

powdered activated carbon

pcf

pounds per cubic foot

PCTFE

polychlorotrifluoroethylene

PDDD

perfluorododecanoate

PFAS

perfluorinated alkyl sulfonates

PFBS

perfluorobutane sulfonic acid/potassium perfluorobutane sulfonate

PFCs

perfluorinated chemicals

PFCA

perfluoroalkyl carboxylic acid or perfluorocarboxylate(s)

PFD

perfluorodecanoate

PFDA

perfluorodecanoic acid

PFDDA

perfluorododecanoic acid

PFHx

perfluorohexanoate

PFHxA

perfluorohexanoic Acid

PFHp

perfluorohepanoate

PFHpA

perfluoroheptanoic Acid

PFN

perfluoronanoate

PFNA

perfluorononanoic acid

PFO

perfluorooctanoate

PFOA

perfluorooctanoic acid

PFOS

perfluorooctane sulfonic acid

PFOSA

perfluorooctane sulfonamide

PFOSF

perfluorooctane sulfonyl fluoride

PFTD

perfluorotridecanoate

PFTDA

perfluorotridecanoic acid

PFU

perfluoroundecanoate

PFUA

perfluoroundecanoate acid

POP

persistent organic pollutant

POSF

perfluorooctylsulfonyl fluoride

PPVE

perfluoropropylvinylether

PSD

particle size distribution

PTFE

polytetrafluoroethylene

PWI

Polyacetal Waste Incinerator

PWSs

public water systems

REACH

Registration, Evaluation, Authorization and Restriction of Chemical (substances)

SAB

Science Advisory Board

SAC

Strategic Air Command

SDWA

Safe Drinking Water Act

SNUR

Significant New Use Rule

SOCs

synthetic organic chemicals

SWMU

Solid Waste Management Unit

TCLP

Toxicity characteristic leaching procedure

TDI

tolerable daily intake

TMF

trophic magnification factor

TNSSS

Total National Sewage Sludge Survey

TSCA

Toxic Substances Control Act

TSDF

Treatment, Storage or Disposal Facility

UK

United Kingdom

UCMR

Unregulated Contaminant Monitoring Rule

UNDP

United Nations Development Program

USEPA

United States Environmental Protection Agency

VDF

vinylidene fluoride

VIC

Voluntary Investigation and Cleanup

VOCs

volatile organic compounds

WHO

World Health Organization

WWTP

waste water treatment plants

Chapter 1What Fluoropolymers Are

1.1 Introduction

Fluorine-based polymers are referred to as fluoropolymers. These are man-made products that impart certain attributes and properties to coatings used in industrial, household, and construction products, as well as in firefighting foam applications. The qualities of fluoropolymer resins and oligomeric additives in coatings make them useful in applications requiring a high resistance to solvents, acids and bases, and most importantly, an ability to greatly reduce friction.

The use of surfactant additives reduces surface energy while increasing chemical, UV, moisture, grease and dirt resistance, and surface lubricity. In addition to more common fluorinated olefin-based polymers, specialty fluoroacrylates, fluorosilicone acrylates, fluorourethanes, and perfluoropolyethers/perfluoropolyoxetanes exhibit properties beneficial to various coatings applications. Coatings containing fluorochemicals find broad applications in electronics such as photomask covers, anti-reflection coatings; in construction as protective coatings for exterior substrates; as cool-roof coatings and optics such as antifouling coatings for eyeglass lenses and liquid crystal displays. Other coatings that often contain fluoropolymers include floor polishes, wood stains, and automotive clear coats, as well as ink jet inks, pigment dispersions, and adhesives.

At the heart of these products is the chemical fluorine. Unique characteristics of the fluorine atom impart certain properties to polymers that contain it. Fluorine is a fairly small atom that has very low polarizability and high electronegativity. Because there is a high degree of overlap between the outer orbitals of fluorine and the corresponding orbitals of second period elements, bonds formed between carbon and fluorine are very strong. The higher bond energy of the C-F bond compared to the C-H bond leads to greater thermal stability.

A perfluorinated chemical (PFC) is an organofluorine compound containing only carbon-fluorine bonds (no C-H bonds) and C-C bonds but also other heteroatoms. PFCs have properties that represent a blend of fluorocarbons (containing only C-F and C-C bonds) and the parent functionalized organic species. For example, perfluorooctanoic acid functions as a carboxylic acid but with strongly altered surfactant and hydrophobic characteristics. Perfluoropolymers, which contain only C-F bonds, have excellent chemical and weather resistance. The small dipole moment of these compounds contributes to their oil and water-repellency, as well as low surface tension, low refractive index, low friction coefficient, and reduced adhesion to surfaces. Even partially fluorinated polymers exhibit a strong electron-attracting ability, resulting in a high dielectric constant and optical activity. In small molecules, this attribute leads to enhanced acidity, lipophilicity, and the ability to block metabolic pathways, making fluorine-substituted compounds well-suited for pharmaceutical applications.

Other characteristics of fluoropolymers, which are determined by the strength of the C-F bond and the low polarizability and high electronegativity of fluorine, include soil resistance, insulating properties, and the ability to act as a gas barrier.

Commercial fluoropolymers are generally classified according to morphology (crystalline, semi-crystalline, and amorphous categories) and perfluorinated and partially fluorinated. See Figure 1.1.

Figure 1.1 The major types of today’s commercial fluoropolymers.

1.2 Evolution of Fluoropolymers and the Markets

The following is a timeline of the evolution of fluoropolymers and the market applications.

1886

Henri Moisson isolated elemental fluorine, for which he received the Nobel Prize in Chemistry.

1890s

SbF3 is applied in a Cl/F exchange reaction to prepare fluorinated aromatics and the first chlorofluorocarbon gas (CF

2

Cl

2

).

1931

General Motors, in partnership with E. I du Pont de Nemours & Co., formed a new corporation, Kinetic Chemicals Inc., to produce commercial quantities of the trademarked product Freon-12.

1930s

Several other Freons were developed, including Freon-114 (CClF

2

CClF

2

) a precursor of tetrafluoroethylene (TFE).

1934

The first patent for a fluoropolymer was filed by IG-Farbenindustrie in Hoechst/Frankfurt, in Germany.

1938

Roy Plunkett, a DuPont chemist working on new types of Freons, independently discovered PTFE (Teflon) while attempting to chlorinate gaseous TFE.

1949

DuPont introduces Teflon. Plunkett began working for DuPont Jackson Laboratory in Deepwater, N.J., as a research chemist in 1936. Plunkett’s discovery was found to be both heat-resistant and stick-resistant. After 10 years of research, DuPont introduced Teflon in 1949.

Late 1940s

3M purchases the Simon Electrofluorination Patent. Electrochemical fluorination (ECF), or electrofluorination, is a foundational organofluorine chemistry method for the preparation of fluorocarbon-based organofluorine compounds. The general approach represents an application of electrosynthesis. The fluorinated chemical compounds produced by ECF are useful because of their distinctive solvation properties and the relative inertness of carbon–fluorine bonds. Two ECF synthesis routes are commercialized and commonly applied, the Simons Process and the Phillips Petroleum Process. Additionally, it is also possible to electrofluorinate in various organic media. Prior to the development of the Simon method, fluorination with fluorine, a dangerous oxidant, was a dangerous and wasteful process. Also, ECF can be cost effective, but it may also result in low yields.

1953

Kellog Co. introduced polychlorotrifluoroethylene (PCTFE) under the trade name Kel-F 81. PCTFE, a homopolymer of CTFE, contained chlorine in the fluoropolymer backbone making it a more processable alternative to PTFE.

1956

3M begins selling Scotchgard Protector. Scotchgard Protector contained a fluorochemical that helped it repel stains.

1960

FEP (fluorinated ethylene propylene), the first copolymer of TFE was introduced.

1961

Dupont released polyvinylfluoride (PVF) which contained only one fluorine in the ethylene monomer unit, and polyvinyldifluoride (PVDF) which contained two.

1962

FDA gives approval for Teflon cookware. The Food and Drug Administration granted final approval to Teflon cookware in 1962.

1965

First commercial grade PVDF, Kynar 500, is introduced by Pennsalt Co.

Late 1960s

DuPont discovered Nafion, a copolymer of TFE containing sulfonate groups. Nafion was the first synthetic ionic polymer (ionomer) and was found to be highly conductive to cations, making it suitable for membrane applications such as in industrial electrolysis and fuel cells. Modified fluoroionomers such as Flemion and Aquivion were later developed to overcome some of the solvent and operating temperature limitations of Nafion.

1967

FDA approved Zonyl, DuPont’s leading brand of fluorinated telomers, for use in food packaging. It was a less costly and less labor-intensive alternative to the waxed-based papers previously used, which could not be recycled.

1970s

Perfluoroalkoxy (PFA) copolymer was introduced by Dupont. PFA, a mix of TFE and perfluoropropylvinylether (PPVE) was transparent in thin sections and possessed a broad range of properties encompassing both FEP and PTFE. PFA found applications in the chemical and semiconductor industries as pipes, fittings, linings, and as specialized films. Dupont also introduced ECTFE and ETFE, ethylene (E) copolymers of CTFE and TFE, respectively. These were the first fluoropolymers to contain non-fluorinated subunits and possessed a mix of hydrocarbon and fluorocarbon polymer properties. In addition to improved mechanical properties, ECTFE and ETFE were more flexible and could be cross-linked using high energy radiation. The reduced production cost of these polymers made them attractive for high strength tubing, films, and fire-resistant cable insulation.

1976

The process whereby PTFE could be heat stretched to give expanded polytetrafluoroethylene (ePTFE) was patented. This process stretched PTFE by up to 800%, forming a microporous structure that was 70% air. The pores could be engineered such that air could pass through but water could not. This new ePTFE material trade-named Gore-Tex found extensive markets in outdoor apparel, medical, and music industries.

Early 1980s

Asahi Glass developed fluoroethylenevinylether (FEVE) resins under the Lumiflon trademark, for coating plastics, architecture, and other materials. FEVE resins are composed of fluorinated ethylene (TFE or CTFE) and a mix of vinyl ethers that can be varied depending on application. FEVE resins were the first fluoropolymers to be soluble in organic solvents and can be cured at room temperature. Similar FEVE resins were later introduced by Daikin under the trade name Zeffle.

mid 1980s

Up until the 1980s, fluoropolymer plastics were semicrystalline materials with poor solubility or low optical transparency. DuPont developed Teflon-AF, which is a copolymer of TFE and perfluoro-2,2-dimethyl-1,3-dioxole (PDD). Asahi Glass introduced Cytop, a homopolymer of perfluoro-3-butenyl-vinyl ether. Both Teflon-AF and Cytop are amorphous high molecular weight perfluoropolymers that, in addition to having excellent thermal, chemical, and electrical properties, also possess outstanding optical clarity and the lowest refractive index of all known organic materials. This opened up markets in optical lenses, fiber optic applications, and high quality transparent coatings. Solvay Solexis later introduced HyflonADas, a more solution processable alternative to Teflon-AF. At present, the consumption of amorphous fluoropolymers is still very small.

1993

Hoechst partnered with 3M to release THV, a semicrystalline three component terpolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride. THV is highly flexible, soluble in polar organic solvents, and has excellent adhesive properties making it very useful for thin film coatings and multilayer constructions.

Since the 1990s, trademarked ranges of fluoropolymers have expanded in various forms to meet the needs of emerging technologies in construction, electronics, and energy sectors. For the most part, these have consisted of modified formulations or newly processed forms of existing fluoropolymer blends. Effort continues to be invested in developing new types and blends of fluoropolymers, particularly in the energy and electronics sectors. Table 1.1 lists some of the most important commercial fluoropolymers that are part of a worldwide annual market that is upwards of 200,000 tons.

Table 1.1 Important Commercial Fluoropolymers.

Year commercialized

Fluoropolymer

Monomer

Typical applications

1947

Polytetrafluoroethylene (PTFE)

Tetrafluoroethylene (TFE)

Chemical processing, resistant components & coatings, pipes & piping aperture, fittings, linings, tapes, seals, filters, wire & cable insulation, laminates, waterproof & stain repellent clothing, architectural & carpet coatings, printing, cookware, fabrics, biomedical devices

1953

Polychlorotrifluoroethylene (PCTFE)

Chlorotrifluoroethylene (CTFE)

Packaging & barrier films, pharmaceutical and electrical packaging, lighting, semi-conductor processing, cryogenic seals

1960

Fluorinated ethylene propylene (FEP)

TFE + hexafluoropropene (HFP)

Chemically resistant components & coatings, plenum cable insulation

1961

Polyvinylfluoride (PVF)

Vinyl fluoride (VF)

Laminates & resistant coatings, architectural coatings, solar panels

1961

Polyvinyldifluoride (PVDF)

Vinylidene fluoride (VDF)

Fluid handling systems, valves, pumps, water piping, resistant paints, architectural coatings, wire & cable insulation, electronic components, solar panels, printing

1970

Ethylene (E) copolymer of CTFE (ECTFE)

Chlorotrifluoroethylene (CTFE)

Flame resistant wire& cable insulation, pipes & components, high strength films, acids and corrosives storage, medical devices

1972

Perfluoroalkoxy- (PFA)

TFE + perfluoroalkylvinylether (PVE)

Chemical processing, resistant components and fittings, electrical insulation, industrial & architectural coatings, semiconductor manufacturing

1973

E copolymer of TFE (ETFE)

E + TFE

Chemical processing, pipes & tubing, automotive & mass transit cabling, fuel tubing and fittings, wire & cable insulation, seals

1996

THV (a semicrystalline three component terpolymer of the given monomers)

TFE + HFP + VDF

Flexible & resistant coatings, wire & cable insulation, multilayer barrier coatings, fuel hoses, bag liners, lighting, optical fiber, solar panels, safety glass

PTFE (Polytetrafluoroethylene), historically and through present times, is the most widely produced of all the fluoropolymers with demand steadily increasing. Current manufacturers producing a range of fluoropolymer resins and products include DuPont, Asahi Glass, Solvay Solexis, 3M, Dyneon, Honeywell, and Daikin.

1.3 PFAS Compounds

1.3.1 General Description

Any organic or inorganic substance that contains at least one fluorine atom is referred to as “fluorinated substances” as a general term. However, their chemical, physical, and biological properties could differ significantly. A subset of fluorinated substances are the highly fluorinated aliphatic substances that contain one or more carbon atoms on which the fluorine atoms have replaced the hydrogen atoms that would normally be found in nonfluorinated substances. These subset substances contain the perfluoroalkyl moiety with the form of CnF2n+1 – and are referred to as perfluoroalkyl or polyfluoroalkyl substances having the acronym PFAS.