Methods for the destruction and measurement of pfas

Abstract

Disclosed is a process for the destruction of per- and polyfluoroalkyl substances (PFAS). The process could include the step of adding a solvent, such as acetonitrile, to PFAS materials to extract / dissolve PFAS. A sodium-metal based solution, such as sodium naphthalene diglyme solution, could be added to the mixture. Also disclosed is a process to measure extractable organic fluorine and total organic fluorine in samples or products containing PFAS using the sodium-metal based solutions.

Description

METHODS FOR THE DESTRUCTION AND MEASUREMENT OF PFASFIELD OF THE DISCLOSURE

[0001] The present disclosure relates to a method for the destruction of per- and polyfluoroalkyl substances (PFAS) and measurement of extractable / total organic fluorine using a solution containing sodium metal (Na°).BACKGROUND

[0002] The physical and chemical properties of per- and polyfluoroalkyl substances (PFAS) have led to their ubiquitous use in several applications, such as aqueous firefighting foams, non-stick cookware, stain repellents, carpets, as well as other industrial applications.1-3The unique structure of PFAS is attributed to the presence of multiple C-F bonds across a C-C skeleton with a terminal functional group such as -COOH, SO3H, etc. The C-F bond is one of the strongest bonds and the presence of multiple C- F bonds imparts extreme thermal and chemical stability to PFAS.21 51 6Hence, PFAS are largely resistant to conventional water treatment techniques, such as coagulation and flocculation1’2but also to certain advanced water treatment technologies, such as advanced oxidation processes2 5as the C-F bonds are highly resistant to oxidation.

[0003] As a result, PFAS have been detected in waters all across the globe7 8, in food webs integrated in the western Arctic,9in sediments and fish tissues8as well as in rainwater.10PFAS have been commonly detected in human blood and serum11’12but also in the liver of polar bears13, demonstrating the widespread scale of PFAS contamination. Although capture technologies, such as granular activated carbon, ionexchange resins, reverse osmosis, and nanofiltration, have been successfully utilized to remove PFAS from contaminated waters1’2’5’7’14-16, such techniques produced a concentrated PFAS waste stream that requires further treatment and adequate disposal steps.

[0004] This has led to research in several destructive techniques for PFAS remediation. The main aim of these technologies is to breakdown the persistent PFAS moleculesinto potentially less toxic and biodegradable products, with the ultimate aim to completely mineralize them into free fluorine and CO2.

[0005] Polytetrafluoroethylene (PTFE) is a commonly used fluoropolymer consisting of C-C backbone with a -CF2 - CF2 - structure. It is similar to polyethylene, but the C-H bonds have been replaced with C-F bonds, imparting high physical and chemical stability. PTFE has been used in high temperature wire coatings, airplane wing manufacturing, and manufacture of seals and bearings in motor vehicles.33However, prior to these applications, the hydrophobic PTFE is converted into a more bondable, hydrophilic form.331 34This is because although PTFE possesses desirable properties, such as chemical resistance, electrical stability, low coefficient of friction, and low dielectric constant, unmodified PTFE displays poor adhesion and wettability, an ability to maintain contact with a solid surface.

[0006] Historically, the surface modification of PTFE was achieved by wet chemical treatment, plasma, or by ion beam treatment. However, as the demands and applications for PTFE increased, more tubular and shapes other than those having a flat base were needed. Ion beam and plasma treatment could not be applied to etch PTFE for those applications effectively, leading to research into wet chemical etching techniques.35Some of the initial wet chemical etching methods involved reactions of metallic sodium and fluorine in the polymer. This is due to the redox potential for sodium metal of -2.71 eV that makes it a very strong reducing agent.36However, this required solvents, such as tetrahydrofuran (THF) and anhydrous ammonia, that were carcinogenic, mutagenic, and reprotoxic.33This led to the development of less hazardous solvents, with the metallic sodium still kept as the primary ingredient. One chemical etchant for PTFE involves metallic sodium complexed with naphthalene to form a sodium-naphthalene complex. This complex is hypothesized to have better reduction capability than pure sodium with the redox potentials reported to be -3.1 eV.37This complex is usually dissolved in glycol ethers / glyme based solvents33, with 1 ,2- dimethoxyethane being a preferred candidate.

[0007] It would be desirable to develop a process for the destruction of environmentally-relevant PFAS (1 ) that can be applied to a wide range of PFASmolecules, (2) does not require high energy to operate, and (3) can be scaled up easily for the destruction of PFAS-containing wastes on-site.SUMMARY

[0008] In accordance with embodiments of the present disclosure, disclosed is a method for the destruction of PFAS using a solution containing sodium metal (Na°). In at least one embodiment, a solution containing sodium metal is used for the defluorination of recalcitrant non-polymeric PFAS. In at least one embodiment, the method could include the step of adding an organic solvent, such as acetonitrile, to PFAS-containing materials to extract and / or dissolve PFAS. A solution containing sodium metal, such as sodium naphthalene in a solvent, could be added to the PFAS extract and / or the mixture. The extract and / or mixture can then be treated either in an aerobic or anaerobic (absence of oxygen) environment and at ambient temperature or room temperature or slightly elevated temperature (45 °C-60 °C), depending on the PFAS-containing materials (e.g. waste stream) and the type of PFAS being treated. Defluorination of PFAS occurs instantaneously when in contact with sodium metal and the overall reaction is expected to complete within few minutes depending on the complexity of the PFAS-containing materials (e.g. waste stream). The treated waste stream can then be further treated for other contaminants including the chemicals present in the added solution (e.g., naphthalene, glycol ether, etc.).

[0009] In at least one embodiment, disclosed is a process and system that utilizes solutions containing sodium metal to completely destroy PFAS, including, but not limited to, perfluoroalkyl acids (PFAAs) like PFOA & PFOS, perfluoroalkane sulfonamides, fluorotelomer substances, and other PFAS contained in aqueous film-forming foams (AFFF) or other PFAS-containing waste or other PFAS-containing materials.

[0010] In at least one embodiment, PFAS is extracted from PFAS-containing materials (e.g. PFAS-containing waste) and is reconstituted into an organic solvent (e.g. acetonitrile). Concentrated solution of PFAS in solvent (e.g. acetonitrile) is then mixed with a solution containing sodium metal to rapidly defluorinate PFAS. The treatedsolution can further be treated to remove co-contaminants using existing treatment approaches (e.g., advanced oxidation processes, filtration, combustion, etc.);

[0011] In at least one embodiment, a process for measuring Total and / or Adsorbable Organic Fluorine (TOF and / or AOF) is disclosed. In one process an aliquot from the organic extracts resulting from solid phase or liquid-liquid extractions (e.g., from EPA Method 1633) can be treated with a solution containing sodium metal to defluorinate concentrated PFAS and successive measurement of fluoride ions by appropriate techniques (e.g. ion selective electrode or ion chromatography) can yield AOF values for the samples. In the second process, a sample containing PFAS (consumer / personal care products, soil, sediments etc.) can directly be treated with a solution containing sodium metal and the resulting fluoride ions can be measured either by appropriate techniques (e.g. ion selective electrode or ion chromatography) to obtain TOF of the sample.

[0012] Any combination and / or permutation of the embodiments is envisioned. Other objects and features will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0014] Figure 1 is a graphical depiction showing percent defluorination with addition of a solution containing sodium metal for neat PFOA powder dissolved in differentsolvents, in accordance with one or more embodiments of the present disclosure. Note sodium metal solution volume: 4 mL, solvent volume: 2 mL in this experiment.

[0015] Figure 2 is a graphical depiction illustrating percent defluorination with solution containing sodium metal addition for neat PFOA powder dissolved in acetonitrile with different percentages of water by volume, in accordance with one or more embodiments of the present disclosure. Note sodium metal solution volume: 4 mL, solvent volume: 2 mL in this exemplary embodiment.

[0016] Figure 3 is graphical depictions showing defluorination efficiencies as a function of the ratio of volume of sodium-containing solution added to the equivalent fluorine (mL Na° solution / mg F eq) in the sample for PFAS of varying chain length and functional group, in accordance with one or more embodiments of the present disclosure. Note: error bars denote standard deviation of replicate samples.DETAILED DESCRIPTION

[0017] Exemplary embodiments are directed to processes for the destruction of PFAS and measurement of fluorine in materials containing PFAS. It should be understood that embodiments could generally be applied to other substances.

[0018] The materials and the methods of the present disclosure used in one or more embodiments will be described below. While the embodiments discuss the use of specific compounds and materials, it is understood that the present disclosure could employ other suitable compounds or materials. Similar quantities or measurements may be substituted without altering the methods embodied below.

[0019] Definitions

[0020] As used herein, per- and polyfluoroalkyl substances (PFAS) refer to non- polymeric organic compounds including at least one carbon-fluorine (C-F) bond. Exemplary PFAS include, but are not limited to, perfluoroalkyl acids (PFAAs) such asperfluoroalkyl carboxylic acids (PFCAs) (e.g. trifluoroacetic acid (TFA), perfluorobutanoic acid (PFBA), perfluorohexane sulfonic acid (PFHxA), perfluorooctanoate (PFOA), perfluorononanoic acid (PFNA), perfluorododecanoic acid (PFDoA), perfluorotetradecanoic acid (PFTA), etc.), perfluorosulfonic acids (PFSAs) (e.g. perfluorooctane sulfonate (PFOS), perfluorobutanesulfonic acid (PFBS), etc.); perfluoroalkyl ether carboxylic acids (PFECAs) such as hexafluoropropylene oxide dimer acid (HFPO-DA); perfluoroalkane sulfonamides (FASAs); and fluorotelomer substances such as fluorotelomer alcohols (FTOH) and fluorotelomersulfonic acids (e.g. 4:2-fluorotelomersulfonic acid (4:2-FTS), 6:2-fluorotelomersulfonic acid (6:2-FTS), etc.). In one or more embodiments, the PFAS comprise PFOA and / or PFOS.

[0021] As used herein, a solution containing sodium metal refers to a solution containing sodium in its metallic (non-ionized) state (Na°). Sodium metal has a strong (very negative) redox potential. In one or more embodiments, the sodium metal is complexed with a complexing agent such as naphthalene and dissolved in a solvent such as tetra hydrofuran (THF) or diglyme. In one or more other embodiments, the solution is sodium metal in liquid ammonia.

[0022] As used herein, an organic aprotic solvent refers to an organic solvent that lacks a protic hydrogen. While not wishing to be bound by any particular theory, it is thought that the sodium metal and / or sodium complex (e.g. sodium naphthalene) reacts with protic hydrogens in solvents and thus the sodium metal and / or sodium complex can be degraded and no longer available for the defluorination reaction. Exemplary organic aprotic solvents include, but are not limited to, acetonitrile, mineral oil, hexane, heptane, toluene, etc. Alternatively, in one or more embodiments a protic organic solvent with a partially protected protic hydrogen (e.g. secondary or tertiary alcohol) may be used such as 2-propanol or t-butyl alcohol.

[0023] The methods described herein can be applied to any materials comprising PFAS, including PFAS-containing waste (e.g. AFFF, soil, sludge, biosolids, liquid / liqu id- phase waste, wastewater, leachate, filter cake, etc.), PFAS-containing environmental components (e.g., water, soil, air, plants, etc.), and PFAS-containing products (e.g. food, vegetables, meats, packaging materials, plastic products, toys, cosmetics,agricultural products, pharmaceutical products, electronics, personal care products, consumer products, etc.).

[0024] One or more embodiments of the present disclosure relate to a process for the destruction of PFAS. In various embodiments, the process comprises (i) extracting PFAS from a material comprising one or more PFAS using an organic solvent to form a PFAS extract; and (ii) adding a solution containing sodium metal to the PFAS extract. In some embodiments, rather than extracting the PFAS to form an extract, the material comprising one or more PFAS is mixed in an organic solvent to provide a mixture and the solution containing sodium metal is added to the mixture. In other embodiments, the material comprising one or more PFAS is added directly to the solution containing sodium metal without a prior step utilizing an organic solvent.

[0025] In one or more embodiments, the organic solvent comprises acetonitrile, 2- propanol, t-butyl alcohol, mineral oil, hexane, heptane, toluene, or combinations thereof.

[0026] In one or more embodiments, the organic solvent comprises an organic aprotic solvent. Exemplary organic aprotic solvents include, but are not limited to, acetonitrile, mineral oil, hexane, heptane, toluene, etc. In one or more embodiments, the organic solvent comprises acetonitrile.

[0027] In one or more embodiments, the solution containing sodium metal comprises sodium naphthalene. The sodium naphthalene may be provided in a solvent. One class of such solvents is glycol ethers / glyme-based solvents such as diglyme. Other solutions containing sodium metal may also be used, such as sodium metal dissolved in ammonia.

[0028] In one or more embodiments, the amount of sodium metal is in molar excess relative to the amount of fluorine in the PFAS. Exemplary molar ratios of sodium to fluorine include, but are not limited to, 1 :1 , 1.1 :1 , 1 .2:1 , 1.3:1 , 1.4: 1 , 1 .5:1 , 1.6:1 , 1.7:1 , 1.8:1 , 1.9:1 , 2:1 , 2.5:1 , 3:1 , 3.5:1 , 4:1 , 4.5:1 or 5:1.

[0029] In one or more embodiments, one or more steps is performed in the absence of water that can react with the solution containing sodium metal. In some embodiments, one or both of (i) extracting PFAS from a material comprising one or more PFAS using an organic solvent to form a PFAS extract or (ii) adding the solution containing sodiummetal to the PFAS extract occurs in the absence of water. In some embodiments, both (i) extracting PFAS from a material comprising one or more PFAS using an organic solvent to form a PFAS extract and (ii) adding the solution containing sodium metal to the PFAS extract occurs in the absence of water.

[0030] The process can be performed in aerobic or anaerobic conditions. In one or more embodiments, one or more steps are performed in aerobic conditions. In one or more embodiments, one or more steps are performed in anaerobic conditions. In some embodiments, adding the solution containing sodium metal to the PFAS extract occurs in anaerobic conditions.

[0031] The process can be performed at various temperatures. For example, one or more steps can be performed at ambient temperature, room temperature and / or an elevated temperature. Exemplary temperatures include 10 to 80 °C, such as 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80 °C or any range therebetween. In one or more embodiments, one or more steps is performed at ambient temperature and / or room temperature. In one or more embodiments, one or more steps is performed at room temperature. In one or more embodiments, one or more steps is performed at an elevated temperature above room temperature. In some embodiments, the defluorination reaction (e.g. adding the solution containing sodium metal to the PFAS extract / mixture) occurs at elevated temperature of 45 - 60 °C.

[0032] One or more embodiments of the present disclosure relate to a process for the measurement of extractable organic fluorine (EOF) in one or more samples. In various embodiments, the process comprises extracting PFAS from one or more samples using solid-phase or liquid-liquid extraction to form an extract of PFAS in an organic solvent; adding a solution containing sodium metal to the extract of PFAS in an organic solvent to form a fluorine-containing mixture, adding the fluorine-containing mixture to a known volume of water to form a fluoride-containing aqueous solution, and measuring fluoride concentration in the fluoride-containing aqueous solution.

[0033] The process for the measurement of EOF can utilize any of the solutions containing sodium metal (e.g. sodium naphthalene), solvents (e.g. organic aproticsolvents) or reaction conditions (e.g. temperatures, aerobic / anaerobic conditions) described herein.

[0034] In one or more embodiments, one or more of the steps up to and / or including the defluorination reaction (adding the solution containing sodium metal) is performed in the absence of water, but once the reaction is concluded, water is added to prepare the fluoride-containing aqueous solution.

[0035] The fluoride concentration can be measured according to any appropriate technique, including, but not limited to, ion selective electrode or ion chromatography.

[0036] One or more embodiments of the present disclosure relate to a process for the measurement of total organic fluorine (TOF) in one or more samples. In various embodiments, the process comprises adding one or more samples of PFAS to a solution containing sodium metal to form a fluorine-containing mixture, adding the fluorine-containing mixture to a known volume of water to form a fluoride-containing aqueous solution, and measuring fluoride concentration in the fluoride-containing aqueous solution.

[0037] The process for the measurement of TOF can utilize any of the solutions containing sodium metal (e.g. sodium naphthalene) or reaction conditions (e.g. temperatures, aerobic / anaerobic conditions) described herein.

[0038] In one or more embodiments, one or more of the steps up to and / or including the defluorination reaction (adding the solution containing sodium metal) is performed in the absence of water, but once the reaction is concluded, water is added to prepare the fluoride-containing aqueous solution.

[0039] As with the measurement of EOF, the fluoride concentration for the measurement of TOF can be measured according to any appropriate technique, including, but not limited to, ion selective electrode or ion chromatography.EXAMPLES

[0040] The present invention is further illustrated by the following non-limiting Examples.Materials, Equipment, and Methods

[0041] All chemicals and solvents were of either certified ACS reagent grade or LC / MS with high purity and were purchased from Sigma-Aldrich (USA) and Fisher Scientific (USA). Samples were prepared in borosilicate glass vials. PFAS powders were carefully transferred into the vials and weight was noted. A solution containing sodium metal, such as sodium and naphthalene suspended in diglyme, was carefully shaken prior to use to dissolve suspended solids and was transferred to a borosilicate glass container and capped before use, with minimal air gap. It will be understood that other suitable solutions could be any solution containing sodium metal besides sodium naphthalene complex, such as sodium metal in liquid ammonia.

[0042] Based on the experiment, different volumes of the solution containing sodium metal were carefully pipetted into the glass vials containing neat PFAS powders. For certain runs, 2 ml of different solvents, such as methanol, DCM, and acetonitrile, were added to the vials with neat PFAS materials to dissolve PFAS prior to sodium-containing solution addition. After the addition of the solution containing sodium metal, the vials were capped and carefully mixed with hand to initiate PFAS-Na reactions. To end the reaction after approximately 5 minutes, 1 ml deionized water (DIW) was added. Post treatment, inorganic fluorine was measured by using an ion selective electrode from Hach (HQ440d). This value was multiplied by the dilution factor to obtain the corrected fluorine concentration. The expected initial fluorine concentration (mg / L) was estimated by dividing the mass of PFAS (mg) by the total volume of liquid added in mL (i.e. volume of organic solvent + water + sodium metal solution). This was utilized to calculate the defluorination efficiency by the following equation:To normalize for the variation in mass of PFAS taken during each run, the volume of the solution containing sodium metal was divided by the initial total fluorine (ITF), calculated by multiplying the mass of PFAS taken by the percentage of molar fluorine.Example 1 - Identification of Solvents

[0043] Preliminary experiments included identifying the solvents to dissolve PFAS in prior to addition of the solution containing sodium metal. This was to ensure that all thePFAS was in the dissolved phase and was able to react fully with the solution containing sodium metal. PFOA was chosen in this embodiment and methanol (MeOH), ethanol (EtOH), acetonitrile (ACN) and dichloromethane (DCM) were chosen as the solvents. Neat PFOA powder (approximately 15-20 mg) was transferred and weighed out and 2 ml solvent and 4 mL solution containing sodium metal were added to the vials. Sample preparation and fluorine measurement steps disclosed herein were followed to calculate the present defluorination efficiency.

[0044] As shown in Figure 1 , there was no defluorination observed when methanol and ethanol were chosen as the solvents. Less than 10% defluorination was observed when PFOA was dissolved in DCM but near complete defluorination was observed when acetonitrile was chosen as the solvent. The poor defluorination efficiency for samples containing ethanol, methanol, and DCM can be attributed to the scavenging effect of sodium naphthalene, the primary reactant / reducing agent. This effect was not observed while using acetonitrile with the corrected inorganic fluorine accounting for approximately 100% of the initial fluorine introduced by addition of PFOA. It will be understood that other suitable solvents, or combination of organic solvents, could be used besides acetonitrile, such as 2-propanol, t-butyl alcohol, mineral oil, hexane, heptane, toluene, etc.

[0045] The presence of moisture can severely impact the effectiveness of the solution containing sodium metal. To investigate this further, different percentages of water (0, 5, 10, 25 and 50%) were tested in a solution with acetonitrile, maintaining the total solvent volume fixed at 2 mL. As shown in Figure 2, with 100% acetonitrile, defluorination efficiency was approximately 100%, which dropped to approximately 30 and 20 % when 5 and 10% water (%v / v) was added to the solvent solution, respectively. Beyond this, at 25, 37.5, and 50% water addition, no defluorination of PFOA was observed, indicating the inactivation of the sodium metal in the solution. This could be attributed to the instantaneous reaction of sodium metal with water, also indicated by a rapid increase in vial temperature. This restricts the formation of sodium naphthalene (Na-naph), thus preventing the reactions with PFOA. Thus, while using the solution containing sodium metal, it is important to ensure that the samples are void of any moisture. Thus, PFAS material in acetonitrile with no water addition was determined tobe the preferred treatment condition for treatment with the solution containing sodium metal.Example 2 - Defluorination of Various PFAS

[0046] The defluorination of seven PFAS (4 PFCAs, 2 PFSAs, and 4:2 FTS) was studied with varying functional groups and chain lengths. 4 PCFCAS (perfluorobutanoic acid (PFBA), perfluorooctanoate (PFOA), perfluorododecanoic acid (PFDoA) and perfluorotetradecanoic acid (PFTA)), 2 PFSAs (potassium perfluorooctane sulfonate (K- PFOS) and perfluorobutanesulfonic acid (PFBS)), and 4:2-fluorotelomersulfonic acid (4:2-FTS) are shown in Figure 3. For each PFAS, the solution containing sodium metal was transferred to a vial containing neat PFAS standards (solid / liquid) + 2 mL acetonitrile, and the sample processing and fluorine analysis was performed using steps disclosed herein. Volumes of solution containing sodium metal tested were 1 , 2, and 4 ml, with the target PFAS weight and acetonitrile volume remaining constant.

[0047] As shown in Figure 3, for PFCAs, increasing the volume of solution containing sodium metal added, denoted by the x axis parameter (mL Na° solution / mg F eq) increased the defluorination efficiency. PFTA showed the highest defluorination efficiencies, with approximately 70, 82, and 100% defluorination observed when 1 , 2, and 4 mL Na° solution was added, respectively (mL Na° solution / mg F eq ratios of 0.1 , 0.16, and 0.36). PFDoA and PFOA showed similar defluorination trends with approximately 25 and 95% and approximately 27 and 80% defluorination observed for PFOA and PFDoA at mL Na° solution / mg F eq ratios of 0.1 , 0.39, 0.08, and 0.35 respectively. Although the defluorination trends under similar conditions for PFBA were comparatively suppressed, it was interestingly observed approximately 53 and 91 % defluorination for PFBA at mL Na° solution / mg F eq ratios of 0.19 and 0.4, respectively. The increase in defluorination efficiencies can be explained by increased sodium metal available to react with PFAS molecules.

[0048] As shown in Figure 3, similar to PFTA, 4:2 FTS showed approximately 80 % defluorination at mL Na° solution / mg F ratio of 0.11 . Near complete defluorination was observed when sodium solution volume was increased to 4 mL (mL Na° solution / mg Fratio = 0.46). K-PFOS showed better degradation than PFOA with approximately 59% defluorination observed at similar mL Na° solution / mg F ratio of 0.1. Increasing this ratio (0.21 , 0.38) led to complete defluorination of K-PFOS. For PFBS, no defluorination was observed at mL Na° solution / mg F ratio of 0.13. As sodium solution volume increased, approximately 23% defluorination was observed at mL Na° solution / mg F ratio of 0.46. This may occur in view of the compact geometry and high bond dissociation energy necessary to break the C-F bonds on the C-C skeleton21. The defluorination efficiency can be further increased by creating an anaerobic environment and increasing the reaction temperature 45-60 °C. While not wishing to be bound by theory, it is believed that increasing the temperature helps with reducing the viscosity of the Na° solution and thus more active sodium is released for the reaction with PFAS.

[0049] While exemplary embodiments have been described herein, it is expressly noted that these embodiments should not be construed as limiting, but rather that additions and modifications to what is expressly described herein also are included within the scope of the invention. Moreover, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and permutations, even if such combinations or permutations are not made express herein, without departing from the spirit and scope of the invention.References1. Appleman, T. D.; Higgins, C. P.; Quinones, O.; Vanderford, B. J.; Kolstad, C.; Zeigler-Holady, J. C.; Dickenson, E. R., Treatment of poly- and perfluoroalkyl substances in U.S. full-scale water treatment systems. Water Res 2014, 51, 246-55.2. Rahman, M. F.; Peldszus, S.; Anderson, W. 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Claims

CLAIMSWhat is claimed is:1 . A process for the destruction of per- and polyfluoroalkyl substances (PFAS), the process comprising:(i) extracting PFAS from a material comprising one or more PFAS using an organic solvent to form a PFAS extract; and(ii) adding a solution containing sodium metal (Na°) to the PFAS extract.

2. The process of claim 1 , wherein the organic solvent comprises an organic aprotic solvent.

3. The process of claim 1 , wherein the organic solvent comprises acetonitrile, 2-propanol, t-butyl alcohol, mineral oil, hexane, heptane, toluene, or combinations thereof.

4. The process of claim 1 , wherein the organic solvent comprises acetonitrile.

5. The process of any one of claims 1-4, wherein the solution containing sodium metal (Na°) comprises sodium naphthalene.

6. The process of any one of claims 1-5, wherein one or both of (i) extracting PFAS from a material comprising one or more PFAS using an organic solvent to form a PFAS extract or (ii) adding the solution containing sodium metal (Na°) to the PFAS extract occursin the absence of water.

7. The process of any one of claims 1-6,, wherein (ii) adding the solution containing sodium metal (Na°) to the PFAS extract occurs in anaerobic conditions.

8. The process of any one of claims 1-7, wherein (ii) adding the solution containing sodium metal (Na°) to the PFAS extract occurs at elevated temperature of 45 - 60 °C.

9. A process for the measurement of extractable organic fluorine (EOF), the process comprising: extracting per- and polyfluoroalkyl substances (PFAS) from one or more samples using solid-phase or liquid-liquid extraction to form an extract of PFAS in an organic solvent; adding a solution containing sodium metal (Na°) to the extract of PFAS in an organic solvent to form a fluorine-containing mixture, adding the fluorine-containing mixture to a known volume of water to form a fluoride-containing aqueous solution; and measuring fluoride concentration in the fluoride-containing aqueous solution.

10. The process of claim 9, wherein the organic solvent comprises an organic aprotic solvent.

11. The process of claim 9, wherein the organic solvent comprisesacetonitrile, 2-propanol, t-butyl alcohol, mineral oil, hexane, heptane, toluene, or combinations thereof.

12. The process of any one of claims 9-11 , wherein the solution containing sodium metal (Na°) comprises sodium naphthalene.

13. The process of any one of claims 9-12, wherein adding a solution containing sodium metal (Na°) to the extract to form a fluorine- containing mixture occurs in the absence of water.

14. The process of any one of claims 9-13, wherein adding a solution containing sodium metal (Na°) to the extract to form a fluorine- containing mixture occurs in anaerobic conditions.

15. The process of any one of claims 9-14, wherein adding a solution containing sodium metal (Na°) to the extract to form a fluorine- containing mixture occurs at elevated temperature of 45 - 60 °C.

16. A process for the measurement of total organic fluorine (TOF), the process comprising: adding one or more samples comprising per- and polyfluoroalkyl substances (PFAS) to a solution containing sodium metal (Na°) to form a fluorine-containing mixture, adding the fluorine-containing mixture to a known volume of water to form a fluoride-containing aqueous solution; and measuring fluoride concentration in the fluoride-containing aqueous solution.

17. The process of claim 16, wherein the solution containing sodium metal (Na°) comprises sodium naphthalene.

18. The process of claim 16 or 17, wherein adding one or more samples comprising per- and polyfluoroalkyl substances (PFAS) to a solution containing sodium metal (Na°) to form a fluorine- containing mixture occurs in the absence of water.

19. The process of any one of claims 16-18, wherein adding one or more samples comprising per- and polyfluoroalkyl substances(PFAS) to a solution containing sodium metal (Na°) to form a fluorine-containing mixture in anaerobic conditions.

20. The process of any one of claims 12-20, wherein adding one or more samples comprising per- and polyfluoroalkyl substances(PFAS) to a solution containing sodium metal (Na°) to form a fluorine-containing mixture occurs at elevated temperature of 45 - 60 °C.

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