Methods and systems for electrochemical removal of perfluoroalkyl compounds from liquid compositions

Abstract

Described herein are methods and systems for electrochemically removing perfluoroalkyl compounds from liquid compositions. The methods and systems described herein achieve a higher degradation rate with cathodes composed of a carbon-based material, while simultaneously requiring lower energy consumption compared to electrochemical oxidation processes for the same level of degradation of perfluoroalkyl compounds. The cathodes can be reactivated by applying an electric current to the cathode, which ultimately increases efficiency and reduces costs with respect to remediating liquid compositions such as, for example, wastewater, contaminated with perfluoroalkyl compounds.

Description

ATTORNEY DOCKET NO. 222105-2400METHODS AND SYSTEMS FOR ELECTROCHEMICAL REMOVAL OF PERFLUOROALKYL COMPOUNDS FROM LIQUID COMPOSITIONSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to co-pending U.S. Provisional Patent Application No. 63 / 754,737, filed on February 6, 2025, the contents of which are incorporated by reference herein in their entireties.BACKGROUND

[0002] Per- and poly-fluoroalkyl substances (PFAS), often referred to as “forever chemicals” due to their persistence in the environment, can cause health risks to humans and wildlife1’3, and have thus prompted significant public concern and regulatory actions worldwide1. The Organization for Economic Co-operation and Development (OECD) defines PFAS as organic substances that contain at least one fluorinated methyl (-CF3) or methylene carbon (-CF2-) atoms but without attaching H, Cl, Br, and I atoms4’5 6. In April 2024, the US EPA finalized the Maximum Contaminant Levels (MCLs) for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) at 4.0 parts per trillion (ppt)7. PFOA and PFOS are among the PFAS most commonly detected in natural waters, both belonging to perfluoroalkyl acids (PFAAs), a subclass of PFAS characterized by a perfluoroalkyl chain and an acid head group8. PFAAs possess extraordinary chemical and thermal stability because of their helical conformations and the strong C-F bonds (~ 485 kJ mok1)9’10, making their degradation for treatment purposes a significant challenge.

[0003] Remediation and treatment of water contaminated by PFOA / PFOS and other PFAS are extremely challenging, because the extreme chemical stability of PFOA / PFOS renders them highly resistant to conventional treatment technologies or advanced oxidation processes (AOPs). Thus, a feasible and economical technology for effectively degrading these chemicals in water or other aqueous solutions is desirable.ATTORNEY DOCKET NO. 222105-2400SUMMARY

[0004] The present disclosure provides methods and systems for electrochemically removing perfluoroalkyl compounds from liquid compositions. The methods and systems described herein achieve a higher degradation rate with cathodes composed of a carbon-based material, while simultaneously requiring lower energy consumption compared to electrochemical oxidation processes for the same level of degradation of perfluoroalkyl compounds. The cathodes can be reactivated by applying an electric current to the cathode, which ultimately increases efficiency and reduces costs with respect to remediating liquid compositions such as, for example, wastewater, contaminated with perfluoroalkyl compounds.

[0005] Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims. In addition, all optional and preferred features and modifications of the described embodiments are usable in all aspects of the disclosure taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described embodiments are combinable and interchangeable with one another.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Further aspects of the present disclosure will be more readily appreciated upon review of the detailed description of its various embodiments, described below, when taken in conjunction with the accompanying drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.ATTORNEY DOCKET NO. 222105-2400

[0007] FIG. 1 shows Schematic mechanism of adsorption and ER of GAC cathode for PFAS treatment.

[0008] FIGS. 2A-2D show the change of PFAS concentration in the anodic chamber (EG) and the cathodic chamber (ER) during ET in a divided reactor with 0.1-g GAC cathode and Ti4O? anode: (a) PFOS for 48 h and (b) PFBS for 1000 h; The ratio of PFAS removal by ER in the cathodic chamber and recovery ratio from the GAC cathode after ER or adsorption by methanol with 1 vol% ammonium hydroxide: (c) PFOS removal and recovery ratio via ER and adsorption after 48 h and (d) PFBS removal and recovery ratio via ER and adsorption after 1000 h.

[0009] FIGS. 3A-3B show (a) change of PFOS concentration in an undivided reactor via ET and adsorption using 3 g GAC and (b) the calculated ko sof ET and adsorption.

[0010] FIGS. 4A-4D show the concentration change of six PFAS species (PFOS, PFNA, PFOA, PFHxS, PFBS, and GenX, 1-ppm initial concentration of each) in the undivided reactor with a 3-g GAC cathode and a Ti4O? anode by (a) ET (20 mA cm'2) and (b) adsorption (without electric current applied). The corresponding observed rate constant (kObs) for the six PFAS under (c) ET and (d) adsorption.

[0011] FIG. 5 shows degradation curves of PFOS under REM reactor at a flow rate of 0.5 ml min-1.

[0012] FIGS. 6A-6E show (a) the change of six PFAS concentrations during ET in two cycles in undivided reactor with 3-g cathode; (b) long-term electrochemical degradation stability of high-concentration PFOS of 100 ppm using 0.1 g of GAC as the cathode; (c) GAC surface morphology before use and after PFOS treatment: (d) adsorption and (e) ET after 48 h.

[0013] FIG. 7 shows an exemplary system described herein for removing perfluoroalkyl compounds from a liquid composition, wherein the system includes a reservoir.ATTORNEY DOCKET NO. 222105-2400

[0014] FIG. 8 shows a cross-section view of an exemplary system described herein for removing perfluoroalkyl compounds from a liquid composition, wherein the system includes alternating cathodes and anodes.

[0015] FIGS. 9A-B show cross-section view of a cathode surrounded by an anode.

[0016] FIG. 10 shows a cross-section view of an exemplary system described herein for removing perfluoroalkyl compounds from a liquid composition, wherein the system includes a cathode surrounded by an anode.

[0017] The drawings illustrate only example embodiments and are therefore not to be considered limiting of the scope described herein, as other equally effective embodiments are within the scope and spirit of this disclosure. The elements and features shown in the drawings are not necessarily drawn to scale, emphasis instead being placed upon clearly illustrating the principles of the embodiments. Additionally, certain dimensions may be exaggerated to help visually convey certain principles. In the drawings, similar reference numerals between figures designate like or corresponding, but not necessarily the same, elements.DETAILED DESCRIPTION

[0018] The details of some embodiments of the present disclosure are set forth in the description below. Other features, objects, and advantages of the present disclosure will be apparent to one of skill in the art upon examination of the following description, drawings, examples and claims. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims

[0019] Before the present compounds, compositions, articles, devices, and / or methods are disclosed and described, it is to be understood that the aspects described below are not limited to specific compounds, synthetic methods, or uses as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.ATTORNEY DOCKET NO. 222105-2400

[0020] Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0021] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present disclosure.

[0022] Any recited method can be carried out in the order of events recited or in any other order that is logically possible. That is, unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

[0023] All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided herein can be different from the actual publication dates, which can require independent confirmation.

[0024] While aspects of the present disclosure can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenienceATTORNEY DOCKET NO. 222105-2400only and one of skill in the art will understand that each aspect of the present disclosure can be described and claimed in any statutory class.

[0025] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed compositions and methods belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0026] Prior to describing the various aspects of the present disclosure, the following definitions are provided and should be used unless otherwise indicated. Additional terms may be defined elsewhere in the present disclosure.Definitions

[0027] In describing and claiming the disclosed subject matter, the following terminology will be used in accordance with the definitions set forth below.

[0028] As used herein, “comprising” is to be interpreted as specifying the presence of the stated features, integers, steps, or components as referred to, but does not preclude the presence or addition of one or more features, integers, steps, or components, or groups thereof. Moreover, each of the terms “by”, “comprising,” “comprises”, “comprised of,” “including,” “includes,” “included,” “involving,” “involves,” “involved,” and “such as” are used in their open, non-limiting sense and may be used interchangeably. Further, the term “comprising” is intended to include examples and aspects encompassed by the terms “consisting essentially of” and “consisting of.” Similarly, the term “consisting essentially of” is intended to include examples encompassed by the term “consisting of.ATTORNEY DOCKET NO. 222105-2400

[0029] As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a perfluoroalkyl compound” includes, but are not limited to, mixtures or combinations of two or more such compounds, and the like.

[0030] It should be noted that ratios, concentrations, amounts, rates, and other numerical data can be expressed herein in a range format. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms a further aspect. For example, if the value “about 10” is disclosed, then “10” is also disclosed and “about 5 to about 15” is also disclosed.

[0031] When a range is expressed, a further aspect includes from the one particular value and / or to the other particular value. For example, where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure, e.g. the phrase “x to y” includes the range from ‘x’ to ‘y’ as well as the range greater than ‘x’ and less than ‘y’. The range can also be expressed as an upper limit, e.g. ‘about x, y, z, or less’ and should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z’ as well as the ranges of ‘less than x’, less than y’, and ‘less than z’. Likewise, the phrase ‘about x, y, z, or greater’ should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z’ as well as the ranges of ‘greater than x’, greater than y’, and ‘greater than z’. In addition, the phrase “about ‘x’ to ‘y’”, where ‘x’ and ‘y’ are numerical values, includes “about ‘x’ to about ‘y’”.ATTORNEY DOCKET NO. 222105-2400

[0032] It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a numerical range of “about 0.1% to 5%” should be interpreted to include not only the explicitly recited values of about 0.1% to about 5%, but also include individual values (e.g., about 1%, about 2%, about 3%, and about 4%) and the sub-ranges (e.g., about 0.5% to about 1.1%; about 5% to about 2.4%; about 0.5% to about 3.2%, and about 0.5% to about 4.4%, and other possible sub-ranges) within the indicated range.

[0033] As used herein, the terms “about,” “approximate,” “at or about,” and “substantially” mean that the amount or value in question can be the exact value or a value that provides equivalent results or effects as recited in the claims or taught herein. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art such that equivalent results or effects are obtained. In some circumstances, the value that provides equivalent results or effects cannot be reasonably determined. In such cases, it is generally understood, as used herein, that “about” and “at or about” mean the nominal value indicated ±10% variation unless otherwise indicated or inferred. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about,” “approximate,” or “at or about” whether or not expressly stated to be such. It is understood that where “about,” “approximate,” or “at or about” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0034] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order.ATTORNEY DOCKET NO. 222105-2400Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; and the number or type of embodiments described in the specification.

[0035] Disclosed are the components to be used to prepare the compositions disclosed herein as well as the compositions themselves to be used within the methods disclosed herein. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds cannot be explicitly disclosed, each is specifically contemplated and described herein. For example, if a particular compound is disclosed and discussed and a number of modifications that can be made to a number of molecules including the compounds are discussed, specifically contemplated is each and every combination and permutation of the compound and the modifications that are possible unless specifically indicated to the contrary. Thus, if a class of molecules A, B, and C are disclosed as well as a class of molecules D, E, and F and an example of a combination molecule, A-D is disclosed, then even if each is not individually recited each is individually and collectively contemplated meaning combinations, A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F are considered disclosed. Likewise, any subset or combination of these is also disclosed. Thus, for example, the sub-group of A-E, B-F, and C-E would be considered disclosed. This concept applies to all aspects of this application including, but not limited to, steps in methods of making and using the compositions of the invention. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps canATTORNEY DOCKET NO. 222105-2400be performed with any specific embodiment or combination of embodiments of the methods of the invention.

[0036] It is understood that the compositions disclosed herein have certain functions. Disclosed herein are certain structural requirements for performing the disclosed functions, and it is understood that there are a variety of structures that can perform the same function that are related to the disclosed structures, and that these structures will typically achieve the same result.

[0037] As used herein, the terms “optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance and instances where it does not.

[0038] As used herein, “Magneli phase” indicates a class of certain transition metal sub-oxides, such as titanium, that have a distinct graphite-like crystalline structure featuring shear planes in the crystalline structure, which provides improved electrical conductivity to the material. For titanium, Magneli phase titanium sub-oxides have the formula TinO2n-i, where n is any integer between 3 and 10.

[0039] A perfluoroalkyl compound refers to a class of highly fluorinated aliphatic compounds having multiple or all hydrogens replaced by fluorine atoms. Polyfluoroalkyl compounds are compounds that contain the perfluoroalkyl moiety CnF2n+i, where n is an integer typically between 3 and 10, where all hydrogens have been replaced by fluorine atoms, whereas polyfluorinated compounds may have only some of the hydrogens replaced by fluorine. Some common perfluoroalkyl compounds include perfluoroalkyl acids (PFAAs), which are typically more difficult to degrade. Examples of PFAAs include, but are not limited to, perfluorocarboxylic acids (PFCAs) and perfluorosulfonates (PFSAs), with perfluorooctanoate (PFOA) being an example of a common PFCA contaminant and perfluorooctane sulfonate (PFOS) being an example of a common PFSA contaminant. Other non-limiting examples include perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS),ATTORNEY DOCKET NO. 222105-2400perfluorobutanesulfonic acid (PFBS), hexafluoropropylene oxide dimer acid (HFPO-DA), perfluoroheptanesulfonic acid (PFHpS), 6:2 fluorotelomer sulfonate (6:2 FTS), perfluoroheptanoic acid (PFHpA), perfluoropentanesulfonic acid (PFPeS), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), and perfluorobutanoic acid (PFBA).

[0040] As used herein, the term “mineralization” refers to the process of breaking down an organic substance, such as polyfluoroalkyl compounds, into mineral and / or inorganic components.

[0041] As used in the present disclosure, two materials are in “electrochemical communication” when electrons generated by a chemical reaction of one material can be transferred to and / or accepted by the other material.

[0042] Methods and Systems for Electrochemically Removing Perfluoroalkyl Compounds from Liquid Compositions

[0043] The present disclosure provides methods and systems for electrochemically removing perfluoroalkyl compounds from liquid compositions. The methods and systems described herein achieve a higher degradation rate with cathodes composed of a carbon-based material, while simultaneously requiring lower energy consumption compared to electrochemical oxidation processes for the same level of degradation of perfluoroalkyl compounds. The cathodes can be reactivated by applying an electric current to the cathode, which ultimately increases efficiency and reduces costs with respect to remediating liquid compositions such as, for example, wastewater, contaminated with perfluoroalkyl compounds.

[0044] In one aspect, methods of electrochemically removing the perfluoroalkyl compound include contacting a liquid composition comprising one or more perfluoroalkyl compounds, such as an aqueous composition (e.g., contaminated wastewater) with a cathode and supplying electric current to the cathode, wherein the cathode electrochemically reduces the perfluoroalkyl compound. With respect to “removing” the perfluoroalkyl compound, in one aspect, the perfluoroalkyl compoundATTORNEY DOCKET NO. 222105-2400is converted to another chemical species. For example, one or more fluorine atoms of the perfluoroalkyl compound can be replaced with hydrogen (i.e., defluorination). In another aspect, one or more carbon-carbon bonds of the perfluoroalkyl compound can be cleaved to produce short chain perfluoroalkyl compounds. In another aspect, the perfluoroalkyl compound can be absorbed by the cathode and / or anode.

[0045] The carbon-based material can be a variety of different materials. In one aspect, the carbon-based material is activated carbon (e.g., fibers, cloth, powder, or granulated particles), graphene, graphite, or carbon nanotubes. In another aspect, the carbon-based material is granular activated carbon (GAC). Activated carbon such as granular activated carbon is made of tiny clusters of carbon atoms stacked upon one another, and is produced by heating the carbon source (coal, lignite, wood, nutshells, or peat) in the absence of air or chemically treating the carbon, which produces a high carbon content material. Granular activated carbon has a random porous structure, containing a broad range of pore sizes ranging from visible cracks and crevices down to molecular dimensions. GAC uses this porous structure to remove dissolved contaminants from water in a process known as adsorption. This porous structure leads to an extremely large amount of adsorption surface area.

[0046] The physical properties of the GAC can be modified depending upon the conditions of the liquid composition and the nature / amount of the perfluoroalkyl compound. In one aspect, the granulated activated carbon has a carbon tetrachloride number (CTN) as determined by ASTM D3467 of at least 50 or from 50 to 200. In another aspect, the granulated activated carbon has a carbon tetrachloride number (CTN) as determined by ASTM D3467 of 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 1900, or 200, where any value can be a lower and upper endpoint of a range (e.g., 70 to 100). In another aspect, the granulated activated carbon has a relative surface area as measured by Iodine Number as determined by ASTM D4607 of at least 800 mg / g, or from 800 mg / g to 1,200 mg / g. In another aspect, the granulated activated carbon has a relative surface area as measured by Iodine Number asATTORNEY DOCKET NO. 222105-2400determined by ASTM D4607 of 800 mg / g, 850 mg / g, 900 mg / g, 950 mg / g, 1,000 mg / g, 1,050 mg / g, 1,100 mg / g, 1,150 mg / g, or 1,200 mg / g, where any value can be a lower and upper endpoint of a range (e.g., 850 mg / g to 1,100 mg / g). In one aspect, the granulated activated carbon has an Abrasion Number as determined by ASTM D3802-16 of at least 70, or from 70 to 120. In another aspect, the granulated activated carbon has an Abrasion Number as determined by ASTM D3802-16 of 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, or 120, where any value can be a lower and upper endpoint of a range (e.g., 80 to 100).

[0047] In other aspect, the cathode consists of only the carbon-based material, where no other components or elements or at most 0.1 weight percent (e.g. , impurities) are present in the cathode. In one aspect, the cathode composed of the carbon-based material can be configured in any form including rods, sheets, plates, discs, or any other suitable form. In other aspects, the carbon-based material can be incorporated into a metal pouch, where the pouch is permeable to the liquid composition.

[0048] In one aspect, the anode is a Magneli phase titanium suboxide (TSO) ceramic electrode. In one aspect, the Magneli phase TSO ceramic material includes titanium oxide materials with the general formula: TinO2n-i, where n is any integer between 3 and 10. In one aspect, the Magneli phase titanium oxide ceramic material includes Ti4O7, Ti5Og, or a combination of both, such as in Ebonex®. In another aspect, the Magneli phase titanium oxide ceramic material consists essentially of or consists of Ti4O7. In another aspect, the Magneli phase titanium oxide ceramic material consists essentially of or consists of Ti4O7, TisOg, or a combination thereof.

[0049] In some aspects, the Magneli phase TSO ceramic material of the anode is a porous material, such as a porous disk or membrane. The porosity increases the surface area of the Magneli phase TSO ceramic material as well as allowing the material / electrode to function as a filter. The use of the porous Magneli phase TSO ceramic material also provides advantages when treating a liquid composition that has not been pre-concentrated. In one aspect, the porous Magneli phase TSO ceramic isATTORNEY DOCKET NO. 222105-2400made of Ti4O?, TisOg, or a combination of both. In one aspect, the pores of the Magneli phase TSO ceramic anode include a plurality of micropores. In one aspect, one or more pores may extend through the Magneli phase TSO ceramic anode. In one aspect, one or more pores may extend into but not through the Magneli phase TSO ceramic anode, for example the pores may extend 1 nm to 10 cm into the Magneli phase TSO ceramic anode. In one aspect, one or more pores may be interconnected. In one aspect, the micropores can have diameters from about 0.1 pm (100nm) to 10 pm. In one aspect, depending on the materials to be passed over the anode, the pore size can be tailored to the application. In one aspect, the micropores have diameters from about 280 nm to 8 pm. In one aspect, the micropores have an average pore diameter of about 1.0 to 5.0 pm. In yet another aspect, the micropores have an average diameter of about 2.0 to 3.6 pm, as well as intervening ranges to those specifically disclosed. In one aspect, the average pore size is about 2.6 pm.

[0050] The porosity of the Magneli phase TSO ceramic anode can also be controlled and tailored to the application. In one aspect, the porosity can be about 5-75%, about 10-50%, about 15-30%, and other intervening ranges. In one aspect, the Magneli phase TSO ceramic anode has a porosity of about 21.6%. In one aspect, at least a portion of the plurality of micropores are interconnected. Interconnected micropores provides advantages if using the electrodes as filters as well, such as in a reactive electrochemical membrane (REM) filtration unit, to improve filtration through the electrode membrane at low applied pressures.

[0051] In another aspect, the anode comprises boron-doped diamond (BDD), PbC>2, or a mixed metal oxide comprising I rC>2, RuC>2, or Ta2Os.

[0052] The liquid composition used in the methods and systems described herein is any fluid that includes one or more perfluoroalkyl compounds. In one aspect, the liquid composition is composed of an organic solvent, water, or a combination thereof. In one aspect, the liquid composition is wastewater (e.g., manufacturing wastewater, runoff, etc.), contaminated groundwater, and the like.ATTORNEY DOCKET NO. 222105-2400

[0053] In one aspect, the liquid composition is pre-treated via electrocoagulation, membrane filtration or other methods to concentrate the perfluoroalkyl compounds in the liquid composition to improve the electrochemical removal of the perfluoroalkyl compounds to less stable and toxic compounds. In one aspect, the pre-concentration of the liquid composition is done by an electrocoagulation technique, such as described in U.S. Patent Publication No. 2015 / 0360975, which is hereby incorporated by reference herein. Briefly described, the electrocoagulation (EC) process produces amorphous hydrophobic zinc hydroxide flocs in situ that effectively sorb the perfluoroalkyl compounds to purify the liquid composition. The sorbed perfluoroalkyl compounds are then released to a concentrated solution via appropriate treatments. The concentrated perfluoroalkyl compounds are subsequently electrochemically removed.

[0054] In one aspect, the pH of the liquid composition containing the perfluoroalkyl compounds can be adjusted prior to electrochemical reduction. As demonstrated herein. Modifying the pH of the liquid composition can enhance the degradation rate of the perfluoroalkyl compounds while minimizing energy consumption. In one aspect, the pH of the liquid composition is about 7.0 to about 9.0, or about 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.6, 8.8, or 9.0, where any value can be a lower and upper endpoint of a range (e.g., 7.2 to 8.4).

[0055] Various perfluoroalkyl compounds can be electrochemically removed by the methods and systems described herein. In one aspect, the perfluoroalkyl compounds include compounds such as, but not limited to, perfluoroalkyl acids (PFAAs), including, but not limited to, perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS), or combinations of PFOA and PFOS. In one aspect, the perfluoroalkyl compound is perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), perfluorobutanesulfonic acid (PFBS), hexafluoropropylene oxide dimer acid (HFPO-DA), perfluoroheptanesulfonic acid (PFHpS), 6:2 fluorotelomer sulfonate (6:2 FTS),ATTORNEY DOCKET NO. 222105-2400perfluoroheptanoic acid (PFHpA), perfluoropentanesulfonic acid (PFPeS), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluorobutanoic acid (PFBA), or any combination thereof. Other contaminants that may be electrochemically reduced using the methods and systems described herein including, but not limited to, substituted phenols, tetracycline, and trichloroethylene.

[0056] The electric current applied to cathode and anode can be any power source such as, for example, a DC power source. The methods and systems described herein are energy efficient, where increased degradation of the perfluoroalkyl compounds is achieved with lower energy consumption when compared to electrochemical oxidation of the perfluoroalkyl compounds at the same energy level. In one aspect, the electric current supplied to the cathode and anode is from about 5 mA / cm2to about 50 mA / cm2, or about 5 mA / cm2, 10 mA / cm2, 12 mA / cm2, 14 mA / cm2, 16 mA / cm2, 18 mA / cm2, 20 mA / cm2, 22 mA / cm2, 24 mA / cm2, 26 mA / cm2, 28 mA / cm2, 30 mA / cm2, 32 mA / cm2, 34 mA / cm2, 36 mA / cm2, 38 mA / cm2, 40 mA / cm2, 42 mA / cm2, 44 mA / cm2, 46 mA / cm2, 48 mA / cm2, or 50 mA / cm2, where any value can be a lower and upper endpoint of a range (e.g., 18 mA / cm2to 22 mA / cm2).

[0057] The methods and systems described herein efficiently remove perfluoroalkyl compounds in liquid compositions. In one aspect, the methods and systems can remove perfluoroalkyl compounds at a rate from about 85% to 99%. The degradation products and mechanisms can vary as demonstrated in the Examples.

[0058] In another aspect, the cathodes described herein can be reactivated after use. In one aspect, the cathode with adsorbed perfluoroalkyl compound can be electrochemically reduced to remove the absorbed perfluoroalkyl compound. For example, an electric current can be applied to the cathode in the absence of liquid composition contaminated with perfluoroalkyl compound to reduce any perfluoroalkyl compound absorbed on the cathode and regenerate the cathode for further use. The Examples provide non-limiting procedures for reactivating a cathode described herein.ATTORNEY DOCKET NO. 222105-2400

[0059] Also described herein are systems for electrochemically removing perfluoroalkyl compounds from a liquid composition. In one aspect, the system includes a reservoir for containing a liquid composition contaminated with one or more perfluoroalkyl compounds and a cathode, wherein the cathode is configured in the reservoir such that it is in electrochemical communication with the liquid composition in the reservoir. The system can also include components of an electrochemical cell such that an electric current is supplied to the cathode. In one aspect, the system further includes a anode / counter electrode, and a power source (e.g., a DC regulated power source).

[0060] Referring to FIG. 7, liquid composition 151 is present in reservoir 150. Cathode 152 and anode 153 are in contact with (i.e., electrochemical communication with) the liquid composition 151. Power source 154 is connected to the cathode 152 and anode 153. In certain aspects, a porous membrane 155 is positioned between the cathode 152 and anode 153. The reservoir has an inlet 156 for receiving contaminated liquid composition and an outlet 157 for releasing the treated liquid composition. The inlet and outlet can be fitted with a valve for providing access to and from the reservoir 150.

[0061] In one aspect, the system can be composed of two or more cathodes and two or more anodes, wherein each cathode and anode are positioned in an alternating format. An example of this aspect is depicted in FIG. 8. Referring to FIG. 8, system 160 has two cathodes 161 and two anodes 162 positioned within vessel 163. The cathodes 161 and anodes 162 can be attached to the inner surface of the vessel 163 by a conductive bracket 164 such that wire leads 165 from a power source 166 can be connected with the vessel 163 and in contact with metal brackets 164. Although not depicted in FIG. 16, a porous membrane can be positioned between each cathode 161 and anode 162. The vessel 163 can have an inlet 167 for receiving contaminated liquid composition and an outlet 168 for releasing the treated liquid composition. TheATTORNEY DOCKET NO. 222105-2400inlet and outlet can be fitted with a valve for providing access to and from the interior volume of vessel 163.

[0062] In one aspect, the system includes an anode that surrounds a portion of a longitudinal surface of the cathode. An example of this aspect is depicted in FIG. 9A. Referring to FIG. 9A, cathode 170 is positioned within anode 171, where there is a space or void 172 such that cathode 170 is not in contact with anode 171. FIG. 9B depicts another view of this aspect, where anode 171 surrounds the longitudinal surface 173 of cathode 170, where there is a space / void 172 between the cathode and anode. In one aspect, a porous membrane can be positioned between cathode 170 and anode 171, which fills the space or void 172. In this aspect, the porous membrane is contact with both the cathode 170 and anode 171.

[0063] Referring to FIG. 10, system 180 has cathode 170 positioned within anode 171, where there is a space 172 such that cathode 170 is not in contact with anode 171. The cathode 170 and anode 171 can be attached to the inner surface of the vessel 181 by a conductive bracket 182 such that wire leads 183 from a power source 184 can be connected with the vessel 181 and in contact with metal brackets 182. Although not depicted in FIG. 10, a porous membrane can be positioned between cathode 170 and anode 171 as discussed above. The vessel 181 can have an inlet 185 for receiving contaminated liquid composition and an outlet 186 for releasing the treated liquid composition. The inlet and outlet can be fitted with a valve for providing access to and from the interior volume of vessel 182.

[0064] The cathode and anode are configured or positioned in the systems described herein so that they are not in contact with one another. In certain aspects, the cathode and anode can be positioned such that a divider (e.g., a porous membrane) is not required. In other aspects, when a porous membrane is used, the porous membrane is composed of any non-conductive material that prevents the cathode and anode from coming into contact with each other but permits the flow of liquid composition in the system from the cathode to anode. In one aspect, theATTORNEY DOCKET NO. 222105-2400membrane is a proton exchange membrane (PEM). In another aspect, the membrane is an anion exchange membrane (AEM). In one aspect, the porous membrane is a polymeric material such as, for example perfluorosulfonic acid (PFSA) (e.g., Nation™). In another aspect, the porous membrane is a ceramic material such as, for alumina, zirconia, and other porous inorganic materials typically used in water filtration.

[0065] In one aspect, the system also includes a pump for moving the aqueous composition into and out of the reservoir through the system. In one aspect, the system may circulate the composition through the system more than once for multiple treatments, as appropriate. The pump can be connected to the inlet of the systems described herein to pump the contaminated liquid composition into the system to ensure the liquid composition comes into contact with the cathode and anode.

[0066] In one aspect, the cathode can perform as a reactive electrochemical membrane (REM) filtration system. Thus, in one aspect, the cathode can be used as a filtration membrane and an electrode to enable a reactive electrochemical membrane (REM) operation. Such a REM operation mode can further significantly increase electrochemical reduction efficiency.

[0067] Embodiments of REM systems can be used in either a dead-end filtration or cross-flow filtration mode. In embodiments of a dead-end or cross-flow REM filtration unit, the system can include a flow-through reactor with at least one cathode configured such that the concentrated solution containing the perfluoroalkyl compounds will be pumped through the reactor in a manner to allow the solution filtered through the membrane in a cross-flow or dead-end filtration mode. In embodiments, the reactor will be designed such that, fora typical run, the concentrated solution will be pumped through the reactor at a constant flow rate with a supporting electrolyte.

[0068] Now having described the embodiments of the present disclosure, in general, the Examples, below, describe some additional embodiments of the present disclosure. While embodiments of the present disclosure are described in connectionATTORNEY DOCKET NO. 222105-2400with the Examples and the corresponding text and figures, there is no intent to limit embodiments of the present disclosure to these descriptions. On the contrary, the intent is to cover all alternatives, modifications, and equivalents included within the spirit and scope of embodiments of the present disclosure.

[0069] Aspects

[0070] Aspect 1. A method for electrochemically removing a perfluoroalkyl compound in a liquid composition, the method comprising:introducing the liquid composition into a vessel comprising a cathode and an anode, wherein the cathode and anode are not in contact with one another, wherein the cathode comprises a carbon-based material, and the liquid composition is in contact with the cathode and the anode; andsupplying electric current to the cathode and anode.

[0071] Aspect 2. The method of Aspect 1, wherein carbon-based material comprises activated carbon, graphene, graphite, or carbon nanotubes.

[0072] Aspect 3. The method of Aspect 1, wherein carbon-based material comprises granulated activated carbon.

[0073] Aspect 4. The method of Aspect 3, wherein the granulated activated carbon has a carbon tetrachloride number (CTN) of at least 50.

[0074] Aspect 5. The method of The method of Aspect 3, wherein the granulated activated carbon has a relative surface area as measured by Iodine Number of at least 800 mg / g.

[0075] Aspect 6. The method of The method of Aspect 3, wherein the granulated activated carbon has an Abrasion Number of at least 70.

[0076] Aspect 7. The method of any one of Aspects 1-6, wherein the anode comprises one or more Magneli phase titanium sub-oxides, boron-doped diamond (BDD), PbC>2, or a mixed metal oxide comprising lrC>2, RuC>2, orTa2Os.

[0077] Aspect 8. The method of any one of Aspects 1-7, wherein a porous membrane is positioned between the cathode and anode.ATTORNEY DOCKET NO. 222105-2400

[0078] Aspect 9. The method of any one of Aspects 1-8, wherein the vessel includes two or more cathodes and two or more anodes, wherein each cathode and anode are positioned in an alternating format.

[0079] Aspect 10. The method of any one of Aspects 1-9, wherein the liquid composition comprises an aqueous composition.

[0080] Aspect 11. The method of Aspect 10, wherein the aqueous composition comprises wastewater.

[0081] Aspect 12. The method of any one of Aspects 1-11 , wherein the pH of the liquid composition is from about 7.0 to about 9.0.

[0082] Aspect 13. The method of any one of Aspects 1-12, wherein the electric current is from about 5 mA / cm2to about 50 mA / cm2.

[0083] Aspect 14. The method of any one of Aspects 1-13, wherein the liquid composition is pre-treated to concentrate the perfluoroalkyl compound prior to introducing the liquid composition into the vessel.

[0084] Aspect 15. The method of Aspect 14, wherein the liquid composition is pretreated via electrocoagulation to concentrate the perfluoroalkyl compound.

[0085] Aspect 16. The method of any one of Aspects 1-15, wherein the perfluoroalkyl compound comprises perfluoroalkyl acid.

[0086] Aspect 17. The method of any one of Aspects 1-15, wherein the perfluoroalkyl compound comprises perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), perfluorobutanesulfonic acid (PFBS), hexafluoropropylene oxide dimer acid (HFPO-DA), perfluoroheptanesulfonic acid (PFHpS), 6:2 fluorotelomer sulfonate (6:2 FTS), perfluoroheptanoic acid (PFHpA), perfluoropentanesulfonic acid (PFPeS), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluorobutanoic acid (PFBA), or any combination thereof.ATTORNEY DOCKET NO. 222105-2400

[0087] Aspect 18. The method of any one of Aspects 1-17, wherein the cathode is electrochemical communication with the liquid solution.

[0088] Aspect 19. The method of any one of Aspects 1-18, wherein the cathode consists of the carbon-based material.

[0089] Aspect 20. The method of any one of Aspects 1-19, wherein the cathode can be reactivated after removing the perfluoroalkyl compound from the liquid composition by applying an electrical current to the cathode.

[0090] Aspect 21. A system for electrochemically removing a perfluoroalkyl compound from a liquid composition, the system comprising:a vessel for containing the liquid composition solution comprising the perfluoroalkyl compound;a cathode and anode, wherein the cathode comprises a carbon-based material, and wherein the cathode and anode are not in contact with one another; anda power supply that supplies an electric current to the cathode and the anode.

[0091] Aspect 22. The system of Aspect 21, wherein the vessel is a closed structure comprising an inlet for introducing the liquid composition into the vessel and an outlet for removing the liquid composition from the vessel.

[0092] Aspect 23. The system of Aspect 21 and 22, wherein the vessel includes two or more cathodes and two or more anodes, wherein each cathode and anode are positioned in an alternating format.

[0093] Aspect 24. The system of Aspect 21 and 22, wherein the anode surrounds a portion of a longitudinal surface of the cathode.

[0094] Aspect 25. The system of any one of Aspects 21-24, wherein a porous membrane is positioned between the cathode and the anode.

[0095] Aspect 26. The system of any one of Aspects 21-25, wherein carbon-based material comprises activated carbon, graphene, graphite, or carbon nanotubes.ATTORNEY DOCKET NO. 222105-2400

[0096] Aspect 27. The system of Aspect 26, wherein carbon-based material comprises granulated activated carbon.

[0097] Aspect 28. The system of Aspect 27, wherein the granulated activated carbon has a carbon tetrachloride number (CTN) of at least 50.

[0098] Aspect 29. The system of Aspect 27, wherein the granulated activated carbon has a relative surface area as measured by Iodine Number of at least 800 mg / g.

[0099] Aspect 30. The system of Aspect 27, wherein the granulated activated carbon has an Abrasion Number of at least 70.

[0100] Aspect 31. The system of any one of Aspects 21-30, wherein the cathode consists of the carbon-based material.

[0101] Aspect 32. The system of any one of Aspects 21-31, wherein the anode comprises one or more Magneli phase titanium sub-oxides, boron-doped diamond (BDD), PbC>2, or a mixed metal oxide comprising lrC>2, RuC>2, orTa2Os.

[0102] Aspect 33. The system of any one of Aspects 21-32, further comprising a pump for moving the liquid composition through the system.

[0103] EXAMPLES

[0104] Experimental

[0105] Materials

[0106] Magneli phase Ti4O? electrode (5 *10 cm2, 3 mm thickness) (Kela Material Co., Hunan, China) was fabricated via a high-temperature sintering method. PFASs were from INDOFINE Chemical Company, Inc (Hillsborough, USA). PFAS internal standards were obtained from Wellington Laboratories (Ontario, Canada). Sodium sulfate (Na2SO4, 99.9%) was purchased from Sigma-Aldrich Chemical Co., Ltd. (St. Louis, MO, USA). Granulated activated carbon (GAC) was purchased from Kolar Labs Crystal (Chicago, IL, USA).

[0107] Divided Reactor

[0108] Experiments were performed using a divided reactor consisting of an anodic and a cathodic chamber (10 x 6 x 6 cm each), separated by a proton-exchangeATTORNEY DOCKET NO. 222105-2400membrane (Nafion 117, Fuel Cell Earth, USA) (FIG. 1). A certain quantity of GAC sealed in a nickel foam pouch (3 x 1.5 cm) was used as the cathode, and a rectangular Ti4O7plate electrode as the anode (5 x 3 cm), placed parallel with a 5-cm distance. Both chambers were filled with 200 mL of 100-mM Na2SO4solution containing PFAS at a certain initial concentration. A direct current was applied using a DC power supply (Electro Industries Inc., Monticello, MN).

[0109] The result obtained with 10-ppm initial concentration of PFOS with 0.1 -g GAC as the cathode operated at 20 mA cm'2current density is present in FIG. 2A. PFOS was removed faster in the cathodic chamber than in the anodic chamber. Its removal ratio in the cathodic chamber at 48 h is compared to that by GAC adsorption that was measured by mixing 0.1 -g GAC with 200-mL Na2SO4solution containing 10-ppm PFOS for 48 h (FIG. 2B). The removal of PFOS by ER (99%) was significantly greater than adsorption (84%), with the aqueous concentration remaining in the aqueous phase being 0.1 ppm and 1.6 ppm respectively. Furthermore, the GAC after adsorption or ER treatment experiment was collected and dried in an oven at 60 °C for 12 h. Subsequently, the dried GAC was mixed in 200-mL of a solvent containing methanol with 1 % (vol) ammonium hydroxide for 48 h at ambient temperature to recover PFOS. The ratio of PFOS recovery, calculated by the quantity of extracted PFOS divided by the total initial quantity, was 12% for the ER treatment and 42% for the adsorption. Apparently, the solvent (methanol with 1% ammonium hydroxide) cannot fully extract the PFOS adsorbed on GAC, but the much lower recovery for the ER treatment indicates PFAS destruction on the GAC cathode. The contrast is more evident for PFBS, where PFBS removal by ER reached 89% after 1000 h of ER treatment (FIG. 2C), while the recovery by methanol with 1% ammonium hydroxide was only 8% (FIG. 2D). Whereas the removal by adsorption was measured to be 77% percent, and the solvent recovery was 85%.

[0110] Undivided ReactorATTORNEY DOCKET NO. 222105-2400

[0111] In addition, experiments were conducted using undivided reactors to directly compare the rates of PFAS removal by electrochemical treatment (ET) and adsorption. The reactor contains 200 mL 100-mM Na2SC>4 without a proton exchange membrane between the cathode and anode. The effect of adsorption was measured using the same reactor and procedure, but without the electric current supplied. FIG.3A compares the changes of PFOS concentrations over time by ET or adsorption. During ET, PFOS concentration decreased rapidly in the first 2 h, reaching 95% removal at 4 h. In contrast, PFOS concentration declined more slowly by adsorption, reaching 60% at 4 h. The contrast of PFOS removal rates based on pseudo-first order reaction rate model (-Ln(C / Co) = ko st) shown in FIG. 3B is more evident, indicating the kobs of PFOS degradation by ET is 3.6 times higher than that by adsorption (0.84 vs 0.25 h-1).

[0112] The effects of ET and adsorption were further compared in an experiment using the undivided reactor with a mixture solution of six PFAS, PFOS, PFNA, PFOA, PFHxS, PFBS, and GenX, each at 1 ppm, using 3-g GAC as the cathode, and the results are present in FIGS. 4A-D. The long-chain PFAS (PFOS, PFNA, PFOA) were removed more rapidly than the short-chain ones (PFBS and GenX) due to the lower C-F bond energy FIG. 4A. PFAS with sulfonic acid terminal groups (e.g., PFOS) exhibit a higher degradation rate than those with carboxylic acid groups (e.g., PFNA and PFOA) due to the stronger e I ectron-wi th drawing effect of -SO3H. For the test of adsorption, the removal rate of long-chain PFAS (PFOS, PFNA, PFOA) is also higher than that of short-chain PFAS (PFHxS, PFBS, and GenX) (FIG. 4B), which is ascribed to stronger hydrophobic interactions between GAC and long-chain PFAS.

[0113] The obtained kobsvalues for ET and adsorption are compared in FIG. 4C-D and Table 1. In all cases except PFBS, ET shows a significantly higher removal rate than adsorption for most PFAS (PFOS, PFNA, PFOA, PFHxS, and Gen X). Although PFBS removal rate by ET is only slightly higher than adsorption during 4 h (kobs= 0.11 IT1VS 0.07 IT1). The ET treatment with a longer term (1000 h) for 10-ppm PFBS shownATTORNEY DOCKET NO. 222105-2400in FIG. 2B reached 89%, while the recovery of PFBS from the GAC cathode by the solvent (methanol with 1 % ammonium hydroxide) extraction was only 8%, indicating the destruction of PFBS on the cathode (FIG. 4D).Table 1. The kObs (IT1) of PFAS obtained in the undivided reactor by ET (20 mA cm-2) or adsorption.

[0114] REM Reactor

[0115] The REM reactor was designed to simulate a flow-through system for practical PFOS removal, employing 0.5 g GAC as the cathode and a circular Ti4O? as the anode at a flow rate of 0.5 ml min-1. The removal performance of PFOS was evaluated with and without an external potential to simulate electrochemical degradation and physical adsorption. FIG. 5 shows the PFOS removal curve as a function of bed volume (BV) at 6.28 ml. At the initial stage of adsorption, GAC absorbs PFOS. As time progresses, the curve gradually rises and becomes saturated at 12 BV. In contrast, under electrochemical conditions, the GAC cathode did not reach adsorption saturation even after 18 BVs, indicating that PFOS degradation occurred.

[0116] Reusability and stability of GAC Cathode

[0117] The reusability and long-term stability of the GAC cathode are evaluated in FIGS. 6A-E. FIG. 6A evaluates the reusability of the GAC cathode for the degradation of six PFAS (PFOS, PFNA, PFOA, PFHxS, PFBS, and GenX) in the undivided reactor. In the first ET cycle, the GAC cathode exhibited excellent removal performance for all six PFAS. After the first cycle, the same GAC electrode was not regenerated by solventATTORNEY DOCKET NO. 222105-2400wash but only dried in the oven at 40 °C for the second ET test under the same electrochemical conditions. Notably, the removal rates of all six PFAS in the second cycle remain over 95% of those in the first cycle, confirming that GAC retains high electrochemical activity and structural stability. As shown in FIGS. 6C-E, when GAC is applied as a cathode, its surface displays no significant morphological change. These results indicate that the simultaneous adsorption and degradation of PFAS on GAC cathode prevent PFAS accumulation or fouling.

[0118] FIG. 6B presents the result of a long-term (500 h) ET treatment of PFOS (100 ppm) using the undivided reactor with 0.1 -g GAC cathode. Steady PFOS removal continued over the long-term treatment. Notably, no sharp decrease or plateau was observed, indicating the absence of electrode fouling or failure. The long-term degradation via ER of 10-ppm PFBS in Fig. 2b also proves the durability of GAC. These results confirm that the GAC cathode exhibits excellent long-term electrochemical stability without significant passivation.

[0119] It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations and are set forth only for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiments of the disclosure without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure.ATTORNEY DOCKET NO. 222105-2400REFERENCESGrunfeld DA, et al. Electrochemical degradation of a C6-perfluoroalkyl substance (PFAS) using a simple activated carbon cathode. Environmental Science-Water Research & Technology 10, 272-287 (2023).Li P, Yu R, Hou F, Zhao Y. Legacy and emerging poly- and perfluoroalkyl substances in wastewater treatment plant and receiving water: abundance, removal, and potential ecological risk. Environmental Science and Pollution Research 30, 29929-29941 (2023).Zhuo Q, Wang J, Niu J, Yang B, Yang Y. Electrochemical oxidation of perfluorooctane sulfonate (PFOS) substitute by modified boron doped diamond (BDD) anodes. Chem Eng J 379, 122280 (2020).Wang Z, et al. A New OECD Definition for Per- and Polyfluoroalkyl Substances. Environmental Science & Technology 55, 15575-15578 (2021).Sharma S, Shetti NP, Basu S, Nadagouda MN, Aminabhavi TM. Remediation of per-and polyfluoroalkyls (PFAS) via electrochemical methods. Chem Eng J 430, 132895 (2022).Tian Q, et al. Fluorine-functionalized MOF modified GCE for highly sensitive electrochemical detection of persistent pollutant perfluorooctanoic acid. Sensors and Actuators B: Chemical 404, 135309 (2024).EPA. Per- and Polyfluoroalkyl Substances (PFAS): Final PFAS National Primary Drinking Water Regulation.) (2024).Li CG, Wang YF, Wang YY, Wang ZY, Huang QG. Electrochemical oxidation combined with UV irradiation for synergistic removal of perfluorooctane sulfonate (PFOS) in water. J Hazard Mater 436, 129091 (2022).Shanmugapriya S, et al. Recent research trends in perfluoropolyether for energy device applications: a mini review. Journal of the Korean Ceramic Society 61, 1-14 (2024).Mifkovic M, Van Hoomissen DJ, Vyas S. Conformational distributions of helical perfluoroalkyl substances and impacts on stability. J Comput Chem 43, 1656-1661 (2022).

Claims

ATTORNEY DOCKET NO. 222105-2400CLAIMS1. A method for electrochemically removing a perfluoroalkyl compound in a liquid composition, the method comprising:introducing the liquid composition into a vessel comprising a cathode and an anode, wherein the cathode and anode are not in contact with one another, wherein the cathode comprises a carbon-based material, and the liquid composition is in contact with the cathode and the anode; andsupplying electric current to the cathode and anode.

2. The method of claim 1, wherein carbon-based material comprises activated carbon, graphene, graphite, or carbon nanotubes.

3. The method of claim 1 , wherein carbon-based material comprises granulated activated carbon.

4. The method of claim 3, wherein the granulated activated carbon has a carbon tetrachloride number (CTN) of at least 50.

5. The method of claim 3, wherein the granulated activated carbon has a relative surface area as measured by Iodine Number of at least 800 mg / g.

6. The method of claim 3, wherein the granulated activated carbon has an Abrasion Number of at least 70.

7. The method of claim 1, wherein the anode comprises one or more Magneli phase titanium sub-oxides, boron-doped diamond (BDD), PbC>2, or a mixed metal oxide comprising lrC>2, RUC>2, or Ta2C>5.

8. The method of claim 1 , wherein a porous membrane is positioned between the cathode and anode.

9. The method of claim 1 , wherein the vessel includes two or more cathodes and two or more anodes, wherein each cathode and anode are positioned in an alternating format.

10. The method of claim 1, wherein the liquid composition comprises an aqueous composition.

11. The method of claim 10, wherein the aqueous composition comprises wastewater.

12. The method of claim 1, wherein the pH of the liquid composition is from about 7.0 to about 9.0.

13. The method of claim 1, wherein the electric current is from about 5 mA / cm2to about 50 mA / cm2.

14. The method of claim 1 , wherein the liquid composition is pre-treated to concentrate the perfluoroalkyl compound prior to introducing the liquid composition into the vessel.

15. The method of claim 14, wherein the liquid composition is pre-treated via electrocoagulation to concentrate the perfluoroalkyl compound.ATTORNEY DOCKET NO. 222105-240016. The method of claim 1 , wherein the perfluoroalkyl compound comprises perfluoroalkyl acid.

17. The method of claim 1, wherein the perfluoroalkyl compound comprises perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), perfluorobutanesulfonic acid (PFBS), hexafluoropropylene oxide dimer acid (HFPO-DA), perfluoroheptanesulfonic acid (PFHpS), 6:2 fluorotelomer sulfonate (6:2 FTS), perfluoroheptanoic acid (PFHpA), perfluoropentanesulfonic acid (PFPeS), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluorobutanoic acid (PFBA), or any combination thereof.

18. The method of claim 1, wherein the cathode is electrochemical communication with the liquid solution.

19. The method of claim 1 , wherein the cathode consists of the carbon-based material.

20. The method of any one of claims 1-19, wherein the cathode can be reactivated after removing the perfluoroalkyl compound from the liquid composition by applying an electrical current to the cathode.

21. A system for electrochemically removing a perfluoroalkyl compound from a liquid composition, the system comprising:a vessel for containing the liquid composition solution comprising the perfluoroalkyl compound;a cathode and anode, wherein the cathode comprises a carbon-based material, and wherein the cathode and anode are not in contact with one another; anda power supply that supplies an electric current to the cathode and the anode.

22. The system of claim 21, wherein the vessel is a closed structure comprising an inlet for introducing the liquid composition into the vessel and an outlet for removing the liquid composition from the vessel.

23. The system of claim 21 , wherein the vessel includes two or more cathodes and two or more anodes, wherein each cathode and anode are positioned in an alternating format.

24. The system of claim 21, wherein the anode surrounds a portion of a longitudinal surface of the cathode.

25. The system of claim 21, wherein a porous membrane is positioned between the cathode and the anode.

26. The system of claim 21, wherein carbon-based material comprises activated carbon, graphene, graphite, or carbon nanotubes.

27. The system of claim 26, wherein carbon-based material comprises granulated activated carbon.

28. The system of claim 27, wherein the granulated activated carbon has a carbon tetrachloride number (CTN) of at least 50.ATTORNEY DOCKET NO. 222105-240029. The system of claim 27, wherein the granulated activated carbon has a relative surface area as measured by Iodine Number of at least 800 mg / g.

30. The system of claim 27, wherein the granulated activated carbon has an Abrasion Number of at least 70.

31. The system of any one of claims 21-30, wherein the cathode consists of the carbonbased material.

32. The system of any one of claims 21-30, wherein the anode comprises one or more Magneli phase titanium sub-oxides, boron-doped diamond (BDD), PbC>2, or a mixed metal oxide comprising lrC>2, RuC>2, orTa2Os.

33. The system of claim 21, further comprising a pump for moving the liquid composition through the system.

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