Method for adsorption and destruction of PFAS chemicals and the recycling of catalyst used therein

Abstract

In one aspect, the disclosure relates to methods for decontaminating PFAS from water sources. The method includes an initial stage of adsorption of the PFAS onto activated carbon, polymeric anion exchange resins, a metal organic framework (MOF), and / or layered double hydroxides containing a rare earth metal ion in a polar, aprotic organic solvent and heating the adsorbed PFAS to break C-F bonds in the PFAS. In an aspect, fluorine is extracted from the PFAS as rare-earth fluorides. The rare-earth fluorides are transformed into rare-earth hydroxides by boiling in water in the presence of a base such as sodium hydroxide. In an aspect, sodium fluoride is a byproduct of the process and can be used further in other processes such as fluoridation of drinking water.

Description

METHOD FOR ADSORPTION AND DESTRUCTION OF PFAS CHEMICALS AND THE RECYCLING OF CATALYST USED THEREINCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Ser. No. 63 / 599,755, filed November 16, 2023, which is incorporated herein by reference in its entirety.BACKGROUND

[0002] Per- and polyfluoroalkyl substances (PFAS) are persistent fluorinated hydrocarbons that contain a carbon chain that is entirely (perfluoroalkyl) or partially (polyfluoroalkyl) replaced by fluorine atoms. PFAS may also contain a terminal functional group (e g., carboxylic acid and sulfonic acid). Due to their amphiphilic properties (hydrophilicity from the terminal group and lipophilicity and hydrophobicity from fluorinated carbon chain), PFAS molecules can be made as both oil and water repellent. They have been widely synthesized since the 1940s and incorporated in more than 200 areas ranging from industrial applications (e.g., polymer synthesis, semiconductors, photolithography, and building and construction) to food and product manufacturing (e.g., food packaging, nonstick cookware, firefighting materials, textile, and paper) because of the high thermal and chemical stability of the carbon-fluorine bond. Over 3000 registered PFAS compounds have been used in the last 80 years. The extensive use and disposal of these persistent / forever chemicals have led to environmental contamination; they have been detected in the air, drinking water, soil, sediments, wildlife, food, human breast milk, and blood. The environmental persistence, bioaccumulation, and possible occupational exposure have raised concerns regarding the potential health effects of PFAS. Because of the exceptional strength of the carbon-fluorine (C-F) bond with high energy (544 kJ mol-1), treatment for PFAS pollutants in the environment is extremely difficult and new methods are needed.

[0003] Given the environmental toxicity and adverse health threats of PFAS to humans and ecosystems, more regulatory standards have been established. The Environmental Protection Agency (EPA) has lowered the previously released health advisory level of combined perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in drinking water from 70 parts per trillion (ppt) in 2016 to 4.0 ppt and 4.0 ppt, respectively. This further confirms the urgent need to develop a technique for not only the removal of PFAS from the environment but also for complete degradation.

[0004] Given the growing public awareness of PFAS and the emergence of various remediation techniques, there have been reports of combining multiple remediation measurements to improve the overall performance and practicality of PFAS remediation such as, nanofiltration and electrochemical anionic oxidation (NF-EO). However, these strategies can be expensive and are often inefficient due to the additional steps involved in combining methods.

[0005] Adsorption by activated carbons (AC) is a simple, efficient, and economically feasible method used industrially by water plants to remove PFAS from water. Activated carbons (AC) have high porosity and large surface areas, as well as thermal and chemical stability which make them effective at removing PFAS. AC is especially effective at the adsorption of longer-chain PFAS like PFOA and PFOS which are the most detected PFAS in the environment. Although AC is the most popular and effective adsorbent used commercially for removing PFAS, there are difficulties with regenerating PFAS-saturated AC (i.e., spent AC). For example, thermal regeneration of AC requires high energy cost, decreases their adsorption properties after several cycles, and changes the AC morphology. Additionally, thermal treatment of PFAS-saturated AC can result in release of HF into the environment. Consequently, the development of a novel treatment process, which allows for the combination of adsorption followed by degradation of PFAS is needed for the sustainable removal of these chemicals.

[0006] Despite advances in PFAS decontamination research, there is still a scarcity of methods of removing these compounds from drinking water and other water sources that are efficacious, inexpensive, renewable, and environmentally benign. These needs and other needs are satisfied by the present disclosure.SUMMARY

[0007] In accordance with the purpose(s) of the present disclosure, as embodied and broadly described herein, the disclosure, in one aspect, relates to methods for decontaminating PFAS from water sources. The method includes an initial stage of adsorption of the PFAS onto activated carbon, polymeric anion exchange resins, a metal organic framework (MOF), and / or layered double hydroxides containing a rare earth metal ion in a polar, aprotic organic solvent and heating the adsorbed PFAS to break C-F bonds in the PFAS. In an aspect, fluorine is extracted from the PFAS as rare-earth fluorides. The rare-earth fluorides are transformed into rare-earth hydroxides by boiling in water in the presence of a base such as sodium hydroxide. In an aspect, sodium fluoride is a byproduct of the process and can be used further in other processes such as fluoridation of drinking water.

[0008] 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

[0009] Many aspects of the present disclosure can be better understood with reference to the following 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.

[0010] FIG. 1 shows a schematic of an exemplary cycle of PFAS destruction as disclosed herein.

[0011] FIG. 2 shows Energy Dispersive X-ray Analysis of perfluorohexanoic acid (PFHxA)- satu rated AC.

[0012] FIGs. 3A-3B show X-ray photoelectron spectra for YF3 (FIG. 3A) survey spectrum (FIG. 3B) high-resolution F 1s spectrum.

[0013] FIG. 4 shows defluorination of PFHxA over time at 120 °C as measured by19F-NMR with a solution of 4,4'-difluorobenzophenone (DFB) as internal standard.

[0014] FIG. 5 shows X-ray diffraction patterns of simulated Y(OH)3and Y(OH)3 / AC.

[0015] Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.DETAILED DESCRIPTION

[0016] Disclosed herein is a new degradation method for PFAS-saturated AC with yttrium ions. In one aspect, in the disclosed method, polar, aprotic solvents such as N,N-dimethylformamide (DMF), or N,N-dimethylacetamide (DMAc) at 120 °C are used and can be reused. In another aspect, the fluorine from the PFAS is extracted to form yttrium fluorides (YF3). In an aspect, while most rare earth (RE) ions work, yttrium was chosen because the cost is comparable to transition metals.

[0017] Liu et al. recovered yttrium (Y) from YF3in waste slag and transformed it to Y(OH)3by employing a mechanochemical method. In that case, a ball-milling alkali method at room temperature was reported with a Y yield of 96.2%. This is an energy intensive method that could damage the AC used herein. Thus, in one aspect, in the method disclosed herein, the rare-earth ions were recovered followed by acid leaching of the rare-earth ions with no mechanical grinding. In a further aspect, the disclosed process is environmentally friendly since it requires mild conditions and low energy and provides a complete transformation of REF3. In a further aspect, the by-product of this reaction is sodium fluoride (NaF) which is usually added to water supplies to prevent tooth decay. In yet another aspect, an advantage of the disclosed process is that REs can be recovered in the form of RE(OH)3and returned to their original salts by acid-leaching to start the cycle again (FIG. 1).Method for Removing One or more PFAS from Water

[0018] In one aspect, disclosed herein is a method for removing one or more perfluoroalkyl and polyfluoroalkyl substances from water, the method including at least the steps of:(a) adsorbing the water comprising the PFAS onto an adsorbent material to form PFAS- saturated adsorbent material; and(b) admixing the PFAS-saturated adsorbent material with a solution of a salt of a rare earth metal in a solvent to produce a rare earth fluoride-loaded activated carbon.

[0019] In a further aspect, the water can be any water source such as, for example, drinking water or a municipal water source, waste water, a natural water source, or the like. In a further aspect, the PFAS can be perfluorohexanoic acid, perfluorooctanoic acid, perfluorooctanesulfonic acid, perfluorobutyric acid, trifluoroacetic acid, another PFAS, or any combination thereof. In a further aspect, the method is generally suitable for perfluorocarboxylic acids with carbon chains having eight or fewer carbons therein. In an aspect, the adsorbent material can be selected from activated carbon, a polymeric anion exchange resin, a metal organic framework (MOF), a layereddouble hydroxide (LDH), or any combination thereof. In some aspects, the ion exchange resin can be a commercial polymeric anion exchange resin such as, for example, AMBERLITE™ resins available from suppliers including DuPont Water Solutions (Wilmington, DE, USA). Exemplary AMBERLITE™ resins include, but are not limited to, AMBERLITE™ HPR weak and strong base anion exchange resins, AMBERLITE™ IRA weak and strong base anion exchange resins including but not limited to AMBERLITE™ IRA910, AMBERLITE™ MB premixed strong base anion exchange resins, and combinations thereof. Other exemplary ion exchange resins include, but are not limited to, PUROLITE™ A860 and A520E from ECOLAB® (King of Prussia, PA, USA), DOWEX™ MARATHON™ available from DuPont Water Solutions (Wilmington, DE, USA), and Sorbtech strong and weak base anion exchange resins available from Sorbent Technologies (Norcross, GA, USA).

[0020] In another aspect, a commercially available LDH can be used as purchased or can be modified by adjusting interlayer spacing or calcination to improve PFAS adsorption capabilities. Useful products include, but are not limited to synthetic hydrotalcite Mgi.xAlx(OH)2(CO3)x / 2-mH2O sold as DHT-4Atm(Kyowa Chemical Industry Co., Kagawa, Japan), SORBOLEX™ LDH products (Clariant Specialty Chemicals, Muttenz, Switzerland), derivatives thereof, and the like.

[0021] In an aspect, amount of removal of PFAS would ideally be 100%, so the water is substantially free of PFAS. In some aspects, it is recognized that amount of PFAS removal can depend on PFAS concentration, time, and other factors, and in cases where a lower amount of PFAS removal is acceptable, amount of PFAS removal can be below 100% (e.g. 90%, 95%, 99%, or the like).

[0022] In one aspect, step (a) can be carried out for from about 1 hour to about 72 hours, or from about 2 hours to about 24 hours, or from about 3 hours to about 12 hours. In an aspect, an ideal adsorbent would work quickly. In a further aspect, length of time should be balanced by cost. Thus, in one aspect, although carbon adsorbents are slower, they are inexpensive, while MOFs can be fast, but are more expensive. In an aspect, which adsorbent to be used when performing the method represents a balance between expense and time and can vary depending on the amount of water to be decontaminated and other factors. In some aspects, step (a) can be carried out in a chromatography column or another suitable vessel.

[0023] In one aspect, the salt of a rare earth metal can be a rare earth nitrate, chloride, or sulfate, such as, for example, Y(NO)3-6H2O, or another salt. Without wishing to be bound by theory, the counter-ion of the salt can determine solubility. In the present case, most rare earth fluorides andhydroxides are insoluble, but nitrates, sulfates, and chlorides are soluble and can also be used in the methods described herein. In a further aspect, the rare earth metal can have a 3+ oxidation state and may, in some aspects, be selected from Y3+, Ce3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tb3+, Yb3+, or any combination thereof. In one aspect, the rare earth metal is Y3+. In another aspect, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, and Yb3+perform similarly to Y3+.

[0024] In any of these aspects, the solvent can be a polar, aprotic solvent such as, for example, dimethylformamide (DMF), dimethylacetamide (DMAc), diethylformamide (DEF), or any combination thereof. In one aspect, step (b) can be conducted at an elevated temperature such as, for example at from about 80 °C to about 120 °C, or at about 80, 85, 90, 95, 100, 105, 110, 115, or about 120 °C, or a combination of any of the foregoing values, or a range encompassing any of the foregoing values. In one aspect, and without wishing to be bound by theory, although destruction of PFAS is somewhat slower at lower temperatures, destruction of PFAS under milder conditions of temperature (e.g. at 80 °C) has not previously been demonstrated and represents an advance in terms of energy input, general safety of the procedure, and the like In another aspect, step (b) is carried out for from about 12 hours to about 24 hours.

[0025] Also disclosed herein is a method for regenerating the rare earth metal used for PFAS decontamination. Further in this aspect, the disclosed method for removing PFAS can be modified to include step (c), refluxing the rare earth fluoride-loaded adsorbent material in a solution comprising a base. In one aspect, prior to performing step (c), the rare earth fluoride- loaded adsorbent material can be separated from the solvent. In one aspect, separation can be achieved by any common means including, but not limited to, sedimentation, filtration, centrifugation, and the like. In another aspect, the base can be sodium hydroxide, potassium hydroxide, barium hydroxide, cesium hydroxide, strontium hydroxide, calcium hydroxide, lithium hydroxide, rubidium hydroxide, or any combination thereof. In a further aspect, this list of bases is non-exhaustive and other bases known in the art are also contemplated and should be considered disclosed. In any of these aspects, the method produces a rare earth hydroxide- loaded adsorbent material and NaF or other fluoride (e.g. KF, Li F, or the like, depending on the base used). In a still further aspect, free rare earth ions can be regenerated by admixing the rare earth hydroxide-loaded adsorbent material with an acid such as, for example, a strong acid selected from hydrochloric acid, perchloric acid, hydroiodic acid, hydrobromic acid, sulfuric acid, nitric acid, chloric acid, or any combination thereof. In one aspect, the acid is 3 M HCI. In a further aspect, the list of acids is non-exhaustive and other acids known in the art are also contemplated and should be considered disclosed.

[0026] Also disclosed herein is a composition including NaF produced by the disclosed method. In one aspect, the NaF is a value-added byproduct of the disclosed method and can be used for any purpose for which NaF is conventionally used including, but not limited to, fluoridation of drinking water or dental products, medical uses, extractive metallurgy, a buffer supplement for biological reactions, or the like.

[0027] Many modifications and other embodiments disclosed herein will come to mind to one skilled in the art to which the disclosed compositions and methods pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the disclosures are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. The skilled artisan will recognize many variants and adaptations of the aspects described herein. These variants and adaptations are intended to be included in the teachings of this disclosure and to be encompassed by the claims herein.

[0028] Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0029] 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.

[0030] 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.

[0031] 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 inventionis 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.

[0032] 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 convenience only 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.

[0033] 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.

[0034] 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

[0035] 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.

[0036] 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 rare earth metal,” “a base,” or “a solvent,” includes, but is not limited to, mixturesor combinations of two or more such rare earth metals, bases, or solvents, and the like.

[0037] It should be noted that ratios, concentrations, amounts, 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.

[0038] 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’”.

[0039] 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 subranges 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.

[0040] 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 equivalentresults 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.

[0041] As used herein, the term “effective amount” refers to an amount that is sufficient to achieve the desired modification of a physical property of the composition or material. For example, an “effective amount” of activated carbon refers to an amount that is sufficient to achieve the desired improvement in the property modulated by the formulation component, e.g. achieving the desired level of C-F bond breakage in a PFAS. The specific level in terms of wt% in a composition required as an effective amount will depend upon a variety of factors including the amount and type of PFAS, amount and type of rare earth metal ion, solvent, and reaction conditions such as temperature.

[0042] 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 occurs and instances where it does not.

[0043] As used herein, “per- and polyfluoroalkyl substances” (abbreviated as PFAS) are synthetic compounds having multiple fluorine atoms attached to an alkyl chain. PFAS, while used in many industrial applications, are persistent organic pollutants that do not easily break down due to the presence of a C-F bond, and can be found in water (including drinking water sources) and bioaccumulated in human and animal tissues. PFASs may act as carcinogens and / or endocrine disruptors. Commonly used PFASs are perfluoroalkyl carboxylic acid (PFCA) and perfluoroalkyl sulfonic acid (PFSA), which are subclassified based on carbon-chain length. In the case of perfluoroalkyl carboxylic acids (PFCA), long-chain refers to more than eight carbons (C > 8), and short-chain to PFCA with up to seven carbons (C < 7). For perfluoroalkyl sulfonic acids (PFSA),the term long-chain applies to more than six carbons (C > 6) and short-chain to PFSA with up to five carbons (C < 5).

[0044] A “layered double hydroxide” or “LDH” as used herein refers to a composition with layers resembling brucite (an Mg(OH)2mineral). Cationic metal-containing layers are charge-balanced by hydrated anions in interlayer spaces. LDHs have the general formula [M2+(1 - X)M3+(X)(OH)2] X+(An-)X / n-mH2O, where M2+and M3+are bivalent (Cu2+, Ca2+, Mg2+, Zn2+, Ni2+, Co2+, and combinations thereof) and trivalent cations (Al3+, Fe3+, Ga3+, Cr3+, and combinations thereof), respectively, while An- represents the interlayer (Cl“, Br", NOs”, I", OH", SO42", and combinations thereof) anion with coulombic charge n, and x is the molar ratio of divalent to trivalent cations, which, in some aspects, can be from about 2.0 to about 6.0.

[0045] Unless otherwise specified, temperatures referred to herein are based on atmospheric pressure (i.e. one atmosphere).

[0046] Now having described the aspects of the present disclosure, in general, the following Examples describe some additional aspects of the present disclosure. While aspects of the present disclosure are described in connection with the following examples and the corresponding text and figures, there is no intent to limit aspects of the present disclosure to this description. On the contrary, the intent is to cover all alternatives, modifications, and equivalents included within the spirit and scope of the present disclosure.EXAMPLES

[0047] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and / or methods claimed herein are made and evaluated, and are intended to be purely exemplary of the disclosure and are not intended to limit the scope of what the inventors regard as their disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric.Example 1 : Experimental DetailsReagents and Raw Materials

[0048] All chemicals and solvents were used as purchased without further purification. Yttrium(lll) nitrate hexahydrate (99.9%), Powdered activated carbon (surface area of 1000 m2 / g),perfluorohexanoic acid (98+%, MilliporeSigma™), Sodium hydroxide (NaOH), and N,N- dimethylformamide (DMF) were purchased from Fisher Scientific. Hydrochloric acid (HCI) was purchased from Acros Organics.Experimental Process

[0049] A 2 mL column was packed with powdered activated carbon and 1 mL of a 6x103mol / L perfluorohexanoic acid (PFHxA) was added to the column to get adsorbed on the AC for 24h at RT. The PFHxA-saturated AC was then dried at RT and transferred to a vial with Y(NO)3-6H2O in 12 mL N,N-dimethylformamide (DMF) at 120 °C for 12h. The yttrium fluoride-loaded AC (YF3 / AC) powder was then added to 10 mL of a 5 mol / L NaOH solution. The reaction mixture was refluxed overnight with stirring. After filtration, washed with DI water to remove NaF, and drying, the (Y(OH)3 / AC) was reacted with 3 mol / L HCI for 30 min to recover free Y3+ions.Characterization

[0050] The powder X-ray diffraction (PXRD) measurements were performed on an Ultima IV X- ray diffractometer (Rigaku) at 45 kV, 40 mA using Cu Ka radiation with a scan speed of 27min and a step size of 0.04°. The scanning electron microscopy (SEM) energy-dispersive X-ray spectroscopy (EDS) was performed on a Zeiss EVO LS SEM and Aztec Instruments Oxford EDS. The samples were mounted on the aluminum holders using double-sided carbon tapes and not coated with gold or carbon. The XPS data was collected on a PHI VersaProbe II Scanning XPS Microprobe (Physical Electronics Inc, Chanhassen, Minnesota) equipped with an Al Ka X-ray source (Ep= 1486.7 eV) at pressure 1.6 x 10-9Torr. Powder samples were mounted on doublesided copper tape and coated with metallic gold for charge reference. Survey spectra were collected at a pass energy of 187 eV. High-resolution spectra were collected at the pass energy of 29 eV with a step size of 0.2 eV. Photoelectron spectra were obtained using a charge compensation of 2 mA using an electron flood gun. The data was processed with the software CasaXPS and energies were calibrated to adventitious C1s at 284.8 eV and Au 4f7 / 2 at 83.95 eV.Example 2: Results and DiscussionPFHxA-Saturated AC

[0051] To confirm the PFHxA adsorbed on the activated carbon, the product was characterized with Energy Dispersive X-ray analysis (EDX). The adsorption of PFHxA into the AC is evident by the signal for fluorine shown in FIG. 2.Transformation of PFHxA-Saturated AC to YF3 / AC

[0052] A solution of Y(NO)3.6H2O in N,N-dimethylformamide (DMF) was reacted with the PFHxA-saturated AC at 120 °C. The product was characterized with X-ray photoelectron spectroscopy (XPS) to confirm the production of YF3as shown in FIGs. 3A-3B. The F-NMR of the supernatant taken every two hours showed complete parent structure degradation within 6 h (FIG. 4).Direct Alkali Transformation of YF3 / AC

[0053] The Reaction product of alkali transformation of YF3 / AC was identified by powder X-ray diffraction (PXRD). The PXRD shown in FIG. 5 confirmed the transformation of yttrium fluoride (YF3) into yttrium hydroxide (Y(OH)3).Conclusion

[0054] One of the main challenges in the adsorptive removal of PFAS is that they produce a new waste sludge containing PFAS which is extremely difficult to regenerate. To overcome this, a degradation technique is reported for PFAS-saturated AC followed by a recycling step of the RE catalyst In this approach, after the adsorption of PFHxA into AC, it is treated with yttrium ions in solvents such as DMF and DM Ac at 120 °C to extract fluorine from the PFHxA. The PFAS tested are model compounds, but this technology is to work with a variety of PFAS molecules. The YF3 / AC residue is then transformed to Y(OH)3 / AC with a direct alkali transformation. Yttrium hydroxide is then dissolved in an acidic solution to give yttrium(lll) ions which is reused to extract more fluorine from PFAS. This method was depicted for removal of adsorbed PFAS on AC. However, this method works with PFAS on ion exchange resins and layered metal hydroxides. The method is anticipated to work with contaminated soil. While this method was demonstrated with the Y3+ion, it will also work with Ce3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, and Tb3+.

[0055] It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations set forth for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the abovedescribed embodiment(s) 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 and protected by the following claims.REFERENCESAsl Aminabadi, N.; et al. The Effect of 0.2% Sodium Fluoride Mouthwash in Prevention of Dental Caries According to the DM FT Index. J Dent Res Dent Clin Dent Prospects 2007, 1 (2), 71-76. Brendel, S.; et al. Short-Chain Perfluoroalkyl Acids: Environmental Concerns and a Regulatory Strategy under REACH. Environ Sci Eur 2018, 30 (1). doi: 10.1186 / s 12302- 018-0134-4. Cantoni, B.; et al. 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Claims

CLAIMSWhat is claimed is:

1. A method for removing one or more perfluoroalkyl and polyfluoroalkyl substances (PFAS) from water, the method comprising:(a) adsorbing the water comprising the PFAS onto an adsorbent material to form PFAS- saturated adsorbent material; and(b) admixing the PFAS-saturated adsorbent material with a solution of a salt of a rare earth metal in a solvent to produce a rare earth fluoride-loaded adsorbent material.

2. The method of claim 1 , wherein the PFAS comprises perfluorohexanoic acid, perfluorooctanoic acid, perfluorooctanesulfonic acid, perfluorobutyric acid, trifluoroacetic acid, or any combination thereof.

3. The method of claim 1, wherein the adsorbent material comprises activated carbon, a polymeric anion exchange resin, a metal organic framework (MOF), a layered double hydroxide, or any combination thereof.

4. The method of claim 1 , wherein step (a) is carried out for from about 1 hour to about 72 hours.

5. The method of claim 1 , wherein step (a) is carried out in a chromatography column.

6. The method of claim 1 , wherein the salt of a rare earth metal comprises a rare earth nitrate, chloride, or sulfate.

7. The method of claim 1 , wherein the rare earth metal has a 3+ oxidation state.

8. The method of claim 1 , wherein the rare earth metal comprises Y3+, Ce3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tb3+, Yb3+, or any combination thereof.

9. The method of claim 8, wherein the rare earth metal is Y3+.

10. The method of claim 1 , wherein the salt of a rare earth metal comprises Y(NO)3-6H2O.

11. The method of claim 1 , wherein the solvent comprises a polar, aprotic solvent.

12. The method of claim 11 , wherein the polar, aprotic solvent comprises dimethylformamide (DMF), dimethylacetamide (DMAc), diethylformamide (DEF), or any combination thereof.

13. The method of claim 1 , wherein step (b) is conducted at an elevated temperature.

14. The method of claim 13, wherein the elevated temperature is from about 80 °C to about 120 o / ^15. The method of claim 1 , wherein step (b) is carried out for about 12 hours to about 24 hours.

16. The method of claim 1 , further comprising(c) refluxing the rare earth fluoride-loaded adsorbent material in a solution comprising a base.

17. The method of claim 16, further comprising separating the rare earth fluoride-loaded adsorbent material from the solvent before performing step (c).

18. The method of claim 17, wherein the base comprises sodium hydroxide, potassium hydroxide, barium hydroxide, cesium hydroxide, strontium hydroxide, calcium hydroxide, lithium hydroxide, rubidium hydroxide, or any combination thereof.

19. The method of claim 16, wherein performing the method produces a rare earth hydroxide- loaded adsorbent material and NaF.

20. The method of claim 19, further comprising regenerating free rare earth ions by admixing the rare earth hydroxide-loaded adsorbent material with an acid.

21. The method of claim 20, wherein the acid comprises hydrochloric acid, perchloric acid, hydroiodic acid, hydrobromic acid, sulfuric acid, nitric acid, chloric acid, or any combination thereof.

22. A composition comprising NaF produced by the method of claim 19.

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