Foam fractionation for PFAS remediation

Abstract

The present disclosure relates to new methods of polyfluoroalkyl substances (PFAS) remediation using one or more Gemini surfactants and foaming agents for use therein.

Description

Docket No.: 1149704.098013FOAM FRACTIONATION FOR PFAS REMEDIATIONRELATED APPLICATIONS

[0001] The present invention relates to and claims benefit of priority to U.S. Provisional Application Number 63 / 737,868 filed on December 23, 2024, and Finnish Application Number FI 20253117, filed on April 4, 2025, the contents of all of which are incorporated by reference in their entireties herein.

[0002] All patents, patent applications and publications cited herein are hereby incorporated by reference in their entirety. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art as known to those skilled therein as of the date of the invention described and claimed herein.FIELD OF THE INVENTION

[0003] The present disclosure relates to new methods of per- and polyfluoroalkyl substances (PFAS) remediation.BACKGROUND OF THE INVENTION

[0004] Foam fractionation is an adsorptive bubble separation technique that can remove per-and polyfluoroalkyl substances (PFAS) dissolved in an aqueous solution The separation process is based on the sorption of PFAS to the air- water interface of rising bubbles according to their adsorption coefficients. The foam fractionation separation technique has been employed in PFAS removal from drinking water sources, sewage sludge, and landfill leachate, AFFF contaminated water, primary industrial wastewater, as well as rejects of nanofiltration and reverse osmosis for PFAS destruction.

[0005] However, in many cases, since PFAS concentrations in the target water sources are often not sufficient to allow for formation of a foam by itself, a co-foaming agent may be added to enhance the foamability of the solution. Studies on the effect of different classes of co-foaming agents, anionic, non-ionic, zwitterionic and cationic surfactants on the removal of PFAS with varying fluorocarbon chain length in a foam fractionation process reveal that cationic surfactants facilitate the most PFAS removal in the foam fractionation process.

[0006] Therefore, based on the foregoing, an efficient and cost-effective PFAS co-foaming agent is desired.Docket No.: 1149704.098013SUMMARY OF THE INVENTION[00071 The present invention relates to a method of removing per- and polyfluoroalkyl substances (PFAS) from an aqueous composition by foam fractionation, optionally wherein the aqueous composition is selected from the group consisting of an aqueous precipitate, surface water, groundwater, sewage sludge, drinking water, wastewater, leachates, sediment pore water, soil solutions, or any combination thereof, wherein the foam fractionation method uses at least one cationic gemini surfactant to promote foam formation, further optionally wherein the at least one cationic gemini surfactant is selected from the group consisting of a compound of formula (I), a compound of formula (II), a compound of formula (III), a compound of formula (IV), a compound of formula (V), a compound of formula (VI), a compound of formula (VII), a compound of formula (VIII), or a combination thereof: / s x "-,-CMS formula (I)t-< V '■ ' °'X / z x z-, A,«s rowula (Ilf)zV •<y.z-x C. K3formula ( 'Mlw z •,:i, ' V formula (V)o X ' 'Ji, fora-ula {VI'fformula (VII)formula (V lliwherein R1, R2, R3. R4, R5, R6, R7. R8, and R9are independently selected from the group consisting of a C5-C30 hydrocarbyl, formula (a), and formula (b), and formula (c);Docket No.: 1149704.098013fonrs-iia (a)ofonrt!la(b)O■'■ xvh '... n® formula (c); andwherein R10and R11, independently, are a C5-C30 hydrocarbyl, and R12and R13, independently, are a Ci -C30 hydrocarbyl. In embodiments, the cationic gemini surfactant is a compound of formula (III), wherein the compound of formula III is selected from the group consisting of formula (IIIa), formula (IIIb), formula (IIIc), formula (Illd), or a combination thereof:(Formula IIIa),(Formula IIIb),(Formula IIIc), or(Formula IIId),wherein x. y. and z, independently, are 4 to 29, and R1and R2independently, are a C1-C30 hydrocarbyl; wherein R is independently selected from the group consisting of C6-C22 alkyl, C6-C22 unsaturated alkyl, C6-C22 alkyl comprising one or more aromatic moieties. or any combination thereof. In embodiments, the cationic gemini surfac tant of formula (IIIa) is a C 12 gemini dibetainate according to the following structure:Docket No.: 1149704.098013In embodiments, the cationic gemini surfactant is a mixture of C12 gemini dibetainate and gemini monobetainate, comprising the C12 gemini dibetainate of claim 3 and a C12 gemini monobetainate according to the following structure:In embodiments, the method further comprises the use of a foaming agent other than a cationic gemini surfactant, wherein the combination of the other foaming agent and the at least one Gemini surfactant optionally results in any one or more of the following: (i) results in more rapid foam formation; (ii) results in a more physically stable foam; (iii) results in more PF AS being immobilized in the foam; (iv) results in the foam having a longer half- life; or (v) any combination thereof. In embodiments, the method comprises: (a) obtaining an aqueous surfactant solution comprising at least one cationic gemini surfactant; (b) contacting an aqueous composition comprising PF AS with the cationic gemini surfactant comprising solution, thereby producing a PFAS-surfactant mixture; (c) subjecting the PFAS-surfactant mixture to an airflow sufficient to produce a bubble flow, thereby producing a PF AS-containing foam; and (d) separating the PF AS-containing foam from the aqueous composition, thereby producing a PFAS foamate and a remediated aqueous composition. In embodiments, said foam fractionation using a cationic gemini surfactant solution as the foaming agent is effected 2 or more times, and preferably 3, 4, 5 or more times. In embodiments, the cationic Gemini surfactant solution comprises about 0.1 ppm to about 10000 ppm of at least one cationic Gemini surfactant. In embodiments, a solution comprising at least one cationic Gemini surfactant is added to a PF AS comprising aqueous composition in an amount sufficient to result in a dosage ranging from about 0.5 mg / L to about 1000 mg / L, more preferably 5.0 mg / L to 200 mg / L or most preferably 20 mg / L to 100 mg / L. In embodiments, the aqueous composition comprises about 0.4 ppt to about 1000 ppm PF AS. In embodiments (i) at least about 30 % to about 40 %, more preferably at least about 60-70 %, and most preferably al least about 85 % of the PFAS is removed by the foam fractionation method; and / or (ii) the method results in an aqueous composition which comprises at most 100 ppt, 10 ppt, and most preferably at most 4 ppt of PFAS. In embodiments, the dosage of the surfactant solution results in a total surfactant concentration of about 0.1 ppm to about 10000 ppm total surfactant. In embodiments, (a) the PFAS-surfactant mixture has increased foamability compared to the aqueous composition comprising PFAS: (b) the PFAS-Docket No.: 1149704.098013containing foam of about 1000 ppm has a half-life for about 10 seconds: and (c) the foamate comprises about 45% to about 100 % of the concentration of the aqueous composition.

[0008] Aspects of the invention are drawn towards a foaming agent composition for promoting foam formation of per- and poly fluoroalkyl substances (PFAS) comprising about 0.1 ppm to about 10000 ppm of a Gemini surfactant, and optionally further comprising one or more anionic surfactants, nonionic surfactants, zwitterionic surfactants, salts, polymers, or a combination thereof.

[0009] Aspects of the invention are drawn towards a multiphase composition obtained during foam fractionation of a per- and polyfluoroalkyl substance (PFAS) comprising aqueous composition, which composition comprises (i) a PFAS comprising foam phase and (li) an aqueous phase from which the PFAS in the foam originated, wherein the foam fractionation method uses at least one cationic gemini surfactant to promote foam formation, optionally wherein the at least one cationic gemini surfactant comprises a compound according to any one of the methods described herein.

[0010] Other objects and advantages of this invention will become apparent from the ensuing description.BRIEF DESCRIPTION OF THE FIGURES

[0011] FIG. 1 shows non-limiting, exemplary test results of alkyl trimethyl quaternary’ bromide surfactants, where C8 and C12 were also tested. At lOOOppm, C8 does not foam up to 150 s. At the same concentration. Cl 2 foams but the foam does not reach the 1000ml mark and test was stopped at 270 s.

[0012] FIG. 2 shows non-limiting, exemplary' foamability' test results of various Gemini dibetainates and Gemini dibronnde.

[0013] FIG. 3 shows a non-limiting, exemplary scheme of a foam fractionation process setup.

[0014] FIG. 4 shows non-limiting, exemplary foam collection results wider various column process conditions.

[0015] FIG. 5 shows non-limiting, exemplary gemini surfactants.

[0016] FIG. 6 shows a graph of non-limiting, exemplary' data collected from PFAS samples processed via foam fractionation.

[0017] FIG. 7 shows a process flow-’ diagram adapted from Remediation. 2021;! -15 (DOI: 10.1002 / rem.21694).Docket No.: 1149704.098013

[0018] FIG. 8 shows a schematic of a foam fractionation column of first stage adapted from RK.2 systems protein fractionator (rk2.com / protein-fractionators-saltwater-HDPE.php).DETAILED DESCRIPTION OF THE INVENTION

[0019] Described herein are cationic gemini surfactants for use in foam fractionation for PFAS removal from an aqueous matrix.

[0020] Detailed descriptions of one or more embodiments are provided herein. It is to be understood, however, that the invention can be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the invention in any appropriate manner.

[0021] The singular forms “a”, “an” and “the” include plural reference unless the context clearly dictates otherwise. The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and / or the specification can mean “one,” but it is also consistent with the meaning of “one or more.” “at least one,” and “one or more than one.”

[0022] Wherever any of the phrases “for example,” “such as,” “including” and the like are used herein, the phrase “and without limitation” is understood to follow unless explicitly stated otherwise. Similarly, “an example.” “exemplary” and the like are understood to be nonlimiting.

[0023] The term “substantially” allows for deviations from the descriptor that do not negatively impact the intended purpose. Descriptive terms are understood to be modified by the term “substantially” even if the word “substantially” is not explicitly recited.

[0024] The terms “comprising” and “including” and “having” and “involving” (and similarly “comprises”, “includes,” “has,” and “involves”) and the like are used interchangeably and have the same meaning Specifically, each of the terms is defined consistent with the common United States patent law definition of “comprising” and is therefore interpreted to be an open term meaning “at least the following,” and is also interpreted not to exclude additional features, limitations, aspects, etc. Thus, for example, “a process involving steps a, b, and c” means that the process includes at least steps a, b and c. Wherever the terras “a” or “an” are used, “one or more” is understood, unless such interpretation is nonsensical in context.

[0025] As used herein, the term “about” can refer to approximately, roughly, around, or in the region of. When the term “about” is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. In general, the term “about” is used herein to modify a numerical value above and below the statedDocket No.: 1149704.098013value by a variance of 20 percent up or down (higher or lower). In embodiments, the term “about"’ can be denoted by “ -

[0026] As used herein, the term “substantially the same” or “substantially” can refer to variability typical for a particular method is taken into account,

[0027] The terms “sufficient” and “effective”, as used interchangeably herein, can refer to an amount (e.g., mass, volume, dosage, concentration, and / or time period) needed to achieve one or more desired result(s).

[0028] Before explaining at least one embodiment of the disclosure in detail, it is to be understood that the disclosure is not necessarily limited in its application to the details set forth in the following description or exemplified by the examples. Hie disclosure can be used for other embodiments or of being practiced or carried out in various ways. Other compositions, compounds, methods, features, and advantages of the disclosure will be or become apparent to one having ordinary skill in the art upon examination of the following drawings, detailed description, and examples. All such additional compositions, compounds, methods, features, and advantages can be included within this description, and be within the scope of the disclosure.

[0029] Before describing the invention in detail, the following definitions are provided. Unless stated otherwise all terms are to be construed as they would be by a person skilled in the art,

[0030] Definitions

[0031] As used herein, the term “foam” can refer to a colloid of gas dispersed in liquid. For example, the gas can be a mixture of gases (e.g., air) or a single gas. For example, the liquid can be an aqueous composition comprising PFAS.

[0032] As used herein, the term “per- and polyfluoroalkyl substances (PFAS)” can refer to one or more compounds with an alkyl chain bonded to multiple fluorine atoms. For example, non-limiting, exemplary PFAS can comprise one or more of the following: perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorobutanesulfonic acid (PFBS), hexafluoropropylene oxide-dimer acid (HFPO-DA or GenX), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS). perfluorodecanoic acid (PFDA), perfluorohexanoic acid (PFHxA), perfluorobutanoic acid (PFBA). ammonium pentadecafluorooctanoate (APFO), perfluoroheptanoic acid (PFHpA), 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctan-l-ol (6:2 FTOH), perfluoropentanoic acid (PFPeA), perfluoroundecanoic acid (PFUnDA), peril uorohexanesulfonami de (PFHxSA), perfluoroheptanesulfonamide (PFHpSA), perfluorooctane sulfonamide (PFOS A), Perfluoroalkyl sulphonic acids (PFSAs)Docket No.: 1149704.098013such as perfluorooctane sulfonate (PFOS), perfluoroalkyl carboxylic acids (PFCAs) such as peril uorooctanoic acid (PFOA), perfluorobutanoic acid (PFBA), Perfluoroether carboxylic acids (PFECAs), and fluorocarbons such as hexafluoropropylene oxide (FIFPO), heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether (fluoroether E-l), and fluoroteloraer alcohols. Additional exemplary7PF AS chemicals can be found in literature, for example, see Trends in Analytical Chemistry' 121 (2019) 115410.

[0033] As used herein, the term “aqueous composition” can refer to any composition comprising water. In embodiments, an aqueous composition is a composition that comprises more than trace amounts of water. For example, an aqueous composition can comprise at least about 1% water, at least about 2% water, at least about 5% water, at least about 10% water, at least about 20% water, at least about 30% water, or more than about 30% water. As used herein, the terms “aqueous composition” and “aqueous matrix” can be used interchangeably

[0034] As used herein, the term “foam fractionation” can refer to an adsorptive bubble separation technique. As described herein, foam fractionation with the surfactants described herein can remove PF AS dissolved in an aqueous solution. The separation process is based on the sorption of PFAS to the air-water interface of rising bubbles according to their adsorption coefficients. The foam fractionation separation technique can be employed in PFAS removal from drinking water sources, sewage sludge, and landfill leachate, as well as rejects of nanofiltration and reverse osmosis for PFAS destruction.

[0035] As used herein, the term “gemini surfactant” can refer to surfactant molecules comprising two hydrophobic tails and two hydrophilic head groups, linked by a spacer. For example, the term gemini surfactant can refer to dimeric structures, comprising two hydrophobic chains and two hydrophilic heads, linked by a spacer at or near the head groups.

[0036] The two terminal hydrocarbon tails of gemini surfactants can be short (e.g., up to about 8 carbon atoms) or long (e.g., about 12 to about 30 carbon atoms); the two polar head groups of a gemini surfactant can be cationic, anionic, or nonionic: and the spacer can be short (e.g., about 1 to about 3 carbon atoms), long (e.g., about 4 to about 6 carbon atoms), flexible, or rigid, and / or may contain one or more heteroatoms (e.g., nitrogen, oxygen, sulfur, phosphorus, etc.). Moreover, components of a gemini surfactant may or may not be symmetrically disposed about the center of the spacer. Some gemini surfactants can self-assemble at much lower concentrations, and / or have improved surface activity compared to conventional surfactants. For example, the critical micelle concentrations (CMCs) of Gemini surfactants can be about 10-100 times lower than those of equivalent monomeric surfactants.Docket No.: 1149704.098013

[0037] As used herein, the term “betainate” can refer to an ester of betaine. As used herein, the term ‘betaine’’ can refer to a neutral chemical compound with a positively charged cationic functional group that bears no hydrogen atom. For example, the betaine can be a quaternary ammonium or phosphonium cation, and with a negatively charged functional group, such as a carboxylate group that is not adjacent to the cationic site.

[0038] As used herein, the term “dibetainate” can refer to a molecule comprising two betainate moieties.

[0039] As used herein, the term “monobetainate” can refer to a molecule comprising one betainate moiety.

[0040] As used herein, the term “foaming agent"’ can refer to a surfactant that can facilitate foam formation. In embodiments, the term “foaming agent” can refer to a primary foaming agent or a co-foaming agent.

[0041] As used herein, the term “co-foaming agent” can refer to a composition used to improve the foaming ability (foamability) of a primary foaming agent or a composition capable of forming a foam. A co-foaming agent can facilitate foaming, enhance foam stability, and / or decrease the rate of draining. As used herein, the terms “co-foam agent,” “foam booster,” “foam stabilizer,” and “foam enhancer” can be used interchangeably.

[0042] As used herein, the term “bubble flow"’ can refer to a liquid stream dispersed with gas bubbles allowing a substance to adsorb to the bubble surfaces. For example, in foam fractionation, a bubble flow through an aqueous composition or matrix can allow for PF AS to adsorb to the bubble surfaces and collect at the top of the liquid as a foam.

[0043] As used herein, the term “foam stability” can refer to the time that foam will maintain its initial properties as generated. Foam stability' can be expressed in terms of foam half-life, which is the time required for half of the volume of liquid contained in the foam to revert to the bulk-liquid phase. The shorter the time, the lower is the stability of the foam.

[0044] As used herein, the term “half-life” can refer to the time required for half of the volume of liquid contained in the foam to revert to the bulk-liquid phase.

[0045] As used herein, the term “foamate” can refer to a concentrated foam that collects at the top of a foam fractionation process, containing the adsorbed target substances (e.g., PFAS). As used herein, the terms “foamate” and “enriched foam product” can be used interchangeably.

[0046] As used herein, the term “remediated” can refer to a contaminated composition that has been cleaned and / or restored. For example, as used herein, remediated can refer to a composition that has had the concentration of PFAS reduced or removed.Docket No.: 1149704.098013

[0047] As used herein, the term ‘'foamability'’ can refer to the ability of a composition to create a foam. Increased foamability’ can be indicated by a shorter time to produce a foam.

[0048] As used herein, the term 'active’7can refer to the active content of a specific chemical component within a product. For example, " PFNA 97% active" can refer to 97% by weight of the product is PFNA, and the remaining 3% can be a non-active component, e.g., water.

[0049] Compositions and Methods Described Herein

[0050] Surprising aspects of the disclosure include, but are not limited to, the low dosage of surfactant required for foam fractionation and stability’ of the resultant foam. Additionally, the surfactants have high water solubility- and exhibit biodegradability'. For example, in some embodiments, the surfactants can comprise a water solubility of about 400 g / L at 25°C,

[0051] Aspects of the disclosure are drawn towards methods of removing per- and polyfluoroalkyl substances (PFAS) from an aqueous composition by foam fractionation, wherein the foam fractionation method uses at least one cationic gemini surfactant to promote foam formation. Optionally, the cationic gemini surfactants can comprised those described in WO 2024 / 155904

[0052] For example, the at least one cationic gemini surfactant is selected from the group consisting of formula (I), a compound of formula (II), a compound of formula (III), a compound of formula (IV), a compound of formula (V), a compound of formula (VI), a compound of formula (VII), a compound of formula (VIII), or a combination thereof:Docket No.: 1149704.098013formula (I)formula (If)formula Uli)formula -IV)formula (V)formula (Vi)ps.!: Wiij'Ns.'-s A formula i VII) Kd ' " ' " "formula (Vlll)wherein R1, R2, R3, R4, R5, R6, R'„ R8. and R9are independently selected from the group consisting of a C5-C30 hydrocarbyl, formula (a), and formula (b), and formula (c);O I I to formula (a)■' 'C'-'’'’o, |i *,1 formula (b)'k A.. R■' '•• •' MHO> 11r - x formula (c); andwherein R10and Rn, independently, are a C5-C30 hydrocarbyl, and R12and R13, independently, are a C1-C30 hydrocarbyl.

[0053] When the formulas or compounds depicted herein include a positively charged moiety or atom, such as a positively charged quaternary nitrogen atom, the formulas or compounds can include any counter anion. In some embodiments, the compound of formula (I), the compound of formula (II), the compound of formula (III), the compound of formula (IV), theDocket No.: 1149704.098013compound of formula (V), and the compound of formula (VI), the compound of formula (VII), the compound of formula (VIII), include a counter anion corresponding to each quaternary nitrogen atom. The counter anions can include inorganic ions, such as a halide ion, or organic ions, such as an alkyl sulfonate or an aryl sulfonate.

[0054] In some embodiments, Rl, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, Ra, and Rb, independently, are a C6-C30 hydrocarbyl, C6-C28hydrocarbyl, C6-C26 hydrocarbyl, C6-C24 hydrocarbyl, C10-C24 hydrocarbyl, C10-C20 hydrocarbyl, C14-C24 hydrocarbyl, C10-C17 hydrocarbyl, or a C18-C24 hydrocarbyl. The number of carbon atoms of a hydrocarbyl can be selected to impart one or more desirable characteristics to a composition or a component thereof. When the compositions described herein include a compound of formula (III), R3and R4can be the same or different. For example, (i) R' can be a branched dodecyl group, and R4can be a linear dodecyl group; (ii) R3can be a branched dodecyl group, and R4can be a branched hexyl group; (iii) R3and R4can be identical linear decyl groups; etc.

[0055] The phrases “C1-C30 h drocarbyl,’" “C10-C24 hydrocarbyl”, and the like, as used herein, can refer to aliphatic, aryl, or aryl alkyl groups containing 1 to 30 carbon atoms, or 10 to 24 carbon atoms, respectively, including substituted derivatives thereof. Examples of aliphatic groups, in each instance, include, but are not limited to, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an alkadienyl group, a cyclic group, and the like, and includes all substituted, unsubstituted, branched, and / or linear analogs or derivatives thereof, in each instance having, for example. 1 to 30 total carbon atoms or 10 to 24 total carbon atoms for a “‘C1-C30 hydrocarbyl ” and ‘" Cio-C24 hydrocarbyl”, respectively. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, n- butyl, t-butyl, isobutyl, pentyl, hexyl, isohexyl, heptyl, 4,4-dimethylpentyl, octyl, 2,2,4-trimethylpentyl, nonyl, decyl, undecyl, and dodecyl. Cycloalkyl moieties may be monocyclic or multicyclic, and examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and adamantyl, including any heteroatom substituted derivative thereof. Additional examples of alkyl moieties have linear, branched and / or cyclic portions (e.g., l-ethyl-4-methyl-cyclohexyl). Representative alkenyl moieties include vinyl, allyl, 1-butenyl, 2-butenyl, isobutylenyl, 1-pentenyl, 2 -pentenyl, 3-methyl-l-butenyl, 2-methyl-2-butenyl, 2,3-dimethyl-2-butenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 1 -heptenyl, 2-heptenyl, 3-heptenyl, 1 -octenyl, 2-octenyl, 3-octenyl, 1-nonenyl, 2-nonenyl, 3-nonenyl, 1-decenyl, 2-decenyl, and 3-decenyl. Representative alkynyl moieties include acetylenyl, propynyl, 1-butynyl, 2-butynyl, 1-pentynyl, 2-pentynyl, 3-methyl-l-butynyl, 4-pentynyl, 1-hexynyl, 2-hexynyl, 5-hexynyl, 1-heptynyl, 2 -heptynyl, 6-heptynyl, 1 -octynyl, 2-octynyl. 7-octynyl, l-nonynyl, 2-nonynyl, 8-Docket No.: 1149704.098013nonynyl, 1 -decynyl, 2-decynyl and 9-decynyl. Examples of aryl or arylalkyl moieties include, but are not limited to. anthracenyl, azulenyl. biphenyl, fluorenyl, indan, indenyl, naphthyl, phenanthrenyl, phenyl, 1,2,3,4-tetrahydro-naphthalene, anthracenyl, tolyl, xylyl, mesityl, benzyl, and the like, including any heteroatom substituted derivative thereof.

[0056] Unless otherwise indicated, the term "substituted," when used to describe a chemical structure or moiety, can refer to a derivative of that structure or moiety wherein (i) a multivalent non-carbon atom (e.g., oxygen, nitrogen, sulfur, phosphorus, etc.) is bonded to one or more carbon atoms of the chemical structure or moiety (e.g.. a “substituted” C4 hydrocarbyl may include, but is not limited to, a pyrimidinyl moiety, a pyridinyl moiety, a dioxanyl moiety, a diethyl ether moiety, a methyl propionate moiety, an N,N-dimethylacetamide moiety, a butoxy moiety, etc., and a “substituted” aryl C12 hydrocarbyl can include, but is not limited to, an oxydibenzene moiety, a benzophenone moiety', etc.) or (ii) one or more of its hydrogen atoms (e.g., chlorobenzene may be characterized generally as an aryl Ce hydrocarbyl “substituted” with a chlorine atom) is substituted with a chemical moiety or functional group such as acyl, alcohol, alkoxy, alkanoyloxy, alkoxycarbonyl, alkenyl, alkyl (e.g., methyl, ethyl, propyl, t-butyl), alkynyl, alkylcarbonyloxy (-OC(O)alkyl), amide (-C(O)NH-alkyl- or - alkylNHC(O)alkyl), primary, secondary, and tertiary' amino (such as alkylammo, arylamino, arylalkyl amino), aryl, arylalkyl, aryloxy, azo, azido, carbamoyl (-NHC(O)O-alkyl- or - OC(O)NH-alkyl), carbamyl (e.g, CONH2, as well as CONH-alkyl, CONH-aryl, and CONH-arylalkyl), carboxyl, carboxylic acid, cyano, cycloalkyl, cycloalkenyl, ester, ether (e.g., methoxy, ethoxy), halo, haloalkyl (e.g.. -CCh, -CF3, -C(CF3)3), haloalkoxy, trihalomethanesulfonyl, trihalomethanesulfonamido. heteroalkyl, heterocycloalkyl, heteroaryl, heteroarylalkyl, isocyanate, isothiocyanate, nitrile, nitro, oxo, phosphodiester, silyl, sulfide, sulfonamide (e.g., SO2NH2), sulfone, sulfenyl, sulfinyl, sulfonyl (including alkylsulfonyl, arylsulfonyl and arylalkylsulfonyl), sulfoxide, thiocarbonyl, thiocarbamyl, thiocyanato, thiol (e.g., sulfhydryl, thioether) or urea (-NHCONH-alkyl-).

[0057] In embodiments, the cationic gemini surfactant is a compound of formula (III), wherein the compound of formula III is selected from the group consisting of formula (IIIa), formula (IIIb), formula (IIIc), formula (IIId), or a combination thereof:(Formula IIIa),0\ / 0\ / 0Docket No.: 1149704.098013(Formula IIIb),(Formula IIIc), or(Formula IIId),wherein x, y, and z, independently, are 4 to 29, and R1and R2independently, are a C1-C30 hydrocarbyl;wherein R is independently selected from the group consisting of C6-C22 alkyl, C6-C22 unsaturated alkyl, C6-C22 alkyd comprising one or more aromatic moieties. or any combination thereof.

[0058] In embodiments, the cationic gemini surfactant of formula (IIIa) is a C12 gemini betainate according to the following structure:

[0059] In embodiments, the cationic gemini surfactant is a mixture of C12 gemini dibetainate and gemini mono betainate, comprising a Cl 2 gemini dibetinate and a C12 gemini monobetmate according to the following structure:

[0060] In embodiments, the mixture of C12 gemini surfactants comprises about 5% dibetainate and about 95% monobetainate, about 10% dibetainate and about 90% monobetainate. about 15% dibetainate and about 85% monobetainate, about 20% dibetainate and about 80% monobetainate, about 25% dibetainate and about 75% monobetainate, about 30% dibetainate and about 70% monobetainate, about 35% dibetainate and about 65% monobetainate, about 40% dibetainate and about 60% monobetainate, about 45% dibetainate and about 55% monobetainate, about 50% dibetainate and about 50% monobetainate, about 55% dibetainate and about 45% monobetainate, about 60% dibetainate and about 40% monobetainate, about 65% dibetainate and about 35% monobetainate, about 70% dibetainate and about 30% monobetainate, about 75% dibetainate and about 25% monobetainate, about 80% dibetainate and about 20% monobetainate, about 85% dibetainate and about 15%Docket No.: 1149704.098013monobetainate, about 90% dibetamate and about 10% monobetainate, or about 95% dibetainate and about 5% monobetainate. For example, the mixture of C12 gemini surfactants can be about 30 % gemini dibetainate and about 70% monobetainate.

[0061] In embodiments, the methods described herein can optionally further comprise the use of a foaming agent other than a cationic gemini surfactant. In embodiments, the combination of the other foaming agent and the at least one Gemini surfactant optionally results in any one or more of the following: results in more rapid foam formation; results in a more physically stable foam; results in more PFAS being immobilized in the foam; results in the foam having a longer half-life; or any combination thereof. In embodiments, the foaming agent can be added in less than about 0.1 wt. %, about 0.1 wt. %, about 0.25 wt. %, about 0.5 wt. %, about 0.75 wt %. about 1.0 wt %. about 1.25 wt. %, about 1.5 wt. %. about 1.75 wt. %, about 2.0 wt. %, about 2.25 wt. %, about 2.5 wt. %, about 2.75 wt. %, about 3.0 wt. %, or greater than about 3.0 wt. %.

[0062] As used herein, the other foaming agent can be any surfactant and / or co-foaming agent known in the art. For example, the other foaming agent can comprise amines such as cocamidopropylamine. short chain alcohols, glucosides such as lauryl glucoside, alkanolamides such as fatty acid diethanolamide (DEA), betaines such as cocamidopropyl betaine, sultaines such as cocaamidopropyl hydroxy sultaine, alkanolamine oxides such as cocamidopropylamine oxide, dihydroxyethyl cocamine oxide, decyldimethyl amine oxide, polymers such as cationic guar, cationic starch. HPMC, and salts such as NaCl, KC1, MgCb, CaCh, or any combination thereof.

[0063] In embodiments, the foam fractionation can be performed at any scale known in the art by a person of ordinary skill in the art. For example, the foam fractionation can be performed at a lab scale or an industrial scale. For example, the foam fractionation can be performed in batch mode or operated in continuous mode.

[0064] In embodiments, the foam fractionation can be performed in a lab scale set up. For example, see the non-limiting, exemplary lab setup illustrated in Figure 3. An acrylic resin column with a length of about 21.5 inch and a diameter of about 2.75 inch was used, a 2 inch nano air stone was sealed at the bottom of column, connecting to a compressed air supply regulated by a compressed air regulator. At the top of column, there is a tube connect to a collecting flask that equipped with vacuum to collect the foam. 1000 mL of C12 Gemini dibetainate aqueous solution (25 ppm) was prepared and 995 g of solution (fills 70% height of column) was poured into a single column foam fractionator. Turn on the compressed air and inDocket No.: 1149704.098013house vacuum, Set air flow rate =500 cc / min, vacuum = 3.5 inHg to start foam collection. Collection time is 20 mins.

[0065] In embodiments, the foam fractionation can be performed at an industrial scale by any method known in the art. For example, at pilot and production scales, the foam fractionation can be operated in continuous mode. For example, see the article of Remediation.2021;1-15 (DOI: 10.1002 / rem.21694), which details a pilot foam fractionator comprised of a train of three foam fractionation stages that are installed in series and operate in a semi-batch mode, as is depicted in the simplified process flow diagram of Figure 7. The first stage (primary fractionator) “strips” PFAS from contaminated feed and produces a PFAS-depleted rejectate (i.e., the treated water) which is then pumped from the bottom of each aeration vessel and sent to a polishing stage and then to the “clean” water stream. The primary foamate containing the PFAS waste stream forms the feed to the second stage (secondary fractionation). The enriched secondary foamate from the secondary unit forms the feed to the third stage (tertiary fractionation), whereas the rejectate from both the secondary / tertiary fractionation stages are recycled / blended back into the feed of the primary fractionation stage. The foamate of the tertiary unit, which is now highly enriched in PFAS but with extraordinarily reduced volume is stored on-site awaiting periodic disposal The primary fractionation stage is comprised of several vessels fabricated from high density polyethylene (HDPE), each with a volume of 2.5 m3. The operation of each successive vessel is offset by approximately 5 min such that they fill with contaminated water in turn. Each of the primary’ foam fractionators is aerated for about 21 min using Venturi-type aerators. Aeration rates can be controlled such that the foam does not flood the column. Hie secondary-’ foam fractionation stage is comprised of a single 1.1 m3HDPE vessel also fitted with Venturi aerators. The tertiary foam fractionation stage, depicted schematically in Figure 7 is not a dedicated unit. Because the volume reduction of foamate versus feed to an individual fractionator is substantial, the tertiary foam fractionation can be conducted in the secondary foam fractionation column, typically once about every 8-10 weeks. The operation of the tertiary' stage presented some challenges with respect to foam handling because the high concentration of PFAS species causes exceptionally tenacious foams, and such a tertiary stage is thought to be optional for designs. Thus, tertiary fractionation is optionally a specialty service brought to the site (e.g., as a mobile trailer unit) or alternatively taken off-site for processing. The tertiary foamate, which is highly enriched in PFAS, can be collected and temporarily stored on-site for disposal once the volume of this waste approaches 1 m3. An ordinary scale of industrial foam fractionator normally handles less than 100,000Docket No.: 1149704.098013gallons per day, or around 70 gallons per minute, of PFAS-containing wastewater. Figure 8 shows a non-limiting, exemplary schematic of the foam fractionation column of primary stage.

[0066] The methods described herein can comprise obtaining an aqueous surfactant solution comprising at least one cationic gemini surfactant; contacting an aqueous composition comprising PF AS with the cationic gemini surfactant comprising solution, thereby producing a PFAS-surfactant mixture; subjecting the PFAS-surfactant mixture to an airflow sufficient to produce a bubble flow, thereby producing a PFAS-containing foam; and separating the PFAS- containing foam from the aqueous composition, thereby producing a PFAS foamate and a remediated aqueous composition.

[0067] In embodiments, the aqueous surfactant solution can comprise about 0.5 ppm to about 10000 ppm of at least one cationic gemini surfactant. For example, the surfactant solution can comprise less than about 0.1 ppm, about 0.2 ppm, about 0.3 ppm, about 0.4 ppm, about 0.5 ppm, about 075 ppm, about I ppm, about 2 ppm, about 3 ppm, about 4 ppm. about 5 ppm, about 6 ppm, about 7 ppm, about 8 ppm, about 9 ppm, about 10 ppm, about 11 ppm, about 12 ppm, about 13 ppm, about 14 ppm. about 15 ppm, about 16 ppm, about 17 ppm. about 18 ppm, about 19 ppm, about 20 ppm, about 25 ppm. about 30 ppm, about 40 ppm. about 45 ppm, about 50 ppm, about 55 ppm, about 60 ppm, about 65 ppm, about 70 ppm, about 75 ppm, about 80 ppm, about 85 ppm, about 90 ppm, about 95 ppm, about 100 ppm, about 110 ppm, about 125 ppm, about 150 ppm, about 175 ppm, about 200 ppm, about 225 ppm, about 250 ppm, about 275 ppm, about 300 ppm. about 325 ppm, about 350 ppm, about 375 ppm. about 400 ppm, about 425 ppm, about 450 ppm, about 475 ppm, about 500 ppm, about 525 ppm, about 550 ppm, about 575 ppm, about 600 ppm, about 625 ppm, about 650 ppm, about 675 ppm, about 700 ppm, about 725 ppm, about 800 ppm, about 850 ppm, about 900 ppm, about 1000 ppm, about 1500 ppm. about 2000 ppm. about 2500 ppm, about 3000 ppm. about 3500 ppm, about 4000 ppm, about 4500 ppm, about 5000 ppm, about 5500 ppm, about 6000 ppm, about 6500 ppm, about 6500 ppm, about 7000 ppm, about 7500 ppm, about 8000 ppm, about 8500 ppm, about 9000 ppm, about 10000 ppm, or greater than about 10000 ppm.

[0068] In some embodiments, the foaming with cationic surfactants can occur at lower than CMC (critical micelle concentration). For example, for C12 gemini dibetainate, the CMC can be about 200 ppm. Without wishing to be bound by theory, the CMC of C 12 mixture betamate can be higher than C 12 gemini dibetainate. Therefore, without wishing to be bound by theory, the CMC of Cl 2 gemini dibetainate can be about 10000 ppm.Docket No.: 1149704.098013

[0069] In embodiments, the aqueous composition comprising PFAS can comprise about 2 ppt to about 50000 ppm of PFAS. For example, the aqueous composition can comprise less than about 0.4 ppt to about 100000 ppm of PFAS

[0070] In embodiments, the PFAS-surfactant mixture can comprise about 0.1 ppm to about 10000 ppm of at least one cationic surfactant. For example, the PFAS-surfactant mixture can comprise less than about 0.1 ppm to greater than about 10000 ppm of at least cationic surfactant.

[0071] In embodiments, the aqueous composition comprising a PFAS can be an aqueous composition comprising an aqueous precipitate, surface water, groundwater, sewage sludge, drinking water, wastewater, the byproduct stream of an industrial facility, leachates, sediment pore water, soil solutions, AFFF contaminated water or any combination thereof. For example, the aqueous composition can be a stream from a byproduct and / or waste stream from an industrial process. For example, the stream can be from metal finishing or electroplating.

[0072] In embodiments, the foam fractionation can be carried out in any reaction vessel known in the art or in situ. For example, the reaction vessel can comprise a column in a laboratory setting. For example, in situ can comprise a water treatment facility, a groundwater remediation site, in downstream processing, or in natural or manmade body of water. For example, the foam fractionation can be performed in a pond, lake, or other body of w ater.

[0073] In embodiments, a foam fractionator can comprise at least one foam generator and at least one foam collector. For example, the foam fractionator can comprise at least one foam generator, two foam generators, three foam generators, four foam generators, five foam generators, or more than five foam generators. For example, the foam fractionator can comprise at least one foam collector, two foam collectors, three foam collectors, four foam collectors, five foam collectors, or more than five foam collectors. In foam fractionation operation, foam can be created by an air pump and taken out from the system with a vacuum. For example, a simple form of foam fractionator comprises a column where the foam generator is an air stone. In embodiments, the vacuum can comprise about 0.5 to about 30 InHg.

[0074] In embodiments, the airflow sufficient to produce a bubble flow can comprise aa range of airflow rates and air source pore sizes. These ranges can be adjusted by one of ordinary skill in the art depending on the volume of the aqueous composition. For example, the pore size can range from about a few' microns to about a few’ millimeters in 200 mL / min of flow’ rate. In embodiments, the airflow rate can be about 100 to about 2500 CC / 'min. However, the pore size and airflow rates can vary and be adjusted by one of ordinary’ skill in the art based upon the application.Docket No.: 1149704.098013

[0075] In embodiments, separating the PFAS -containing foam can be performed by any method known in the art. In embodiments, the PF AS-containing foam can be defoamed into a liquid. In embodiments, the separated foam or defoamed liquid can be destroyed or disposed of via any method known in the art.

[0076] In embodiments, the foam fractionation using a cationic gemini surfactant solution as the foaming agent is effected 2 or more times, and preferably 3, 4, 5 or more times. In embodiments, the foam fractionation can be performed on the aqueous composition until the desired PFAS concentration is reached In some embodiments, desired PFAS concentration is an undetectable amount. In some embodiments, the PFAS concentration is reduced by at least about 30 % to about 40 %, more preferably at least about 60-70 %, and most preferably at least about 85 % of the PFAS is removed by the foam fractionation method; and / or the method results in an aqueous composition which comprises at most 100 ppt, 10 ppt, and most preferably at most 0.4 ppt of PFAS.

[0077] In embodiments, the dosage of the cationic gemini surfactant can comprise about 0.5 mg / L to about 1000 mg / L, more preferably 5.0 mg / L to 200 mg / L or most preferably 20 mg / L to 100 mg / L.

[0078] In embodiments, the PFAS-surfactant mixture has increased foamability compared to the aqueous composition comprising PFAS. For example, two solutions of PFOS and PFNS at ppt each did not produce foams. However, upon addition of about 25 ppm Cl 2 gemini dibetainate to each solution, the solutions exhibited foamability.

[0079] In embodiments, the PFAS-containing foam has a half-life of at 1000 ppm of about 1 second to about 1 minute. For example, the half-life can comprise about 2 seconds, about 5 seconds, about 10 seconds, about 15 seconds, about 20 seconds, about 25 seconds, about 30 seconds, about 35 seconds, about 40 seconds, about 45 seconds, about 50 seconds, about 55 seconds, about 60 seconds, about 1.1 minutes, about 1.2. minutes, about 1.3 minutes, about 1.4 minutes, about 1.5 minutes, about 1.6 minutes, about 1.7 minutes, about 1.8 minutes, about 1.8 minutes, about 1.9 minutes, about 2 minutes, about 2.25 minutes, about 2.5 minutes, about 2.75 minutes, about 3 minutes, about 3.25 minutes, about 3.5 minutes, about 3.75 minutes, about 4 minutes, or greater than about 4 minutes.

[0080] Aspects of the disclosure are drawn towards a foaming agent to promote foam formation of per- and polyfluoroalkyl substances (PFAS) comprising about 0.5 ppm to about 100 ppm of a Gemini surfactant. In embodiments, the foaming agent optionally further a co-foaming agent. In embodiments, the co-foaming agent comprises anionic surfactants, nonionicDocket No.: 1149704.098013surfactants, zwitterionic surfactants, salts, polymers, or a combination thereof. For example, the salts can comprise NaCl, KC1, MgCh, CaCh, or any combination thereof.

[0081] Aspects of the disclosure are drawn towards a multiphase composition obtained during foam fractionation of a per- and polyfluoroalkyl substance (PF AS) comprising aqueous composition. In embodiments, the composition comprises (i) a PF AS comprising foam phase and (li) an aqueous phase from which the PF AS in the foam originated. In embodiments, the foam fractionation method uses at least one cationic gemini surfactant to promote foam formation. Additionally, the cationic surfactants described herein can interact with anionic PF AS moieties through coulombic attraction. Optionally, in some embodiments, the at least one cationic gemini surfactant comprises a compound described herein.EXAMPLES

[0082] Examples are provided herein to facilitate a more complete understanding of the invention. The following examples illustrate the exemplary’ modes of making and practicing the invention. However, the scope of the invention is not limited to specific embodiments disclosed in these Examples, which are for purposes of illustration only, since alternative methods can be utilized to obtain similar results.EXAMPLE 1

[0083] Example EFoam Fractionation, for PFAS Removal with Cationic Gemini Surfactants PFAS before PFAS PFAS PFAS after FF RL MDL FF (average) before FF (standard after FF Standard dev (average) (average) (PPt) dev.) (ppt) Average (ppt) (ppt) (PPt) (PPt) PFNA (C9) 197 17.52 55.95 25.0 1.89 0.09 PFOA (C8) 184 32.70 15.4 5.4 1.89 0.47 PFOS (C8) 129 17.78 89.55 21.8 408 1.02 PFHxS (C6) 170 13.87 29.85 9.3 1.88 0.47 GENX(C6) 206 20.50 8.9 7.6 1.41 0.47PFBS(C4) 180 33.08 27 1.0 1.88 0.47Table 4: The PFAS samples were processed in the foam fractionation set up using an air flow of 200 cc / min and vacuum of 1 inHg. Each treated water sample was ca, 995 g. This is equal to ca. 70% of the column maximum capacity. RL = reporting limit. MDL = Method detection limit. However, a wider range of processing conditions have been tested to remove PFAS. For example, PFAS samples were processed in the foam fractionation set up using an air flowDocket No.: 1149704.098013of about 100-500 cc / min and vacuum of about 1-5 inHg. Each treated water sample was about 900- 1150g. This is equal to ca. 70-80% of the column maximum capacity.

[0084] Foam fractionation is an adsorptive bubble separation technique that can remove per-and polyfluoroalkyl substances (PF AS) dissolved in an aqueous solution. The separation process is based on the sorption of PFAS to the air- water interface of rising bubbles according to their adsorption coefficients. The foam fractionation separation technique has been employed in PFAS removal from drinking water sources, sewage sludge, and landfill leachate, as well as rejects of nanofiltration and reverse osmosis for PFAS destruction.

[0085] How ever, in the majority of cases, PFAS concentrations in the target w-ater sources are often not sufficient to allow for formation of a foam by itself, a co-foaming agent may be added to enhance the foamability of the solution. Studies on the effect of different classes of co-foaming agents, anionic, non-ionic, zwitterionic and cationic surfactants on the removal of PFAS with varying fluorocarbon chain length in a foam fractionation process reveal that cationic surfactants facilitates the most to the PFAS removal in the foam fractionation process [1].

[0086] Described herein is a family of cationic Gemini surfactants to be used in the foam fractionation process for PFAS removal.

[0087] Background

[0088] Cationic surfactants are the substances that bear positive hydrophilic head and hydrophobic tail. The charges can be efficiently adsorbed on the materials such as many PFAS substances possessed with negative charges through strong electrostatic or charge-charge interactions. According to their chemical structures, cationic surfactants can be divided into amine salt type, quaternary ammonium salt type, and heterocyclic type (mainly nitrogencontaining morpholine rings, pyridine rings, imidazole rings, piperazine rings and quinoline rings), where quaternary7ammonium salts saw a wide application because their pH-independent performance nature. Cetrimonium bromide (CTAB) has been mostly tested to exhibit improvements the removal of short chain negative charge PFAS chemicals via the foam fractionation [2], Li, et al. also reported their studies on impact of tetra-n-butyl -ammonium bromide, decyl-trimethyl-ammonium bromide, n-octyl-trimethyl-ammonium bromide in addition to CTAB on peril uorooctanic acid (PFOA) removal [3],

[0089] Preserving properties of regular surfactants, Gemini surfactants, as modem surfactants, comprise two typical surfactant molecules chemically bonded together using a spacer. Consequentially, Gemini surfactants pose better surface active properties, such as, critical micelle concentrations (CMCs) of Gemini surfactants are generally 10-100 times low er thanDocket No.: 1149704.098013those of equivalent monomeric surfactants. Dimeric surfactants outperform their monomeric counterparts in terms of their ability’ to reduce surface tension. The variations in the Gemini surfactants as comparing to monomeric surfactants depend on their size of the hydrophobic tails, and the nature of the spacer (flexible or rigid). Gemini surfactants are presently receiving substantial attention.

[0090] Foam fractionator, as key component of the foam fractionation, is constructed of several foam generators and foam collectors. In the foam fractionation operation, foam is created by an air pump and taken out from the system with a vacuum. The simplest form of foam fractionator can be built out of a column where the foam generator is an air stone. Depending on the pore size, the air stone can be classified as regular stone or fine stone such as merchandises sold on market for aquatic tanks.

[0091] Foam fractionation efficacy for PFAS removal may be assessed by treating PFAS containing water such as the source water of drinking water or leachate from landfill collection system. However, natural sources of the waters may introduce many unknown precursors of PFAS which impairs the efficacy assessment. The synthetic water of PFAS spiked by a defined matrix are often instead used to examine the foam fractionation efficacy.

[0092] Invention Description

[0093] Metsala, et al. [4] recently discloses a family of Gemini quaternary amine surfactants, o | odialkyl dibetainates,where Ri, Rz are hydrocarbyl groups (the same length or different lengths) Due to existent ether link, the spacer of the Gemini surfactants may be viewed as semi-flexible. The cationic surfactants were observed to exhibit superior foaming ability. We, hereby, discovered that lire Gemini dibetainate exhibit good results for PFAS removal when being incorporated in PFAS containing water via foam fractionation.

[0094] Equipment Details:

[0095] Column: Acrylic resin column with 20.625 inch in length, 2.5 inch in diameter; Column can take maximum 1421 g of water sample. 70% of column capacity is 995 g of water sample

[0096] Air stone: Carefree Fish NANO AIR STONE 2 inch in diameter

[0097] Air flow meter: DWYER Variable Area Flowmeter RMA-14-SSV, range 200-2500 cc / min air.

[0098] Vacuum: in house vacuum controlled by Ashcroft pressure gauge, range 0-30 inllg

[0099] Graduated cylinder: KIMBLE® KIMAX® Soil Testing Cylinders. 1000 mLDocket No.: 1149704.098013

[0100] Collecting Flask: K1MAX® Erlenmeyer Flask, 1000 mL[001011 Foamability test

[0102] Foamability test were conducted in a 1000 mL graduated cylinder equipped with an air stone (made of mineral material and sintered at a high temperature) at the bottom. The air stone was connected to an aquarium air pump equipped with 120 VAC receptacle output 12A constant current variable transformer to control the air flow rate precisely, pre-determined amount of surfactant was dissolved in distilled water to prepare a series of surfactant aqueous solutions with various concentrations. Each solution has a volume of -500 ml. The solutions were well mixed on a shaking bed for 120 mins to insure all the surfactant compounds were well dissolved in water. Once the surfactant solution was ready and poured into the cylinder, the air pump was turned on, appropriate flow rate was set, A timer was used to start counting time. The surfactant solution started to foam, and the foam kept climbing in the cylinder. Wheo the foam reached 1000 ml mark in the cylinder, the timer was stopped and the time from 500 ml mark to 1000 ml was recorded.

[0103] Example 1:

[0104] An aqueous solution containing 1000 ppm Tnmethyloctylammonium bromide (C8) was prepared following the above method. The solution was poured into the graduated cylinder. The initial liquid height is 500mL mark of the cylinder. Foamability testing condition: airflow7rate =1500 cc / min, No foam 'as generated for this surfactant solution,

[0105] Example 2:

[0106] An aqueous solution containing 1000 ppm Dodecyltrimethyl ammonium bromide (Cl 2) was prepared following the above method. The solution as poured into the graduated cylinder, The initial liquid height is 500mL mark of the cylinder. Foamability testing condition: air flow rate =1500 cc / min, The foam reached up to 90% of column height.

[0107] Example 3:

[0108] A series of aqueous solutions containing different level (1000 / 500 / 250 ppm) of Tetradecyltrimethylammonium bromide (Cl 4) was prepared following the above method. Each solution was poured into the graduated cylinder, The initial liquid height is 500mL mark of the cylinder. Foamability testing condition: air flow rate =1500 cc / min. Record the time of each solution foam climb from 500 mL to 1 OOOmL mark.

[0109] Example 4:

[0110] A series of aqueous solutions containing different level (1000 / 500 / 250 / 100 ppm) of Cetyltri methylammonium bromide (Cl 6) was prepared following the above method. Each solution was poured into the graduated cylinder, The initial liquid height is 500mL mark of theDocket No.: 1149704.098013cylinder. Foamability testing condition: air flow rate =1500 cc / min, Record the time of each solution foam climb from 500 mL to lOOOmL mark.

[0111] Example 5:

[0112] A series of aqueous solutions containing different level (1000 / 500 / 250 / 100 / 50 / 25ppm) of Tnmethyioctadecylammonium bromide (Cl 8) were prepared following the above method. Each solution was poured into the graduated cylinder, The initial liquid height is 500mL mark of the cylinder. Foamability testing condition: air flow rate =1500 cc / min. Record the time of each solution foam climb from 500 mL to 1 OOOmL mark.

[0113] Example 6:

[0114] A series of aqueous solutions containing different level (1000 / 200 / 100 / 50 / 25 / 12.5 ppm) of C12 Gemini betainate were prepared following the above method. Each solution was poured into the graduated cylinder. The initial liquid height is 500mL mark of the cylinder. Foamability testing condition: air flow rate =1500 cc / min, Record the time of each solution foam climb from 500 mL to lOOOmL mark.

[0115] Example 7:

[0116] A senes of aqueous solutions containing different level (1000 / 200 / 100 / 50 ppm) of Cl 8 Oleyl Gemini betainate were prepared following the above method Each solution was poured into the graduated cylinder. The initial liquid height is 500mL mark of the cylinder. Foamability' testing condition: air flow rate =1500 cc / min, Record the time of each solution foam climb from 500 mL to lOOOmL mark.

[0117] Figure 1 and Figure 2 show non-limiting, exemplary' foamability' test results on a series of Gemini quaternary' amine surfactants (including both Gemini dibetainates and Gemini dibromides) (Figure 2) and alkyltrimethyl quaternary bromide surfactants (Figure 1).

[0118] Among the surfactants, C12 Gemini dibetainate and C18 Oleyl gemim betainate both show good foamability. When solution concentration changes from 1000 ppm to 100 ppm, C12 Gemini dibetainate and Cl 8 Oleyl gemini betamate both can generate consistent and steady foam and it took similar time for the foam to achieve 1000 ml target at different ppm levels. However, when both the solutions went to further dilution to 50 ppm, C12 Gemini betainate can still generate strong foam and the foam achieve 1000 ml mark using about 40 seconds while the C 18 Oleyl gemini betainate solution start to show' weak foamability and it took almost 2 minutes for the foam achieving 1000 ml mark. So C12 gemini betainate surfactant will be the best candidate for the following foam fractionation process.

[0119] PF AS water preparationDocket No.: 1149704.098013

[0120] A synthetic water sample was made with 6 PFAS substances, Perfluorononanoic acid (PFNA)(97% active), Perfluorooctanoic acid, (PFOA)(95% active), Perfluorooctane sulfonate(PFOS)(97% active). Perfluorohexane sulfonic acid (PFHxS)(95% active). Perfluoro butane sulfonic acid (PFBS)(97% active), and Hexafluoropropylene oxide dimer acid (HFPO-DA''GenX)(96% active), in single distilled water for a purpose of checking efficacy of a single column foam fractionator. 160 ppt (parts per trillion) active of each PFAS chemicals were spiked in the distilled water. The solution was prepared in the method as below:

[0121] Each PFAS chemicals were prepared separately into solutions and combined only in the final solution. The target level for each PFAS chemicals in the final mixture was at 160 ppt. Due to the low target concentration level, three dilution steps were chosen: ppm » ppb » ppt. All samples were prepared using high concentration PF S chemicals, as described above, and distilled water. HDPE containers were used throughout the sample preparation. As an example, the procedure for preparing the PFNA sample is described in detail. The other PFAS samples were prepared following the same three-step procedure. PFNA (97%, active) was measured at 0,0117g into a 60 ml HDPE bottle on an analytical scale. Distilled water w'as measured at 65.7713g into the same bottle. The bottle w'as placed on a shaking bed for ca. 3 hours to ensure a thorough mixing of the sample The concentration calculation was based on 97% purity. The final concentration for the first solution was 172.55 ppm. The target PFNA concentration level of the second solution was at 0.2 ppm. From the first solution, 0,3014 g was measured directly to a 250 ml HDPE bottle and distilled water was measured to the same bottle at 298.36 g. The final concentration of the second solution was 0.174ppm. The second solution tvas on a shaking bed for ca. 20 min before the preparation of the final solution. The target weight of the final PFAS mixture was 300g. The second PFNA solution w as measured at 0.2655 g to a 500 ml bottle. All the other PFAS samples were prepared in a similar way and added in the final mixture. The target concentration for each PFAS m the final mixture was 1 0 ppt. Distilled water was added at 298.48 g in the bottle. PFNA concentration in the final solution w'as therefore calculated to be 154 ppt All the solutions ere prepared within the same day. The final solution (PFAS mix) was stored in the fridge (2 - 4 °C) over night before the shipment of the sample for analysis.

[0122] The prepared water sample plus a distilled water reference sample w7ere tested for PFAS level under EPA method 1633 (LC-MS / MS). The results are summarized in Table 1.

[0123] Table 1: PFAS analysis results by EPA Method 1633PFAS Chemical Synthetic water Distilled waterPFNA 180 22Docket No.: 1149704.098013PFOA 172 7PFBS 167 N. D.*PFOS 143 N. D.*PFHxS 166 N. D.*HFPO-DA / GenX 226 3.82N. D. means non detectable; reporting limit: 1 98 ppt

[0124] The prepared syntheti c water sample shows that the PFAS concentrations are close to the target 160 ppt. Also, this water solution do not show' an foam in a single column foam fractionator.

[0125] Foam Fractionation

[0126] Foam fractionation was done in a lab setup illustrated in Figure 3 An acrylic resin column w ith a length of 21.5 inch and a diameter of 2.75 inch was used, a 2 inch nano air stone was sealed al the bottom of column, connecting to a compressed air supply regulated by a compressed air regulator At the top of column, there is a tube connect to a collecting flask that equipped with vacuum to collect the foam.

[0127] Example 8:

[0128] 1000 mL of C 12 Gemini dibetainate aqueous solution (25 ppm) was prepared and 995 g of solution (fills 70% height of column) was poured into a single column foam fractionator. Turn on the compressed air and in house vacuum. Set air flow rate =500 cc / min, vacuum = 3.5 inHg to start foam collection. Collection time is 20 mins

[0129] Example 9:

[0130] 1000 mL of CT AB aqueous solution (50 ppm) was prepared and 995 g of solution (fills 70% height of column) w?as poured into a single column foam fractionator. um on the compressed air and in house vacuum. Set air flow rate =500 cc / min, vacuum = 35 inHg to start foam collection. Collection time is 20 mins

[0131] Example 10

[0132] The synthetic water was made following method 2 in PFAS water preparation section. To the water, 25 ppm Cl 2 Gemini dibetainate was added to make a 1000 mL solution. Then 995 g of soluti on was poured into the single column fractionator to foam, and the foamate v. as collected w ith a 1000 mL glass filtering flask. The initial w ater height is 70% of the total column height. Foam fractionation condition: air flow’ rate =500 cc / min, vacuum = 2 inHg. After fractionation, the 'ater sample was analyzed via EP A method 1633.

[0133] Table 2 and Figure 4 summarize non-limiting, exemplary foam collection results from various solutions of C12 Gemini dibetainate and CTAB under different process conditions.Docket No.: 1149704.098013[001341 Table 2; Foam collection results at different column process conditions Surfactant Concentration Airflow Vacuum Foam Foamate (ppm) Rate (x100 level(lnHg) Collection Weight (g) cc / min) Time (min)C12 gemini 25 2 10 111.31 dibetainateC12 gemini 25 5 2 15 206 11 dibetainateC12 gemini 25 2 32 243.86 dibetainateC12 gemini 25 5 3.5 10 256.77 dibetainateC12 gemini 35 3.5 20 519.26 dibetainateC12 gemini 50 5 3.5 18 243.12 dibetainateC12 gemini 5 15 7 9 19.8 dibetainateCTAB 50 5 3.5 20 286.11CTAB 35 5 3.5 20 410.11

[0135] Example 11

[0136] Cationic Gemini dibetamate are used as foam agent to facilitate PFAS removal from water containing PFAS chemicals. In some embodiments, the Gemini dibetainate surfactant p i oJk_has a chemical structure, where Ri and R2 is C6 - C22 alkyl, or C6 - C22 alkene, or C6-C22 alkyne, or C6 - C22 alkyd chain containing one or more aromatic ring structure(s). In embodiments, the surfactant concentrations for foam fractionation can be equal to or are more than about 0.5 ppm to about 1000 ppm. In embodiments, the process conditions for foam fractionation using cationic Gemini dibetainate can be vacuum between about 2 and about 15 Inl lg. An air flow rate between about 1 0 and about 1500 CC / min. In embodiments, the initial solution height in column can be between about 80% and about 50%.

[0137] References Cited Herein

[0138]

[0001] Water Research 230 (2023) 119532

[0139] [2] Chemosphere 310 (2023) 136869

[0140] [3] Chemosphere 266 (2021) 128949

[0141] [4] WO 2024 / 155904 AlEXAMPLE 2

[0142] Ex imple 2: Non-Limiting, Exemplary' Foam Stability Tests and Results

[0143] Foam stability7is defined as the time that foam will maintain its initial properties as generated. Foam stability can be expressed in terms of foam half-life, which is the time requiredDocket No.: 1149704.098013for half of the volume of liquid contained in the foam to revert to the bulk-liquid phase. The shorter the time, the lower is the stability of the foam.

[0144] There are a few foam stability analyzers on the market, such as Foam Analyzer DFA 100 from Krtiss Scientific and FoamScan from TECLIS Scientific. They measure the foam and drainage liquid after stopping sparging gas to the foam in a column

[0145] In this work, we constructed a single column of 31 mm in inside diameter and 650mm in length To the bottom of column, a cylindrical gas diffuser was inserted. The diffuser was connected with a 32W Vivosun aquarium air pump which air flowrate was controlled with a 120V AC receptacle output 12A constant current variable transformer. The full output of the air pump is spacified at 60 L / min. During sparging, the transformer was set at 40%. If a linear proportion was assumed between the flowrate and the transformer scale, the air flowrate would be estimated at 24 L / min.

[0146] The foam was created before the foam stability test was performed. The liquid level of drainage was video recorded at the same time of the air pump being powered off. 55 ml surfactant solutions were introduced to the column The foam was created until its level reaching the maximum height of the column. At 27.5 ml of drainage level, the half-life time was recorded as in Table 3.

[0147] Table 3: Non-Limiting, Exemplary Foam Drainage and Half-Life Results Surfactant Concentration (ppm) Half-life time (s)C14 trimethylammoniumbromide 1000 34.6 C16 trimethylammoniumbromide 1000 20.4 C18 trimethylammoniumbromide 1000 7.9 C12 Gemini Betainate 1000 20.3C18 Gemini Betainate 1000 19.8C16 trimethylammoniumbromide 25 3.4C12 Gemini Betainate 25 3.8

[0148] Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific substances and procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the following claims.* * * *EQUIVALENTSDocket No.: 1149704.098013

[0149] Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific substances and procedures described herein Such equivalents are considered to be within the scope of this invention and are covered by the following claims.

Claims

Docket No.: 1149704.098013CLAIMSWhat is claimed is:

1. A method of removing per- and polyfluoroalkyl substances (PF AS) from an aqueous composition by foam fractionation, optionally wherein the aqueous composition is selected from the group consisting of an aqueous precipitate, surface water, groundwater, sewage sludge, drinking water, wastewater, leachates, sediment pore water, soil solutions, or any combination thereof, wherein the foam fractionation method uses at least one cationic gemini surfactant to promote foam formation, further optionally wherein the at least one cationic gemini surfactant is selected from the group consisting of a compound of formula (I), a compound of formula (II), a compound of formula (III), a compound of formula (IV), a compound of formula (V), a compound of formula (VI), a compound of formula (VII), a compound of formula (VIII), or a combination thereof:formula (!;formula {!!)formula (Illiformula (IV)formula (V)fo'rnute (VI)formula (VII)formula (VIII ■Docket No.: 1149704.098013wherein R1, R2, R3, R4, R5, R6, R7, R8, and R9are independently selected from the group consisting of a C5-C30 hydrocarbyl, formula (a), and formula (b), and formula (c);O II formula (a)A'" O’"O II H formula (b)A R'NHformula (c)andwherein R10and R11, independently, are a C5-C30 hydrocarbyl, and R12and R13, independently, are a C1-C30 hydrocarbyl.

2. The method of claim 1, wherein the cationic gemini surfactant is a compound of formula (III), wherein the compound of formula III is selected from the group consisting of formula (IIIa), formula (IIIb), formula (IIIc), formula (IIId), or a combination thereof:(Formula IIIa),(Formula IIIb),(Formula IIIc), orDocket No.: 1149704.098013(Formula IIId),wherein x, y. and z, independently, are 4 to 29, and R1and R2independently, are a C1-C30 hydrocarbyl;wherein R is independently selected from the group consisting of C6-C22 alkyd. C6-C22 unsaturated alkyl, C6-C22 alkyl comprising one or more aromatic moieties, or any combination thereof.

3. The method of claim 2, wherein the cationic gemini surfactant of formula (IIIa) is a C12 gemini dibetainate according to the following structure:

4. The method of claim 1, wherein the cationic gemini surfactant is a mixture of Cl 2 gemini dibetainate and gemini monobetainate, comprising the Cl 2 gemini dibetainate of claim 3 and a C12 gemini monobetainate according to the following structure:

5. The method of any of the previous claims which further comprises the use of a foaming agent other than a cationic gemini surfactant, wherein the combination of the other foaming agent and the at least one Gemini surfactant optionally results in any one or more of the following:(i) results in more rapid foam formation;(ii) results in a more physically stable foam;Docket No.: 1149704.098013(iii) results in more PF AS being immobilized in the foam;(iv) results in the foam having a longer half-life; or(v) any combination thereof.

6. The method of any of the previous claims which comprises:(a) obtaining an aqueous surfactant solution comprising at least one cationic gemini surfactant;(b) contacting an aqueous composition comprising PF AS with the cationic gemini surfactant comprising solution, thereby producing a PFAS-surfactant mixture; (c) subjecting the PFAS-surfactant mixture to an airflow sufficient to produce a bubble flow, thereby producing a PF AS -containing foam; and(d) separating the PF AS-containing foam from the aqueous composition, thereby producing a PFAS foamate and a remediated aqueous composition.

7. The method of any of the previous claims, wherein said foam fractionation using a cationic gemini surfactant solution as the foaming agent is effected 2 or more times, and preferably 3, 4, 5 or more times.

8. The method of any of the previous claims, wherein the cationic Gemini surfactant solution comprises about 0.1 ppm to about 10000 ppm of at least one cationic Gemini surfactant.

9. The method of any of the previous claims, wherein a solution comprising at least one cationic Gemini surfactant is added to a PFAS comprising aqueous composition in an amount sufficient to result in a dosage ranging from about 0.5 mg / L to about 1000 mg / L, more preferably 5.0 mg / L to 200 mg / L or most preferably 20 mg / L to 100 mg / L.

10. The method of any of the previous claims, wherein the aqueous composition comprises about 0.4 ppt to about 1000 ppm PFAS.

11. The method of any of the previous claims, whereinDocket No.: 1149704.098013(i) at least about 30 % to about 40 %, more preferably at least about 60-70 %, and most preferably at least about 85 % of the PF AS is removed by the foam fractionation method; and / or(ii) the method results in an aqueous composition which comprises at most 100 ppt, 10 ppt, and most preferably at most 4 ppt of PF AS.

12. The method of any of the previous claims, wherein the dosage of the surfactant solution results in a total surfactant concentration of about 0.1 ppm to about 10000 ppm total surfactant.

13. The method of any of the previous claims, wherein:(a) the PFAS-surfactant mixture has increased foamability compared to the aqueous composition comprising PF AS;(b) the PF AS-containing foam of about 1000 ppm has a half-life for about 10 seconds;and(c) the foamate comprises about 45% to about 100 % of the concentration of the aqueous composition.

14. A foaming agent composition for promoting foam formation of per- and polyfluoroalkyl substances (PFAS) comprising about 0.1 ppm to about 10000 ppm of a Gemini surfactant, and optionally further comprising one or more anionic surfactants, nonionic surfactants, zwitterionic surfactants, salts, polymers, or a combination thereof.

15. A multiphase composition obtained during foam fractionation of a per- and polyfluoroalkyl substance (PFAS) comprising aqueous composition, which composition comprises (i) a PFAS comprising foam phase and (ii) an aqueous phase from which the PFAS in the foam originated, wherein the foam fractionation method uses at least one cationic gemini surfactant to promote foam formation, optionallyDocket No.: 1149704.098013wherein the at least one cationic gemini surfactant comprises a compound according to any one of claims 1-4.

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