Method for removing PFAS from water

Abstract

1. A method for removing PFAS from a PFAS-containing aqueous phase, the method comprising: adding to the aqueous phase a surfactant composition comprising at least one cationic surfactant and allowing the surfactant to form micelles in the aqueous phase; and contacting the micelle-containing aqueous phase with an ultrafiltration membrane under pressure to obtain a permeate stream aqueous phase having a reduced concentration of PFAS.

Description

[Technical Field]

[0001] The present invention relates to a method for removing perfluorocompounds from water. More specifically, the present invention relates to a method for removing PFAS from water by the use of micellar-enhanced ultrafiltration combined with the addition of a cationic surfactant and / or detergent, or a mixture of a cationic surfactant and / or detergent and a nonionic surfactant and / or detergent, to water. [Background technology]

[0002] Ultrafiltration (UF) is a type of membrane filtration in which a force, such as pressure or a concentration gradient, leads to separation through a semipermeable membrane. High molecular weight suspended solids and solutes are retained in a so-called holding liquid, while water and low molecular weight solutes pass through the membrane in a permeate (filtrate). 1 This separation process involves the polymer solution 2 , especially protein solutions 3 It is used in industry and research for the purification and concentration of [unclear / unclear].

[0003] Ultrafiltration can be used to remove particulate matter and macromolecules from raw water to produce drinking water. Ultrafiltration has been used in water treatment facilities to replace existing secondary (coagulation, flocculation, sedimentation) and tertiary (sand filtration, and chlorination) filtration systems, or as a standalone system in isolated areas with growing populations. 4 Ultrafiltration is used by the dairy industry to concentrate milk proteins and remove water from milk. Ultrafiltration is also used by the bio-industry to concentrate proteins. 5 .

[0004] Micelle-enhanced ultrafiltration (hereinafter referred to as MEUF) is known as a powerful separation process that has recently been developed to remove various impurities, such as heavy metals (e.g., lead, cadmium, or zinc), toxic organic materials (e.g., phenol, dibutyl phosphate, tributyl phosphate, or trihalomethanes), and low molecular weight impurities including organic dyes. 6,8 .

[0005] In MEUF, detergent is added to water at a concentration exceeding the critical micelle concentration of the detergent. When the detergent forms micelles, the hydrophobic parts of the detergent molecules aggregate together to form a hydrophobic space, while the hydrophilic groups of the detergent molecules remain exposed to the water. 9 This forms a spherical structure that typically has a hydrophilic surface and a hydrophobic interior. The weight of a spherical micelle is at least 60,000 Daltons, which allows the detergent micelles to be separated by ultrafiltration. The hydrophilic groups on the surface of the micelle form a phase separation between the hydrophobic interior of the micelle and water. Since organic contaminants are often quite hydrophobic, they generally prefer to reside inside the micelles, which is the basis of MEUF for removing contaminants. 7 .

[0006] PFAS (per- and polyfluoroalkyl substances) is a collective name for more than 3,000 industrially manufactured chemical substances. PFAS can be classified into (1) long-chain PFAAs, (2) short-chain PFAAs, (3) nonpolymeric and polymeric fluorotelomer products, and (4) fluororesins and fluoropolymers; long-chain PFAAs include perfluoroalkanesulfonic acids (PFSAs) with a carbon chain length of 6 or more, and perfluorocarboxylic acids (PFCAs) with a carbon chain length of 8 or more; short-chain PFAAs include PFSAs with a carbon chain length of 5 or less, and PFCAs with a carbon chain length of 7 or less.

[0007] The most common PFASs are perfluorobutanoic acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluorobutanesulfonic acid, perfluorohexanosulfonic acid, perfluorooctanesulfonic acid, 6:2 fluorotelomer sulfonate, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid, perfluoropentanesulfonic acid, perfluoroheptanesulfonic acid, perfluorononanosulfonic acid, perfluorodecanesulfonic acid, perfluorododecanesulfonic acid, and 4:2 fluorotelomers. These include sulfonates, 8:2 fluorotelomer sulfonates, perfluorooctanesulfonamides, N-methylperfluorooctanesulfonamides, N-ethylperfluorooctanesulfonamides, N-methylperfluorooctanesulfonamide ethanol, N-ethylperfluorooctanesulfonamide ethanol, perfluorooctanesulfonamide acetate, N-methylperfluorooctanesulfonamide acetate, N-ethylperfluorooctanesulfonamide acetate, 7H-perfluoroheptanoic acid, perfluoro-3,7-dimethyloctanoic acid, and isomers, homologs, and other permutations of these substances.

[0008] The most common standard for PFAS is the so-called "PFAS Sum11," which covers 11 of the most common PFAS, namely perfluorobutanoic acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluorobutanesulfonic acid, perfluorohexanesulfonic acid, perfluorooctanesulfonic acid, and 6:2 fluorotelomersulfonate.

[0009] PFAS are used globally in many products, such as fire extinguishers and impregnating agents. PFAS have spread widely in the environment; they are persistent and some are toxic. Contaminated land with PFAS has been found in many parts of the world, where PFAS is leaking into groundwater and drinking water reservoirs. Recent research has shown some health problems caused by PFAS, and the PFAS threshold in drinking water is ongoing 10~12 .

[0010] PFAS are all created by humans, and their supply to nature stems exclusively from human activities. They occur globally in many manufacturing processes, for example as fabric protectors. For example, the most common point source of PFAS in the Swedish environment is the extinguishing foam used at airports. Military airports are the largest source of PFAS leaking into the environment, followed closely by civilian airports. Since PFAS do not break down in nature and some PFAS are bioaccumulative, in addition to restricting their use, it is necessary to fight this pollution through proactive measures

[0011] PFAS enter people through contaminated drinking water, through food such as fish and livestock, through the irrigation of crops with contaminated water, and through the inhalation of dust 13 . PFAS can cause liver damage and reproductive toxicity in humans. The largest investigation was conducted on approximately 60,000 people in the United States who received large amounts of the highly fluorinated substance PFOA (perfluorooctanoic acid) from drinking water. The conclusion of the investigation was that there was a probable relationship between the PFOA exposure of the people investigated and high blood cholesterol levels, high blood pressure during pregnancy, ulcerative colitis, thyroid diseases, and cancers of the testis and kidney (C8 Science Panel 2013).

[0012] The most common water-soluble PFASs in the environment have a negatively charged portion that makes them soluble in water. Common PFASs, such as perfluorobutanoic acid, perfluorooctanesulfonic acid, and fluorotelomer sulfonates, are all present in high concentrations in most contaminated locations. These perfluoro molecules are extremely difficult to decompose and cannot be removed by biological wastewater treatment methods, and they are resistant to oxidation by ozonated water treatment.

[0013] The usual methods for removing PFAS from water are different types of carbon filtration, often granular activated carbon (GAC) filtration. Carbon filtration removes long-chain PFAS molecules such as perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluorooctanesulfonic acid, 6:2 fluorotelomer sulfonate, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid, perfluorononanosulfonic acid, perfluorodecanesulfonic acid, perfluorododecanesulfonic acid, 4:2 fluorotelomer sulfonate, 8:2 fluorotelomer sulfonate, perfluorooctanesulfonamide, and N-methylphenyl Oroctanesulfonamide, N-ethylperfluorooctanesulfonamide, N-methylperfluorosulfonamide ethanol, N-ethylperfluorooctanesulfonamide ethanol, perfluorooctanesulfonamide acetate, N-methylperfluorooctanesulfonamide acetate, N-ethylperfluorooctanesulfonamide acetate, 7H-perfluoroheptanoic acid, and perfluoro-3,7-dimethyloctanoic acid are effective. However, GAC and other carbon filtration methods are less effective with respect to shorter PFAS molecules, such as perfluorobutanoic acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluoropentanesulfonic acid, and perfluoroheptanesulfonic acid. If low molecular weight PFAS molecules are present in high concentrations in the wastewater stream, it will be necessary to replace the carbon filter at more frequent intervals; if the water also contains high levels of organic matter, this will lead to the need to replace the carbon filter even more frequently. 14 .

[0014] Another proposed method for treating PFAS-contaminated wastewater is reverse osmosis (RO). Reverse osmosis can efficiently separate individual metal ions from water and has been shown to be able to remove all types of PFAS from water. 15However, a disadvantage of RO is that it cannot filter water with high ion concentrations. In fact, since RO relies on the osmotic mobility of the membrane, if the salt concentration of the water being treated is high, the osmotic mobility of the membrane can hardly be achieved at atmospheric pressure. While the efficiency of RO can be quite high, efficiencies exceeding 90% are rarely achieved, and RO can reduce the amount of waste volume by at best 90%; more typically, this means the volume is about 75-80%. Compared to ultrafiltration, RO consumes more energy. A further disadvantage of RO is that it often requires an ultrafiltration unit as a pre-filter, increasing the complexity of the system. [Overview of the Initiative] [Problems that the invention aims to solve]

[0015] There appears to be an urgent and increasing need for methods to efficiently remove PFAS from water. [Means for solving the problem]

[0016] A method for removing PFAS from water is disclosed herein. Advantageously, this method is generally useful for all types of PFAS, with improved efficiency and reduced waste volume, regardless of the molecular weight of the PFAS, for example. This method is also generally useful for removing PFAS from any type of PFAS-containing water, such as wastewater, leachate, process water, groundwater, etc., i.e., from any type of PFAS-containing aqueous phase. Therefore, the method of the present invention makes it possible to obtain water of improved purity from the viewpoint of reducing PFAS contamination.

[0017] Therefore, disclosed herein is a method for removing PFAS from a PFAS-containing aqueous phase, (i) Adding a surfactant composition containing at least one cationic surfactant to the aqueous phase, enabling the surfactant to form micelles in the aqueous phase, (ii) contacting the micelle-containing aqueous phase with an ultrafiltration membrane under pressure to obtain a permeate flow aqueous phase having a reduced concentration of PFAS; The method includes the above steps.

[0018] In some embodiments, the method for removing PFAS from a PFAS-containing aqueous phase comprises: (i) adding a surfactant composition containing at least one cationic surfactant to the aqueous phase to enable the surfactant to form micelles in the aqueous phase; (ii) contacting the micelle-containing aqueous phase with an ultrafiltration membrane under pressure to obtain a permeate flow aqueous phase having a reduced concentration of PFAS, and optionally (iii) repeating (i) and (ii) at least once. The method includes the above steps.

[0019] In some embodiments, (i) and (ii) are repeated at least once. In some embodiments, (i) and (ii) are repeated once. In some embodiments, (i) and (ii) are repeated two or more times.

[0020] In some embodiments, the method for removing PFAS from a PFAS-containing aqueous phase comprises: (i) adding a surfactant composition containing at least one cationic surfactant to the aqueous phase to enable the surfactant to form micelles in the aqueous phase; (ii) contacting the micelle-containing aqueous phase with an ultrafiltration membrane under pressure to obtain a permeate flow aqueous phase having a reduced concentration of PFAS; (iii) optionally, determining the concentration of one or more PFAS in the permeate flow aqueous phase having a reduced concentration of PFAS; (iv) optionally repeating (i) to (iii) when the determined concentration is higher than a predetermined threshold. The method includes the above steps.

[0021] In some embodiments, a method for removing PFAS from a PFAS-containing aqueous phase is: (i) Adding a surfactant composition containing at least one cationic surfactant to the aqueous phase to enable the surfactant to form micelles in the aqueous phase, (ii) The step of bringing the micelle-containing aqueous phase into contact with an ultrafiltration membrane under pressure to obtain a permeate-flow aqueous phase having a reduced concentration of PFAS, (iii) A step of determining the concentration of one or more PFAS in the permeate flow aqueous phase having a reduced concentration of PFAS, (iv) If the determined concentration is higher than a predetermined threshold, repeat steps (i) to (iii) and Includes.

[0022] The method of the present invention enables various types of water to be purified from PFAS to residual levels of PFAS that are very low or even negligible, which is important considering the persistence of PFAS in the environment and its toxic effects on animals and humans. [Brief explanation of the drawing]

[0023] [Figure 1A] Figure 1A is a schematic diagram showing a surfactant molecule having a hydrophilic head and a hydrophobic tail. [Figure 1B] Figure 1B schematically shows a micelle structure formed by several surfactant molecules, which have a hydrophilic surface and a hydrophobic interior. [Figure 2] This figure shows the chemical structure of the most common PFAS, also known as "PFAS Sum11". [Figure 3A] Figure 3A shows a schematic diagram illustrating the principle by which PFAS is removed from water by adding a surfactant followed by ultrafiltration. [Figure 3B] Figure 3B shows micelles formed during the process that contain PFAS on their surface and inside the micelles. [Figure 4]This is a block diagram illustrating a schematic ultrafiltration procedure for removing PFAS from PFAS-containing water as disclosed herein. [Figure 5] This bar graph shows the remaining portion of PFAS, expressed as % residual PFAS Sum11, in water with an initial PFAS Sum11 concentration of 25.13 μg / L, after ultrafiltration with no surfactant (Comparative Example 10), or with the addition of an anionic surfactant (Comparative Example 11), a nonionic surfactant (Comparative Example 12), a mixture of anionic and nonionic surfactants (Comparative Example 13), a cationic surfactant (Example 14), or a mixture of cationic and nonionic surfactants (Examples 15 and 16). [Figure 6] This graph shows the concentration of PFAS Sum11 (μg / L) after ultrafiltration in water initially containing PFAS Sum11 at a concentration of 12 μg / L, with no surfactant added, or with different amounts of the cationic surfactant cetyltrimethylammonium chloride (CTAC) added. [Figure 7] This bar graph shows the remaining portion of PFAS, expressed as % residual PFAS Sum11, after one (1), two (2), or three (3) iterations of the process in water with an initial concentration of 69 μg / L, in the presence of cetyltrimethylammonium chloride (CTAC) as a surfactant. [Modes for carrying out the invention]

[0024] definition As used herein, “surfactant” refers to an organic compound that reduces the surface tension (or interfacial tension) between two liquids, between a gas and a liquid, or between a liquid and a solid. Surfactants are amphiphilic compounds, that is, compounds containing a hydrophobic portion ("hydrophobic tail") and a hydrophilic portion ("hydrophilic head" or "polar head") (see Figure 1A).

[0025] Most commonly, surfactants are classified by their hydrophilic head. Nonionic surfactants have no electrically charged groups in their head; cationic surfactants have a net positive charge in their hydrophilic head; and anionic surfactants have a net negative charge in their hydrophilic head.

[0026] As used herein, "micelle" refers to an aggregate or supramolecular assembly of surfactant molecules dispersed in a liquid phase. A typical micelle in an aqueous solution forms an aggregate in which the hydrophilic portion ("hydrophilic head") is in contact with the surrounding liquid phase and the hydrophobic portion ("hydrophobic tail") is isolated at the center of the micelle. See Figure 1B.

[0027] As used herein, “critical micelle concentration” (“CMC”) refers to the concentration of surfactant in the liquid phase at which micelle formation occurs. As used herein, "hydrophilicity" refers to an affinity for water, that is, a property of being soluble in water.

[0028] As used herein, "hydrophobic" refers to the property of repelling water or being improper with water. As used herein, "ultrafiltration" refers to a process in which a liquid is placed in contact with a semipermeable membrane (ultrafiltration membrane) containing pores of a specified size (cutoff size), typically under some head of pressure, thereby allowing molecules or complexes smaller than the membrane's cutoff size to pass through the pores, while molecules or complexes larger than the membrane's cutoff size are not allowed to pass through the pores and are retained upstream of the membrane.

[0029] As used herein, “retentate” refers to molecules or complexes that do not pass through the pores of the semipermeable membrane during ultrafiltration but are retained on the upstream side of the membrane. As used herein, “permeate” refers to molecules or complexes that have passed through the pores of a semipermeable membrane during ultrafiltration.

[0030] As used herein with respect to ultrafiltration membranes, the terms “cutoff size” or “molecular weight cutoff” refer to the molecular weight of molecules or particles that are retained by 90% of the membrane. Dalton (Da) 12 It is a unit of mass equal to one-twelfth of the mass of a carbon atom. It is approximately 1.66 × 10⁻¹⁶ -27 This corresponds to kilograms.

[0031] The unit kDa is 10 3 It corresponds to Dalton. As used herein, "CTAC" refers to cetyltrimethylammonium chloride. As used herein, "CTAB" refers to cetyltrimethylammonium bromide.

[0032] As used herein, "SDS" refers to sodium dodecylsulfonate. As used herein, "PFAS Sum11" refers to perfluorobutanoic acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluorobutanesulfonic acid, perfluorohexanesulfonic acid, perfluorooctanesulfonic acid, and 6:2 fluorotelomer sulfonate.

[0033] As used herein, “PFAS” refers to perfluoroalkyl (or polyfluoroalkyl) substances. Thus, while the term “PFAS” is a collective reference to a type of compound, it may also be used herein to refer to simply one such compound, or a mixture of two or more such compounds. For example, PFAS as used herein include, for example, perfluorobutanoic acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluorobutanesulfonic acid, perfluorohexanesulfonic acid, perfluorooctanesulfonic acid, 6:2 fluorotelomer sulfonate, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid, perfluoropentanesulfonic acid, perfluoroheptanesulfonic acid, perfluorononanosulfonic acid, perfluorodecanesulfonic acid, perfluorododecanesulfonic acid, and 4:2 fluorotelomer This may include sulfonates, 8:2 fluorotelomer sulfonates, perfluorooctanesulfonamides, N-methylperfluorooctanesulfonamides, N-ethylperfluorooctanesulfonamides, N-methylperfluorooctanesulfonamide ethanol, N-ethylperfluorooctanesulfonamide ethanol, perfluorooctanesulfonamide acetate, N-methylperfluorooctanesulfonamide acetate, N-ethylperfluorooctanesulfonamide acetate, 7H-perfluoroheptanoic acid, and perfluoro-3,7-dimethyloctanoic acid, as well as one or more isomers, homologs, and other variants and combinations of these substances.

[0034] The term "PFAA" refers to perfluoroalkyl acids (or polyfluoroalkyl acids). The term "PFSA" refers to perfluoroalkyl sulfonic acid (or polyfluoroalkyl sulfonic acid).

[0035] The term "PFCA" refers to perfluoroalkyl carboxylic acid (or polyfluoroalkyl carboxylic acid). Generally as used herein, the term PFAS does not refer to polymeric substances; that is, as generally used herein, the term PFAS refers to non-polymeric PFAS, in particular water-soluble PFAS.

[0036] Therefore, as used herein, the term PFAS generally refers to one or more nonpolymerizable PFAS, such as long-chain PFAAs, short-chain PFAAs, and nonpolymerizable fluorotelomer products.

[0037] PFAS-containing water The aqueous phase treated by the method of the present invention may be any type of water containing PFAS, such as contaminated water, wastewater, leachate, process water, groundwater, and other types of water contaminated with PFAS, as well as / or aqueous solutions containing PFAS. Generally, the aqueous phase containing PFAS treated by the present invention is not an emulsion of PFAS in water. Generally, the aqueous phase contains PFAS dissolved in the aqueous phase.

[0038] The concentration of PFAS present in the treated aqueous phase can vary over time, for example, from very low to high. Furthermore, the specific types of PFAS present in the treated water may be unknown or variable without impairing the effectiveness of the method of the present invention.

[0039] In some embodiments, the aqueous phase treated by the method of the present invention is perfluorobutanoic acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluorobutanesulfonic acid, perfluorohexanosulfonic acid, perfluorooctanesulfonic acid, 6:2 fluorotelomer sulfonate, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid, perfluoropentanesulfonic acid, perfluoroheptanesulfonic acid, perfluorononanosulfonic acid, perfluorodecanesulfonic acid, perfluorododecanesulfonic acid, 4:2 fluoro This material contains fluorotelomer sulfonate, 8:2 fluorotelomer sulfonate, perfluorooctanesulfonamide, N-methylperfluorooctanesulfonamide, N-ethylperfluorooctanesulfonamide, N-methylperfluorooctanesulfonamide ethanol, N-ethylperfluorooctanesulfonamide ethanol, perfluorooctanesulfonamide acetate, N-methylperfluorooctanesulfonamide acetate, N-ethylperfluorooctanesulfonamide acetate, 7H-perfluoroheptanoic acid, and perfluoro-3,7-dimethyloctanoic acid, as well as one or more isomers, congeners, and other substituted forms of these substances.

[0040] In some embodiments, the aqueous phase treated by the method of the present invention contains one or more perfluorobutanoic acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluorobutanesulfonic acid, perfluorohexanesulfonic acid, perfluorooctanesulfonic acid, and 6:2 fluorotelomersulfonate.

[0041] In some embodiments, the water treated by the method of the present invention contains PFAS at an initial total concentration of at least 10 g / L, or at least 5 g / L, or at least 2 g / L, or at least 1 g / L, or at least 500 mg / L, or at least 200 mg / L, or at least 100 mg / L, or at least 50 mg / L, or at least 20 mg / L, or at least 10 mg / L, or at least 5 mg / L, or at least 2 mg / L, or at least 1 mg / L, or at least 500 μg / L, or at least 200 μg / L, or at least 100 μg / L, or at least 50 μg / L, or at least 20 μg / L, or at least 10 μg / L, or at least 5 μg / L, or at least 2 μg / L, or at least 1 μg / L, or at least 0.5 μg / L, or at least 0.2 μg / L, or at least 0.1 μg / L.

[0042] In some embodiments, the water treated by the method of the present invention contains PFAS at an initial total concentration of 10 g / L or less, or 5 g / L, or 2 g / L or less, or 1 g / L or less, or 500 mg / L or less, or 200 mg / L or less, or 100 mg / L or less, or 50 mg / L or less, or 20 mg / L or less, or 10 mg / L or less, or 5 mg / L or less, or 2 mg / L or less, or 1 mg / L or less, or 500 μg / L or less, or 200 μg / L or less, or 100 μg / L or less, or 50 μg / L or less, or 20 μg / L or less.

[0043] In some embodiments, the water treated by the method of the present invention has an initial concentration within the range from any of the specified lower limits to any of the specified upper limits, for example, 0.1 μg / L to 10 g / L, 0.1 μg / L to 5 g / L, 0.1 μg / L to 2 g / L, 0.1 μg / L to 1 g / L, 0.1 μg / L to 500 mg / L, 0.1 μg / L to 200 mg / L, 0.1 μg / L to 100 mg / L, 0.1 μg It contains PFAS in initial concentrations ranging from 0.1 μg / L to 50 mg / L, 0.1 μg / L to 20 mg / L, 0.1 μg / L to 10 mg / L, 0.1 μg / L to 5 mg / L, 0.1 μg / L to 2 mg / L, 0.1 μg / L to 1 mg / L, 0.1 μg / L to 500 μg / L, 0.1 μg / L to 200 μg / L, 0.1 μg / L to 100 μg / L, 0.1 μg / L to 50 μg / L, or 0.1 μg / L to 20 μg / L.

[0044] In some of the embodiments described above, the water treated by the method of the present invention contains PFAS at an initial concentration of at least 0.2 μg / L, or at least 0.5 μg / L, or at least 1 μg / L, or at least 2 μg / L, or at least 5 μg / L, or at least 10 μg / L.

[0045] Accordingly, in some embodiments, the water treated by the method of the present invention contains PFAS at initial concentrations ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 10 g / L.

[0046] In some embodiments, the water treated by the method of the present invention contains PFAS at initial concentrations ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 2 g / L, or from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 1 g / L.

[0047] In some embodiments, the water treated by the method of the present invention contains PFAS at initial concentrations ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 500 mg / L, or from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 200 mg / L.

[0048] In some embodiments, the water treated by the method of the present invention contains PFAS at an initial concentration ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 100 mg / L.

[0049] In some embodiments, the water treated by the method of the present invention contains PFAS at initial concentrations ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 50 mg / L, or from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 20 mg / L.

[0050] In some embodiments, the water treated by the method of the present invention contains PFAS at an initial concentration ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 10 mg / L.

[0051] In some embodiments, the water treated by the method of the present invention contains PFAS at an initial concentration ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 5 mg / L.

[0052] In some embodiments, the water treated by the method of the present invention contains PFAS at an initial concentration ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 2 mg / L.

[0053] In some embodiments, the water treated by the method of the present invention contains PFAS at an initial concentration ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 1 mg / L.

[0054] In some embodiments, the water treated by the method of the present invention contains PFAS at an initial concentration ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 500 μg / L.

[0055] In some embodiments, the water treated by the method of the present invention contains PFAS at an initial concentration ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 200 μg / L.

[0056] In some embodiments, the water treated by the method of the present invention contains PFAS at an initial concentration ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 100 μg / L.

[0057] In some embodiments, the water treated by the method of the present invention contains PFAS at an initial concentration ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 50 μg / L.

[0058] In some embodiments, the water treated by the method of the present invention contains PFAS at an initial concentration ranging from 0.2 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, or 10 μg / L to 20 μg / L.

[0059] In some embodiments, the initial concentration of PFAS is determined by measuring the initial concentration of at least one PFAS selected from PFAS Sum11 and adopting the measured value as the total initial PFAS concentration.

[0060] In some embodiments, the initial concentration of PFAS is determined by measuring the initial total concentration of PFAS Sum11 and adopting the measured value as the total initial PFAS concentration. In some embodiments, the initial concentration of PFAS is determined by measuring the initial concentration of PFAS Sum11 and multiplying the measured value by a coefficient k, for example, in the range of 1.2 to 10, or 1.2 to 5, or 1.2 to 4, or 1.2 to 3, or 1.2 to 3, or 1.2 to 2, or 1.2 to 1.5, and adopting the calculated value as the total initial concentration of PFAS. A specific coefficient k may be determined for each type of water, for example, by determining the average total concentration of PFAS (other than polymeric PFAS) in the water and the average concentration of PFAS Sum11 for a particular type of water.

[0061] Surfactant composition To achieve effective separation of PFAS from the aqueous phase, a surfactant composition containing at least one cationic surfactant is mixed with the aqueous phase to enable the formation of micelles in the aqueous phase.

[0062] As used herein, the term “surfactant composition” may optionally refer to one specific surfactant compound or a mixture of surfactant compounds in a liquid carrier, e.g., water. Accordingly, in some embodiments, the method of the present invention comprises (i) adding a cationic surfactant to a PFAS-containing aqueous phase to form micelles in the aqueous phase, and (ii) subjecting the aqueous phase to ultrafiltration, for example, as described herein.

[0063] In some other embodiments, the method of the present invention includes (i) adding a mixture of cationic surfactants to a PFAS-containing aqueous phase to form micelles in the aqueous phase, and (ii) subjecting the aqueous phase to ultrafiltration, for example, as described herein.

[0064] In some embodiments, in addition to a cationic surfactant or a mixture of cationic surfactants, the surfactant composition further comprises a nonionic surfactant or a mixture of nonionic surfactants. For example, the surfactant composition comprises a cationic surfactant and a nonionic surfactant in a weight ratio of cationic surfactant to nonionic surfactant of 100:1 to 1:100, or 50:1 to 1:50, or 20:1 to 1:20, or 10:1 to 1:10, or 5:1 to 1:5, for example, 2:1 to 1:2.

[0065] In some further embodiments, the surfactant composition comprises a cationic surfactant and a nonionic surfactant in a weight ratio of cationic surfactant to nonionic surfactant of 100:1 to 1:1, or 50:1 to 1:1, or 20:1 to 1:1, or 10:1 to 1:1, or 5:1 to 1:1, for example, 2:1 to 1:1.

[0066] In some further embodiments, the surfactant composition comprises a cationic surfactant and a nonionic surfactant in a weight ratio of cationic surfactant to nonionic surfactant of 100:1 to 2:1, or 50:1 to 2:1, or 20:1 to 2:1, or 10:1 to 2:1, or 5:1 to 2:1.

[0067] In some further embodiments, the surfactant composition comprises a cationic surfactant and a nonionic surfactant in a weight ratio of cationic surfactant to nonionic surfactant of 100:1 to 5:1, or 50:1 to 5:1, or 20:1 to 5:1, or 10:1 to 5:1.

[0068] In some further embodiments, the surfactant composition comprises a cationic surfactant and a nonionic surfactant in a weight ratio of cationic surfactant to nonionic surfactant of 1:1 to 1:100, or 1:1 to 1:50, or 1:1 to 1:20, or 1:1 to 1:10, or 1:1 to 1:5, for example, 1:1 to 1:2.

[0069] In some further embodiments, the surfactant composition comprises a cationic surfactant and a nonionic surfactant in a weight ratio of cationic surfactant to nonionic surfactant of 1:2 to 1:100, or 1:2 to 1:50, or 1:2 to 1:20, or 1:2 to 1:10, or 1:2 to 1:5.

[0070] In some further embodiments, the surfactant composition comprises a cationic surfactant and a nonionic surfactant in a weight ratio of cationic surfactant to nonionic surfactant of 1:5 to 1:100, or 1:5 to 1:50, or 1:5 to 1:20, or 1:5 to 1:10.

[0071] In some embodiments, the surfactant composition comprises only cationic surfactants.

[0072] Cationic surfactants Any cationic surfactant or mixture of cationic surfactants is generally considered useful in the methods of the present invention. As described above herein, surfactants include a hydrophobic moiety and a hydrophilic moiety. The hydrophobic moiety of surfactants useful herein is generally a C4-C20 hydrocarbyl group, for example, alkyl groups containing 4-20 carbon atoms, such as butyl, pentyl, hexyl, heptyl, octyl, nonyl, decanyl, undecanyl, dodecanyl, tridecanyl, tetradecanyl, pentadecanyl, hexadecanyl, heptadecanyl, octadecenyl, nonadecanyl, and acosanyl. The hydrophilic moiety of cationic surfactants used herein may be selected from, for example, ammonium, methylammonium, dimethylammonium, trimethylammonium, hydroxyethylammonium, methylhydroxyethylammonium, and dimethylhydroxyethylammonium.

[0073] For example, in some embodiments, the surfactant composition is (e.g., Cl - salt or Br - (As a salt) General formula R4N + The formula includes a quaternary ammonium salt [wherein at least one R is a hydrophobic moiety, e.g., a C10-C20 alkyl chain, and the R group may further contain an NC or OC bond, and may be branched or linear, substituted or unsubstituted, saturated or unsaturated, and aromatic or aliphatic]. An example of a cationic surfactant is, for example, a C10-C20 alkyltrimethylammonium salt, e.g., a C10-C20 alkyltrimethylammonium halide.

[0074] In some embodiments, the surfactant composition includes a cationic surfactant selected from cetyltrimethylammonium bromide and cetyltrimethylammonium chloride. However, it should be recognized that the present invention is not limited to any particular type of cationic surfactant. Furthermore, as noted above herein, unless otherwise specified or evident from the context, references to "cationic surfactants" should be understood to refer to mixtures of cationic surfactants.

[0075] Furthermore, cationic surfactants may also be cationic polymeric surfactants, such as those described in Rawessling & D.M. Pickelman (1981) Cationic Polymeric Surfactants, Journal of Dispersion Science and Technology, 2:2~3, 281~313, the entire contents of which are incorporated herein by reference.

[0076] In some embodiments, the surfactant composition includes a cetyltrimethylammonium halogenate, such as CTAB or CTAC. In some embodiments, the surfactant composition comprises only cationic surfactants. In some embodiments, the surfactant composition comprises one or more cationic surfactants in a liquid carrier, for example, one or more cationic surfactants in an aqueous liquid carrier.

[0077] Nonionic surfactants Examples of nonionic surfactants are alcohol ethoxylates and alkylphenol ethoxylates. Alcohol ethoxylates have the general formula R(OCH2CH2) n It can be represented by OH [wherein R can be, for example, a linear or branched alkyl group of C9 to C18, and n can be an integer from 1 to 40, for example, from 5 to 20]. Alkylphenol ethoxylate surfactants have the general formula R-(C6H4)-(OCH2CH2) nIt can be represented by OH [wherein R can be, for example, a linear or branched alkyl group of C8 to C16, and n can be an integer from 1 to 30, for example, from 5 to 15].

[0078] For the purposes of this invention, unless otherwise specified or evident from the context, references to "nonionic surfactants" should be understood to include mixtures of nonionic surfactants.

[0079] Ultrafiltration membrane Ultrafiltration membranes are typically specified to have a specific cutoff size or molecular cutoff weight. Many types of ultrafiltration membranes (or filters) exist, made from various materials, such as polyethersulfone, regenerated cellulose, or ceramic materials. Any type of ultrafiltration technique can be used in this invention. Ultrafiltration can be performed by cross-flow filtration in a helical-wound membrane, where the feed flow is introduced into the membrane element under pressure and passes across the membrane surface through a controlled flow path, the permeate passes through the membrane, while rejected material can be flushed out as a retaining liquid.

[0080] Another common type of ultrafiltration apparatus uses hollow fiber membranes. The membrane is formed from long, very thin tubes or fibers (typically 0.6–2 mm in diameter) sealed in connectors at both ends. Hundreds of these fibers, each with a single inlet and outlet connector, are grouped together to form a "module," and are called a "bundle" or "cartridge." The supply solution typically flows through one end of the fiber, while the opposite end is completely or partially closed. The fluid is then collected in the cartridge region surrounding the fiber, forced through the membrane, and the suspended material remains inside the membrane.

[0081] Accordingly, in the method of the present invention, any type of ultrafiltration membrane can be used, such as a spiral-wound membrane, tubular membrane, hollow fiber membrane or flat sheet membrane, made from materials such as cellulose acetate (CA), polyvinylidene fluoride (PVDF), polyacrylonitrile, polypropylene, polysulfone (PS), polyethersulfone (PES), or other polymers, and the membrane can also be made from ceramic material.

[0082] Preferably, the ultrafiltration membrane has a molecular weight cutoff of 100,000 Daltons (100 kD) or less, for example, preferably 50 kDa or less, more preferably 30 kDa or less, 25 kDa or less, 20 kDa or less, 15 kDa or less, or 10 kDa or less, for example, 1 to 100 kD, 5 to 50 kD, 1 to 30 kD, 1 to 25 kDa, 1 to 20 kDa, 1 to 15 kDa, or 1 to 10 kDa.

[0083] method In the method of the present invention, a surfactant composition as defined herein is mixed with a PFAS-containing aqueous phase to form surfactant-containing micelles.

[0084] The surfactant composition is added to the aqueous phase in an amount that induces micelle formation, i.e., to achieve at least a critical micelle concentration (CMC). In some embodiments, an excess amount of the surfactant composition may be added, for example, 10-100% (e.g., 20-50%) more than the amount estimated to be necessary to reach the CMC.

[0085] The surfactant composition can be added to the aqueous phase as a liquid solution or in solid form (e.g., powder or granules), for example, as a salt that dissolves in the aqueous phase. Micelle formation is considered to be a rapid process as long as it reaches the CMC. Furthermore, once micelles are formed and can provide an emulsion of micelles in the PFAS-containing aqueous phase, the micelle-containing aqueous phase can be subjected to ultrafiltration with virtually no delay. That is, the separation (partition) of PFAS into the micelle phase is considered to occur fairly quickly, for example, in a few minutes (e.g., 1 to 10 minutes, or 1 to 5 minutes, or 2 to 5 minutes) or less.

[0086] The amount of surfactant composition to be added to any particular type of water can be determined by those skilled in the art, for example, by collecting a representative sample of water, determining the PFAS before and after ultrafiltration in the presence of a selected surfactant composition at least the concentration of CMC, and optionally testing several different surfactant compositions and / or different surfactant concentrations. Typically, the concentration of PFAS present in any water being treated is considerably lower than the CMC of any surfactant, and therefore, in terms of CMC, the surfactant compositions of the present invention are considered effective in the method of the present invention.

[0087] An aqueous phase contaminated with PFAS, containing a surfactant composition as defined herein at a concentration exceeding the CMC, is brought into contact with an ultrafiltration membrane under pressure to obtain a permeate flow and a retained flow. The retained flow will have a higher concentration of PFAS than the PFAS-contaminated aqueous phase entering the ultrafiltration unit, while the aqueous permeate flow will have a reduced PFAS concentration. It is assumed that the PFAS is incorporated within and on the surface of the micelles and is therefore essentially retained in the retained flow.

[0088] In some embodiments of the present invention, PFAS-containing water is repeatedly treated with the surfactant compositions described herein by ultrafiltration. Thus, in some embodiments, the permeate containing a reduced amount of PFAS compared to the aqueous flow entering the ultrafiltration apparatus is subjected to further addition of a surfactant composition containing a cationic surfactant and optionally a nonionic surfactant, which may be the same as or different from the previously added surfactant composition, and is then brought into contact with the ultrafiltration apparatus again, which may be the same as or different from the apparatus used in the previous filtration step.

[0089] In some embodiments, iteration is achieved using a recirculation system, in which the permeate is recirculated multiple times through an ultrafiltration unit containing an ultrafilter, with the surfactant composition added each time in an amount exceeding the amount required to reach the CMC in the aqueous phase, and each time separating the retaining liquid rich in PFAS from the permeate having a reduced concentration of PFAS.

[0090] The recirculation may be repeated a set number of times, for example 1 to 5 times, or 1 to 3 times (more iterations may be used if necessary, for example in the case of highly contaminated water), or it may be repeated until the analysis of the ultrafiltration permeate indicates that a satisfactory low PFAS concentration has been reached.

[0091] Therefore, in some embodiments, the method for removing PFAS from a PFAS-containing aqueous phase is (i) Adding a surfactant composition to the aqueous phase, wherein the surfactant composition comprises at least one cationic surfactant, and the surfactant enables the formation of micelles in the aqueous phase; (ii) The step of bringing the micelle-containing aqueous phase into contact with an ultrafiltration membrane under pressure to obtain a permeate flow aqueous phase having a reduced concentration of PFAS. Includes.

[0092] In some embodiments, a method for removing PFAS from a PFAS-containing aqueous phase is: (1) Adding a surfactant composition to the aqueous phase, wherein the surfactant composition comprises at least one cationic surfactant, and the surfactant enables the formation of micelles in the aqueous phase; (2) The step of bringing the micelle-containing aqueous phase into contact with an ultrafiltration membrane under pressure to obtain an aqueous phase permeate flow having a reduced concentration of PFAS, (3) Adding a surfactant composition to the aqueous phase having a reduced concentration of PFAS, wherein the surfactant composition comprises at least one cationic surfactant, and the surfactant enables the formation of micelles in the aqueous phase having a reduced concentration of PFAS, (4) The steps of bringing the micelle-containing aqueous phase having a reduced concentration of PFAS into contact with an ultrafiltration membrane under pressure to obtain an aqueous phase permeate flow having an even reduced concentration of PFAS, and optionally repeating (3) and (4) once or more times, for example, 1, 2, 3 or 4 times. Includes.

[0093] In some embodiments, a method for removing PFAS from a PFAS-containing aqueous phase is: (1) Adding a surfactant composition to the aqueous phase containing PFAS at an initial concentration c0 of PFAS, wherein the surfactant composition comprises at least one cationic surfactant, and the surfactant enables the formation of micelles in the aqueous phase. (2) The step of bringing the micelle-containing aqueous phase into contact with an ultrafiltration membrane under pressure to obtain an aqueous phase permeate flow having a reduced concentration c1 of PFAS, and optionally (3) Adding a surfactant composition to the aqueous phase having a reduced concentration c1 of PFAS, wherein the surfactant composition comprises at least one cationic surfactant, and the surfactant enables the formation of micelles in the aqueous phase having a reduced concentration c1 of PFAS, (4) The step of bringing the micelle-containing aqueous phase having a reduced concentration c1 of PFAS into contact with an ultrafiltration membrane under pressure to obtain an aqueous phase permeate flow having an even reduced concentration c2 of PFAS, (5) Optionally, perform (3) and (4) once or more times, for example, 1, 2, 3 or 4 or more times, for example, a predetermined number of times, or for example, c n+1 ga c n The step of repeating until it is essentially equal to and Includes. In some embodiments, a method for removing PFAS from a PFAS-containing aqueous phase is: (1) Adding a surfactant composition to the aqueous phase containing PFAS at an initial concentration c0 of PFAS, wherein the surfactant composition comprises at least one cationic surfactant, and the surfactant enables the formation of micelles in the aqueous phase. (2) The step of bringing the micelle-containing aqueous phase into contact with an ultrafiltration membrane under pressure to obtain an aqueous phase permeate flow having a reduced concentration c1 of PFAS, (3) Adding a surfactant composition to the aqueous phase having a reduced concentration c1 of PFAS, wherein the surfactant composition comprises at least one cationic surfactant, and the surfactant enables the formation of micelles in the aqueous phase having a reduced concentration c1 of PFAS; (4) The step of bringing the micelle-containing aqueous phase having a reduced concentration c1 of PFAS into contact with an ultrafiltration membrane under pressure to obtain a permeate flow of the aqueous phase having a further reduced concentration c2 of PFAS, and optionally repeating (3) and (4) once or more times, for example, 1, 2, 3 or 4 or more times, for example, a predetermined number of times, or for example, c n+1 ga c n The step of repeating until it is essentially equal to and Includes.

[0094] In some embodiments, a method for removing PFAS from a PFAS-containing aqueous phase is: (1) Adding a surfactant composition to the aqueous phase containing PFAS at an initial concentration c0, wherein the surfactant composition comprises at least one cationic surfactant, and the surfactant enables the formation of micelles in the aqueous phase. (2) The step of bringing the micelle-containing aqueous phase into contact with an ultrafiltration membrane under pressure to obtain an aqueous phase permeate flow having a reduced concentration c1 of PFAS, (3) A step of determining the concentration of one or more PFAS in the permeate flow aqueous phase having a reduced concentration of PFAS, and optionally (4) If the concentration determined in (3) is higher than the threshold, the surfactant composition is added to the aqueous phase having a reduced concentration c1 of PFAS, wherein the surfactant composition comprises at least one cationic surfactant, and the surfactant enables the formation of micelles in the aqueous phase having a reduced concentration c1 of PFAS. (5) The steps of bringing the micelle-containing aqueous phase having a reduced concentration c1 of PFAS into contact with an ultrafiltration membrane under pressure to obtain a permeate flow of the aqueous phase having a further reduced concentration c2 of PFAS; and optionally repeating (3) and (4) once or more times, for example, 1, 2, 3 or 4 or more times, for example, a predetermined number of times, or until the concentration determined in (3) no longer exceeds a threshold. Includes.

[0095] By repeatedly treating PFAS-contaminated water with the surfactant compositions defined herein, PFAS can be removed to below the detection limit for PFAS analysis by ultrafiltration.

[0096] In some embodiments, as described herein, in the step of determining the concentration of one or more PFAS in the aqueous phase (e.g., permeate flow aqueous phase), the concentration of at least one PFAS selected from PFAS Sum11 is determined, for example, the overall concentration of PFAS Sum11 is determined.

[0097] The surfactant composition added in each step may generally be one of those described herein, for example, a cationic surfactant, such as CTAB or CTAC, or a concentrated aqueous solution thereof.

[0098] In some other embodiments, the step involves adding a micelle-forming amount of surfactant composition to a permeate flow coming out of a single ultrafiltration filter, in which the micelle-forming amount and surfactant may differ for each point of addition. It is assumed that ultrafiltration may be carried out using several ultrafiltration filters in series, either of the same type or of different types having different molecular weight cutoff sizes, rather than recirculating the aqueous phase through the same single ultrafiltration membrane.

[0099] Furthermore, it is assumed that recirculation in the same ultrafiltration filter and its combination with a series of ultrafiltration units are possible. The principle of the present invention is schematically shown in Figure 3A, where the surfactant composition described herein ("surfactant") is added to PFAS-containing water 1 at a concentration that enables micelle formation. The PFAS present in the aqueous phase is assumed to be an anionic compound 2 and a nonionic compound 3. As also shown in Figure 3B, the anionic PFAS 2 will associate with the micelle at the micelle surface as a counterion to the cationic surfactant of the micelle, while the nonionic PFAS 3 will essentially separate into a hydrophobic space within the micelle, forming a PFAS-retaining micelle 4. The reaction is considered to be rapid compared to ultrafiltration, and therefore the solution can be ultrafiltered essentially immediately through an ultrafiltration membrane 5 having a molecular weight cutoff smaller than the size of the formed micelle 4 to obtain a retention solution 6 with an increased concentration of PFAS and a permeate 7 (not shown) with a reduced concentration of PFAS.

[0100] A favorable feature of the method of the present invention is that the proportion of retained liquid in the treated water is quite small, accounting for approximately less than 15% by volume, or even less than 10% by volume, of the inflow volume of water. This reduces the problems inherent in large volumes of wastewater.

[0101] Advantageously, the present invention can achieve a reduction in the initial concentration of PFAS in water by at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 98%, at least 99%, or even higher, for example, to a detection level.

[0102] The efficiency of removing PFAS from PFAS-contaminated water depends not only on the choice of surfactant but also on the molecular weight cutoff of the selected ultrafiltration membrane. Generally, the optimal molecular weight cutoff for ultrafiltration membranes has been found to be less than 100 kDa, more preferably less than 50 kDa, and even more preferably less than 30 kDa, for example, 5–20 kDa. For example, membranes with molecular weight cutoffs of 5–100 kDa or 5–50 kDa, for example, 5–30 kDa, may be used.

[0103] The present invention has been shown to function in small-scale ultrafiltration systems for laboratory use, such as membrane-equipped centrifuge tubes, or tangential flow ultrafiltration systems for laboratory use that can process from 100 ml to several liters, and in large-scale ultrafiltration systems used for treating cubic meters of PFAS-contaminated water.

[0104] The present invention is illustrated by the following non-limiting embodiments. For comparison, comparative examples not relating to the present invention are also described. [Examples]

[0105] material All surfactants used were of commercially available quality and obtained from commercial chemical suppliers, for example, in the form of commercially available detergents. The water tested was contaminated water obtained from various sources at a PFAS-contaminated site located in Sweden. The ultrafiltration membranes were commercially available membranes obtained from ultrafiltration equipment suppliers.

[0106] PFAS analysis The water was analyzed step-by step by an accredited environmental analysis laboratory located in Sweden, and the water analysis was performed using LC-MS-MS.

[0107] General Procedures for Purifying PFAS-Contaminated Water All experiments were carried out according to the general procedure shown in Figure 4. A cationic surfactant ("cationic detergent") was added to PFAS-contaminated water, the mixture was allowed to mix for several seconds, and then passed through an ultrafiltration membrane. Two fractions were generally obtained from the ultrafiltration process: the main fraction, usually comprising 90–95% of the total volume, was a permeate with a reduced concentration of PFAS compared to the unfiltered water; and the smaller fraction, usually comprising 5–10% of the total volume, contained micelles retained by the membrane and harboring PFAS.

[0108] General Procedure 1 As shown in the examples, a surfactant was added to a 15 ml sample of PFAS-contaminated water, the sample was shaken for 1 to 5 seconds, and then transferred to a Vivaspin® Turbo15 ultrafiltration centrifuge tube with different molecular weight cutoff values. The centrifuge tube was then centrifuged at 3000 rpm for 15 minutes, and the permeate was analyzed for PFAS. The results shown are essentially for PFAS Sum11.

[0109] Example 1 Water: Leachate from landfill Surfactant: Cetyltrimethylammonium bromide (CTAB) Surfactant concentration: 3g / L Membrane molecular weight cutoff: 10 kDa The experiment was conducted by adding CTAB to water at a concentration of 3 g / L, following general procedure 1. For comparison, an experiment without the addition of a surfactant was also performed. The results are shown in Table 1, where the residual concentration of PFAS Sum11 ("residual PFAS Sum11") is also shown as a percentage of the amount measured in untreated water.

[0110] [Table 1]

[0111] Example 2 Water: Leachate from landfill Surfactant: CTAB Surfactant concentration: 1g / L Membrane molecular weight cutoff: 5 kDa The experiment was conducted according to general procedure 1, by adding CTAB to water at a concentration of 1 g / L. For comparison, an experiment without the addition of a surfactant was also performed. The results are shown in Table 2.

[0112] [Table 2]

[0113] Example 3 Water: Leachate from landfill Surfactant: CTAB Surfactant concentration: 5g / L Membrane molecular weight cutoff: 10 kDa The experiment was conducted according to general procedure 1, by adding CTAB to water at a concentration of 5 g / L. For comparison, an experiment without the addition of a surfactant was also performed. The results are shown in Table 3.

[0114] [Table 3]

[0115] Example 4 Water: PFAS-contaminated water Surfactant: Luviquat® Mono LS (CAS number: 68002-60-8) Surfactant concentration: 1g / L Membrane molecular weight cutoff: 5 kDa Luviquat® Mono LS is an aqueous solution of lauryl / myristyltrimethylammonium methosulfate, a cationic quaternary ammonium salt, which is sold, for example, by Sigma Aldrich, and has a solids content of approximately 30%.

[0116] The experiment was carried out according to general procedure 1, by adding Luviquat Mono LS to water at a concentration of 1 g / L (based on the dry weight of the surfactant). The results are shown in Table 4.

[0117] [Table 4]

[0118] Example 5 Water: PFAS-contaminated water Surfactant: Tetranyl(registered trademark) CO-40 (CAS number 155042-51-6) Surfactant concentration: 0.5 g / L Membrane molecular weight cutoff: 10 kDa Tetranyl(registered trademark)CO-40 is a dioleoylethylhydroxyethylmonium methosulfate, a cationic quaternary ammonium salt, and is sold, for example, by Kao Chemicals.

[0119] The experiment was conducted according to general procedure 1, by adding Tetranyl® CO-40 to water at a concentration of 0.5 g / L. For comparison, an experiment without the addition of a surfactant was also conducted. The results are shown in Table 5.

[0120] [Table 5]

[0121] Example 6 Water: PFAS-contaminated water Surfactant: Tetranyl(registered trademark)CO-40 Surfactant concentration: 5g / L Membrane molecular weight cutoff: 10 kDa The experiment was conducted according to general procedure 1, by adding Tetranyl® CO-40 to water at a concentration of 5 g / L. For comparison, an experiment without the addition of a surfactant was also conducted. The results are shown in Table 6.

[0122] [Table 6]

[0123] reference Example 7 Water: PFAS-contaminated water Surfactant: Dehyquart(registered trademark) H81 Surfactant concentration: 2.5 g / L Membrane molecular weight cutoff: 10 kDa Dehyquart® H81 (manufactured by BASF) is a pseudo-cationic surfactant in the form of a polyglycol-polyamine condensation resin (INCI name: PEG-15 Cocopolyamine).

[0124] The experiment was conducted according to general procedure 1, by adding Dehyquart® H81 to water at a concentration of 2.5 g / L. The results are shown in Table 7.

[0125] [Table 7]

[0126] Comparative Example 8 Water: Leachate from landfill Surfactant: Empigen(registered trademark) BB Surfactant concentration: 5g / L Membrane molecular weight cutoff: 3 kDa Empigen® BB is a 30% dry weight aqueous solution of lauryldimethylbetaine, an amphoteric surfactant.

[0127] The experiment was carried out according to general procedure 1, by adding Empigen® BB to water at a surfactant concentration of 5 g / L (based on the dry weight of the surfactant). The results are shown in Table 8.

[0128] [Table 8]

[0129] Comparative Example 9 Water: Leachate from landfill Surfactant: Cremophor EL Surfactant concentration: 5g / L Membrane molecular weight cutoff: 3 kDa Cremophor is a nonionic surfactant obtained by ethoxylation of hydrogenated castor oil.

[0130] The experiment was carried out according to general procedure 1, by adding Cremophor to water at a concentration of 5 g / L. The results are shown in Table 9.

[0131] [Table 9]

[0132] Comparative Examples 10-13 and Examples 14-16 were performed with PFAS-containing water having a PFAS concentration of 25.13 μg / L from the perspective of PFAS Sum11.

[0133] Comparative Example 10 Water: PFAS-contaminated water (PFAS Sum11 at 25.13 μg / L) No surfactants are added.

[0134] Membrane molecular weight cutoff: 10 kDa The experiment followed general procedure 1, but without the addition of a surfactant. The results are shown in Table 10.

[0135] [Table 10]

[0136] Comparative Example 11 Water: PFAS-contaminated water (PFAS Sum11 at 25.13 μg / L) Surfactant: Sodium dodecyl sulfate (SDS) Surfactant concentration: 3g / L Membrane molecular weight cutoff: 10 kDa The experiment was conducted according to general procedure 1, by adding SDS to water at a concentration of 3 g / L. The results are shown in Table 11.

[0137] [Table 11]

[0138] Comparative Example 12 Water: PFAS-contaminated water (PFAS Sum11 at 25.13 μg / L) Surfactant: Glucopon(registered trademark) 600 CSUP, nonionic surfactant Surfactant concentration: 3g / L Membrane molecular weight cutoff: 10 kDa Glucopon® CSUP is a nonionic surfactant containing lauryl / myristyl glucoside, sold by BASF. The experiment was conducted according to general procedure 1, by adding Glucopon® CSUP to water at a concentration of 3 g / L (based on the dry weight of the surfactant). The results are shown in Table 12.

[0139] [Table 12]

[0140] Comparative Example 13 Water: PFAS-contaminated water (PFAS Sum11 at 25.13 μg / L) Surfactant: Glucopon® 600 CSUP and SDS mixture Surfactant concentration: 1 g / L for each surfactant Membrane molecular weight cutoff: 10 kDa The experiment was carried out according to general procedure 1, by adding the entire amount of the indicated surfactant mixture to water at a concentration of 2 g / L. The results are shown in Table 13.

[0141] [Table 13]

[0142] Example 14 Water: PFAS-contaminated water (PFAS Sum11 at 25.13 μg / L) Surfactant: Luviquat® HOLD (CAS No. 174761-16-1) (Solid content 20%) Surfactant concentration: 3g / L Membrane molecular weight cutoff: 10 kDa Luviquat®HOLD is a viscous liquid polymer cationic surfactant containing polyquaternium-68 (Quaternium-68, CAS number 827346-45-2), specifically a polymer having 1-ethenyl-2-pyrrolidinone, 1-ethenylimidazole, and 1-ethenyl-3-methylimidazolium methyl sulfate, also known as 1H-imidazolium, 1-ethenyl-3-methyl-methyl sulfate (1:1), 1-ethenyl-1H-imidazole, 1-ethenyl-2-pyrrolidinone, and 2-methyl-2-propenamide (Mw 510.6g).

[0143] The experiment was carried out according to general procedure 1, by adding Luviquat® HOLD to water at a concentration of 3 g / L (based on the dry weight of the surfactant). The results are shown in Table 14.

[0144] [Table 14]

[0145] Example 15 Water: PFAS-contaminated water (PFAS Sum11 at 25.13 μg / L) A mixture of surfactant compositions Glucopon® CSUP and Luviquat® Mono LS. Surfactant concentration: 2g / L each Membrane molecular weight cutoff: 10 kDa The experiment was carried out according to general procedure 1, by adding the entire surfactant mixture to water at a concentration of 4 g / L. The results are shown in Table 15.

[0146] [Table 15]

[0147] Example 16 Water: PFAS-contaminated water (PFAS Sum11 at 25.13 μg / L) Surfactants: A mixture of Glucopon® CSUP and Luviquat® Mono LS. Surfactant concentration: 1 g / L for each surfactant Membrane molecular weight cutoff: 10 kDa The experiment was carried out according to general procedure 1, by adding the entire surfactant mixture to water at a concentration of 2 g / L. The results are shown in Table 16.

[0148] [Table 16]

[0149] The results for Comparative Examples 10-13 and Examples 14-16 are shown in Figure 5 in terms of the percentage of residual PFAS Sum11 relative to the concentration of PFAS Sum11 in untreated water.

[0150] Example 17 Water: Leachate from landfill Surfactant: CTAB Surfactant concentration: 5g / L Membrane molecular weight cutoff: 50 kDa The experiment was conducted according to general procedure 1, by adding CTAB to water at a concentration of 5 g / L. For comparison, an experiment without the addition of a surfactant was also performed. The results are shown in Table 17.

[0151] [Table 17]

[0152] General Procedure 2 A surfactant composition was added to 0.3–1 L of PFAS-contaminated water samples, and the samples were stirred for 1–5 minutes. Then, tangential flow ultrafiltration was performed using a Vivaflow 50 polyethersulfone ultrafiltration filter. Tangential flow filtration was carried out until only 10% of the original volume remained in the retaining liquid. The resulting permeates were analyzed for PFAS.

[0153] Comparative Example 18 and Examples 19-21 were all performed with PFAS-containing water having a PFAS concentration of 12 μg / L from the perspective of PFAS Sum11.

[0154] Comparative Example 18 Water: PFAS-contaminated water (PFAS Sum11 at 12 μg / L) No surfactants are added. Membrane molecular weight cutoff: 10 kDa The experiment was conducted according to general procedure 2, but without the addition of a surfactant. The results are shown in Table 18.

[0155] [Table 18]

[0156] Example 19 Water: PFAS-contaminated water (PFAS Sum11 at 12 μg / L) Surfactant: CTAC Surfactant concentration: 0.25 g / L Membrane molecular weight cutoff: 10 kDa The experiment was carried out according to general procedure 2, by adding 0.25 g / L of CTAC as a surfactant. The results are shown in Table 19.

[0157] [Table 19]

[0158] Example 20 Water: PFAS-contaminated water (PFAS Sum11 at 12 μg / L) Surfactant: CTAC Surfactant concentration: 0.5 g / L Membrane molecular weight cutoff: 10 kDa The experiment was carried out according to general procedure 2, by adding 0.5 g / L of CTAC as a surfactant. The results are shown in Table 20.

[0159] [Table 20]

[0160] Example 21 Water: PFAS-contaminated water (PFAS Sum11 at 12 μg / L) Surfactant: CTAC Surfactant concentration: 1g / L Membrane molecular weight cutoff: 10 kDa The experiment was carried out according to general procedure 2, by adding 1 g / L of CTAC as a surfactant. The results are shown in Table 21.

[0161] [Table 21]

[0162] The results for Comparative Example 18 and Examples 19-21 are shown in Figure 6 in terms of the percentage of residual PFAS Sum11 relative to the concentration of PFAS Sum11 in untreated water. Examples 22-24 were all performed with PFAS-containing water having a PFAS concentration of 18 μg / L from the perspective of PFAS Sum11.

[0163] Example 22 Water: PFAS-contaminated water (PFAS Sum11 at 18 μg / L) Surfactant: Cetyltrimethylammonium chloride (CTAC) Surfactant concentration: 0.5 g / L Membrane molecular weight cutoff: 10 kDa The experiment was carried out according to general procedure 2, by adding 0.5 g / L of CTAC as a surfactant. The results are shown in Table 22.

[0164] [Table 22]

[0165] Example 23 Water: PFAS-contaminated water (PFAS Sum11 at 18 μg / L) Surfactant: Cetyltrimethylammonium chloride (CTAC) Surfactant concentration: 0.7 g / L Membrane molecular weight cutoff: 10 kDa The experiment was carried out according to general procedure 2, by adding 0.7 g / L of CTAC as a surfactant. The results are shown in Table 23.

[0166] [Table 23]

[0167] Example 24 Water: PFAS-contaminated water (PFAS Sum11 at 18 μg / L) Surfactant: Cetyltrimethylammonium chloride (CTAC) Surfactant concentration: 1g / L Membrane molecular weight cutoff: 10 kDa The experiment was carried out according to general procedure 2, by adding 1 g / L of CTAC as a surfactant. The results are shown in Table 24.

[0168] [Table 24]

[0169] General procedure 3 A surfactant composition was added to a 0.3-1 L sample of PFAS-contaminated water, the sample was stirred for 1-5 minutes, and then subjected to tangential flow ultrafiltration in a Vivaflow® 50 polyethersulfone ultrafiltration filter. Tangential flow filtration was carried out until only 10% of the original volume remained in the retaining liquid. The resulting permeate was analyzed for PFAS. The procedure was repeated n times to obtain a total of n+1 replicates.

[0170] Example 25 Water: Leachate from landfill Surfactant: CTAB Number of iterations: 4 Membrane molecular weight cutoff: 10 kDa The experiment was carried out according to general procedure 3, using different amounts of CTAB as shown in Table 25. PFAS concentrations were additionally measured in the leachate water before treatment and in water that had undergone ultrafiltration without surfactant. The results are shown in Table 25.

[0171] [Table 25]

[0172] Example 26 Water: PFAS-contaminated water Surfactant: CTAB Number of iterations: 3 Membrane molecular weight cutoff: 10 kDa The experiment was carried out according to general procedure 3, using different amounts of CTAB as shown in Table 26. PFAS concentrations were additionally measured in the water before treatment. The results are shown in Table 26.

[0173] [Table 26]

[0174] General Procedure 4 A surfactant composition was added to a 25 L sample of PFAS - contaminated water, and the sample was stirred for 1 - 5 minutes. Next, it was subjected to tangential flow ultrafiltration in an ultrafiltration unit having a filtration capacity of 40 - 100 L / h. The tangential flow filtration was carried out until only 10% of the original liquid volume remained in the retentate. The obtained permeate was analyzed for PFAS. The procedure was repeated n times to obtain a total number of n + 1 repetitions.

[0175] Example 27 Water: PFAS - contaminated water Surfactant: CTAC Number of repetitions: 3 Membrane molecular weight cut - off: 10 kDa The experiment was carried out according to General Procedure 4 using different amounts of CTAC shown in Table 27. The PFAS concentration was additionally measured in the water before treatment. The results are shown in Table 27 and Figure 7.

[0176]

Table 27

[0177] Cited literature 1. American Water Works Association Research Foundation; Ed. group Joel Mallevialle (1996). “Water treatment membrane processes.” New York [u.a.]: McGraw Hill 2. Tamime, A. Y. “Membrane Processing Dairy and Beverage Applications”. Chicester: Wiley. 3.Rizvi, Anil Kumar; Pabby, Ana Maria; Sastre, Syed S.H., eds. (2007). “Handbook of membrane separations : chemical, pharmaceutical, and biotechnological applications.” Boca Raton, Fla.: CRC Press. 4.Clever, M.; Jordt, F.; Knauf, R.; Rabiger, N.; Rudebusch, M.; Hilker-Scheibel, R. (1 December 2000). "Process water production from river water by ultrafiltration and reverse osmosis". Desalination. 131 (1-3): 325-336. 5.Tamime, A. Y. “Membrane Processing Dairy and Beverage Applications.” Chicester: Wiley 6.Kaustubha Mohanty, Mihir K. Purkait; “Membrane technologies and applications” 2012, CRC Press 7.Kandori, K., Schechter, R.S.; “Selection of surfactants for micellar- enhanced ultrafiltration”, Separation Science and Technology (1990), 25(1-2), 83-108 8.Ponisseril Somasundaran, Shaohua Lu; ”REMOVAL OF CONTAMINANTS FROM WATER USING SUGAR BASED SURFACTANT ENHANCED ULTRAFILTRATION”, US Patent no 8,002,988 9.Puasa S.W., Ruzitah M.S and Sharifah A.S.A.K; “An Oerview of Micellar - Enhanced Ultrafiltration in Wastewater Treatment Process”, IPCBEE vol.12 (2011) 10.Lehmler, HJ (2005). "Synthesis of environmentally relevant fluorinated surfactants-a review". Chemosphere. 58(11): 1471-96. 11.Renner R (2006). "The long and the short of perfluorinated replacements". Environ. Sci. Technol. 40 (1): 12-3. 12.Calafat AM, Wong LY, Kuklenyik Z, Reidy JA, Needham LL (2007). "Polyfluoroalkyl chemicals in the U.S. population: data from the National Health and Nutrition Examination Survey (NHANES) 2003-2004 and comparisons with NHANES 1999-2000". Environ. Health Perspect. 115 (11): 1596-602 13.Berger, U., Glynn, A., Holmstrom, K.E., Berglund, M., Ankarberg, H.E., Tornkvist, A.; ” Fish consumption as a source of human exposure to perfluorinated alkyl substances in Sweden - Analysis of edible fish from Lake Vattern and the Baltic Sea”, Chemosphere, Volume 76, Issue 6, August 2009, Pages 799-804 14.McCleaf, P., Englund, S., Ostlund, A., Lindegren, K., Wiberg, K., Ahrens, L.; ” Removal efficiency of multiple poly- and perfluoroalkyl substances (PFASs) in drinking water using granular activated carbon (GAC) and anion exchange (AE) column tests”, Water research, Volume 120, 1 September 2017, Pages 77-87 15.Busch, J., Ahrens, L., Sturm, R., Ebinghaus, R.; ”Polyfluoroalkyl compounds in landfill leachates”, Environmental pollution, Volume 158, Issue 5, May 2010, Pages 1467-1471

Claims

1. A method for removing PFAS from an aqueous phase containing PFAS, (i) Adding a surfactant composition containing at least one cationic surfactant to the PFAS-containing aqueous phase, thereby enabling the cationic surfactant to form micelles in the PFAS-containing aqueous phase, to obtain a micelle-containing aqueous phase; (ii) The step of bringing the micelle-containing aqueous phase into contact with an ultrafiltration membrane under pressure to obtain a permeate flow aqueous phase having a reduced concentration of PFAS, Includes, The PFAS is one or more PFAS selected from anionic PFAS and nonionic PFAS. The method wherein the cationic surfactant contains a C4-C20 aliphatic group as a hydrophobic portion.

2. The method according to claim 1, wherein the cationic surfactant comprises a hydrophilic portion selected from ammonium, methylammonium, dimethylammonium, trimethylammonium, hydroxyethylammonium, methylhydroxyethylammonium, and dimethylhydroxyethylammonium.

3. The aforementioned PFAS is perfluorobutanoic acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluorobutanesulfonic acid, perfluorohexanosulfonic acid, perfluorooctanesulfonic acid, 6:2 fluorotelomer sulfonate, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid, perfluoropentanesulfonic acid, perfluoroheptanesulfonic acid, perfluorononanosulfonic acid, perfluorodecanesulfonic acid, perfluorododecanesulfonic acid, 4:2 fluoro The method according to claim 1 or 2, comprising one or more of telomer sulfonate, 8:2 fluorotelomer sulfonate, perfluorooctanesulfonamide, N-methylperfluorooctanesulfonamide, N-ethylperfluorooctanesulfonamide, N-methylperfluorooctanesulfonamide ethanol, N-ethylperfluorooctanesulfonamide ethanol, perfluorooctanesulfonamide acetate, N-methylperfluorooctanesulfonamide acetate, N-ethylperfluorooctanesulfonamide acetate, 7H-perfluoroheptanoic acid, and perfluoro-3,7-dimethyloctanoic acid.

4. The method according to claim 3, wherein the PFAS contains one or more of perfluorobutanoic acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluorobutanesulfonic acid, perfluorohexanesulfonic acid, perfluorooctanesulfonic acid, and 6:2 fluorotelomersulfonate.

5. The method according to any one of claims 1 to 4, wherein the ultrafiltration membrane has a molecular weight cutoff of 100,000 daltons or less.

6. The method according to any one of claims 1 to 5, wherein the ultrafiltration membrane has a molecular weight cutoff in the range of 1,000 to 30,000 daltons.

7. The method according to any one of claims 1 to 6, wherein the surfactant composition comprises at least one nonionic surfactant.

8. The method according to claim 7, wherein the surfactant composition comprises a cationic surfactant and a nonionic surfactant in a weight ratio of 1:100 to 100:1 between the cationic surfactant and the nonionic surfactant.

9. The method according to claim 8, wherein the weight ratio is 1:10 to 10:

1.

10. The method according to claim 9, wherein the weight ratio is 1:5 to 5:

1.

11. The method according to any one of claims 1 to 10, comprising the step of repeating (i) and (ii) at least once.

12. The method according to claim 11, comprising the step of repeating (i) and (ii) one to five times.

13. (iii) The method according to any one of claims 1 to 12, comprising the step of determining the concentration of one or more PFAS in the permeate flow aqueous phase having a reduced concentration of PFAS, and if the determined concentration is higher than a predetermined threshold, repeating (i) and (ii).

14. The method according to any one of claims 1 to 13, wherein the PFAS-containing aqueous phase is selected from landfill leachate, wastewater, groundwater, and process water.

15. The method according to any one of claims 1 to 14, wherein the PFAS-containing aqueous phase contains PFAS at an initial concentration in the range of 0.1 μg / L to 10 g / L.

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