Modified clay sorbents having multifunctional quaternary ammonium compounds and monoquaternary ammonium compounds and methods for sorbing perfluoroalkyl and polyfluoroalkyl substances (pfas) from contaminated samples with modified clay sorbents

Abstract

A method of adsorbing PFAS compounds from a contaminated sample includes mixing a modified clay adsorbent with the sample. The modified clay includes a clay intercalated with a blend of a mono-quaternary ammonium compound and a multi-functional quaternary ammonium compound having a functionality of 3 or greater.

Description

[0001] Cross-reference to related applications

[0002] The benefit of priority to U.S. Provisional Patent Application No. 63 / 029,261, filed May 22, 2020, is claimed herein, and the disclosure thereof is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to a method for adsorbing PFAS compounds, and more particularly to a method for adsorbing PFAS compounds using clay modified with one or more polyfunctional quaternary amine compounds having a functionality of 3 or greater. Background Technology

[0004] Perfluorinated compounds (PFCs) are widely used and have therefore become a global concern for water pollution. Perfluoroalkyl and polyfluoroalkyl substances (commonly referred to as PFAS) are a group of man-made chemicals, including PFOA, PFOS, GenX, and many others. PFAS have been manufactured and used in various industries, including the United States, since the 1940s. Perfluorooctane sulfonic acid (PFOS) is one of the typical PFCs and has been used in many industries as a surfactant, flame retardant, lubricant, and polymer additive. Perfluorooctanoic acid (PFOA) and PFOS are among the most widely produced and researched of these chemicals. PFCs accumulate in the human body over time, and many do not break down naturally. PFAS exposure has been proven harmful to human health. Removing PFCs from wastewater sources is crucial to preventing pollution of natural waterways. Because PFCs are generally very stable, they are difficult to break down in the surrounding environment using some conventional techniques, including biodegradation, oxidation, and reduction. Adsorption has been used as an alternative method to effectively remove PFCs from wastewater, soil and other contaminated sources using conventional adsorbents, including activated carbon, resins and biosorbents. Summary of the Invention

[0005] The technical information listed below may in some respects exceed the scope of this invention, as specifically defined in the description below. Additional technical information is provided to place the actual invention within a broader technical context and to illustrate potentially related technical developments. Such additional technical information, which does not fall within the scope of the description below, is not part of this invention.

[0006] There is a need to improve methods for adsorbing PFAS compounds from soil, wastewater and other contaminated sources.

[0007] The modified clay adsorbent according to this disclosure may comprise clay embedded with one or more multifunctional quaternary amine compounds having a functionality of 3 or greater and one or more monoquaternary amine compounds. In embodiments, the one or more multifunctional quaternary amine compounds are present in a molar percentage of about 25 mol% to about 95 mol%, based on the total molar number of quaternary amine compounds present in the modified clay adsorbent.

[0008] The modified clay adsorbent according to this disclosure may comprise a first modified clay and a second modified clay, the first modified clay comprising clay embedded with one or more monoquaternary amine compounds, and the second modified clay comprising clay embedded with one or more polyfunctional quaternary amine compounds having a functionality of 3 or greater. In embodiments, the second modified clay may be present in the modified clay adsorbent in such an amount that, based on the total molar number of quaternary amine compounds present in the modified clay adsorbent, the one or more polyfunctional quaternary amine compounds are present in an amount of about 25 mol% to about 95 mol%.

[0009] The method for adsorbing PFAS compounds from a contaminated sample according to this disclosure may include mixing a modified clay adsorbent with the sample, wherein the modified clay adsorbent comprises clay embedded with one or more polyfunctional quaternary amine compounds having a functionality of 3 or greater.

[0010] The method for adsorbing PFAS compounds from a contaminated sample according to this disclosure may include mixing a modified clay adsorbent with the sample, wherein the modified clay adsorbent comprises clay embedded with one or more monoquaternary amine compounds and one or more polyfunctional quaternary amine compounds having a functionality of 3 or greater. In embodiments, the one or more polyfunctional quaternary amine compounds are present in an amount from about 25 mol% to about 95 mol% based on the total molar percentage of the quaternary amine compounds in the modified clay adsorbent.

[0011] A method for adsorbing PFAS compounds from a contaminated sample may include mixing a modified clay adsorbent with the sample, wherein the modified clay adsorbent comprises a first modified clay and a second modified clay, the first modified clay comprising clay embedded with one or more monoquaternary amine compounds, and the second modified clay comprising clay embedded with one or more polyfunctional quaternary amine compounds having a functionality of 3 or greater. In an embodiment, the ratio of the amount of the first modified clay to the amount of the second modified clay is selected such that, based on the total molar percentage of the quaternary amine compounds mixed with the sample, the one or more polyfunctional quaternary amine compounds are present in an amount of about 25 mol% to about 95 mol%.

[0012] In any of the modified clay sorbets or methods described herein, the polyfunctional quaternary amine compound may be a trifunctional quaternary amine compound (also referred to herein as “triquat”). Attached Figure Description

[0013] Figure 1 It is a graph showing the removal percentage of various PFAS as the molar percentage of trifunctional quaternary ammonium compounds changes; and

[0014] Figure 2 This is a bar graph showing the removal percentage of various PFAS as the molar percentage of trifunctional quaternary ammonium compounds changes. Detailed Implementation

[0015] The technical information listed below may in some respects exceed the scope of this invention, as specifically defined in the description below. Additional technical information is provided to place the actual invention within a broader technical context and to illustrate potentially related technical developments. Such additional technical information, which does not fall within the scope of the description below, is not part of this invention.

[0016] This document discloses modified clay adsorbents for adsorbing PFAS compounds. The modified clay adsorbent may comprise a clay component modified with a blend of one or more monoquaternary amine compounds and one or more polyfunctional quaternary amine compounds with a functionality of 3 or greater. The modified clay adsorbent may be modified with one or more polyfunctional quaternary amine compounds with a functionality of 3 or greater. Methods for adsorbing PFAS compounds from contaminated samples may include contacting the sample with one or more modified clay adsorbents or otherwise exposing the sample to one or more modified clay adsorbents. In such methods, the modified clay adsorbent may be modified with a polyfunctional quaternary amine compound with a functionality of 3 or greater, or with a blend of a monoquaternary amine compound and a polyfunctional quaternary amine compound with a functionality of 3 or greater. In any adsorbent described herein, the clay may be modified with more than one monoquaternary amine compound and / or more than one polyfunctional quaternary amine compound. In any of the adsorbents or methods described herein, the multifunctional quaternary amine compound may be a trifunctional quaternary amine compound (a triquaternary ammonium salt).

[0017] The modified clay adsorbents of this disclosure can be prepared by reacting clay with one or more quaternary ammonium compounds or blends thereof. The reaction is carried out under conditions in which one or more quaternary ammonium compounds are embedded in the clay. The modified clay adsorbents may comprise clay embedded with one or more polyfunctional quaternary ammonium compounds with a functionality of 3 or greater. The clay may further embed one or more monoquaternary ammonium compounds and / or one or more diquaternary ammonium compounds. The modified clay adsorbent blends may comprise a blend of a first clay and a second clay, wherein the first clay is embedded with one or more monoquaternary ammonium compounds and the second clay is embedded with one or more polyfunctional quaternary ammonium compounds with a functionality of 3 or greater. The one or more polyfunctional quaternary ammonium compounds in any adsorbent of this disclosure may be or may comprise triquaternary ammonium salts.

[0018] Modifying clay to embed quaternary ammonium compounds can be carried out according to any method known in the art, including wet processing and dry, extrusion-based methods. In examples, the reaction may involve mixing approximately 1 mole of a quaternary ammonium salt with each exchangeable cation in the clay. For example, the quaternary ammonium compound or compound blend may be mixed with water, and clay may then be added to the mixture to react the clay with the multifunctional quaternary ammonium compound. The mixture may then be dried and ground into granules or powder for use.

[0019] The adsorbents disclosed herein should be understood as reagents that can bind, immobilize, or otherwise associate with pollutants by adsorbing them onto a modified clay adsorbent. As used herein, “adsorption” should be understood to include the adsorption of pollutants onto the surface of the adsorbent and / or the adsorption of pollutants into all or part of the adsorbent.

[0020] In any of the adsorbents disclosed herein, the clay can be a layered silicate, such as montmorillonite clay minerals, for example, montmorillonite, particularly sodium montmorillonite; magnesium montmorillonite and / or calcium montmorillonite; attapulgite, heat-treated attapulgite, chlorodiazepite; bedeite; chromium bentonite; lithium montmorillonite; soapstone; zinc montmorillonite; sobockite; magnesia; svinfordite; vermiculite; palygorskite; kalonite; sepiolite, etc. Other useful layered materials include mica minerals such as illite, klindrite, muscovite, biotite, etc., and mixed layered illite / montmorillonite minerals such as rettoite, tarosovite, reddice, and mixtures of illite with the aforementioned clay minerals.

[0021] The swellable layered material can be a 2:1 type layered silicate having a negative charge ranging from about 0.15 to about 0.9 per unit on the layers and a corresponding number of exchangeable metal cations in the interlayer spaces. The most preferred layered materials are chlorite clay minerals, such as montmorillonite, chlorite, bedesite, chromium bentonite, lithium montmorillonite, saponite, zinc montmorillonite, spukkaite, magnesia, and svenfelite.

[0022] Modified clay adsorbents and modified clay adsorbent blends with mono- and polyfunctional quaternary blends

[0023] Modified clay adsorbents may comprise clay embedded in a blend of one or more monoquaternary amine compounds and one or more polyfunctional quaternary amine compounds with a functionality of 3 or greater. Modified clay adsorbents may also be provided having a first modified clay and a second modified clay, the first modified clay having clay embedded in one or more monoquaternary amine compounds, and the second modified clay having clay embedded in one or more polyfunctional quaternary amine compounds with a functionality of 3 or greater. Modified clay adsorbents having a first modified clay and a second modified clay may be provided as a single blend composition or as a separate component to be added to a contamination source. It is further envisioned herein that modified clay adsorbents having a first modified clay and a second modified clay may comprise additional clay embedded in a blend of one or more monoquaternary amine compounds and one or more polyfunctional quaternary amine compounds with a functionality of 3 or greater. The modified clay adsorbent according to this disclosure can contain any suitable amount of modified clay components, including, for example, multiple clay components embedded with blends of mono-quaternary amine compounds and polyfunctional quaternary amine compounds with different ratios of mono-quaternary amine compounds to polyfunctional quaternary amine compounds. Further, the modified clay adsorbent of this disclosure can contain unmodified clay. The modified clay adsorbent of this disclosure can be provided with all or some of the pre-blended components for individual addition to a contaminated source to remove PFAS. Alternatively, one or more components can be provided for individual addition to a contaminated source. In embodiments, the modified clay adsorbent, whether a single-component blend, a single clay component modified with a blend of quaternary amine compounds, or a single component, can consist of one or more polyfunctional quaternary amine compounds with a functionality of 3 or greater and one or more mono-quaternary amine compounds. That is, the adsorbent can contain only polyfunctional and monofunctional quaternary amine compounds.

[0024] In embodiments, based on the total molar amount of quaternary ammonium compounds in the modified clay adsorbent, the modified clay adsorbent may contain about 5 mol% to about 95 mol% or about 25 mol% to about 95 mol% of a polyfunctional quaternary ammonium compound with a functionality of 3 or greater. The modified clay adsorbents of this disclosure can be used to remove PFAS compounds, and particularly to remove long-chain PFAS compounds, short-chain PFAS compounds, and currently widely regulated PFAS compounds. It has been found that modified clay adsorbents having 20 mol% to about 80 mol% of polyfunctional quaternary ammonium compounds with a functionality of 3 or greater, based on the total molar amount of quaternary ammonium compounds in the modified clay adsorbent, improve the removal of short-chain compounds compared to molar percentages outside this range. For example, based on the total molar amount of quaternary ammonium compounds in the modified clay adsorbent, modified clay adsorbents for the removal of short-chain PFAS may have about 20 mol% to about 80 mol% of a triquaternary ammonium salt. Such clay adsorbents may contain a monoquaternary ammonium compound as the remaining amount of the quaternary ammonium compound. It has been found that modified clay adsorbents with 20 mol% or more of polyfunctional quaternary ammonium compounds with a functionality of 3 or greater demonstrate improved carboxylate-PFAS removal compared to amounts below 20 mol%, based on the total molar amount of quaternary ammonium compounds in the modified clay adsorbent. For example, modified clay adsorbents for carboxylate-PFAS removal may contain at least 20 mol% of a triquaternary ammonium salt. For long-chain PFAS removal, improved adsorption has been found with amounts exceeding 60 mol% of polyfunctional quaternary ammonium compounds with a functionality of 3 or greater, based on the total molar amount of quaternary ammonium compounds in the modified clay adsorbent. For example, modified clay adsorbents for long-chain PFAS removal may have more than 60 mol% of a triquaternary ammonium salt. The molar amount of polyfunctional quaternary ammonium compounds with a functionality of 3 or greater can be adjusted to selectively remove desired classes of PFAS compounds. In embodiments where the modified clay adsorbent is provided as a separate component, the component may be added sequentially or simultaneously to the contaminated sample. For example, based on the total moles of quaternary ammonium compounds added to the contaminated sample, the components may be added such that the amount of a multifunctional quaternary ammonium compound with a functionality of 3 or greater is from about 25 mol% to about 95 mol%. As used herein, “long-chain PFAS compound” refers to a PFAS compound having 6 or more carbons. As used herein, “short-chain PFAS compound” refers to a PFAS compound having fewer than 6 carbons. As used herein, “controlled PFAS compound” includes perfluorononanoic acid (PFNA), perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluoroheptanoic acid (PFHpA).

[0025] In the embodiments, the modified clay adsorbent comprises one or more polyfunctional quaternary ammonium compounds, the molar amounts of which are based on the total amount of quaternary ammonium compounds in the adsorbent from about 5 mol% to 20 mol%, from 25 mol% to about 95 mol%, from about 30 mol% to about 70 mol%, from about 25 mol% to about 50 mol%, from about 30 mol% to about 50 mol%, from about 25 mol% to about 40 mol%, and from about 25 mol% to about 30 mol%. Other suitable amounts of the polyfunctional quaternary ammonium compound include about 5 mol%, 10 mol%, 15 mol%, 20 mol%, 25 mol%, 26 mol%, 27 mol%, 28 mol%, 29 mol%, 30 mol%, 31 mol%, 32 mol%, 33 mol%, 34 mol%, 35 mol%, 36 mol%, 37 mol%, 38 mol%, 39 mol%, 40 mol%, 41 mol%, 42 mol%, 43 mol%, 44 mol%, 45 mol%, 46 mol%, 47 mol%, 48 mol%, 49 mol%, 50 mol%, 52 mol%, 54 mol%, 56 mol%, 58 mol%, 60 mol%, 62 mol%, 64 mol%, 66 mol%, 68 mol%, 70 mol%, 72 mol%, 74 mol%, 76 mol%, 78 mol%, 80 mol%, 82 mol%, 84 mol%, 86 88 mol%, 90 mol%, 92 mol%, 94 mol%, and 95 mol%. In applications where extractables from the adsorbent are unfavorable, limiting the amount of polyfunctional quaternary ammonium compounds with a functionality of 3 or greater to an upper limit of about 50 mol% can be useful.

[0026] Advantageously, the modified clay adsorbents or modified clay adsorbent blends of this disclosure exhibit high PFAS removal capacity and efficiency. This improvement in PFAS removal capacity and efficiency compared to conventional clay adsorbents using monoquaternary amine compounds allows for the removal of the same or substantially the same percentage of PFAS from contaminated sources using less adsorbent. Furthermore, the improved removal efficiency allows for high-flow-rate material pumping through the modified clay adsorbents and modified clay adsorbent blends of this disclosure, thereby improving overall equipment efficiency.

[0027] Unbound by theory, it is believed that combinations of monoquaternary amine compounds and polyquaternary amine compounds with a functionality of 3 or greater introduce electrostatic forces between clay lamellar crystals, which can allow PFAS to better penetrate the interior of the adsorbent material. This, along with the hydrophobicity provided by quaternary amine compounds, and especially monoquaternary amine compounds, is thought to lead to improvements in adsorbent capacity and efficiency.

[0028] Further investigation revealed that embedding quaternary ammonium compounds into clay to achieve a cation exchange capacity of at least about 50% of the clay is advantageous. For example, clay can be embedded to achieve a CEC of about 50% to about 120%, about 80% to about 100%, about 60% to about 90%, or about 75% to about 115%. Other suitable values ​​include CECs of about 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, 100%, 102%, 104%, 106%, 108%, 110%, 112%, 114%, 116%, 118%, and 120%. In embodiments where the modified clay adsorbent comprises a first clay embedded with a mono-quaternary compound and a second clay embedded with one or more polyfunctional quaternary amine compounds having a functionality of 3 or greater, the first clay and the second clay can be embedded to achieve the same or different CECs.

[0029] In the embodiments, the polyfunctional quaternary amine compound with a functionality of 3 or greater can be a polyfunctional quaternary amine compound having at least 18 carbon atoms. It is believed that in modified clay adsorbents, polyfunctional quaternary amine compounds with a functionality of 3 or greater, having small head groups and hydrophobicity, work well in combination with monoquaternary amine compounds to significantly improve the removal efficiency and capacity of the modified clay adsorbent.

[0030] For example, modified clay adsorbents may contain one or more of the following multifunctional quaternary amine compounds with a functionality of 3 or greater: N-tallow alkyl diallyl triamine (Triameen® T); N-tallow alkyl tripropylene tetraamine (Tetrameen® T); hexaethylguanidine chloride; 1H-pyrido[3,4-b]indole cation, 2,3,4,9-tetrahydro-1,2-dimethyl-2-[3-(trimethylammonium)propyl]-, bromide (1:2); 4-aza-1-azabicyclo[2.2.2]octene, 1,1'-(1,10-decanediyl)bis-, bromide (1:2); piperazine cation, 1,1'-(1,6-hexadiyl)bis[4-(3-chloro-2-hydroxypropyl)-1-methyl-, dibromide, dihydrochloride (9CI); 1,10-decadiammonium, N1,N10-bis[4-(hydroxyimino)butyl]-N1,N1 N10,N10-tetramethyl-, bromide (1:2); 1,2-ethylenediammonium, N1,N2-bis[2-[bis(2-hydroxyethyl)methylamino]ethyl]-N1,N2-bis(2-hydroxyethyl)-N1,N2-dimethyl-, chloride (1:4); piperazine cation, 1,1'-(1,10-decanediyl)bis[4-(3-chloro-2-hydroxypropyl)-1-methyl-, dibromide, dihydrochloride (9CI); 1,6-hexammonium, N1,N6-bis[2-[[bis(1-methylethoxy)phosphino]amino]ethyl]-N1,N1,N6,N6-tetramethyl-, bromide (1 :2); 1,3-propanediammonium, N-[2-[(12-hydroxy-1-oxo-9-octadecenyl)amino]ethyl]-N,N,N',N',N'-pentamethyl-, dichloride, [R-(E)]-(9CI); 1,6-hexammonium, N1,N1,N6,N6-tetramethyl-N1,N6-bis[6-(trimethylammonium)hexyl]-, bromide (1:4); 1,6-hexammonium, N1,N1,N6,N6-tetramethyl-N1,N6-bis[6-(trimethylammonium)hexyl]-, iodide (1:4); ammonium, cyclooctane bis[dimethyl[2-(phosphonoamino)ethyl]-, di Bromine, tetraisopropyl ester (8CI); 5'-thymidine, 3'-[5-[diethyl[4-(triethylammonium)butyl]ammonium]valerate], bis(internal salt) (9CI); thymidine, 3'-[5-[diethyl[4-(triethylammonium)butyl]ammonium]valerate], dichloride (9CI); 1,3-propanediammonium, N1,N1,N3-tributyl-N3-[3-(dibutylmethylammonium)propyl]-N1,N3-dimethyl-, 1,3-propanediammonium, N1,N1,N3-tributyl-N3-[3-(dibutylmethylammonium)propyl]-N1,N3-dimethyl-, iodide (1:3);1,6-Hexammoniadiammonium, N,N'-bis[3-(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)propyl]-N,N,N',N'-tetramethyl- (9CI); piperazine cation, 1,1'-(1,6-hexammoniadiammonium)bis[1,4-dimethyl-4-(phenylmethyl)-, tetraiodide (9CI); 1,3-Propanediammonium, N1,N3-diethyl-N1-[3-(ethyldimethylamino)propyl]-N1-(2-hydroxyhexadecyl)-N3,N3-dimethyl-, ethyl sulfate (1:3); 1,3-Propanediammonium, N1-[3-[bis(2-hydroxyethyl)methylammonium]propyl]-N1-[3-(dodecyloxy)-2 [-hydroxypropyl]-N1,N3-bis(2-hydroxyethyl)-N1,N3-dimethyl-, methyl sulfate (1:3); 3-aza-9-azabicyclo[3.3.1]nonane, 9,9'-trimethylenebis[3-benzyl-9-methyl-, diiodide (8CI); 1,6-hexammonium, N1,N6-bis[6-(diethylmethylamino)hexyl]-N1,N6-diethyl-N1,N6-dimethyl-, iodide (1:4); 3-aza-9-azabicyclo[3.3.1]nonane, 9,9'-(1,6-hexamethylenediyl)bis[9-methyl-3-(phenylmethyl)-, diiodide (9CI); 1,6-hexammonium, N1,N1-bis[6-(diethylmethylamino)hexyl]-N1,N6-diethyl-N1,N6-dimethyl-, iodide (1:4); 3-aza-9-azabicyclo[3.3.1]nonane, 9,9'-(1,6-hexamethylenediyl)bis[9-methyl-3-(phenylmethyl)-, diiodide (9CI); 1,6-hexammonium, N1,N1-bis[6-(diethylmethylamino)hexyl]-N1,N6-dimethyl-, diiodide (9CI); [Methylpropylammonium(hexyl)]-N6,N6-dimethyl-N1,N6-dipropyl-, iodide (1:4); 3-aza-9-azabicyclo[3.3.1]nonane, 9,9'-(1,7-heptadiyl)bis[9-methyl-3-(phenylmethyl)-, diiodide (9CI); 1,6-hexammonium, N1,N6-bis[2-(9H-carbazol-9-yl)ethyl]-N1,N1,N6,N6-tetramethyl-, bromide (1:2); 10H-phenthiazine-10-ethylammonium, N-[2-[diethyl[2-(10H-phenthiazine-10-yl)ethyl]ammonium]ethyl]-N,N-diethyl-; 1,6-hexammonium, N1,N1,N6, N6-Tetramethyl-N1,N6-bis[2-(10H-phenothiazin-10-yl)ethyl]-, bromide (1:2); 10H-phenothiazin-10-ethylammonium, N-[2-[diethyl[2-(10H-phenothiazin-10-yl)ethyl]ammonium]ethyl]-N,N-diethyl-, bromide (1:2); 1,6-hexammonium, N1,N1,N1,N6-tetraethyl-N6,N6-bis[6-(triethylammonium)hexyl]-, iodide (1:4); 1,6-hexammonium, N,N'-bis[3-(1,3-dioxo-1H-benzo[de]isoquinoline-2(3H)-yl)propyl]-N,N,N',N'-tetramethyl-(9CI);1,6-Hexammoniadiammonium, N1,N1,N6,N6-Tetramethyl-N1,N6-bis[3-[dimethyl(4-phenylbutyl)ammonium]propyl]-; 1,8-Octadiamine, N1,N1,N8,N8-Tetraethyl-N1,N8-bis[6-(triethylammonium)hexyl]-, Iodide (1:4); 1,6-Hexammoniadiammonium, N1,N6-Dimethyl-N1,N1-bis[6-(methyldipropylamine)hexyl]-N6,N6-Dipropyl-, Iodide (1:4); Benzoxazole cation, 2,2'-[1,3-propadiylbis[(dimethylimino)-3,1-propadiyl-1(4H)-pyridyl-4-methylenemethoxy]]bis[3-methyl-, Iodide (1:4) ); benzothiazole cation, 2,2'-[1,3-propanediylbis[(dimethylimino)-3,1-propanediyl-1(4H)-pyridyl-4-methylenemethoxy]]bis[3-methyl-, iodide (1:4); 1,6-hexammonium hexammonium, N,N,N',N'-tetraethyl-N,N'-bis[2-(10H-phenthiazin-10-yl)ethyl]- (9CI); 1,6-hexammonium hexammonium, N1,N1,N6,N6-tetraethyl-N1,N6-bis[2-(10H-phenthiazin-10-yl)ethyl]-, bromide (1:2); 1,6-hexammonium hexammonium, N1,N6-bis[6-(diethylpropylammonium)hexyl]-N1,N6-diethyl-N1,N6-dipropane 1,10-decanoic acid diammonium, N1,N1,N10,N10-tetraethyl-N1,N10-bis[6-(triethylammonium)hexyl]-, iodide (1:4); 1,6-hexammonium hexammonium, N1,N6-bis[3-(3,4-dihydro-4-oxo-2-phenyl-1(2H)-quinazolinyl)propyl]-N1,N1,N6,N6-tetramethyl-, bromide (1:2); 1,8-octanediammonium, N1,N1,N8,N8-tetraethyl-N1,N8-bis[8-(triethylammonium)octyl]-, iodide (1:4); benzoxazole, 2,2'-[1,3-propanediylbis[(dimethylimino)-3,1-propanediyl-1(4H)]- -pyridyl-4-alkylene-1-propen-1-yl-3-alkylene]]bis[3-methyl-, iodide (1:4); benzothiazolium cation, 2,2'-[1,3-propadiylbis[(dimethylimino)-3,1-propadiyl-1(4H)-pyridyl-4-alkylene-1-propen-1-yl-3-alkylene]]bis[3-methyl-, iodide (1:4); 1,10-decanediamine, N,N''-1,6-hexadiylbis[N,N,N',N',N'-pentaethyl-, tetraiodide (9CI); 1,6-hexammonium, N,N''-[(ethyl sulfone)di-6,1-hexadiyl]bis[N,N,N',N',N'-pentamethyl-, pentaiodide (9CI);1,10-Decanediamine, N,N,N',N'-Tetraethyl-N,N'-Bis[2-(10H-Phenothiazin-10-yl)ethyl]-(9CI); 10H-Phenothiazin-10-ethylammonium, N-[10-[diethyl[2-(10H-Phenothiazin-10-yl)ethyl]ammonium]decyl]-N,N-diethyl-, bromide (1:2); quinoline cation, 1,1'-[1,3-propanediylbis[(dimethylimino)-3,1-propanediyl]]bis[4-[(3-methyl-2(3H)-benzoxazolyl)methyl]-, iodide (1:4); quinoline cation, 1,1'-[1,3-propanediylbis[(dimethylimino)-3,1-propanediyl]]bis[4-[(3-methyl-2(3H)-benzoxazolyl)methyl]-, iodide (1:4); quinoline cation, 1,1'-[1,3-propanediylbis[(dimethylimino)-3,1-propanediyl]- 3,8-Diamino-5-[3-[[3-[dimethyl-2(3H)-benzothiazolyl)methyl]-, iodide (1:4); phenanthridine cation, 3,3'-[1,6-hexadiylbis[(dimethylimino)-4,1-butadiyl]]bis[2-[2-[4-(dimethylamino)phenyl]vinyl]-, iodide (1:4); benzothiazolium cation, 3,3'-[1,6-hexadiylbis[(dimethylimino)-4,1-butadiyl]]bis[2-[2-[4-(dimethylamino)phenyl]vinyl]-, iodide Compound (1:4); Quinoline cation, 1,1'-[1,3-propanediylbis[(dimethylimino)-3,1-propanediyl]]bis[4-[3-(3-methyl-2(3H)-benzoxazolyl)-1-propen-1-yl]-, Iodide (1:4); Quinoline cation, 1,1'-[1,3-propanediylbis[(dimethylimino)-3,1-propanediyl]]bis[4-[3-(3-methyl-2(3H)-benzothiazolyl)-1-propen-1-yl]-, Iodide (1:4); 1,3-propanediammonium, N1-[3-[[3-[bis(phenylmethyl)amino]propyl](phenylmethyl)amino] [propyl]-N1,N3-dimethyl-N1,N3,N3-tris(phenylmethyl)-, methyl sulfate (1:2); 1,2-ethylenediamine, N1-[2-[dimethyl[2-(octadecyloxy)-2-oxoethyl]ammonium]ethyl]-N1,N2,N2-trimethyl-N1,N2-bis[2-(octadecyloxy)-2-oxoethyl]-, chloride (1:3); poly[(dimethylimino)-2-buten-1,4-diyl chloride (1:1)], α-[4-[tris(2-hydroxyethyl)ammonium]-2-buten-1-yl]-ω-[tris(2-hydroxyethyl)ammonium]-, chloride (1:2).

[0031] For example, modified clay adsorbents may contain one or more multifunctional quaternary ammonium compounds as part of a multifunctional quaternary ammonium compound, said multifunctional quaternary ammonium compound being partially associated with or incorporated into the polymer backbone as a detached component. These polymer-containing polycationic compounds may contain suitable cationic polymeric flocculants / accelerators, said cationic polymeric flocculants / accelerators including polyquaternium-1 (CAS No.: 68518-54-7); polyquaternium-2 (CAS No.: 63451-27-1); polyquaternium-4 (a copolymer of hydroxyethyl cellulose and diallyl dimethyl ammonium chloride); polyquaternium-5 (CAS No.: 26006-22-4); polyquaternium-6 (polyallyl dimethyl ammonium chloride; polydimethyl diallyl ammonium chloride; Magnafloc). 370 (CAS No.: 26062-79-3); Polyquaternium-7 (CAS No.: 26590-05-6); Polyquaternium-8 (poly(methyl, stearyl)methacrylate dimethylaminoethyl ester), Polyquaternium-9 (poly(methyl, stearyl)methacrylate dimethylaminoethyl ester bromide); Polyquaternium-10 (CAS No.: 53568-66-4, 55353-19-0, 54351-50-7, 81859-24-7, 68610-92- 4. 81859-24-7); Polyquaternium-11 (polyethylene-N-ethyl-methylpyrrolidone); Poly(ethyl dimethylammonium methacrylate) sulfate copolymer; Polyquaternium-12 (CAS No.: 68877-50-9); Polyquaternium-13 (CAS No.: 68877-47-4); Polyquaternium-14 (CAS No.: 27103-90-8); Polyquaternium-15 (CAS No.: 35429-19-7); Polyquaternium Salt-16 (quaternary ammonium salt of methyl vinyl imidazolium cation chloride and vinylpyrrolidone) (CAS No.: 95144-24-4); Polyquaternary ammonium salt-17 (adipic acid-dimethylaminopropylamine polymer) (CAS No.: 90624-75-2); Polyquaternary ammonium salt-18 (azelaic acid, dimethylaminopropylamine, dichloroethyl ether polymer) (CAS No.: 113784-58-0); Polyquaternary ammonium salt-19 (polyvinyl alcohol, 2,3-epoxypropylamine polymer) (CAS No.: 90624-75-2); CAS No.: 110736-85-1); Polyquaternium-20 (polyethylene octadecyl ether, 2,3-epoxypropylamine polymer (CAS No.: 110736-86-2); Polyquaternium-22 (CAS No.: 53694-17-0); Polyquaternium-24 (hydroxyethyl cellulose, dodecyl dimethyl ammonium epoxide polymer); Polyquaternium-27 (polymer of polyquaternium-2 and polyquaternium-17, CAS No.: 131954-48-4);Polyquaternium-28 (vinylpyrrolidone, dimethylaminopropyl methacrylamide copolymer, CAS No.: 131954-48-8), polyquaternium-29 (chitosan, CAS No.: 9012-76-4); propylene oxide polymers reacted with epichlorohydrin; polyquaternium-30 (methyl methacrylate, (dimethylacetaminomethyl)acrylate copolymer, CAS No.: 147398-77-4); polyquaternium-33 (CAS No.: 69418-26-4); poly(ethylene(dialkyl)ammonium)polymethacrylamidepropylammonium trichloride (CAS No.: 68039-13-4); and poly(2-acryloyloxyethyl)trimethylammonium.

[0032] According to embodiments, the monoquaternary amine compound can be a monoquaternary amine compound having at least 8 carbon atoms. For example, the monoquaternary amine compound can be a long-chain alkylammonium compound containing an alkyl group having at least 8 carbon atoms. In embodiments, the monoquaternary amine can have at least 14 carbon atoms. Any such known monoquaternary compound can be used. For example, suitable monoquaternary amine compounds are disclosed in U.S. Patent Application Publication No. 2004 / 00185109, the relevant disclosure of which is incorporated herein by reference. For example, the monoquaternary amine compound can be an ammonium cation containing at least one straight-chain or branched, saturated or unsaturated alkyl group having 12 to 22 carbon atoms. The remaining group may be selected from (a) a straight-chain or branched alkyl group having 1 to 22 carbon atoms; (b) an aralkyl group, which is a benzyl group and a substituted benzyl group, comprising a fused ring moiety having 1 to 22 carbon atoms in the alkyl moiety of the structure; (c) an aryl group, such as a benzyl group and a substituted benzyl group comprising a fused ring aromatic substituent; (d) a β-unsaturated group, a γ-unsaturated group or a hydrogen alkyl group having 2 to 6 carbon atoms having one or fewer carbon atoms; and (e) hydrogen.

[0033] Suitable monoquaternary amines for embedding in clay are well known in the art. Onium ions are typically represented by the following formula:

[0034]

[0035] Preferred monoquaternary ammonium compounds for treating clay can be one or more onium salt compounds, typically represented by the following formula:

[0036]

[0037] Where Q = N, P, S;

[0038] Where A = halide, acetate, methyl sulfate, hydroxide, preferably chloride;

[0039] R1, R2, R3, and R4 are independently organic moieties, or oligomers, or hydrogen. Suitable compounds are disclosed in U.S. Patent No. 6,376,591, the contents of which are hereby incorporated by reference. Examples of useful organic moieties include, but are not limited to, straight-chain or branched alkyl, benzyl, aryl, or aralkyl moieties having 1 to about 24 carbon atoms.

[0040] Suitable monoquaternary ammonium compounds include, for example, bis(hydrogenated tallow alkyl)dimethylammonium chloride (Arquad® 2HT); benzylbis(hydrogenated tallow alkyl)methylammonium chloride (Arquad® M2HTB); bis(tallow alkyl ethyl ester)dimethylammonium chloride (Arquad® DE-T); benzyl(hydrogenated tallow alkyl)dimethylammonium chloride (Arquad® DMHTB); hexadecylmethylammonium chloride (Arquad® 316); tallow alkyltrimethylammonium chloride (Arquad® T-27W and Arquad® T-50); hexadecyltrimethylammonium chloride (Arquad® 16-29W and Arquad® 16-50); octadecyltrimethylammonium chloride (Arquad® 18-50(m)); and dimethyl hydrogenated tallow-2-ethylhexylmethylammonium sulfate; dimethyl di(C14-C18 alkyl)ammonium chloride (Adogen). ® 442 (EVONIK).

[0041] Onium ions can be functionalized, such as protonated α,ε-amino acids, with the general formula (H3N-(CH2)). n -COOH). Alkoxylated quaternary ammonium chloride compounds may include those disclosed in U.S. Patent No. 5,366,647, the relevant disclosure of which is hereby incorporated by reference. Examples of suitable compounds may include cocoyl alkylmethyl bis(2-hydroxyethyl) ammonium chloride (Ethoquad® C / 12); octadecylmethyl [polyoxyethylene (15)] ammonium chloride (Ethoquad® 8 / 25); and octadecylmethyl (2-hydroxyethyl) ammonium chloride (Ethoquad 18 / 12).

[0042] The modified clay adsorbent disclosed herein may further comprise one or more additives. Additives may include, for example, binders, dispersants, and functional additives. For example, dispersants may be one or more acrylic copolymers or biopolymers such as guar gum, xanthan gum, veslaw gum, cellulose, polysaccharides, starch, lactic acid, polyester, citric acid / sodium bicarbonate, soy protein, and combinations thereof. Binders may comprise any suitable binder, such as starch, superabsorbent polymers, and clay. Functional additives may comprise, for example, activated carbon, anthracite, coke, topsoil rich in organic matter, sediments rich in organic matter, humus, apatite, zeolite, iron ore-rich materials, organic shale, lime, gypsum, elemental sulfur, bauxite, fishmeal, oxides or hydroxides of zero-valent iron and / or iron, manganese, and / or aluminum, and combinations thereof. Any other additives required for the specific application or environment in which the modified clay adsorbent is used may also be included.

[0043] Method for adsorbing PFAS using modified clay adsorbent and modified clay adsorbent blend

[0044] In use, modified clay adsorbents can be mixed with PFAS-contaminated sources to bind and immobilize PFAS. For example, modified clay adsorbents can be mixed with PFAS-contaminated soil. Modified clay adsorbents can be mixed with cement admixtures into PFAS-contaminated soil to bind and immobilize PFAS. Modified clay adsorbents can be added to containers and PFAS-contaminated water or other sources can be pumped through the containers to interact with the modified clay adsorbents and remove PFAS from the water. Modified clay adsorbents can be used in treatment containers along with activated carbon, ion exchange resins, and other PFAS removal media. In embodiments, modified clay adsorbents can be used in “mud wall” constructions to prevent the underground diffusion of PFAS in groundwater. Modified clay adsorbents can be suspended in water and injected into contaminated groundwater plumes. Modified clay adsorbents can be contained in geotextile mats for placement at or above contaminated sources, such as at the bottom of rivers, lakes, and oceans, to prevent the diffusion of PFAS compounds into larger bodies of water.

[0045] In a method comprising using a modified clay adsorbent with a blend having a first modified clay and a second modified clay, the blend may be provided as a single composition for single addition to the contaminated source. Alternatively, the first modified clay and the second modified clay may be provided as separate components for separate addition. In such embodiments, the first modified clay may be added simultaneously with the second modified clay. The first modified clay and the second modified clay may be added sequentially in any order. The method may further comprise the addition of an additional component, such as a third modified clay. The third modified clay may, for example, be a blend containing a monoquaternary amine compound and a polyfunctional quaternary amine compound with a functionality of 3 or greater.

[0046] A kit for PFAS adsorption may comprise a first modified clay embedded with a monoquaternary amine compound and a second modified clay embedded with a polyfunctional quaternary amine compound having a functionality of 3 or greater. The kit may further comprise instructions for adding the first and second modified clays at a molar ratio of monoquaternary amine compound to polyfunctional quaternary amine compound having a functionality of 3 or greater, at a ratio of about 75:25 to about 5:95 or about 75:25 to about 50:50. In other words, the kit may comprise instructions for adding the modified clay sorbet components such that the total amount of polyfunctional quaternary amine compound having a functionality of 3 or greater added to the sample is about 25 mol% to about 95 mol% of the total moles of quaternary amine compounds added to the sample. For example, the molar ratio of monoquaternary amine compound to polyfunctional quaternary amine compound may be about 75:25 to about 50:50, about 80:20 to about 60:40, and about 75:25 to about 70:30 or about 40:60 to about 10:90. The molar ratio may include any of the aforementioned amounts of the modified clay adsorbent and the polyfunctional quaternary amine compound with a functionality of 3 or greater for the modified clay adsorbent blend. The kit may further include instructions for the simultaneous or sequential addition of the first and second modified clays.

[0047] In an embodiment, the kit for adsorbing PFAS may comprise a modified clay adsorbent comprising a single blend containing a first modified clay embedded with a monoquaternary amine compound and a second modified clay embedded with a polyfunctional quaternary amine compound having a functionality of 3 or greater. The kit may further comprise one or more additional modified clays embedded with one or more monoquaternary amine compounds or one or more polyfunctional quaternary amine compounds having a functionality of 3 or greater. The kit may further comprise instructions for simultaneously or sequentially adding one or more additional modified clays to the modified clay adsorbent blend at the contamination source, thereby allowing for on-site modification of the molar ratio of the monoquaternary amine compound to the polyfunctional quaternary amine compound having a functionality of 3 or greater for a given contamination source.

[0048] In any embodiment of the method for adsorbing PFAS using a modified clay adsorbent, the modified clay adsorbent can be provided in a variety of forms. For example, the method may include flow-through containers, reactive needle pads, rigid metal baskets, and batch processing. For example, the modified clay adsorbent can be applied to the contaminated source as a reactive core pad via in-situ stabilization methods, by mixing with cement and / or soil, and by pumping and treatment-type applications. PFAS compounds can be adsorbed at various stages of contamination. For example, the modified clay adsorbent can be applied at the contaminated source, such as at the site where fire extinguishing foam is applied directly. Soil, groundwater, and surface water can also be contaminated with PFAS compounds and can be treated at one or more of these sites. The methods disclosed herein can be tailored to the location and environment where PFAS compound remediation is required. For example, in embodiments, a dry particulate mixture or a reactive pad can be applied. In other embodiments, slurries and other wet application methods can be used. The application method may involve solid mixing. This may involve drilling and / or trenching in the soil and distributing and mixing the modified clay paste into the soil. Where application of modified clay adsorbents in slurry or other wet methods is useful, spray application can be used.

[0049] For example, contaminated wastewater streams or other waste samples can be treated by passing the contaminated water through a bed of modified clay adsorbent. In an embodiment, the contact time between the contaminated water and the modified clay adsorbent bed is at least 1 minute.

[0050] Methods for adsorbing PFAS compounds from contaminated wastewater streams or other waste samples may involve contacting the contaminated water stream with a modified clay adsorbent in a pre-filled pre-filled pad or metal basket.

[0051] Methods for adsorbing PFAS compounds from contaminated wastewater streams or other waste samples may include delivering a modified clay adsorbent in particulate or powder form into the water body, such that the modified clay adsorbent forms a permeable reactive barrier layer.

[0052] Methods for adsorbing PFAS compounds from contaminated wastewater streams or other waste samples may include treating the contaminated water in a reaction vessel by mixing a modified clay tank with the contaminated water in the reaction vessel.

[0053] Methods for adsorbing PFAS compounds from contaminated wastewater streams or other waste samples may involve suspending modified clay in water and injecting it into a contaminated groundwater plume.

[0054] For example, modified clay adsorbents can be prepared by mixing an aqueous solution of N-tallow alkyl diallyltriamine (50 mol%) and dimethyl dehydrotallow ammonium chloride (50 mol%) (Adogen 442) into a bentonite dispersion in water. In an alternative example, an aqueous solution of polydiallyl dimethyl ammonium chloride (50 mol% ammonium group) and dimethyl dehydrotallow ammonium chloride (50 mol%) (Adogen 442) is added to the bentonite dispersion in water. The modified clay can be prepared as follows: 700 ml of deionized water is placed in a 1-liter metal cup. The cup is placed on a hot plate equipped with a raised stirrer. The water is heated to 70°C and stirred at 200 RPM using a stirring blade. Bentonite clay (Volcay APIGel NT) can be added slowly in small increments, allowing time for hydration, and stirring continues for 10 minutes. The mono- and tri-quaternary amine compounds are weighed and added separately. The monoquaternary amine compound can be slowly added to the bentonite-clay-water mixture and stirred for 10 minutes. Then, the triquaternary amine compound can be slowly added and mixed for another 10 minutes. The sample can be stirred for two hours at a temperature between 70°C and 75°C. The mixture can be vacuum filtered, and the solid collected on Whatman #1 filter paper. The solid is then rinsed with 1000 mL of water. The solid is collected and rinsed in 800 mL of deionized water heated to 60°C to 65°C. The sample is stirred at 200 RPM for 4 hours. The solid is then vacuum filtered a second time and rinsed with 2500 mL of deionized water. The solid is then transferred to a glass dish and dried at 50°C for 16 hours. The material can then be ground using a Retsch grinder equipped with a 0.2 µm sieve.

[0055] Example

[0056] Modified clay adsorbents were prepared using a solution process. These adsorbents comprised clay functionalized with a blend of mono- and tri-quaternary amine compounds. The amounts of mono- and tri-quaternary amine compounds are shown in Table 1 below. The clay was treated such that the total quaternary charge accounted for 88% of the total cation exchange capacity of the clay. Different ratios of mono- and tri-quaternary amine compounds, ranging from 5 mol% tri-quaternary amine mixture to 95 mol% tri-quaternary amine compound, were analyzed. Samples containing 100% mono- and 100% tri-quaternary amines were used as comparative examples.

[0057] Tallow diallyltriamine, marketed under the trade name Triameen T, was purchased from Nouryon. The protonated form of tallow diallyltriamine was produced by mixing 58 g of Triameen T with 23.7 g of ethanol and 245.4 g of water in a 500 mL three-necked round-bottom flask. The mixture was stirred overnight using a stainless steel overhead mixing shaft. The mixture was cooled to 0°C using an ice bath. 49.16 g of 35% hydrochloric acid was added dropwise to the mixture using a pipette. The temperature of the mixture was monitored and maintained below 25°C during the addition of hydrochloric acid. The mixture was stirred at room temperature for two hours.

[0058] Modified clay was prepared using a 1-liter metal cup filled with 700 ml of deionized water. The water was heated to 70°C while stirring at 200 RPM using a stirring blade on a hot plate equipped with an elevated stirrer. Bentonite clay (Volcay API Gel NT) was added individually in small increments, allowing time for hydration, and stirring continuously for 10 minutes. The mono- and tri-quaternary amine compounds were weighed and added separately. A solution of Adogen® 442 (Evonik Industries), dimethyl di(C14-C18 alkyl)ammonium chloride (86 wt%) was used as the mono-quaternary amine compound. Protonated tallow diallyl triamine was used as the tri-quaternary amine compound. The mono-quaternary amine compound was slowly added to the bentonite clay-water mixture and stirred continuously for 10 minutes. The tri-quaternary amine compound was then slowly added and mixed continuously for 10 minutes. The sample was then stirred for two hours at a temperature ranging from 70°C to 75°C. The mixture was vacuum filtered and the solids were collected on Whatman #1 filter paper. The solids were then rinsed with 1000 ml of water. The solid was then collected and washed in 800 ml of deionized water heated to 60°C to 65°C. The sample was stirred at 200 RPM for 4 hours, and then the solid was vacuum filtered a second time and washed with 2500 mL of deionized water. The solid was then transferred to a glass dish and dried at 50°C for 16 hours. The material was then ground using a Retsch grinder equipped with a 0.2 µm sieve.

[0059] Table 1: Modified Clay Blends

[0060]

[0061] PFAS adsorption assays were performed by adding 3 mg of a modified clay adsorbent blend to a 500 ml water sample in a screw-cap Nalgene® HDPE bottle. The bottle was placed on a fixed-track shaker at 10 RMP and mixed for 168 hours to approximate adsorption equilibrium. Synthetic PFAS water (SPW) was used to simulate contaminated water in this assay. SPW was prepared by dissolving perfluorobutyric acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorobutane sulfonic acid (PFBS), perfluorohexane sulfonic acid (PHxS), and perfluorooctane sulfonic acid (PFOS) in deionized water. The compounds were purchased from Wellington Laboratory and packaged in flame-sealed glass ampoules. SPW was prepared in a clean 5-gallon polypropylene drum equipped with a sealed cap. The PFAS compounds were obtained as a 50 µg / ml ethanol solution. The ampoules were opened, and the solutions were individually transferred to DI water using a glass transfer pipette. The water used was carefully weighed in increments of 1000 grams, totaling 15,000 grams. The concentrations of the individual compounds in the SPW are shown below, expressed as parts per billion (PPB) or µg / L. The “short-chain” PFAS compounds in the SPW are PFBS, PFBA, and PFHxA molecules. The “long-chain” compounds are PFHxS, PFOS, and PFOA molecules.

[0062] Table 2: Synthetic PFAS Water (SPW) Compositions

[0063]

[0064] Table 3: Sample Composition and Results

[0065]

[0066] Table 4: PFAS Removal Percentage Results

[0067]

[0068] Table 4 (continued)

[0069]

[0070] Figure 1 and Figure 2 This is a graph showing the removal percentages of various PFAS compounds. It was found that the presence of triquaternary amine compounds greater than 20 mol% significantly increased the removal of carboxylate-PFAS pollutants. When the triquaternary amine compounds were in the range of 20 mol% to 80 mol%, improved removal of short-chain compounds was observed. For long-chain removal, amounts exceeding 60 mol% were found to improve removal compared to 100 mol% of monoquaternary ammonium compounds containing adsorbent.

[0071] Although specific embodiments of the invention have been shown and described in detail, it will be apparent to those skilled in the art that changes and modifications can be made without departing from the broader aspects of the invention. Therefore, it is intended to cover all such changes and modifications that fall within the true spirit and scope of the invention. The matters set forth in the foregoing description and drawings are provided by way of illustration only, not limitation. The actual scope of the invention is defined by the following claims as viewed from its proper angle based on the prior art.

Claims

1. A modified clay adsorbent for adsorbing PFAS compounds from contaminated samples, said modified clay adsorbent comprising: Clay, wherein the clay is embedded with (i) protonated tallow diallyltriamine and (ii) one or more monoquaternary amine compounds.

2. The modified clay adsorbent according to claim 1, wherein the clay is embedded with the protonated tallow diallyltriamine and one or more monoquaternary amine compounds to achieve at least 50% of the total cation exchange capacity of the clay.

3. A modified clay adsorbent for adsorbing PFAS compounds from contaminated samples, said modified clay adsorbent comprising: The first modified clay includes clay embedded with one or more monoquaternary amine compounds; as well as The second modified clay comprises clay embedded with protonated tallow diallyltriamine.

4. The modified clay adsorbent according to any one of the preceding claims, wherein the protonated tallow diallyltriamine is present at a molar percentage of at least 20 mol% based on the total molar number of quaternary ammonium compounds present in the modified clay adsorbent. The quaternary ammonium compounds include (i) protonated tallow diallyltriamine and (ii) one or more monoquaternary ammonium compounds.

5. The modified clay adsorbent according to claim 4, wherein the protonated tallow diallyltriamine is present at a molar percentage of 20 mol% to 80 mol% based on the total molar number of quaternary ammonium compounds present in the modified clay adsorbent. The quaternary ammonium compounds include (i) protonated tallow diallyltriamine and (ii) one or more monoquaternary ammonium compounds.

6. The modified clay adsorbent according to claim 4, wherein the protonated tallow diallyltriamine is present in a molar percentage greater than 60 mol% and less than or equal to 95 mol% based on the total molar number of quaternary ammonium compounds present in the modified clay adsorbent. The quaternary ammonium compounds include (i) protonated tallow diallyltriamine and (ii) one or more monoquaternary ammonium compounds.

7. The modified clay adsorbent according to claim 3, wherein the first modified clay and the second modified clay are each embedded with one or more corresponding monoquaternary amine compounds and protonated tallow diallyltriamine to achieve at least 50% of the cation exchange capacity of the corresponding first modified clay or second modified clay.

8. The modified clay adsorbent according to any one of claims 1 to 3, wherein the clay is one or more of attapulgite, bentonite, montmorillonite, chlorodiazepite, bedesulfurite, chromium bentonite, lithium montmorillonite, saponite, zinc montmorillonite, sporestone, magnesia, svenfol, vermiculite, palygorskite, karonite, and sepiolite.

9. The modified clay adsorbent according to any one of claims 1 to 3, wherein the modified clay adsorbent is present in the pad.

10. The modified clay adsorbent according to any one of claims 1 to 3, wherein the monoquaternary ammonium compound is one or more of dimethyl di(C14-C18 alkyl)ammonium chloride.

11. A reagent kit comprising: The modified clay adsorbent according to any one of the preceding claims and the description of adding the clay adsorbent to the contaminated sample to adsorb PFAS compounds.

12. A reagent kit comprising: The modified clay adsorbent according to claim 3, wherein the first modified clay and the second modified clay exist as separate components; as well as Instructions for individually adding the first modified clay and the second modified clay to a contaminated sample to form the modified clay adsorbent, wherein the amounts of the first modified clay and the second modified clay are such that, based on the total moles of the quaternary ammonium compound added to the sample, the protonated tallow diallyltriamine is present in an amount of 20 mol% to 80 mol%. The quaternary ammonium compounds include (i) protonated tallow diallyltriamine and (ii) one or more monoquaternary ammonium compounds.

13. The kit according to claim 12, wherein the first modified clay and the second modified clay are added simultaneously.

14. The kit according to claim 12, wherein the first modified clay and the second modified clay are added sequentially.

15. A method for adsorbing PFAS compounds from a contaminated sample, the method comprising: The modified clay adsorbent is mixed with the sample, wherein the modified clay adsorbent comprises clay embedded with (i) one or more monoquaternary amine compounds and (ii) protonated tallow diallyltriamine.

16. A method for adsorbing PFAS compounds from a contaminated sample, the method comprising: Clay, one or more monoquaternary amine compounds, and protonated tallow diallyltriamine are mixed with the sample, wherein the clay is in situ embedded with the one or more monoquaternary amine compounds and the protonated tallow diallyltriamine to form a modified clay adsorbent, which is used to adsorb PFAS compounds from the contaminated sample.

17. The method according to claim 15 or 16, wherein the protonated tallow diallyltriamine is present in an amount of at least 20 mol% based on the total molar number of the quaternary ammonium compound in the modified clay adsorbent. The quaternary ammonium compounds include (i) protonated tallow diallyltriamine and (ii) one or more monoquaternary ammonium compounds.

18. The method according to claim 15 or 16, wherein the protonated tallow diallyltriamine is present in an amount of 20 mol% to 80 mol% based on the total molar number of quaternary ammonium compounds in the modified clay adsorbent. The quaternary ammonium compounds include (i) protonated tallow diallyltriamine and (ii) one or more monoquaternary ammonium compounds.

19. A method for adsorbing PFAS compounds from a contaminated sample, the method comprising: The modified clay adsorbent is mixed with the sample, wherein the modified clay adsorbent comprises a first modified clay and a second modified clay, the first modified clay comprising clay embedded with one or more monoquaternary amine compounds, and the second modified clay comprising clay embedded with protonated tallow diallyltriamine.

20. The method of claim 19, wherein the ratio of the amount of the first modified clay to the amount of the second modified clay is selected such that, based on the total moles of the quaternary ammonium compound mixed with the sample, the protonated tallow diallyltriamine is present in an amount of 20 mol% to 80 mol%. The quaternary ammonium compounds include (i) protonated tallow diallyltriamine and (ii) one or more monoquaternary ammonium compounds.

21. The method of claim 19, wherein each of the first modified clay and the second modified clay is embedded to achieve at least 50% of the cation exchange capacity of the clay.

22. The method according to claim 19 or 20, wherein the first modified clay and the second modified clay are pre-blended to form the modified clay adsorbent such that, based on the total molar number of the quaternary ammonium compound in the modified clay adsorbent blend, the protonated tallow diallyltriamine is present in an amount of 20 mol% to 80 mol%, and the first modified clay and the second modified clay are mixed with the sample as a single composition. The quaternary ammonium compounds include (i) protonated tallow diallyltriamine and (ii) one or more monoquaternary ammonium compounds.

23. The method according to claim 19 or 20, wherein mixing the modified clay adsorbent with the sample comprises adding the first modified clay and the second modified clay separately to the sample in amounts such that, based on the total moles of the quaternary ammonium compound mixed with the sample, the protonated tallow diallyltriamine is present in an amount of 20 mol% to 80 mol%. The quaternary ammonium compounds include (i) protonated tallow diallyltriamine and (ii) one or more monoquaternary ammonium compounds.

24. The method of claim 23, wherein the first modified clay and the second modified clay are added simultaneously.

25. The method of claim 23, wherein the first modified clay and the second modified clay are added sequentially.

26. The method according to any one of claims 15, 16, and 19, wherein the protonated tallow diallyltriamine is present in an amount of 20 mol% to 80 mol% based on the total molar number of the quaternary ammonium compound in the modified clay adsorbent. The quaternary ammonium compounds include (i) protonated tallow diallyltriamine and (ii) one or more monoquaternary ammonium compounds.

27. The method according to any one of claims 15, 16 and 19, wherein the clay is one or more of attapulgite, bentonite, montmorillonite, chlorodiazepite, bedesite, chromium bentonite, lithium montmorillonite, soapstone, zinc montmorillonite, sporestone, magnesia, svenfol, vermiculite, palygorskite, carnelian, and sepiolite.

28. The method according to any one of claims 15, 16 and 19, wherein each gram of modified clay adsorbent in the adsorbent is capable of adsorbing at least 0.2 milligrams of PFAS compound.

29. The method according to any one of claims 15, 16 and 19, wherein the sample is contaminated soil, and the method comprises mixing the contaminated soil and the modified clay adsorbent such that the modified clay adsorbent is present in the mixture in an amount greater than 0.5 wt%.

30. The method according to any one of claims 15, 16 and 19, wherein the sample is a contaminated wastewater stream, and the method comprises mixing the modified clay adsorbent and the contaminated wastewater stream by passing the contaminated wastewater stream through a bed of the modified clay adsorbent at a certain flow rate to maintain a contact time between the contaminated wastewater stream and the bed for at least 1 minute.

31. The method according to any one of claims 15, 16 and 19, wherein the modified clay adsorbent is in the form of a pre-filled permeable pad or metal basket.

32. The method according to any one of claims 15, 16 and 19, wherein the modified clay adsorbent in particulate or powder form enters the water body, such that the modified clay forms a permeable reactive barrier layer.

33. The method according to any one of claims 15, 16 and 19, comprising treating the PFAS compound from the contaminated water stream by mixing the modified clay and the contaminated water in a tank.

34. The method according to any one of claims 15, 16 and 19, comprising treating PFAS compounds from contaminated water streams by injecting a suspension of the modified clay into contaminated soil and / or a contaminated groundwater plume.

35. The method according to any one of claims 15, 16 and 19, wherein the contaminated sample is wastewater.

36. The method according to any one of claims 15, 16 and 19, wherein the contaminated sample is groundwater.

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