Product for PFAS adsorption

Abstract

A product for adsorbing one or more PFAS from a liquid is disclosed. The product may comprise green palygorskite or sepiolite for undersurface functionalization: (a) a quaternary amine surface coating solution comprising a mono-quaternary amine compound or a bis-quaternary amine compound and (b) a mercapto surface coating solution comprising a surface coating agent, the surface coating agent comprises one or more sulfydryl groups which are chemically combined with the surface of the green palygorskite or the sepiolite. When the quaternary amine surface coating solution contains a mono-quaternary amine compound, the product does not contain di-quaternary amine. When the quaternary amine surface coating solution contains a bis-quaternary amine compound, the product does not contain mono-quaternary amine. Methods of making the product and methods of using the product to adsorb PFAS in a liquid are also disclosed.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority and benefit of U.S. Patent Application Serial No. 17 / 865,721, filed on July 15, 2022, and also claims the priority and benefit of U.S. Patent Application Serial No. 18 / 203,892, filed on May 31, 2023, which is a partial continuation of U.S. Patent Application Serial No. 17 / 865,721, filed on July 15, 2022. Technical Field

[0003] The present disclosure generally relates to products containing attapulgite or sepiolite or containing attapulgite and sepiolite, which are suitable for adsorbing PFAS from liquids. Background Art

[0004] Per- and polyfluoroalkyl substances (commonly referred to as PFAS and collectively as PFAS) are a class of man-made chemicals, including but not limited to: perfluorobutyric acid (PFBA), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnA), perfluorododecanoic acid (PFDoA), perfluorotridecanoic acid (PFTriA), perfluorotetradecanoic acid (PFTeA), perfluorohexadecanoic acid, perfluorooctadecanoic acid, perfluorobutanesulfonic acid (PFBS), perfluoropentanesulfonic acid (PFPeS), perfluorohexanesulfonic acid (PFHxS), perfluoroheptanesulfonic acid (PFHpS), perfluorooctanesulfonic acid (PFOS), perfluorononanesulfonic acid (PFNS), perfluorodecanesulfonic acid (PFDS), perfluorododecanesulfonic acid (PFDoS), perfluorooctanesulfonamide (FOSA), N-ethyl perfluoro-1-octanesulfonamide, NMeFOSA, N-methyl perfluorooctanesulfonamide acetic acid (NMeFOSAA), N-ethyl perfluorooctanesulfonamide acetic acid (NEtFOSAA), 2-(N-methyl perfluoro-1-octanesulfonamide) ethanol, 2-(N-ethyl perfluoro-1-octanesulfonamide) ethanol, 4:2 FTS, 6:2 FTS, 8:2 FTS, 10:2 FTS, HFPO-DA, 9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid, 11-chloroeicosadecafluoro-3-oxaundecane-1-sulfonic acid or similar chemicals. PFAS have been widely used in industrial and consumer products. PFAS are regarded as emerging pollutants. PFAS pollutants in industrial and municipal wastewater can enter groundwater, water bodies and other water environments, posing health risks to humans, wildlife and plants. It is known that PFAS are relatively stable chemicals with long-term persistence. PFAS have been found in the blood of people and animals around the world. Low concentrations of PFAS are present in various foods and the environment. Studies have shown that exposure to certain PFAS in the environment may have harmful effects on the health of humans and animals. Remediating PFAS-contaminated water is often very challenging.

[0005] Commonly available commercial removal technologies include activated carbon adsorption, anion exchange resins and high-pressure membranes. Activated carbon is a less efficient technology. Anion exchange resins and high-pressure membrane technologies are expensive due to high material and equipment costs.

[0006] U.S. Patent No. 9,284,201 ('201 patent), issued on March 15, 2016, describes a method of modifying clay adsorbents using oleylamine and octylamine or mixtures thereof. There is a need for an effective and relatively inexpensive removal medium capable of separating PFAS from liquids. Summary of the Invention

[0007] In one aspect of the present disclosure, a product for adsorbing at least one PFAS in a liquid is disclosed. The product may comprise palygorskite that has been surface-functionalized with: (a) a quaternary amine surface coating solution comprising a monoquaternary amine compound or a diquaternary amine compound, the monoquaternary amine compound comprising one or more monoquaternary amines attached to the surface of the palygorskite, the diquaternary amine compound comprising one or more diquaternary amines attached to the surface of the palygorskite, and (b) a surface coating agent comprising one or more thiol groups chemically bonded to the surface of the palygorskite, wherein when the quaternary amine surface coating solution comprises one or more monoquaternary amine compounds, the product does not contain diquaternary amines, and wherein when the quaternary amine surface coating solution comprises one or more diquaternary amine compounds, the product does not contain monoquaternary amines, and wherein the surface area of the product or the surface-functionalized palygorskite, measured using the BET method, is in the range of 45 - 160 square meters per gram (m 2 / g) or 50 - 100 m 2 / g, and wherein the d50 of the particle size distribution of the product or the surface-functionalized palygorskite is 6 - 30 microns or 10 - 25 microns or 12 - 25 microns or 12 - 23 microns.

[0008] In one embodiment, the surface coating agent may be a thiol silane.

[0009] In any of the above embodiments, the product may be in powder form and / or non-extruded form.

[0010] In any of the above embodiments, when the loading of the product in the liquid is 0.5 - 2 grams (g) per liter of the liquid, the PFAS removal efficiency of the product for at least one PFAS in the liquid may be 70 - 100%, 80 - 100%, 90 - 100%, 95 - 100% or 97 - 100% within 12 - 25 hours.

[0011] In any of the above embodiments, the porosity of the product or the surface-functionalized palygorskite may be 40 - 90%, and the pore volume is 0.7 - 1.5 mL / g.

[0012] In any of the above embodiments, the weight percentage of the components of the product comprises: 85 - 94 weight% of palygorskite; 2.5 - 15 weight% of (i) monoquaternary amine or (ii) diquaternary amine; and 1 - 8 weight% of the surface coating agent.

[0013] In any of the above embodiments, the product may not contain oleylamine and octylamine.

[0014] In any of the above embodiments, the product may not contain residual acid.

[0015] In another aspect of the present disclosure, a method for preparing a product for adsorbing at least one PFAS from a liquid is disclosed. The method may include selecting palygorskite as the feed, wherein the selected palygorskite as the feed contains 7-16 wt% or 9-14 wt% moisture when measured at a temperature of 104 °C before surface treatment. The method further includes surface-treating the palygorskite with a quaternary amine surface coating solution, the quaternary amine surface coating solution comprising (i) a monoquaternary amine compound, the monoquaternary amine compound comprising one or more monoquaternary amines attached to the surface of the palygorskite or (ii) a diquaternary amine compound, the diquaternary amine compound comprising one or more diquaternary amines attached to the surface of the palygorskite; and surface-treating the palygorskite with a mercapto surface coating solution, the mercapto surface coating solution including a surface coating agent, the surface coating agent including one or more mercapto groups chemically bonded to the surface of the palygorskite, wherein the surface area of the prepared product is in the range of 45-160 m 2 / g as measured using the BET method, wherein when the quaternary amine surface coating solution includes a monoquaternary amine compound, the product does not contain diquaternary amines, and wherein when the quaternary amine surface coating solution contains a diquaternary amine compound, the product does not contain monoquaternary amines.

[0016] In one embodiment, the weight percentages of the components of the product may include: 85-94 wt% palygorskite; 2.5-15 wt% of (i) one or more monoquaternary amines or (ii) one or more diquaternary amines; and 1-8 wt% of a surface coating agent including one or more mercapto groups, wherein the product does not contain oleylamine and octylamine.

[0017] In any embodiment of the above method, the quaternary amine surface coating solution may further contain water, wherein the mercapto surface coating solution further contains a solvent, and wherein the surface coating agent includes mercapto silane.

[0018] In any embodiment of the above method, surface-treating the palygorskite with the mercapto surface coating solution may be performed after surface-treating the palygorskite with the quaternary amine surface coating solution.

[0019] In any embodiment of the above method, the quaternary amine surface coating solution may further contain water.

[0020] In any embodiment of the above method, the method may further include drying the palygorskite, wherein: (a) drying one or more monoquaternary amines on the palygorskite of the prepared product, or drying one or more diquaternary amines on the palygorskite of the prepared product, (b) drying the mercapto surface coating solution on the palygorskite of the prepared product, and (c) the prepared product is in powder form or non-extruded form.

[0021] In any embodiment of the above method, the d of the particle size distribution of the product 50 can be 6 - 30 μm or 10 - 25 μm or 12 - 25 μm or 12 - 23 μm.

[0022] In any embodiment of the above method, when the liquid product loading is 0.5 - 2 g per liter, the PFAS removal efficiency of the product for at least one PFAS in the liquid within 12 - 25 hours can be 70 - 100%, 80 - 100%, 90 - 100%, 95 - 100% or 97 - 100%.

[0023] In another aspect of the present disclosure, a method for adsorbing at least one PFAS in a liquid is disclosed. The method may include: contacting the liquid with a product comprising palygorskite surface-functionalized with: (a) a quaternary amine surface coating solution comprising a monoquaternary amine compound or a diquaternary amine compound, the monoquaternary amine compound comprising one or more monoquaternaries attached to the surface of the palygorskite, the diquaternary amine compound comprising one or more diquaternaries attached to the surface of the palygorskite, and (b) a surface coating agent comprising one or more thiol groups chemically bonded to the surface of the palygorskite; and separating the product from the liquid to recover the resulting liquid, the PFAS content of which is lower than that of the liquid before mixing, wherein the component weight percentages of the product include: 85 - 94 wt% of palygorskite, 2.5 - 15 wt% of (i) one or more monoquaternaries or (ii) one or more diquaternaries, and 1 - 8 wt% of a surface coating agent comprising one or more thiol groups, wherein when the quaternary amine surface coating solution comprises one or more monoquaternary amine compounds, the product does not contain diquaternary amine compounds, and when the quaternary amine surface coating solution comprises one or more diquaternary amine compounds, the product does not contain monoquaternary amine compounds, wherein measured using the BET method, the surface area of the product is in the range of 45 - 160 m 2 / g, and wherein when the liquid product loading is 0.5 - 2 g per liter, the removal efficiency of the product for PFAS is 10 - 100%.

[0024] In any embodiment of the above method, the liquid may comprise water, edible oil, wastewater, process water, or a combination thereof.

[0025] In any embodiment of the above method, the surface coating agent may comprise mercapto silane.

[0026] In any embodiment of the above method, when the contact time can be 12 - 25 hours, when the liquid product loading is 0.5 - 2 g per liter, the PFAS removal efficiency of the product for at least one PFAS is 70 - 100%, 80 - 100%, 90 - 100%, 95 - 100% or 97 - 100%.

[0027] In another aspect of the present disclosure, a product for adsorbing at least one PFAS in a liquid is disclosed. The product may comprise sepiolite surface-functionalized with: (a) a quaternary amine surface coating solution comprising a monoquaternary amine compound or a diquaternary amine compound, the monoquaternary amine compound comprising one or more monoquaternary amines attached to the sepiolite surface, the diquaternary amine compound comprising one or more diquaternary amines attached to the sepiolite surface, and (b) a surface coating agent comprising one or more thiol groups chemically bonded to the sepiolite surface, wherein when the quaternary amine surface coating solution comprises one or more monoquaternary amine compounds, the product does not contain diquaternary amines, and wherein when the quaternary amine surface coating solution comprises one or more diquaternary amine compounds, the product does not contain monoquaternary amines, and wherein the surface area of the surface-functionalized product or sepiolite, measured using the BET method, is in the range of 76 - 276 m 2 / g or 80 - 254 m 2 / g, and wherein the d 50 of the particle size distribution of the surface-functionalized product or sepiolite is 10 - 25 microns or 11 - 22 microns or 12 - 21 microns. In one embodiment, the surface coating agent may be a thiolsilane. In any one or more embodiments, the product may be in powder form and / or non-extruded form. In any one or more embodiments, when the liquid product load is 0.5 - 2 g per liter, the PFAS removal efficiency of the product for at least one PFAS in the liquid may be 70 - 100%, 80 - 100%, 90 - 100%, 95 - 100% or 97 - 100% within 12 - 25 hours. In any one or more embodiments, the porosity of the product may be 62 - 86%, and the pore volume may be 1.3 - 3 mL / g. In any one or more embodiments, the weight percentage of the components of the product may include: 76 - 97 wt% of palygorskite; 1 - 16 wt% of (i) monoquaternary amine or (ii) diquaternary amine; and 0.5 - 8 wt% of the surface coating agent. In any one or more embodiments, the product does not contain oleylamine and octylamine. In any one or more embodiments, the product may be free of residual acid.

[0028] In another aspect of the present disclosure, a method for preparing a product for adsorbing at least one PFAS from a liquid is disclosed. The method may include selecting sepiolite as a feedstock, wherein before surface treatment, the selected attapulgite as the feedstock contains 16 - 20 wt% moisture as measured by loss on ignition (LOI); surface treating the sepiolite with a quaternary amine surface coating solution, the quaternary amine surface coating solution comprising (i) a monoquaternary amine compound, the monoquaternary amine compound comprising one or more monoquaternary amines attached to the surface of the sepiolite or (ii) a diquaternary amine compound, the diquaternary amine compound comprising one or more diquaternary amines attached to the surface of the sepiolite; and surface treating the sepiolite with a mercapto surface coating solution, the mercapto surface coating solution comprising a surface coating agent, the surface coating agent including one or more mercapto groups chemically bonded to the surface of the sepiolite, wherein the surface area of the prepared product can be in the range of 76 - 276 m 2 / g as measured by the BET method, wherein when the quaternary amine surface coating solution comprises a monoquaternary amine compound, the product does not contain diquaternary amines, and wherein when the quaternary amine surface coating solution comprises a diquaternary amine compound, the product does not contain monoquaternary amines. In one embodiment, the weight percentage of the components of the product may include: 76 - 97 wt% sepiolite; 1 - 16 wt% of (i) one or more monoquaternary amines or (ii) one or more diquaternary amines; and 0.5 - 8 wt% of a surface coating agent including one or more mercapto groups, wherein the product does not contain oleylamine and octylamine. In any one or more embodiments, (a) the quaternary amine surface coating solution may further comprise water, (b) the mercapto surface coating solution may further comprise a solvent, and (c) the surface coating agent may comprise mercapto silane. In any one or more embodiments, surface treating the attapulgite with the mercapto surface coating solution may be carried out after surface treating the sepiolite with the quaternary amine surface coating solution. In an improvement, the quaternary amine surface coating solution may further comprise water. In any one or more embodiments and / or improvements, the method may further include drying the sepiolite, wherein one or more monoquaternary amines are dried on the sepiolite of the prepared product, or one or more diquaternary amines are dried on the sepiolite of the prepared product, wherein the mercapto surface coating solution is dried on the sepiolite of the prepared product, and wherein the prepared product may be in powder form or non-extruded form. In any one or more embodiments and / or improvements, the d 50 of the particle size distribution of the product may be 10 - 25 microns or 11 - 22 microns or 12 - 21 microns. In any one or more embodiments and / or improvements, when the liquid product load is 0.5 - 2 g per liter, the PFAS removal efficiency of the product for at least one PFAS in the liquid within 12 - 25 hours may be 70 - 100%, 80 - 100%, 90 - 100%, 95 - 100% or 97 - 100%.

[0029] In yet another aspect of the present disclosure, a method for adsorbing at least one PFAS in a liquid is disclosed. The method may include: contacting the liquid with a product comprising sepiolite surface-functionalized with: (a) a quaternary amine surface coating solution comprising a monoquaternary amine compound or a diquaternary amine compound, the monoquaternary amine compound comprising one or more monoquaternaries attached to the sepiolite surface, the diquaternary amine compound comprising one or more diquaternaries attached to the sepiolite surface, and (b) a surface coating agent comprising one or more thiol groups chemically bonded to the sepiolite surface; and separating the product from the liquid to recover the resulting liquid having a lower PFAS content than the liquid before mixing, wherein the component weight percentages of the product may include: 76-97 wt% sepiolite, 1-16 wt% of (i) one or more monoquaternaries or (ii) one or more diquaternaries, and 0.5-8 wt% of a surface coating agent comprising one or more thiol groups, wherein when the quaternary amine surface coating solution comprises one or more monoquaternary amine compounds, the product does not contain diquaternary amine compounds, and wherein when the quaternary amine surface coating solution comprises one or more diquaternary amine compounds, the product does not contain monoquaternary amine compounds, and wherein the surface area of the product, measured using the BET method, may be in the range of 76-276 m 2 / g, and wherein the product has a PFAS removal efficiency of 10-100% at a loading of 0.5–2 g of product per liter of liquid. In one embodiment, the liquid may comprise water, edible oil, wastewater, process water, or a combination thereof. In any one or more embodiments, the surface coating agent may comprise a thiolsilane. In any one or more embodiments, at a loading of 0.5-2 g of product per liter of liquid, the contact may continue for 12-25 hours, and the PFAS removal efficiency of the product for at least one PFAS may be 70-100%, 80-100%, 90-100%, 95-100%, or 97-100%.

[0030] Brief description of the drawings

[0031] Figure 1A is an SEM image of a feed containing natural palygorskite at 25,000-fold magnification.

[0032] Figure 1B is an SEM image of a feed containing natural palygorskite at 200,000-fold magnification.

[0033] Figure 2 is a diagram showing exemplary surface functionalization and PFAS adsorption.

[0034] Figure 3 shows the pore size distributions (measured by mercury intrusion porosimetry) of the feeds and surface-functionalized samples of Examples 4 and 7.

[0035] Figure 4 It is a graph showing the total PFAS removal efficiency in a solution containing 40 ppt PFAS.

[0036] Figure 5 It is a graph showing the effect of treatment with thiol surface coating solution and quaternary amine surface coating solution on the removal of selected PFAS substances in a solution containing 40 ppt PFAS.

[0037] Figure 6 It is a graph showing the effect of thiol silane and quaternary amine loading (Examples 4 - 9) on the total PFAS removal efficiency in an 80 ppt PFAS solution.

[0038] Figure 7 It is a graph showing the effect of the surface of palygorskite functionalized with thiol silane and quaternary amine on the PFAS removal efficiency of selected PFAS substances.

[0039] Figure 8 It is a graph showing the number of PFAS substances (out of a total of 35 PFAS substances) with a removal efficiency of 80% or greater, 85% or greater, or 90% or greater in Example 8.

[0040] Figure 9 It is a graph showing the effect of thiol silane and quaternary amine loading (Examples 4 - 12) on the total PFAS removal efficiency in an 80 ppt PFAS solution;

[0041] Figure 10 It is a graph showing the number of PFAS substances (out of a total of 35 PFAS substances) with a removal efficiency of 90% or greater, 95% or greater, or 97% or greater in Example 11.

[0042] Figure 11 It is a graph of the removal efficiency of Example 11 for the most common PFAS substances.

[0043] Figure 12 It is an SEM image of the feed containing natural sepiolite at a magnification of 10,000 times.

[0044] Figure 13 It shows the pore size distribution (measured by mercury intrusion porosimetry) of the surface - functionalized samples of Examples 13 and 18.

[0045] Figure 14 It is a graph showing the number of PFAS substances (out of a total of 35 PFAS substances) with a removal efficiency of 90% or greater, 95% or greater, or 97% or greater in Example 13.

[0046] Detailed description

[0047] The present disclosure relates to products for adsorbing PFAS from liquids. The products disclosed herein may comprise palygorskite or sepiolite, or palygorskite and sepiolite. Palygorskite is sometimes referred to as attapulgite. To avoid confusion, the term "palygorskite" as used herein refers to palygorskite and / or attapulgite. As is known in the art, palygorskite is a clay mineral of the chain lattice type, and its structure is different from other clays such as montmorillonite or bentonite. That is, the tetrahedral sheets of palygorskite are divided into bands by inversion, because the adjacent tetrahedral bands within one tetrahedral sheet point in opposite directions rather than in one direction, thus forming a banded structure of 2:1 layers connected at their edges, and the octahedral sheets are only two-dimensionally continuous. Sepiolite is hydrated magnesium silicate. The structures of palygorskite and sepiolite are similar, with tetrahedra pointing in the same direction forming 2:1 bands extending along the a-axis direction. The average b-axis width in sepiolite is 3 connected tetrahedral chains, and the average b-axis width in palygorskite is 2 connected tetrahedral chains.

[0048] Generally, activated carbon is used for PFAS adsorption. However, this is a less efficient technique. Other techniques (such as anion exchange resins and high-pressure membrane techniques) are expensive due to high material and equipment costs.

[0049] Disclosed herein are new products that can be used as adsorbents for at least one PFAS in liquids. Such liquids may include, but are not limited to, water (such as fresh water, seawater, etc.), edible oil, wastewater, process water, or combinations thereof. For example, the liquid may include or be oil-in-water or water-in-oil.

[0050] Such new products for reducing at least one PFAS in such liquids may comprise palygorskite, or sepiolite, or palygorskite and sepiolite surface-functionalized with: (a) a quaternary amine surface coating solution comprising a monoquaternary amine compound or a diquaternary amine compound, the monoquaternary amine compound comprising one or more monoquaternary amines attached to the palygorskite / sepiolite surface, the diquaternary amine compound comprising one or more diquaternary amines attached to the palygorskite / sepiolite surface, and (b) a thiol surface coating solution comprising a surface coating agent comprising one or more thiol groups chemically bonded to the palygorskite / sepiolite surface.

[0051] In one embodiment, the weight percentages of the components of the product may include: 85 - 94 wt% palygorskite; 2.5 - 15 wt% of (i) one or more monoquaternary amines or (ii) one or more diquaternary amines; and 1 - 8 wt% of a surface coating agent comprising one or more thiol groups. When the quaternary amine surface coating solution comprises one or more monoquaternary amine compounds, the product does not contain all diquaternary amines. When the quaternary amine surface coating solution comprises one or more diquaternary amine compounds, the product does not contain all monoquaternary amines. The quaternary amine surface coating solution may also comprise water. The thiol surface coating solution may also comprise a solvent.

[0052] Measured using the Brunauer-Emmett-Teller (BET) theory, the surface area of natural palygorskite (as feed) can be in the range of 90 - 160 m 2 / g or 120 - 145 m 2 / g or 130 - 145 m 2 / g. In any of the above embodiments, the d 50 of the particle size distribution of natural palygorskite (as feed) can be 5 - 25 microns or 6 - 18 microns or 8 - 17 microns or 10 - 15 microns. In any of the above embodiments, the porosity of natural palygorskite (as feed) is 50 - 90%, or 55 - 80%, or 60 - 75%. In any of the above embodiments, the pore volume of natural palygorskite (as feed) can be 0.8 - 3 mL / g or 0.9 - 2 mL / g or 1 - 1.2 mL / g. In any one or more of the above embodiments or improvements, for natural palygorskite (as feed), the peak position of the inherent pores can be in the range of about 5 nm (nanometers) to about 25 nm and / or the peak position of the internal pores can be in the range of about 2 microns to about 16 microns. In one improvement, for natural palygorskite (as feed), the peak position of the inherent pores can be in the range of about 10 nm to about 18 nm and / or the peak position of the internal pores can be in the range of about 2.5 microns to about 10 microns.

[0053] Measured using the Brunauer-Emmett-Teller (BET) theory, the surface area of the (surface-functionalized) product (containing palygorskite) can be in the range of 45 - 160 m 2 / g or 45 - 150 m 2 / g or 45 - 130 m 2 / g or 50 - 100 m 2 / g. In any of the above embodiments, the d 50It can be 6 - 30 microns, or 10 - 25 microns, or 12 - 25 microns, or 12 - 23 microns. In any of the above embodiments, the porosity of such (surface-functionalized) products (including palygorskite) can be 40 - 90%, or 40 - 80%, or 50 - 75%, or 55 - 70%. In any of the above embodiments, the pore volume of such (surface-functionalized) products (including palygorskite) can be 0.7 - 1.5 mL / g, or 0.9 - 1.2 mL / g, or approximately 0.9 - 1.0 mL / g. In any one or more of the above embodiments or improvements, for such (surface-functionalized) products (including palygorskite), the peak position of the inherent pores can be in the range of about 5 nanometers (nm) to about 35 nm and / or the peak position of the inter-pores can be in the range of about 2 microns to about 20 microns. In one improvement, for such (surface-functionalized) products (including palygorskite), the peak position of the inherent pores can be in the range of about 10 nm to about 25 nm and / or the peak position of the internal pores can be in the range of about 3 microns to about 11 microns. In any one or more of the above embodiments, such products can be in powder form or non-extruded form (without extrusion before or after surface functionalization). In any one or more of the above embodiments, palygorskite can be or can include: (a) natural palygorskite that can be without heat treatment (at 300 °C to about 1000 °C) and / or without calcination (e.g., at about 1000 °C or above) before surface functionalization. In any one or more of the above embodiments, palygorskite can be in powder form. In any one or more of the above embodiments, palygorskite has not been extruded (without extrusion before or after surface functionalization).

[0054] In any of the above embodiments, when the liquid product loading is 0.5 - 2 g per liter or 1 - 1.3 g per liter, the PFAS removal efficiency of the (surface-functionalized) product containing palygorskite for PFAS in the liquid can be 70 - 100%, 80 - 100%, 90 - 100%, 95 - 100% or 97 - 100% within 12 - 25 hours. For example, in one embodiment, when the liquid product loading is 0.5 - 2 g per liter, the PFAS removal efficiency of such a product for PFAS within a contact time of about 12 - 25 hours in the liquid can be 70% - 100%; in an improvement, when the liquid product loading is 0.5 - 2 g per liter, the PFAS removal efficiency of this product for PFAS within a contact time of about 12 - 25 hours in the liquid can be 80% - 100%; in an improvement, when the liquid product loading is 0.5 - 2 g, the PFAS removal efficiency of such a product for PFAS within a contact time of about 12 - 25 hours in the liquid can be 90% - 100%; in another improvement, when the liquid product loading is 0.5 - 2 g, the PFAS removal efficiency of such a product for PFAS within a contact time of about 12 - 25 hours in the liquid can be 95% - 100%, or when the liquid product loading is 0.5 - 2 g, the PFAS removal efficiency of such a product for PFAS within a contact time of about 12 - 25 hours in the liquid can be 97% - 100%.

[0055] In any of the above embodiments, when the liquid product loading is 0.5 - 2 g per liter, the total PFAS removal efficiency of the surface-functionalized product containing palygorskite for various PFAS in the liquid can be 10 - 95%, 15 - 95% or 18 - 95% within a contact / mixing time of 12 - 25 hours in the liquid.

[0056] In any one or more of the above embodiments or improvements, palygorskite or the product containing palygorskite is not acid-activated. In any one or more of the above embodiments or improvements, palygorskite or the product may be free of residual acid (acid-free).

[0057] In any one or more of the above embodiments or improvements, the product does not contain oleylamine and octylamine.

[0058] In another embodiment, the product may comprise sepiolite, and the weight percentages of the components of the product may include: 76-97 wt% of sepiolite; 1-16 wt% of (i) one or more monoquaternary amines or (ii) one or more diquaternary amines; and 0.5-8 wt% of a surface coating agent comprising one or more mercapto groups. When the quaternary amine surface coating solution comprises one or more monoquaternary amine compounds, the product does not contain any diquaternary amines. When the quaternary amine surface coating solution comprises one or more diquaternary amine compounds, the product does not contain any monoquaternary amines. The quaternary amine surface coating solution may further comprise water. The mercapto surface coating solution may further comprise a solvent.

[0059] Measured using the Brunauer-Emmett-Teller (BET) theory, the surface area of natural sepiolite (as feed) may be in the range of 200-300 m 2 / g or 240-300 m 2 / g or 258-285 m 2 / g or 270-274 m 2 / g or about 272 m 2 / g. In any of the above embodiments, the d 50 of the particle size distribution of natural sepiolite (as feed) may be 10-20 microns or 12-16 microns or 13-15 microns or about 14.2 microns. In any of the above embodiments, the porosity of the natural sepiolite (as feed) may be 75-95% or 76-93%, or 80-89% or about 84.5%. In any of the above embodiments, the pore volume of the natural sepiolite (as feed) may be 2.5-4 mL / g or 3.1-3.8 mL / g or 3.2-3.6 mL / g or 3.3-3.5 mL / g or about 3.45 mL / g. In any one or more of the above embodiments or modifications, for natural sepiolite (as feed), the intrinsic pores may be about 8 nm to about 25 nm, and the peak position of the intrinsic pores may be in the range of about 12 nm to about 16 nm; and / or the inter-pores may be about 40 nm to about 4 microns, and the peak position of the inter-pores may be in the range of about 1.2 microns to about 1.6 microns.

[0060] Measured using the Brunauer-Emmett-Teller (BET) theory, the surface area of the (surface-functionalized) product (comprising sepiolite) may be in the range of 76-276 m 2 / g, or 86-254 m 2 / g, or 91-243 m 2 / g, or about 96-231 m 2 / g. In any of the above embodiments, the d 50It can be about 10 - 25 microns, or about 11 - 22 microns, or about 12 - 21 microns. In any of the above embodiments, the porosity of such (surface-functionalized) products (including sepiolite) can be about 62 - 86%, or about 65 - 82%, or about 69 - 78%. In any of the above embodiments, the pore volume of such (surface-functionalized) products (including sepiolite) can be 1.3 - 3.0 mL / g, or 1.4 - 2.8 mL / g, or about 1.5 - 2.7 mL / g. In any one or more of the above embodiments or improvements, for such (surface-functionalized) products (including sepiolite), the intrinsic pores can be about 9 to about 28 nm, and the peak position of the intrinsic pores can be in the range of about 12 nm to about 19 nm; and / or the inter-pores can be about 540 nm to about 44 microns, and the peak position of the inter-pores can be in the range of about 1.8 microns to about 32 microns. In one improvement, for such (surface-functionalized) products (including sepiolite), the intrinsic pores can be about 10 to about 25 nm, and the peak position of the intrinsic pores can be in the range of about 14 nm to about 17 nm; and / or the inter-pores can be about 600 nm to about 40 microns, and the peak position of the inter-pores can be in the range of about 2 microns to about 29 microns. In any one or more of the above embodiments, such (surface-functionalized) products (including sepiolite) can be in powder form or non-extruded form (without extrusion before or after surface functionalization). In any one or more of the above embodiments, sepiolite can be or can include: (a) natural sepiolite that may not be heat-treated (at 300 °C to about 1000 °C) and / or not calcined (e.g., at about 1000 °C or above) before surface functionalization. In any one or more of the above embodiments, sepiolite can be in powder form. In any one or more of the above embodiments, sepiolite has not been extruded (without extrusion before or after surface functionalization).

[0061] In any of the above embodiments, when the liquid product loading is 0.5 - 2 g per liter or the liquid product loading is 1 - 1.3 g per liter, the PFAS removal efficiency of the (surface-functionalized) product (including sepiolite) for PFAS in the liquid can be 70 - 100%, 80 - 100%, 90 - 100%, 95 - 100% or 97 - 100% within 12 - 25 hours. For example, in one embodiment, when the liquid product loading is 0.5 - 2 g per liter, the PFAS removal efficiency of such a product within the contact time of 12 - 25 hours in the liquid can be 70% - 100%; in an improvement, when the liquid product loading is 0.5 - 2 g per liter, the PFAS removal efficiency of such a product within the contact time of about 12 - 25 hours in the liquid can be 80% - 100%; in an improvement, when the liquid product loading is 0.5 - 2 g per liter, the PFAS removal efficiency of such a product within the contact time of 12 - 25 hours in the liquid can be 90% - 100%; in another improvement, when the liquid product loading is 0.5 - 2 g per liter, the PFAS removal efficiency of such a product within the contact time of 12 - 25 hours in the liquid can be 95% - 100%, or when the liquid product loading is 0.5 - 2 g per liter, the PFAS removal efficiency of such a product within the contact time of 12 - 25 hours in the liquid can be 97% - 100%.

[0062] In any of the above embodiments, when the liquid product loading is 0.5 - 2 g per liter, the total PFAS removal efficiency of the (surface-functionalized) product (including sepiolite) for various PFAS in the liquid within the contact / mixing time of 12 - 25 hours can be 10 - 100%, 15 - 100% or 18 - 100%.

[0063] In any one or more of the above embodiments or improvements, the sepiolite or the product is not acid-activated. In any one or more of the above embodiments or improvements, the sepiolite or the product may not contain residual acid (acid-free).

[0064] In any one or more of the above embodiments or improvements, the product does not contain oleylamine and octylamine.

[0065] Preparation of the product

[0066] The method for preparing the products of Examples 1 - 12 discussed herein may include: selecting palygorskite. Palygorskite / attapulgite has the chemical formula (Mg,Al)2Si4O 10Magnesium aluminum layered silicate of (OH)·4H2O. The percentages of various elements may vary depending on the deposit from which the sepiolite is sourced. In any one or more of the above embodiments, the palygorskite may be or may comprise natural palygorskite, which may be untreated (at 300 °C to about 1000 °C) and uncalcined (e.g., at about 1000 °C or higher) before surface functionalization. Measured by the nitrogen adsorption method based on the Brunauer-Emmett-Teller (BET) theory, the high surface area of the selected natural palygorskite can be in the range of 90 m 2 / g - 160 m 2 / g, with a particle size (d50) of 5 - 25 microns (measured by a laser particle size analyzer). In one improvement, measured by the nitrogen adsorption method based on the Brunauer-Emmett-Teller (BET) theory, the surface area of the natural palygorskite can be in the range of 120 m 2 / g - 145 m 2 / g, or 130 m 2 / g - 145 m 2 / g. In a further improvement, measured by a laser particle size analyzer, the particle size (d50) of the feed can be 6 - 18 microns, 8 - 17 microns, or 10 - 15 microns. In each of the above embodiments and improvements, the palygorskite (feed) may contain 7 - 16 wt% or 9 - 14 wt% moisture (measured at 104 °C (220 °F)). Figure 1A and 1B are SEM images of the feed containing natural palygorskite at magnifications of x25000 and x200000. It can be seen from Figure 1A and 1B that the feed may comprise palygorskite, which may comprise or be multiple rod-shaped palygorskite particles. Although not wishing to be bound by theory, the inventors believe that this moisture content of the palygorskite used as the feed can facilitate the binding or anchoring of a surface coating agent containing one or more mercapto groups (e.g., mercapto silane) to the palygorskite surface. For example, when the surface coating agent is mercapto silane, the silane molecules will first be hydrolyzed by the trace water present on the surface of the palygorskite and then form covalent bonds with the palygorskite surface.

[0067] The method includes mixing a quaternary amine compound with water to form a quaternary amine surface coating solution for surface coating palygorskite. In one embodiment, the quaternary amine compound can comprise (or can be) a monoquaternary amine compound, and the quaternary amine surface coating solution obtained by mixing does not contain a diquaternary amine. In another embodiment, the quaternary amine compound can comprise (or can be) a diquaternary amine compound, and the quaternary amine surface coating solution obtained by mixing does not contain a monoquaternary amine. In other words, in the quaternary amine surface coating solution, if there are one or more monoquaternary amine compounds, there is no diquaternary amine. Similarly, in the quaternary amine surface coating solution, if there are one or more diquaternary amine compounds, there is no monoquaternary amine.

[0068] In various exemplary embodiments discussed herein, the quaternary amine surface coating solution is prepared by mixing 50 wt% of a monoquaternary amine compound (e.g., 10 g of Kemira Superfloc C-577) and 50 wt% water (e.g., 10 g of deionized (DI) water) in a 100 mL glass beaker on a magnetic stirrer plate for about 10 minutes, but other mixing methods known in the art can be used. The exemplary monoquaternary amine compound used is Kemira Superfloc C-577 [aqueous solution of a polymer of 1,2-ethylenediamine with (chloromethyl)oxirane and N-methylmethanamine at a concentration of about 50%]. In other words, the exemplary monoquaternary amine compound contains about 50% quaternary amine. The resulting quaternary amine surface coating solution does not contain a diquaternary amine. In other embodiments, the quaternary amine surface coating solution can be prepared by mixing other appropriate amounts of the monoquaternary amine compound and water (e.g., DI water). For example, the quaternary amine surface coating solution can comprise 25-56 wt% monoquaternary amine compound and 44-75 wt% water (e.g., DI water), and the resulting quaternary amine surface coating solution does not contain a diquaternary amine. In other alternative embodiments discussed herein, the quaternary amine surface coating solution is prepared by mixing 50 wt% of a diquaternary amine compound (e.g., 10 g of Evonik ADOGEN< >477, N,N,N’,N’-pentamethyl-N’-tallowalkyltrimethylenediammonium chloride at a concentration of about 50% in an aqueous ethanol solution) and 50 wt% water (e.g., 10 g of DI water) uniformly in a 100 mL glass beaker on a magnetic stirrer plate (e.g., for about 10 minutes). The exemplary diquaternary amine compound used (Evonik ADOGEN< >477) contains about 50% diquaternary amine. The resulting quaternary amine surface coating solution does not contain a monoquaternary amine. In other embodiments, the quaternary amine surface coating solution can comprise other appropriate amounts of the diquaternary amine compound and water (e.g., DI water). For example, the quaternary amine surface coating solution can comprise 33-60 wt% of the diquaternary amine compound and 40-67 wt% of water (e.g., DI water), and the resulting quaternary amine surface coating solution does not contain a monoquaternary amine.

[0069] The method further includes surface treating the palygorskite with a quaternary amine surface coating solution to functionalize the surface of the palygorskite. In one embodiment, the surface treatment may include spraying the quaternary amine surface coating solution onto the palygorskite, or otherwise adding / applying the quaternary amine surface coating solution to the palygorskite, and then mixing until the quaternary amine surface coating solution is fully dispersed on the palygorskite. In various embodiments discussed herein, the quaternary amine surface coating solution is sprayed onto the sepiolite, and then the combination of the quaternary amine surface coating solution and the sepiolite is mixed until the quaternary amine surface coating solution is fully dispersed throughout the sepiolite material. For example, in various exemplary embodiments disclosed in the tables herein, the quaternary amine surface coating solution is sprayed onto the palygorskite feed, and then the mixture is mixed at a low speed in a KitchenAid 5 quart food mixer for about 30 minutes. In embodiments other than the exemplary embodiments, other appropriate amounts of the sepiolite quaternary amine surface coating solution may be used to functionalize the surface of the palygorskite. Figure 2 Illustratively shown is the surface functionalization of a feed (comprising natural palygorskite) with a quaternary amine surface coating solution. The quaternary amine in the quaternary amine surface coating solution attaches to the surface of the palygorskite in the feed.

[0070] The method further includes mixing a solvent and a surface coating agent to form a mercapto surface coating solution for surface coating the palygorskite. The surface coating agent includes one or more mercapto groups. For example, in one embodiment, the surface coating agent may include one or more mercapto groups and a silane. In the exemplary embodiments discussed herein, the mercapto surface coating solution is formed by mixing 20 wt% of the surface coating agent (e.g., 5 g of γ-mercaptopropyltrimethoxysilane (Momentive Silquest A-189)) and 80 wt% of the solvent (e.g., 20 g of ethanol) until well mixed (e.g., mixed in a 100 mL glass beaker on a magnetic stirrer plate for about 10 minutes, but other mixing methods known in the art may be used). In other embodiments, the mercapto surface coating solution may include other appropriate amounts of the surface coating agent and the solvent. For example, the mercapto surface coating solution may contain about 5-20 wt% of the surface coating agent and about 95-80 wt% of the solvent.

[0071] The method further includes surface treating the palygorskite with the mercapto surface coating solution to functionalize the surface of the palygorskite. In one embodiment, the palygorskite surface-functionalized with the mercapto surface coating solution may have been surface-functionalized with the quaternary amine surface coating solution. Figure 2 Illustratively shown is the surface functionalization of the palygorskite with the mercapto surface coating solution. In Figure 2In the illustrated embodiment, prior to surface functionalization with the mercapto surface coating solution, the quaternary amine of the quaternary amine surface coating solution attaches to the surface of the as-received palygorskite. The mercapto groups of the mercapto surface coating solution chemically bond to the surface of the as-received palygorskite.

[0072] In one embodiment, the surface treatment can include spraying the mercapto surface coating solution onto the palygorskite or otherwise adding the mercapto surface coating solution to the palygorskite and then mixing until the mercapto surface coating solution is fully dispersed on the palygorskite. In the various embodiments discussed herein, the mercapto surface coating solution is sprayed onto the palygorskite (which has been previously surface functionalized with the quaternary amine surface coating solution), and then the combination is mixed until the mercapto surface coating solution is fully dispersed throughout the palygorskite. For example, in the various embodiments herein, the mercapto surface coating solution is sprayed onto the palygorskite material and then the combination is mixed at low speed in a KitchenAid 5 quart food mixer for about 30 minutes. In the exemplary embodiments herein, after the quaternary amine surface coating solution (which contains water (e.g., DI water) and a monoquaternary amine compound or a diquaternary amine compound) is sprayed / added / applied to the palygorskite, the mercapto surface coating solution is sprayed / added / applied to the palygorskite. The inventors have found that when the palygorskite feed is first treated with the quaternary amine surface coating solution and then with the mercapto surface coating solution, the water (e.g., DI water) in the quaternary amine surface coating solution promotes the mercapto silane hydrolysis reaction and the formation of Si-O-Si-SH bonds on the palygorskite surface, thereby effectively anchoring the mercapto groups to the surface of the palygorskite.

[0073] The method can further include: after surface treating the palygorskite with the quaternary amine surface coating solution and the mercapto surface coating solution, drying the surface-treated (twice) palygorskite in an oven or the like (at about 60 - 70 °C) for about 4 - 6 hours or until the palygorskite is dry (both surface coating solutions are dried on the surface of the palygorskite particles). In the above embodiment, after mixing, the mixture is dried in an oven at 60 - 70 °C for about 4 hours. In some embodiments, the prepared product can be in powder form or in a non-extruded (no extrusion) form. In some embodiments, the palygorskite particles of the resulting product can exhibit a generally round particle shape. In other embodiments, the palygorskite particles of the resulting product can exhibit an irregular shape. As previously mentioned, in one embodiment, the palygorskite can include a plurality of rod-shaped palygorskite particles. After surface coating and drying, the quaternary amine attaches to the palygorskite surface, and the mercapto is chemically bonded to the palygorskite surface.

[0074] The surface coating agent may include (or may be): mercapto silane or non-silane mercapto thiol compound or a mixture thereof. Mercapto silanes may include but are not limited to: 3-mercaptopropyltrimethoxysilane; 3-(mercapto propyl)triethoxysilane; 3-mercaptopropylmethyldimethoxysilane; (mercaptomethyl)dimethylethoxysilane; (mercaptomethyl)methyldiethoxysilane; 3-mercaptomethyltrimethoxysilane, 3-mercaptomethyltriethoxysilane, 11-mercaptoundecyltrimethoxysilane; or a mixture thereof. Non-silane mercapto thiol compounds may include but are not limited to: 3-mercapto-1,2-propanediol, mercaptobenzothiazole, ethanethiol, 1-butanethiol, 1-propanethiol, cyclopentanethiol; or a mixture thereof. The above list is exemplary. Mercapto silanes are not limited to these listed examples. Non-silane mercapto thiol compounds are not limited to the listed examples. The solvent may include or may be methanol, ethanol, isopropanol, chloroform, toluene or a mixture thereof. In one embodiment, the mercapto surface coating solution may include or may be γ-mercaptopropyltrimethoxysilane and ethanol.

[0075] Surface area measurements before and after surface treatment of sepiolite with this solution indicate that the surface area decreases after treatment with the quaternary amine surface coating solution and the mercapto surface coating solution (e.g., see Table 5).

[0076] Similar to the above, the method for preparing the products of Preparation Examples 13 - 18 discussed herein may include: selecting sepiolite. Sepiolite is magnesium hydrosilicate with the chemical formula Mg4Si6O 15 (OH)2·6H2O. The percentages of various elements may vary depending on the deposit from which the sepiolite is sourced. In any one or more of the above embodiments, the sepiolite may be or may contain natural sepiolite, which may be untreated (at 300 °C to about 1000 °C) and uncalcined (e.g., at about 1000 °C or higher temperature) before surface functionalization. Measured by the nitrogen adsorption method based on the Brunauer - Emmett - Teller (BET) theory, the high surface area of the selected natural sepiolite may be in the range of 200 m 2 / g - 300 m 2 , and the particle size (d50) is 10 - 20 microns (measured using a laser particle size analyzer). In one improvement, measured by the nitrogen adsorption method based on the Brunauer - Emmett - Teller (BET) theory, the surface area of the natural sepiolite may be in the range of 240 m 2 / g - 300 m 2 / g or 258 m 2 / g - 285 m 2 / g or 270 m 2 / g - 274 m 2within the range of / g. In a further improvement, as measured by a laser particle size analyzer, the particle size (d50) of the feed can be 12 - 16 microns, or 13 - 15 microns, or approximately 14.2 microns. In each of the above embodiments and improvements, the loss on ignition of sepiolite (feed) can be 16 - 22% moisture, and the drying loss is 5 - 10% moisture. Moisture drying can be measured at around 100°C. In each of the above embodiments and improvements, the porosity of natural sepiolite (as feed) can be 75 - 95% or 76 - 93%, or 80 - 89% or approximately 84.5%. In each of the above embodiments and improvements, the pore volume of natural sepiolite (as feed) can be 2.5 - 4 mL / g or 3.1 - 3.8 mL / g or 3.2 - 3.6 mL / g or 3.3 - 3.5 mL / g or approximately 3.45 mL / g. For natural sepiolite (as feed), in one embodiment, the inherent pores can be from about 8 nm to about 25 nm, and the peak position of the inherent pores can be in the range of about 12 nm to about 16 nm; and / or the inter-pores can be from about 40 nm to about 4 microns, and the peak position of the inter-pores can be in the range of about 1.2 microns to about 1.6 microns. Figure 12 is an SEM image of the feed containing natural sepiolite at a magnification of 10,000 times. As Figure 12 shown, the feed can contain or can be sepiolite, which can contain or can be a plurality of fibrous sepiolite particles. Although not wishing to be bound by theory, the inventors believe that this moisture content and morphology of the sepiolite used as the feed can facilitate the binding or anchoring of a surface coating agent containing one or more mercapto groups (such as mercapto silane) to the sepiolite surface. For example, when the surface coating agent is mercapto silane, the silane molecules can first be hydrolyzed by trace amounts of water present on the sepiolite surface and then form covalent bonds with the sepiolite surface.

[0077] The method includes mixing a quaternary amine compound and water to form a quaternary amine surface coating solution for surface coating sepiolite. In one embodiment, the quaternary amine compound can contain (or can be) a monoquaternary amine compound, and the quaternary amine surface coating solution obtained by mixing does not contain a diquaternary amine. In another embodiment, the quaternary amine compound can contain (or can be) a diquaternary amine compound, and the quaternary amine surface coating solution obtained by mixing does not contain a monoquaternary amine. In other words, in the quaternary amine surface coating solution, if there are one or more monoquaternary amine compounds, there are no diquaternary amines. Similarly, in the quaternary amine surface coating solution, if there are one or more diquaternary amine compounds, there are no monoquaternary amines.

[0078] In various exemplary embodiments discussed herein, a quaternary amine surface coating solution is prepared by mixing 50 wt% of a monoquaternary amine compound (e.g., 10 g of Kemira Superfloc C-577) and 50 wt% water (e.g., 10 g of deionized (DI) water) in a 100 mL glass beaker on a magnetic stirrer plate for about 10 minutes, although other mixing methods known in the art may be used. The exemplary monoquaternary amine compound used is Kemira Superfloc C-577 [a polymer of 1,2-ethylenediamine, (chloromethyl)oxirane, and N-methylmethanamine in an aqueous solution at a concentration of about 50%]. In other words, the exemplary monoquaternary amine compound contains about 50% quaternary amine. The resulting quaternary amine surface coating solution is free of diquaternary amines. In other embodiments, the quaternary amine surface coating solution may be prepared by mixing other suitable amounts of the monoquaternary amine compound and water (e.g., DI water). For example, the quaternary amine surface coating solution may contain 25-56 wt% of the monoquaternary amine compound and 44-75 wt% of water (e.g., DI water), wherein the resulting quaternary amine surface coating solution is free of diquaternary amines. In other alternative embodiments discussed herein, the quaternary amine surface coating solution is prepared by mixing 50 wt% of a diquaternary amine compound (e.g., 10 g of Evonik 477, N,N,N’,N’-pentamethyl-N’-tallow alkyltrimethylenediammonium chloride in an aqueous ethanol solution at a concentration of about 50% and 50 wt% water (e.g., 10 g of DI water) in a 100 mL glass beaker on a magnetic stirrer plate until well mixed (e.g., about 10 minutes). The exemplary diquaternary amine compound (Evonik 477) contains about 50% diquaternary amine. The resulting quaternary amine surface coating solution is free of monoquaternary amines. In other embodiments, the quaternary amine surface coating solution may contain other suitable amounts of the diquaternary amine compound and water (e.g., DI water). For example, the quaternary amine surface coating solution may contain 33-60 wt% of the diquaternary amine compound and 40-67 wt% of water (e.g., DI water), wherein the resulting quaternary amine surface coating solution is free of monoquaternary amines.

[0079] The method further includes surface treating the sepiolite with a quaternary amine surface coating solution to functionalize the sepiolite surface. In one embodiment, the surface treatment can include spraying the quaternary amine surface coating solution onto the sepiolite, or otherwise adding / applying the quaternary amine surface coating solution to the sepiolite, and then mixing until the quaternary amine surface coating solution is fully dispersed on the sepiolite. In various embodiments discussed herein, the quaternary amine surface coating solution is sprayed onto the sepiolite, and then the combination of the quaternary amine surface coating solution and the sepiolite is mixed until the quaternary amine surface coating solution is fully dispersed throughout the sepiolite material. For example, in various exemplary embodiments disclosed in the tables herein, the quaternary amine surface coating solution is sprayed onto the sepiolite feed, and then the mixture is mixed at low speed in a KitchenAid 5 quart food mixer for about 30 minutes. When using the quaternary amine surface coating solution to functionalize the feed (comprising natural sepiolite), the quaternary amine in the quaternary amine surface coating solution attaches to the sepiolite surface of the feed. In other embodiments, other suitable amounts of the quaternary amine surface coating solution for sepiolite can be used to functionalize the sepiolite.

[0080] The method further includes mixing a solvent and a surface coating agent to form a mercapto surface coating solution for surface coating sepiolite. The surface coating agent includes one or more mercapto groups. For example, in one embodiment, the surface coating agent can include one or more mercapto groups and silane. In various exemplary embodiments discussed herein, the mercapto surface coating solution is prepared by mixing 20 wt% of the surface coating agent (e.g., 5 g of γ-mercaptopropyltrimethoxysilane (Momentive Silquest A-189)) and 80 wt% of the solvent (e.g., 20 g of ethanol) until well mixed (e.g., mixing in a 100 mL glass beaker on a magnetic stirrer plate for about 10 minutes, but other mixing methods known in the art can be used). In other embodiments, the mercapto surface coating solution can contain other appropriate amounts of the surface coating agent and the solvent. For example, the mercapto surface coating solution can contain about 5-20 wt% of the surface coating agent and about 95-80 wt% of the solvent.

[0081] The method further includes surface treating the sepiolite with the mercapto surface coating solution to functionalize the sepiolite surface. In one embodiment, the sepiolite surface-functionalized with the mercapto surface coating solution may have been surface-functionalized with the quaternary amine surface coating solution. Similar to Figure 2 the illustration of palygorskite, the quaternary amine of the quaternary amine surface coating solution attaches to the sepiolite surface of the feed before being surface-functionalized with the mercapto surface coating solution. The mercapto groups of the mercapto surface coating solution chemically bond to the sepiolite surface of the feed.

[0082] In one embodiment, the surface treatment may include spraying a mercapto surface coating solution onto the sepiolite or otherwise adding the mercapto surface coating solution to the sepiolite, and then mixing until the mercapto surface coating solution is fully dispersed on the sepiolite. In various embodiments discussed herein, the mercapto surface coating solution is sprayed onto the sepiolite (which has been surface-functionalized with a quaternary amine surface coating solution), and then the combination is mixed until the mercapto surface coating solution is fully dispersed throughout the sepiolite. For example, in various exemplary embodiments herein, the mercapto surface coating solution is sprayed onto the sepiolite material, and then the combination is mixed at low speed in a KitchenAid 5-quart food mixer for about 30 minutes. In other embodiments, other appropriate amounts of the mercapto surface coating solution may be used to surface-functionalize the sepiolite. In one embodiment, after spraying / adding / applying a quaternary amine surface coating solution (which includes water (e.g., DI water) and a monoquaternary amine compound or a diquaternary amine compound) onto the sepiolite, the mercapto surface coating solution is sprayed / added / applied to the sepiolite. The inventors have found that when the sepiolite feed is first treated with a quaternary amine surface coating solution and then with a mercapto surface coating solution, the water (e.g., DI water) in the quaternary amine surface coating solution promotes the mercapto silane hydrolysis reaction and the formation of Si-O-Si-SH bonds on the sepiolite surface, thereby effectively anchoring the mercapto groups to the surface of the sepiolite.

[0083] The method may further include: after surface-treating the sepiolite with the quaternary amine surface coating solution and the mercapto surface coating solution, drying the surface-treated sepiolite (twice) in an oven or the like (at about 60 - 70 °C) for about 4 - 6 hours or until the sepiolite is dry (both surface coating solutions are dried on the surface of the sepiolite particles). In the above embodiment, after mixing, the mixture is dried in an oven at 60 - 70 °C for about 4 hours. In some embodiments, the resulting product may be in powder form or in a non-extruded (no extrusion) form. In some embodiments, some or substantially all of the sepiolite particles of the resulting product may be in the form of fibrous particles. After surface coating and drying, the quaternary amine attaches to the sepiolite surface, and the mercapto groups are chemically bonded to the sepiolite surface.

[0084] The surface coating agent may comprise (or may be): a mercapto silane or a non-silane mercapto thiol compound or a mixture thereof. Mercapto silanes may include but are not limited to: 3-mercaptopropyltrimethoxysilane; 3-(mercaptopropyl)triethoxysilane; 3-mercaptopropylmethyldimethoxysilane; (mercaptomethyl)dimethylethoxysilane; (mercaptomethyl)methyldiethoxysilane; 3-mercaptomethyltrimethoxysilane, 3-mercaptomethyltriethoxysilane, 11-mercaptoundecyltrimethoxysilane; or a mixture thereof. Non-silane mercapto thiol compounds may include but are not limited to: 3-mercapto-1,2-propanediol, mercaptobenzothiazole, ethanethiol, 1-butanethiol, 1-propanethiol, cyclopentanethiol; or a mixture thereof. The above list is exemplary. Mercapto silanes are not limited to these listed examples. Non-silane mercapto thiol compounds are not limited to the listed examples. The solvent may include or may be methanol, ethanol, isopropanol, chloroform, toluene or a mixture thereof. In one embodiment, the mercapto surface coating solution may comprise or may be γ-mercaptopropyltrimethoxysilane and ethanol.

[0085] Surface area measurements before and after surface treatment of sepiolite with this solution showed that the surface area decreased after treatment with the quaternary amine surface coating solution and the mercapto surface coating solution (see, for example, Table 5).

[0086] In the method disclosed herein, the feed may comprise or may be attapulgite, or sepiolite, or attapulgite and sepiolite.

[0087] Description of the test method

[0088] Surface area, pore volume, pore size distribution, porosity

[0089] The surface area is measured by nitrogen adsorption by the BET (Brunauer-Emmett-Teller) method. The pore volume and pore size distribution of the material sample are determined by mercury porosimetry. Mercury porosimetry uses mercury as the intrusion fluid to measure the pore volume of the (weighed) material sample enclosed in the penetrometer sample chamber. The sample chamber is evacuated to remove air from the pores of the sample. The sample chamber and the penetrometer are filled with mercury. Since mercury does not wet the material surface, it must be forced into the pores by an external pressure. A gradually increasing pressure is applied to allow mercury to enter the pores. The equilibrium pressure required is inversely proportional to the size of the pores, and only a slight pressure is required to intrude mercury into large pores, while a greater external pressure is required to press mercury into small pores. The penetrometer reads the volume of mercury intruded, and the intrusion data is used to calculate the pore size distribution, porosity, average pore size and total pore volume. Micromeritics AutoPore IV 9500 is used herein to analyze the samples.

[0090] Assume the pores are cylindrical, and the surface distribution can be derived from the pore volume distribution used in the calculation. The estimation of the total surface area of the material sample can be carried out from the pressure / volume curve (Rootare, 1967) without using the following pore models:

[0091]

[0092] where A = total surface area,

[0093] γ = surface tension of mercury,

[0094] θ = contact angle of mercury with the pore walls of the material,

[0095] p = externally applied pressure,

[0096] V = pore volume,

[0097] From the function V = V(p), the integral can be calculated numerically.

[0098] Based on the pressure and mercury intrusion data, the instrument generates the volume and size distribution of the pores according to the following Washburn equation (Washburn, 1921):

[0099]

[0100] where d i = pore diameter at the equilibrium external pressure

[0101] γ = surface tension of mercury

[0102] θ = contact angle of mercury with the pore walls of the material

[0103] P i = externally applied pressure

[0104] The average pore diameter is determined from the cumulative intrusion volume and the total surface area of the material sample as:

[0105]

[0106] where D = average pore diameter

[0107] V = total intrusion volume of mercury

[0108] S = total surface area

[0109] Porosity is the fraction of the total material volume occupied by the pore space. Porosity is calculated from the mercury intrusion data.

[0110] EPA Method 533 (Determination of perfluoroalkyl and polyfluoroalkyl substances in drinking water by isotope dilution anion - exchange solid - phase extraction and liquid chromatography / tandem mass spectrometry) EPA Method SW846 Method 3535A: Solid - phase extraction (SPE)

[0111] Analyze a 100 - 250 mL sample fortified with an isotopically labeled analyte analogue using an isotopic dilution standard. The sample is passed through a solid - phase extraction (SPE) cartridge of polystyrene divinylbenzene with a positively charged diamino ligand to extract the analyte and the isotopic dilution analogue. The cartridge is rinsed with an aqueous ammonium acetate solution and then successively with methanol, and then the compounds are eluted from the solid - phase adsorbent with methanol containing ammonium hydroxide. The extract is concentrated to dryness with nitrogen in a heated water bath. The extract volume is adjusted to 1.0 mL with 20% water (v / v) in methanol, and three isotopically labeled isotopic performance standards are added. The extract is analyzed by liquid chromatography - tandem mass spectrometry (LC - MS / MS) in the multiple reaction monitoring (MRM) detection mode. The concentration of each analyte is calculated using isotopic dilution techniques. For quality control (QC) purposes, the percent recovery of the isotopic dilution analogue is calculated using the integrated peak areas of the isotopic performance standards, which are added to the final extract and used as conventional internal standards specifically for the isotopic dilution analogue.

[0112] Loss on ignition (LOI)

[0113] Sample preparation procedures vary depending on the analyte group. For the extraction of some analyte groups, the pH of the sample is adjusted to a specified value before extraction. Other groups do not require pH adjustment. After any necessary pH adjustment, a measured volume of the sample is extracted by passing the sample through a solid - phase extraction medium (disk or cartridge) that is held in an extraction device designed for vacuum filtration of the sample. The target analyte is eluted from the solid - phase medium using an appropriate solvent collected in a receiving container. The resulting solvent extract is dried with sodium sulfate and concentrated as needed. Depending on the specific analysis requirements, the concentrated extract can be exchanged into a solvent - compatible extract, followed by a cleanup procedure or a determination procedure to measure the target analyte.

[0114] Examples

[0115] Loss on ignition (LOI) can be used to determine the water of hydration in the feed sample. Such LOI tests should be carried out at a high temperature (e.g., 980 °C - 1200 °C, preferably 982 °C - 1000 °C) for a sufficient length of time (at least 1 hour) so that the chemically bound water has the opportunity to separate and volatilize. Precise measurement of the sample mass (accurate to 0.1 mg) before and after this treatment allows quantification of the water of hydration. Examples

[0116] The products of Examples 1 - 12 all contain palygorskite. The products of Examples 1 - 12 are prepared from the natural palygorskite feed listed in Table 1.

[0117] Table 1. Feed

[0118]

[0119] Natural attapulgite feedstock is prepared from natural attapulgite mined near Climax, Georgia, by Active Minerals International, LLC. The major elemental composition of this natural attapulgite feedstock, as determined by wavelength dispersive XRF analysis, is shown in Table 2.

[0120] Table 2. Major oxide composition (%) of natural attapulgite material used as feedstock

[0121]

[0122] 1 Although the elements are reported in oxide form, they actually exist as complex aluminosilicates.

[0123] The high surface area of the feedstock containing natural attapulgite is about 141 m 2 / g, as measured by nitrogen adsorption method based on Brunauer-Emmett-Teller (BET) theory. The particle size (d 50 ) of this feedstock is about 13.49 micrometers (μm), as measured by a laser particle size analyzer. The natural attapulgite feedstock is in powder form and not extruded. The natural attapulgite feedstock has no heat treatment (at 300 °C to about 1000 °C), and / or is not calcined (e.g., at about 1000 °C or above). In any one or more embodiments herein, the attapulgite used can be in powder form.

[0124] The natural attapulgite feedstock contains about 7 - 16 wt% or about 9 - 14 wt% moisture (at 104 °C (220 °F)). Without being bound by theory, the inventors believe that this moisture aids in the binding of surface coating agents (such as mercapto silane) to the attapulgite surface. For example, when the surface coating agent comprises or is mercapto silane, it is believed that the silane molecules may first be hydrolyzed by trace amounts of water present on the sepiolite surface and then form covalent bonds with the attapulgite surface.

[0125] Table 3A-3B shows Examples 1-12 prepared from natural palygorskite raw materials using surface functionalization treatment. In Table 3A-3B, the weight percentage of the surface coating agent (such as mercapto silane) is determined as a percentage of the weight of the resulting adsorbent. More specifically, for the mercapto surface coating solution, the portion of the solvent (such as ethanol) evaporated during the drying process is not included in the weight of the resulting adsorbent calculated in Table 3B. Similarly, in Table 3A-3B, the weight percentage of the quaternary amine (contained in the quaternary amine compound (e.g., about 50% of the weight of the quaternary amine compound used)) is determined as a percentage of the weight of the resulting adsorbent. For the amine surface coating solution, the portion of deionized water in which the quaternary amine compound is dispersed (evaporated during the drying process) is not included in the weight of the resulting adsorbent calculated in Table 3B.

[0126] For example, in Example 1, 5 g of mercapto silane accounts for 5 wt% of the total weight of the resulting adsorbent of 100 g (5 g of mercapto silane plus 95 g of palygorskite). In Example 3, 4.73 g of mercapto silane accounts for 4.7 wt% of the total weight of the resulting adsorbent of 99.73 g (4.73 g of mercapto silane plus 5 g of quaternary amine plus 90 g of palygorskite), and 5 g of quaternary amine accounts for 5 wt% of the total weight of the resulting adsorbent of 99.73 g. For clarity, in Example 3, 10 g of a monoquaternary amine compound was used, of which 50% (5 g) is the quaternary amine. The weight percentage of the quaternary amine in deionized water is calculated as follows: [weight of quaternary amine / (weight of quaternary amine + weight of deionized water)] * 100). Similarly, the weight percentage of the mercapto group in the solvent is calculated as follows: [weight of mercapto silane / (weight of mercapto silane + weight of solvent)] * 100

[0127] Table 3A. Naturally occurring palygorskite surface-functionalized with PFAS adsorbents prepared at different mercapto silane and quaternary amine loading levels; and naturally occurring sepiolite surface-functionalized with PFAS adsorbents prepared at different mercapto silane and quaternary amine loading levels.

[0128]

[0129]

[0130] *Quaternary ammonium weight is approximately 50% of the exemplary quaternary ammonium compound used

[0131] Table 3B. Naturally occurring palygorskite surface-functionalized with PFAS adsorbents prepared at different mercapto silane and quaternary amine loading levels; and naturally occurring sepiolite surface-functionalized with PFAS adsorbents prepared at different mercapto silane and quaternary amine loading levels.

[0132]

[0133] *[Quaternary amine weight / (quaternary amine weight + DI water weight)] * 100

[0134] **[Weight of mercapto - silane / (Weight of mercapto - silane+Weight of solvent)]*100

[0135] Example 1

[0136] Example 1 was prepared using mercapto - silane surface functionalization treatment. A mercapto surface coating solution for coating natural palygorskite was prepared by mixing 5 g of a surface coating agent [γ - mercaptopropyltrimethoxysilane (Momentive Silquest A - 189)] with 20 g of a solvent (ethanol) in a 100 mL glass beaker on a magnetic stirrer plate for 10 minutes. 95 g of palygorskite feed was mixed with 25 g of the mercapto surface coating solution in a KitchenAid 5 - quart food mixer. After mixing at low speed for 30 minutes, the mixture was dried in an oven at 60 - 70 °C for four hours.

[0137] Example 2

[0138] Example 2 was prepared using quaternary amine surface functionalization treatment. A quaternary amine surface coating solution for coating palygorskite was prepared by mixing 10 g of Kemira Superfloc C - 577 (a mono - quaternary amine compound, a polymer of 1,2 - ethylenediamine with (chloromethyl)oxirane and N - methylmethylamine) with 10 g of DI water in a 100 mL glass beaker on a magnetic stirrer plate for 10 minutes. The weight of the mono - quaternary amine in the exemplary mono - quaternary amine compound (Kemira Superfloc C - 577) was estimated to be about 50% of the total weight of the Kemira Superfloc C - 577 solution. Thus, in Example 2, the mono - quaternary amine compound (Kemira Superfloc C - 577) contained about 5 g of mono - quaternary amine. 90 g of palygorskite raw material was mixed with 20 g of the quaternary amine surface coating solution in a KitchenAid 5 - quart food mixer. After mixing at low speed for 30 minutes, the mixture was dried in an oven at 60 - 70 °C for four hours.

[0139] Examples 3 - 9

[0140] Each of Examples 3 - 9 was prepared using a dual - surface treatment with a quaternary amine surface coating solution and a mercapto surface coating solution. Tables 3A - 3B show the different loading levels of the quaternary amine surface coating solution and the mercapto surface coating solution to study the effect of PFAS - affinity functional groups on PFAS removal.

[0141] As previously discussed, the quaternary amine surface coating solution contains a quaternary amine compound and water (the quaternary amine compound is dispersed in DI water). In Examples 3-9, the quaternary amine surface coating solution used for surface coating palygorskite was prepared by mixing Kemira Superfloc C-577 (a monoquaternary amine compound, a polymer of 1,2-ethylenediamine with (chloromethyl)oxirane and N-methylmethylamine]) in 100 mL of deionized water in a glass beaker on a magnetic stirrer plate for 10 minutes. Then the palygorskite feed was mixed with the quaternary amine surface coating solution in a KitchenAid 5-quart food mixer at low speed for about 30 minutes. In Examples 3-9, the quaternary amine compound comprises (or is) a monoquaternary amine compound, and thus each of the quaternary amine surface coating solutions of Examples 3-9 contains a monoquaternary amine compound and deionized water. The weight estimate of the monoquaternary amine in the exemplary monoquaternary amine compound (Kemira Superfloc C-577) is about 50% of the total weight of the Kemira Superfloc C-577 solution used. In addition, each of the quaternary amine surface coating solutions of Examples 3-9 contains no diquaternary amine, no oleylamine, and no octylamine.

[0142] As seen in Tables 3A-3B, in Examples 3-9, for the thiol surface coating solution, different loading levels of the surface coating agent and the solvent were used. As previously discussed, the thiol surface coating solution contains a surface coating agent and a solvent. The surface coating agent contains one or more thiol groups. In Examples 3-9, the surface coating agent contains a silane and one or more thiol groups. In Tables 3A-3B, the surface coating agent is referred to as "thiol silane". In each of Examples 3-9, the surface coating agent used is γ-mercaptopropyltrimethoxysilane (Momentive Silquest A-189), and the solvent is ethanol.

[0143] In Examples 3-9, the thiol surface coating solution used for surface coating palygorskite was prepared by mixing the surface coating agent (thiol silane) in the solvent (ethanol) in a 100 mL glass beaker on a magnetic stirrer plate for 10 minutes. Then the palygorskite feed that had been surface-functionalized with the quaternary amine surface coating solution was mixed with the thiol surface coating solution in a KitchenAid 5-quart food mixer. After mixing at low speed for 30 minutes, the mixture was dried in an oven at 60-70 °C for 4 hours. The resulting adsorbent is in powder form, without extrusion, without acid activation, and without residual acid (acid-free).

[0144] Table 4 lists the pore volume, porosity, and particle size distribution (psd) of the palygorskite feed and Examples 4 and 7, as well as the sepiolite raw material and Examples 13-18.

[0145] Table 4. Pore volume, porosity, and particle size distribution.

[0146] Pore volume (mL / g) Porosity (%) Sepiolite feed <![CDATA[d 50 (μm)]]> Example 4 1.1935 68 13.49 Example 7 0.9658 58 12.25 Palygorskite feed 0.9691 63 22.35 Example 13 3.4586 84.5 14.2 Example 14 2.6909 77.6 12.5 Example 15 2.2901 76.4 14.2 Example 16 1.9089 74.5 14.1 Example 17 2.3715 77.5 16.1 Example 18 1.5887 69.7 20.6 Example 2.2150 77 20.4

[0147] Examples 10 - 12

[0148] Examples 10 - 12 were prepared using a double surface treatment and drying similar to Examples 3 - 9, except that each quaternary amine compound included a bis - quaternary amine compound. Thus, each quaternary amine surface coating solution of Examples 10 - 12 included a bis - quaternary amine compound and deionized water. More specifically, in Examples 10 - 12, the quaternary amine surface coating solution for surface - coating sepiolite was prepared by mixing Evonik 477, N,N,N,N’,N’ - pentamethyl - N’ - tallow alkyl trimethylene diammonium chloride (bis - quaternary amine compound) in a 100 mL glass beaker on a magnetic stirrer plate for 10 minutes. The bis - quaternary amine weight in the exemplary bis - quaternary amine compound (Evonik 477) was estimated to be about 50% of the total weight of the Evonik 477 solution used. Then the sepiolite feed was mixed with the quaternary amine surface coating solution at low speed in a KitchenAid 5 - quart food mixer for about 30 minutes. Each quaternary amine surface coating solution of Examples 10 - 12 contained no mono - quaternary amine, no oleylamine, and no octylamine. As described in the previous Examples 3 - 9, the amine - surface - functionalized sepiolite was further surface - functionalized with a thiol surface coating solution and dried. The resulting adsorbent was in powder form, without extrusion, without acid activation, and without residual acid (acid - free).

[0149] The products of Examples 13 - 18 all contained sepiolite. The products of Examples 13 - 18 were prepared from the sepiolite feeds listed in Table 1.

[0150] The feed for Examples 13 - 18 was prepared using natural sepiolite obtained from Sigma - Aldrich. The natural sepiolite contained about 13 wt% magnesium (Mg).

[0151] Measured by the nitrogen adsorption method based on the Brunauer - Emmett - Teller (BET) theory, the high surface area of the feed used was about 272 m 2 / g. Measured by a laser particle size analyzer, the particle size (d 50 ) of this feed was about 14.2 microns. The sepiolite feed was in powder form and without extrusion. The natural sepiolite feed had no heat treatment (at 300 °C to about 1000 °C), and / or no calcination (e.g., at about 1000 °C or above).

[0152] The feedstock contains approximately 16 - 22 wt% moisture (determined by loss on ignition). Without being bound by theory, the inventors believe that this moisture aids in the binding of the surface coating agent (e.g., mercapto - silane) to the surface of sepiolite. For example, when the surface coating agent comprises or is mercapto - silane, the polysilane molecules may first be hydrolyzed by trace amounts of water present on the sepiolite surface and then form covalent bonds with the sepiolite surface.

[0153] Tables 3A - 3B show the preparation of Examples 13 - 18 from natural sepiolite feedstock using surface functionalization treatment. In Tables 3A - 3B, the weight percentage of the surface coating agent (e.g., mercapto - silane) is determined as a percentage of the weight of the resulting adsorbent. More specifically, for the mercapto surface - coating solution, the portion of the solvent (e.g., ethanol) evaporated during the drying process is not included in the weight of the resulting adsorbent used in the calculations in Table 3B. Similarly, in Tables 3A - 3B, the weight percentage of the quaternary amine (contained in the quaternary amine compound (e.g., approximately 50% of the weight of the quaternary amine compound used)) is determined as a percentage of the weight of the resulting adsorbent. For the amine surface - coating solution, the portion of deionized water in which the quaternary amine compound is dispersed (evaporated during the drying process) is not included in the weight of the resulting adsorbent used in the calculations in Table 3B.

[0154] For example, in Example 13, 1 g of mercapto - silane accounts for 1 wt% of the total adsorbent weight of 97.5 g (1 g of mercapto - silane plus 2.5 g of quaternary amine plus 94 g of sepiolite), and 2.5 g of quaternary amine accounts for 3 wt% of the total resulting adsorbent weight of 97.5 g. For clarity, in Example 13, 5 g of a bis - quaternary amine compound was used, of which 50% (2.5 g) is quaternary amine.

[0155] The weight % of the quaternary amine in deionized water is calculated as follows: [weight of quaternary amine / (weight of quaternary amine+weight of deionized water)] * 100. Similarly, the weight percentage of the mercapto group in the solvent is calculated as follows: [weight of mercapto - silane / (weight of mercapto - silane+weight of solvent)] * 100.

[0156] Examples 13 - 15

[0157] Examples 13 to 15 were all prepared using a dual - surface treatment of a quaternary - amine surface - coating solution and a mercapto - surface - coating solution. Tables 3A - 3B show the different loading levels of the quaternary - amine surface - coating solution and the mercapto - surface - coating solution to study the effect of PFAS - affinity functional groups on PFAS removal.

[0158] As previously discussed, the quaternary amine surface coating solution contains a quaternary amine compound and water (the quaternary amine compound is dispersed in deionized water). Examples 13 - 15 were prepared using a dual surface treatment and drying similar to that of Examples 10 to 12. Each quaternary amine compound contains a bis - quaternary amine compound, so the quaternary amine surface coating solutions of Examples 13 - 15 all contain a bis - quaternary amine compound and deionized water. More specifically, in Examples 13 - 15, the quaternary amine surface coating solution for surface coating sepiolite was prepared by mixing Evonik 477, N,N,N,N’,N’ - pentamethyl - N’ - tallow alkyl trimethylenediammonium dichloride (a bis - quaternary amine compound) in a 100 mL glass beaker on a magnetic stirrer plate for 10 minutes. The weight of the bis - quaternary amine in the exemplary bis - quaternary amine compound (Evonik 477) was estimated to be approximately 50% of the total weight of the Evonik 477 solution used. Then the sepiolite feed was mixed with the quaternary amine surface coating solution in a KitchenAid 5 - quart food mixer at low speed for about 30 minutes. Each quaternary amine surface coating solution of Examples 10 - 12 contained no mono - quaternary amine, no oleylamine, and no octylamine. As in the previous Examples 3 - 9, the amine - surface - functionalized sepiolite was further surface - functionalized with a mercapto - surface coating solution and dried. The resulting adsorbent was in powder form, without extrusion, without acid activation, and without residual acid (acid - free). The quaternary amine surface coating solutions of Examples 13 - 15 all contain no mono - quaternary amine, no oleylamine, and no octylamine. Thereafter, the amine - surface - functionalized sepiolite was further surface - functionalized with a mercapto - surface coating solution.

[0159] As can be seen in Tables 3A - 3B, the mercapto - surface coating solutions in Examples 13 - 15 used different loading levels of the surface coating agent and solvent. As previously discussed, the mercapto - surface coating solution contains a surface coating agent and a solvent. The surface coating agent contains one or more mercapto groups. In Examples 13 - 15, the surface coating agent contains a silane and one or more mercapto groups. The surface coating agent is referred to as "mercapto - silane" in Tables 3A - 3B. In each of Examples 13 - 15, the surface coating agent used was γ - mercaptopropyltrimethoxysilane (Momentive Silquest A - 189)), and the solvent was ethanol.

[0160] In Examples 13 - 15, the mercapto surface coating solution for surface coating sepiolite was prepared by mixing a surface coating agent (mercapto silane) in a solvent (ethanol) in a 100 mL glass beaker on a magnetic stirrer plate for 10 minutes. Then, the sepiolite feedstock that had been surface-functionalized with a quaternary amine surface coating solution was fed and mixed with the mercapto surface coating solution in a KitchenAid 5 quart food mixer. After mixing at low speed for 30 minutes, the mixture was dried in an oven at 60 - 70 °C for 4 hours. The resulting adsorbent was in powder form, without extrusion, without acid activation, and without residual acid (acid-free).

[0161] Examples 16 - 18

[0162] Each of Examples 16 to 18 was prepared using a dual surface treatment with a quaternary amine surface coating solution and a mercapto surface coating solution. Tables 3A - 3B show the different loading levels of the quaternary amine surface coating solution and the mercapto surface coating solution used to study the effect of PFAS affinity functional groups on PFAS removal. As previously discussed, the quaternary amine surface coating solution contains a quaternary amine compound and water (the quaternary amine compound is dispersed in DI water). In Examples 16 - 18, the quaternary amine surface coating solution for surface coating sepiolite was prepared by mixing Kemira Superfloc C-577 (a monoquaternary amine compound, a polymer of 1,2-ethylenediamine with (chloromethyl)oxirane and N-methylmethylamine]) in DI water in a 100 mL glass beaker on a magnetic stirrer plate for 10 minutes. Then, the sepiolite feedstock was mixed with the quaternary amine surface coating solution in a KitchenAid 5 quart food mixer at low speed for approximately 30 minutes. In Examples 16 - 18, the quaternary amine compound contains (or is) a monoquaternary amine compound, so the quaternary amine surface coating solutions of Examples 16 - 18 each contain a monoquaternary amine compound and DI water. The estimated weight of the monoquaternary amine in the exemplary monoquaternary amine compound (Kemira Superfloc C-577) is about 50% of the total weight of the Kemira Superfloc C-577 solution used. In addition, each of the quaternary amine surface coating solutions of Examples 16 - 18 contains no diquaternary amine, nor does it contain oleylamine and octylamine.

[0163] As can be seen in Tables 3A - 3B, the mercapto surface coating solutions in Examples 16 - 18 used different loading levels of the surface coating agent and the solvent. The mercapto surface coating solution contains a surface coating agent and a solvent. The surface coating agent contains one or more mercapto groups. In Examples 16 - 18, the surface coating agent contains silane and one or more mercapto groups, and this surface coating agent is referred to as "mercapto silane" in Tables 3A - 3B. In each of Examples 16 - 18, the surface coating agent used is γ-mercaptopropyltrimethoxysilane (Momentive Silquest A-189), and the solvent is ethanol.

[0164] In Examples 16 - 18, the mercapto surface coating solution for surface coating sepiolite was prepared by mixing the surface coating agent (mercapto silane) in a solvent (ethanol) in a 100 mL glass beaker on a magnetic stirring plate for 10 minutes. Then, the sepiolite previously surface - functionalized with the quaternary amine surface coating solution was fed and mixed with the mercapto surface coating solution in a KitchenAid 5 - quart food mixer. After mixing at low speed for 30 minutes, the mixture was dried in an oven at 60 - 70 °C for 4 hours. The resulting adsorbent was in powder form, without extrusion, without acid activation, and without residual acid (acid - free).

[0165] Examples 3 - 18 were prepared at different mercapto silane and quaternary amine loading levels to study the effect on PFAS removal. As shown in Table 5, the surface area measurements of the products containing doubly surface - functionalized natural palygorskite (Examples 4 - 12) showed that the surface coating reduced the surface area of the sepiolite used as the feed, and the surface area measurements of the products containing doubly surface - functionalized natural sepiolite (Examples 13 - 18) showed that the surface coating reduced the surface area of the sepiolite used as the feed.

[0166] Table 5. Doubly surface - functionalized natural palygorskite and doubly surface - functionalized natural sepiolite, each prepared at different mercapto silane and quaternary amine loading levels.

[0167] Sepiolite feed <![CDATA[Surface area (m 2 / g)]]> Example 4 141 Example 5 130 Example 6 120 Example 7 98 Example 8 64 Example 9 60 Example 10 51 Example 11 127 Example 12 94 Palygorskite feed 61 Example 13 272 Example 14 164 Example 15 140 Example 16 96 Example 17 231 Example 18 175 Figure 3 105

[0168] Figure 3 The pore size distributions (measured by mercury intrusion porosimetry) of the palygorskite feed and the surface - functionalized samples of Examples 4 and 7 are shown. Figure 13 It is shown (for the palygorskite feed and Examples 4 and 7) that the peak positions of the small intrinsic pores are from about 10 nm to about 25 nm, and the peak positions of the large mesopores are from about 2.5 microns to about 11 microns. As used herein, "intrinsic pores" are (a) pores located on the particle surface of palygorskite or (b) pores located in the structure of palygorskite particles. As used herein, "inter - pores" are pores located between palygorskite particles. Figure 13 The pore size distributions (measured by mercury intrusion porosimetry) of the sepiolite feed and the surface - functionalized samples of Examples 13 and 18 are shown. Figure 13 It is shown (for Examples 13 and 18) that there are small intrinsic pores of about 10 - 25 nm, and the peak positions of the small intrinsic pores are at about 14 nm (Example 13) and about 17 nm (Example 18). Figure 13 It is also shown (for Example 13) that there are large inter - pores from 600 nm to 40 microns, and the peak positions of the large inter - pores are at about 2 microns (large peak), 5.7 microns (small peak), 12 microns (medium peak), and 29 microns (small peak). PFAS adsorption testAlso shown (for Example 18) are macropores from 600 nm to 22 microns, with peak positions of the macropores at about 2.5 microns (large peak), 5.7 microns (small peak), and 16 microns (small peak). As shown in Table 4, surface functionalization slightly reduces the pore volume and porosity. Table 4 also shows that after surface functionalization with mercapto silane, the particle size measured by a laser particle size analyzer may increase slightly. The high surface area and unique mesoporous structure of the palygorskite feedstock containing natural palygorskite contribute to the resulting product being effectively used as an adsorbent for various applications including PFAS adsorption. Similarly, the high surface area and unique mesoporous structure of the sepiolite feedstock containing natural sepiolite contribute to the resulting product being effectively used as an adsorbent for various applications including PFAS adsorption.

[0169] Figure 4

[0170] The products disclosed herein can all be used for adsorbing PFAS in liquids. For the PFAS adsorption tests of each feedstock and adsorbent in Examples 1 - 3, the influent PFAS solution was prepared by incorporating a 20 parts per billion (ppb) PFAS standard solution containing 35 PFAS substances into deionized water to bring the PFAS concentration to about 40 parts per trillion (ppt). For the PFAS adsorption tests of each adsorbent in Examples 4 - 18, the influent PFAS solution was prepared by incorporating a 20 ppb PFAS standard solution containing 35 PFAS substances into deionized water to bring the PFAS concentration to about 80 parts per trillion (ppt). The actual PFAS concentration was measured using liquid chromatography - mass spectrometry (LC - MS) according to the standard EPA method 533 (Determination of Per - and Polyfluoroalkyl Substances in Drinking Water by Isotope Dilution Anion - Exchange Solid - Phase Extraction and Liquid Chromatography / Tandem Mass Spectrometry).

[0171] For the PFAS adsorption tests of each of Examples 1 - 18, 300 mg of the corresponding adsorbent (Examples 1 - 18) was mixed with 250 mL of the prepared PFAS solution on an oscillator at room temperature for 18 hours. After the adsorption test, the adsorbent was separated from the liquid using the EPA standard solid - phase extraction (SPE) method SW846 (Test Methods for Evaluating Solid Wastes, Physical / Chemical Methods). The PFAS concentration of the filtrate was measured using LC - MC based on EPA method 533.

[0172] The individual PFAS removal efficiency is calculated as follows:

[0173]

[0174] The total PFAS removal efficiency is calculated as follows:

[0175]

[0176] The results of PFAS adsorption tests conducted using a preparation solution with a PFAS concentration of 40 ppt are shown in Tables 6 and 7. Figure 5 (Or Table 8) shows that, compared with the untreated natural palygorskite feed and the sample treated with the quaternary amine surface coating solution of Example 2 (containing a monoquaternary amine compound), the total PFAS removal efficiency of the sample treated with the mercapto surface coating solution of Example 1 is significantly improved. Surface treatment using a mercapto surface coating solution (such as mercapto silane and ethanol) and a quaternary amine surface coating solution (containing a monoquaternary amine compound and DI water) (Example 3) unexpectedly further improves the total PFAS removal efficiency. This may be due to the interaction of these two functional groups (the mercapto functional group and the monoquaternary amine compound functional group), which enhances the affinity of PFAS for the palygorskite surface.

[0177] Figure 6 Shows the effects of surface functionalization of palygorskite feed with the mercapto surface coating solution of Example 1 (see Tables 3A, 3B, and 6), treatment with the quaternary amine surface coating solution of Example 2 (see Tables 3A, 3B, and 6), and dual surface functionalization with the quaternary amine surface coating solution and the mercapto surface coating solution of Example 3 (see Tables 3A, 3B, and 7) on the removal of selected PFAS substances in a 40 ppt synthetic PFAS starting solution. Similar to the total PFAS removal efficiency, compared with treatment with the mercapto surface coating solution alone (Example 1) and treatment with the quaternary amine surface coating solution alone (Example 2), treatment with both the mercapto surface coating solution (containing mercapto silane and ethanol) and the quaternary amine surface coating solution (containing a monoquaternary amine compound and deionized water) in Example 3 enhances the removal of these selected PFAS substances.

[0178] Table 6. PFAS Adsorption Using Feed and Examples 1 and 2 as Adsorbents.

[0179]

[0180]

[0181]

[0182] Table 7. PFAS Adsorption Using Example 3 as an Adsorbent.

[0183]

[0184]

[0185] Table 8 shows a comparison of the total PFAS removal efficiency of untreated attapulgite feedstock and Examples 1-3 prepared from the feedstock using surface functionalization treatment in a 40 ppt PFAS solution. Similar to Tables 3A-3B, in Table 8, the weight percentage of the surface coating agent (e.g., mercapto silane) is determined as the weight percentage of the resulting adsorbent, and the weight percentage of the quaternary amine is determined as the weight percentage of the resulting adsorbent. Unexpectedly, compared with the individual quaternary amine or mercapto silane surface coating on attapulgite, the combination of the quaternary amine and mercapto silane surface coating on attapulgite enhances PFAS adsorption.

[0186] Table 8. Total PFAS removal efficiency in 40 ppt PFAS solution.

[0187]

[0188] Tables 9 and 10 show the results of PFAS adsorption tests using Examples 4-9 (samples treated with both a mercapto surface coating solution (containing mercapto silane and ethanol) and a quaternary amine surface coating solution (containing a quaternary amine compound and DI water)) in a prepared solution with a PFAS concentration of 80 ppt. Figure 7 show that the total PFAS removal efficiency increases with the increase in the total mercapto silane and quaternary amine loading levels. A similar trend was also observed for the selected PFAS substances ( Figure 8 ).

[0189] Figure 9 show that for Example 8, among 35 PFAS substances (see Table 10), the removal efficiency of 20 PFAS substances is greater than or equal to 80%, the removal efficiency of 18 PFAS substances is greater than or equal to 85%, and the removal efficiency of 12 PFAS substances is greater than or equal to 90%.

[0190] Table 9: PFAS adsorption using Examples 4-6 as adsorbents.

[0191]

[0192]

[0193] Table 10. PFAS adsorption using Examples 7-9 as adsorbents.

[0194]

[0195]

[0196]

[0197] Table 11 shows a comparison of the total PFAS removal efficiency of Examples 4-9 prepared from the feedstock using surface functionalization treatment in an 80 ppt PFAS solution. Similar to Tables 3B and 8, the weight percentage of the surface coating agent (e.g., mercapto silane) is determined as a percentage of the weight of the resulting adsorbent, and the percentage of quaternary amine is determined as a percentage of the weight of the resulting adsorbent.

[0198] Table 11. Total PFAS removal efficiency in an 80 ppt PFAS solution.

[0199]

[0200] Table 12 shows a comparison of the total PFAS removal efficiency of Examples 10-12 prepared from the feedstock using surface functionalization treatment in an 80 ppt PFAS solution. Figure 10 Shows that the total PFAS removal efficiency increases with the increasing total loading level of mercapto silane and quaternary amine. Similar to Tables 3B and 8, the weight percentage of the surface coating agent (e.g., mercapto silane) is determined as a percentage of the weight of the resulting adsorbent, and the percentage of quaternary amine is determined as a percentage of the weight of the resulting adsorbent.

[0201] Table 12: PFAS adsorption using Examples 10-12 as adsorbents.

[0202]

[0203]

[0204] Figure 11 Is a graph showing the number of PFAS substances in Example 11 with a removal efficiency greater than or equal to 90%, greater than or equal to 95%, or greater than or equal to 97% (out of a total of 35 PFAS substances in Table 12). Figure 11 Shows the exemplary PFAS removal efficiency of Example 11 for the most common PFAS substances (see Table 12). Figure 14 Shows that, among the 35 PFAS substances, the removal efficiency of Example 11 for the 35 PFAS substances tested exceeds 90%, the removal efficiency of Example 11 for PFOA exceeds 96%, the removal efficiency of Example 11 for PFOS exceeds 97%, the removal efficiency of the adsorbent of Example 11 for PFHxS exceeds 95%, and the removal efficiency of the adsorbent of Example 11 for PFNA exceeds 98%.

[0205] Table 13 shows the comparison of the total PFAS removal efficiency of Examples 13 - 15 prepared from the feedstock using surface functionalization treatment in an 80 ppt PFAS solution. As used herein and in Table 13, "ND" means "not detected" or "undetected". As can be seen in Table 13, various PFAS in the effluent of Example 13 are ND (undetected). ND is measured when the effluent contains no PFAS content, or when the PFAS content in the effluent is so minimal that it is below the amount that the instrument can detect (in other words, such PFAS content is below the detection limit of the instrument). For example, in Table 13, PFOA was not detected in the effluent of Example 13. In Table 13, when PFAS is not detected / undetected in the effluent, the removal efficiency (%) of that example is in the range of greater than 99% to 100%, depending on the detection limit of that PFAS (see Table 16 for the detection limits of PFAS).

[0206] Table 13: PFAS Adsorption Using Examples 13 - 15 as Adsorbents

[0207]

[0208]

[0209]

[0210] Table 14 shows the comparison of the total PFAS removal efficiency of Examples 16 - 18 prepared from the feedstock using surface functionalization treatment in an 80 ppt PFAS solution. As used herein and in Table 14, "ND" means "not detected" or "undetected". As can be seen in Table 14, various PFAS in the effluent of various examples are ND (undetected). As described above, ND is measured when the effluent contains no PFAS content or when such PFAS content is so minimal that it is below the amount that the instrument can detect (such PFAS content is below the detection limit of the instrument). For example, in Table 14, PFNA was not detected in the effluent of Example 18. In Table 14, when PFAS is not detectable / undetected in the effluent of an example, the removal efficiency (%) of that example is in the range of greater than 99% to 100%, depending on the detection limit of that PFAS (see Table 16 for the detection limits of PFAS).

[0211] Table 14: PFAS Adsorption Using Examples 16 - 18 as Adsorbents

[0212]

[0213]

[0214]

[0215] Figure 14 Based on the data in Table 13. PFAS substances A graph showing the number of PFAS substances with a removal efficiency greater than or equal to 90%, greater than or equal to 95%, or greater than or equal to 97% for Example 13 (out of a total of 35 PFAS substances in Table 13). As discussed above, when a selected PFAS is not detected in the effluent of Example 13, the removal efficiency (%) of Example 13 for the selected PFAS is in the range of 99% to 100%, depending on the detection limit of the PFAS. Table 15 shows the removal efficiency of Example 13 for the most common PFAS substances. After separation in Example 13, PFOA, PFOS, PFHxS, and PFNA were not detected in the effluent. Specifically, when the PFOA content is in the range of zero to less than 0.38 ppt, the instrument used to measure PFOA in the effluent will not detect the PFOA content in the effluent. Therefore, when the PFOA level is 0 ppt to less than 0.38 ppt, the removal efficiency is greater than 99.53%. Similarly, when the PFOS content is in the range of 0 ppt to less than 0.26 ppt, the instrument used to measure PFOS in the wastewater will not detect the PFOS content in the wastewater. Therefore, when the PFOS content is in the range of 0 ppt to less than 0.26 ppt, the removal efficiency is greater than 99.69%. When the PFHxS content is in the range of 0 ppt to less than 0.23 ppt, the instrument used to measure PFHxS in the wastewater will not detect the PFHxS content in the wastewater. Therefore, when the PFHxS content is in the range of 0 ppt to less than 0.23 ppt, the removal efficiency is greater than 99.69%. When the PFNA content is in the range of 0 to less than 0.21 ppt, the instrument used to measure PFNA in the effluent cannot detect the PFNA content in the effluent. Therefore, when the PFNA content is 0 ppt to less than 0.21 ppt, the removal efficiency is greater than 99.72%.

[0216] Table 15. Removal efficiency of Example 13 for the most common PFAS substances.

[0217] Effluent concentration PFOA PFOS ND(<0.38ppt) PFHxS ND (<0.26 ppt) PFNA ND (<0.23 ppt) Industrial applicability ND(<0.21 ppt)

[0218] Table 16 shows the detection limits of various PFAS substances that are ND in Tables 13 - 14. The detection limit is the lowest amount of the selected PFAS that the instrument used to measure such PFAS content can detect. When the PFAS content is below the detection limit shown in Table 16, the instrument used to measure such PFAS substances in the effluent cannot detect such PFAS substances in the effluent. For example, when the PFOA content level is 0 ppt to below 0.38 ppt, the instrument used cannot detect the PFOA content in the effluent.

[0219] Table 16. Instrument detection limits of various PFASs.

[0220]

[0221] Table 17 shows a comparison of the total PFAS removal efficiency of Examples 13 - 18 prepared from the feed using surface functionalization treatment in an 80 ppt PFAS solution. Similar to Table 3B, the weight percentage of the surface coating agent (such as mercapto silane) is determined as the weight percentage of the resulting adsorbent, and the percentage of quaternary amine is determined as the weight percentage of the resulting adsorbent.

[0222] Table 17. Total PFAS removal efficiency in an 80 ppt PFAS solution.

[0223]

[0224] Disclosed herein is a method for adsorbing at least one PFAS from a liquid. The liquid can include but is not limited to water (such as fresh water, seawater, etc.), edible oil, wastewater, process water, or a combination thereof. For example, the liquid can include or can be water-in-oil or oil-in-water. The method can include: mixing / contacting the liquid with any one of the products disclosed herein that contain palygorskite and / or sepiolite surface-functionalized with a quaternary amine surface coating solution and a mercapto surface coating solution. The liquid and the product can form a slurry.

[0225] The mixing / contacting can occur for a contact time and a product loading sufficient to reduce the amount of PFAS in the liquid during the contact time, thereby achieving a PFAS efficiency of 70 - 100%, 80 - 100%, 90 - 100%, 95 - 100%, or 97 - 100% (for removing PFAS from the liquid). For example, in an exemplary embodiment, at a product loading of 0.5 - 2 g per liter of liquid, the product can have a PFAS removal efficiency of 70% - 100% in the liquid within a contact time of about 12 - 25 hours; in an improvement, at a product loading of 0.5 - 2 g per liter of liquid, the product can have a PFAS removal efficiency of 80% - 100% in the liquid within a contact time of about 12 - 25 hours; in an improvement, at a product loading of 0.5 - 2 g per liter of liquid, the product can have a PFAS removal efficiency of 90% - 100% in the liquid within a contact time of about 12 - 25 hours; in another improvement, at a product loading of 0.5 - 2 g per liter of liquid, the product can have a PFAS removal efficiency of 95% - 100% in the liquid within a contact time of about 12 - 25 hours. Other loadings and contact times can also be employed.

[0226] The quaternary amine surface coating solution can contain water (e.g., deionized water) and (a) a monoquaternary amine compound containing one or more monoquaternary amines attached to the surface of palygorskite / sepiolite, or (b) a diquaternary amine compound containing one or more diquaternary amines attached to the surface of palygorskite / sepiolite. When the quaternary amine surface coating solution contains one or more monoquaternary amine compounds, the quaternary amine surface coating solution (and the product) does not contain diquaternary amines. When the quaternary amine surface coating solution contains one or more diquaternary amine compounds, the quaternary amine surface coating solution (and the product) does not contain monoquaternary amines. The mercapto surface coating solution can contain a solvent and one or more mercapto groups chemically bonded to the surface of palygorskite or sepiolite.

[0227] The method can also include separating the product from the liquid to recover the resulting liquid, which has a lower PFAS content than the liquid before mixing. In one embodiment, the weight percentages of the product components can include: 85 - 94 wt% palygorskite; 2.5 - 15 wt% of (i) one or more monoquaternary amines or (ii) one or more diquaternary amines; and 1 - 8 wt% of a surface coating agent containing one or more mercapto groups. Measured using the BET method, the surface area of the product can be in the range of 45 - 160 m 2 / g or 45 - 150 m 2 / g or 45 - 130 m 2 / g or 50 - 100 m 2 / g. In another embodiment, the weight percentages of the product components can include: 76 - 97 wt% sepiolite; 1 - 16 wt% of (i) one or more monoquaternary amines or (ii) one or more diquaternary amines; and 0.5 - 8 wt% of a surface coating agent containing one or more mercapto groups. Measured using the BET method, the surface area of the product can be in the range of 76 - 276 m 2 / g or 86 - 254 m 2 / g or 91 - 243 m 2 / g or 96 - 231 m 2 / g. The resulting liquid can be recovered from the slurry by filtration or any other suitable method known to those skilled in the art. The products disclosed herein can be used alone as a main feed and / or as a pre - coat mixed with filter aids (e.g., diatomaceous earth and perlite) in a filtration system.

[0228] Other adsorption methods can be used. Such other adsorption methods can include passing the PFAS - containing liquid through a column filled with the dual - surface - functionalized palygorskite / sepiolite disclosed herein. The contact time can be adjusted by changing process parameters (such as column length, column diameter, adsorbent packing density, and / or liquid flow rate, etc.).

[0229] ​

[0230] Generally speaking, the above disclosure can be used to remove PFAS contained in liquids. Historically, common commercially available PFAS removal technologies have included activated carbon adsorption, anion exchange resins, and high-pressure membranes. Activated carbon is a less efficient technology. Anion exchange resin and high-pressure membrane technologies are expensive due to high material and equipment costs.

[0231] The new products disclosed herein can be used as adsorbents for reducing PFAS in liquids. Such products have a high removal efficiency for PFAS, which significantly reduces the treatment time and provides a greater removal of PFAS from liquids. In addition, compared with commercially used activated carbon, the products disclosed herein can be used in significantly smaller amounts, which generates less waste to be treated. For example, the new product can be used as a main feed or precoat (with or without filter aid) in a liquid filtration system to remove PFAS substances. It can also be used to cover PFAS-contaminated sediments for PFAS soil remediation.

[0232] As can be seen from the above, although certain embodiments have been described for illustrative purposes only, alternative and modification options will be apparent to those skilled in the art from the above description. These and other alternatives are considered equivalent and are within the spirit and scope of the present disclosure and the appended claims.

Claims

1. A product for adsorbing at least one PFAS in a liquid, the product comprising palygorskite surface-functionalized with: (a) a quaternary amine surface coating solution comprising a monoquaternary amine compound or a diquaternary amine compound, the monoquaternary amine compound comprising one or more monoquaternary amines attached to the surface of the palygorskite, the diquaternary amine compound comprising one or more diquaternary amines attached to the surface of the palygorskite, and (b) a surface coating agent comprising one or more thiol groups chemically bonded to the surface of the palygorskite, wherein when the quaternary amine surface coating solution comprises one or more monoquaternary amine compounds, the product does not contain diquaternary amines, wherein when the quaternary amine surface coating solution comprises one or more diquaternary amine compounds, the product does not contain monoquaternary amines, wherein measured by the BET method, the surface area of the product is in the range of 45 - 160 m 2 / g or 50 - 100 m 2 / g, wherein the d 50 of the particle size distribution of the product is 6 - 30 microns or 10 - 25 microns or 12 - 25 microns or 12 - 23 microns.

2. The product according to claim 1, wherein the surface coating agent is a thiol silane.

3. The product according to claim 1, wherein the product is in powder form and / or unextruded.

4. The product according to claim 1, wherein: When the loading of the product in the liquid is 0.5 - 2 g per liter, the PFAS removal efficiency of the product for the at least one PFAS in the liquid is 70 - 100%, 80 - 100%, 90 - 100%, 95 - 100% or 97 - 100% within 12 - 25 hours.

5. The product according to claim 1, wherein the porosity of the product is 40 - 90%, and the pore volume is 0.7 - 1.5 mL / g.

6. The product according to claim 1, wherein the weight percentage of the components of the product comprises: 85 - 94 wt% palygorskite; 2.5 - 15 wt% of (i) a monoquaternary amine or (ii) a diquaternary amine; and 1 - 8 wt% of a surface coating agent.

7. The product according to claim 1, wherein the product does not contain oleylamine and octylamine.

8. The product according to claim 1, wherein the product does not contain residual acid.

9. A method for preparing a product for adsorbing at least one PFAS from a liquid, the method comprising: Palygorskite is selected as the feedstock, and before surface treatment, the selected palygorskite as the feedstock contains 7 - 16 wt% or 9 - 14 wt% moisture when measured at a temperature of 104 °C; The palygorskite is surface-treated with a quaternary amine surface coating solution, and the quaternary amine surface coating solution contains (i) a monoquaternary amine compound, the monoquaternary amine compound containing one or more monoquaternary amines attached to the surface of the palygorskite, or (ii) a diquaternary amine compound, the diquaternary amine compound containing one or more diquaternary amines attached to the surface of the palygorskite; and The palygorskite is surface-treated with a mercapto surface coating solution, and the mercapto surface coating solution contains a surface coating agent, the surface coating agent including one or more mercapto groups chemically bonded to the surface of the palygorskite, Among them, measured by the BET method, the surface area of the prepared product is in the range of 45 - 160 m 2 / g, wherein when the quaternary amine surface coating solution contains the monoquaternary amine compound, the product does not contain a diquaternary amine, wherein when the quaternary amine surface coating solution contains the diquaternary amine compound, the product does not contain a monoquaternary amine.

10. The method according to claim 9, wherein the weight percentages of the components of the product include: 85 - 94 wt% palygorskite; 2.5 - 15 wt% of (i) one or more monoquaternary amines or (ii) one or more diquaternary amines; and 1 - 8 wt% of a surface coating agent including one or more of the mercapto groups, wherein the product does not contain oleylamine and octylamine.

11. The method according to claim 9, wherein the quaternary ammonium surface coating solution further comprises water, wherein the mercapto surface coating solution further comprises a solvent, wherein the surface coating agent comprises mercapto silane.

12. The method according to claim 9, wherein the surface treatment of the palygorskite with the mercapto surface coating solution is carried out after the surface treatment of the palygorskite with the quaternary ammonium surface coating solution.

13. The method according to claim 12, wherein the quaternary ammonium surface coating solution further comprises water.

14. The method according to claim 9, further comprising: The palygorskite is dried, wherein the one or more monoquaternary amines are dried on the palygorskite of the prepared product, or the one or more diquaternary amines are dried on the palygorskite of the prepared product, and wherein the mercapto surface coating solution is dried on the palygorskite of the prepared product, wherein the prepared product is in powder form or unextruded.

15. The method according to claim 9, wherein the d of the particle size distribution of the product 50 is 6 - 30 microns or 10 - 25 microns or 12 - 25 microns or 12 - 23 microns.

16. The method according to claim 9, wherein when the loading of the product in each liter of the liquid is 0.5 - 2 g, the PFAS removal efficiency of the product for the at least one PFAS in the liquid is 70 - 100%, 80 - 100%, 90 - 100%, 95 - 100% or 97 - 100% within 12 - 25 hours.

17. A method for adsorbing at least one PFAS in a liquid, the method comprising: Contact the liquid with a product comprising palygorskite surface-functionalized with: (a) a quaternary amine surface coating solution, the quaternary amine surface coating solution containing a monoquaternary amine compound or a diquaternary amine compound, the monoquaternary amine compound containing one or more monoquaternary amines attached to the palygorskite surface, the diquaternary amine compound containing one or more diquaternary amines attached to the palygorskite surface, and (b) a surface coating agent, the surface coating agent including one or more mercapto groups chemically bonded to the palygorskite surface; and Separate the product from the liquid to recover the resulting liquid, the PFAS content of the resulting liquid being lower than that of the liquid before mixing. The weight percentages of the components of the product include: 85-94% by weight of sepiolite, 2.5-15% by weight of (i) one or more monoquaternary amines or (ii) one or more diquaternary amines, and 1-8% by weight of a surface coating agent comprising the one or more mercapto groups, wherein when the quaternary amine surface coating solution comprises one or more monoquaternary amine compounds, the product does not contain diquaternary amine compounds, wherein when the quaternary amine surface coating solution comprises one or more diquaternary amine compounds, the product does not contain monoquaternary amine compounds, Measured using the BET method, the surface area of the product is in the range of 45 - 160 m 2 / g, wherein when the loading of the product in each liter of the liquid is 0.5-2 g, the removal efficiency of the product for PFAS is 10-100%.

18. The method according to claim 17, wherein the liquid comprises water, edible oil, wastewater, production water, or a combination thereof.

19. The method according to claim 17, wherein the surface coating agent comprises mercapto silane.

20. The method according to claim 17, wherein when the contact lasts for 12 - 25 hours and the loading of the product in each liter of the liquid is 0.5 - 2 g, the PFAS removal efficiency of the product for the at least one PFAS is 70 - 100%, 80 - 100%, 90 - 100%, 95 - 100%, or 97 - 100%.

21. A product for adsorbing at least one PFAS in a liquid, the product comprising sepiolite surface - functionalized with: (a) a quaternary amine surface - coating solution, the quaternary amine surface - coating solution comprising a mono - quaternary amine compound or a bis - quaternary amine compound, the mono - quaternary amine compound comprising one or more mono - quaternary amines attached to the surface of sepiolite, the bis - quaternary amine compound comprising one or more bis - quaternary amines attached to the surface of the sepiolite, and (b) a surface coating agent, the surface coating agent comprising one or more mercapto groups chemically bonded to the surface of the sepiolite, wherein when the quaternary amine surface - coating solution comprises one or more mono - quaternary amine compounds, the product does not contain bis - quaternary amines, wherein when the quaternary amine surface - coating solution comprises one or more bis - quaternary amine compounds, the product does not contain mono - quaternary amines, wherein the surface area of the surface - functionalized product or the sepiolite, measured by the BET method, is in the range of 76 - 276 m 2 / g or 80 - 254 m 2 / g, wherein the d 50 of the particle size distribution of the surface - functionalized product or the sepiolite is 10 - 25 microns or 11 - 22 microns or 12 - 21 microns.

22. The product according to claim 21, wherein the surface coating agent is mercapto silane.

23. The product according to claim 21, wherein the product is in powder form and / or unextruded.

24. The product according to claim 21, wherein: When the loading of the product in each liter of the liquid is 0.5-2 g, the PFAS removal efficiency of the product for the at least one PFAS in the liquid is 70-100%, 80-100%, 90-100%, 95-100% or 97-100% within 12-25 hours.

25. The product according to claim 21, wherein the porosity of the product is 62 - 86% and the pore volume is 1.3 - 3 mL / g.

26. The product according to claim 21, wherein the weight percentage of the components of the product includes: 76-97% by weight of sepiolite; 1-16% by weight of: (i) monoquaternary amine or (ii) diquaternary amine; and 0.5-8% by weight of a surface coating agent.

27. The product according to claim 21, wherein the product does not contain oleylamine and octylamine.

28. The product according to claim 21, wherein the product does not contain residual acid.

29. A method for preparing a product for adsorbing at least one PFAS from a liquid, the method comprising: Sepiolite is selected as the feedstock, and before surface treatment, the sepiolite selected as the feedstock contains 16-20% by weight of moisture measured by loss on ignition (LOI); The sepiolite is surface-treated with a quaternary amine surface coating solution, and the quaternary amine surface coating solution comprises (i) a monoquaternary amine compound, and the monoquaternary amine compound comprises one or more monoquaternary amines attached to the surface of the sepiolite, or (ii) a diquaternary amine compound, and the diquaternary amine compound comprises one or more diquaternary amines attached to the surface of the sepiolite; and The sepiolite is surface-treated with a mercapto surface coating solution, and the mercapto surface coating solution comprises a surface coating agent, and the surface coating agent comprises one or more mercapto groups chemically bonded to the surface of the sepiolite, Among them, measured by the BET method, the surface area of the prepared product is in the range of 76 - 276 m 2 / g, wherein when the quaternary amine surface coating solution comprises the monoquaternary amine compound, the product does not contain diquaternary amine, wherein when the quaternary amine surface coating solution comprises the diquaternary amine compound, the product does not contain monoquaternary amine.

30. The method according to claim 29, wherein the weight percentage of the components of the product comprises: 76-97% by weight of sepiolite; 1-16% by weight of (i) one or more monoquaternary amines or (ii) one or more diquaternary amines; and 0.5-8% by weight of a surface coating agent comprising the one or more mercapto groups, wherein the product does not contain oleylamine and octylamine.

31. The method according to claim 29, wherein the quaternary amine surface coating solution further comprises water, wherein the mercapto surface coating solution further comprises a solvent, wherein the surface coating agent comprises mercapto silane.

32. The method according to claim 29, wherein the surface treatment of the sepiolite with the mercapto surface coating solution is after the surface treatment of the sepiolite with the quaternary amine surface coating solution.

33. The method according to claim 32, wherein the quaternary amine surface coating solution further comprises water.

34. The method according to claim 29, further comprising: The sepiolite is dried, and the one or more monoquaternary amines are dried on the sepiolite of the prepared product, or the one or more diquaternary amines are dried on the sepiolite of the prepared product, and the mercapto surface coating solution is dried on the sepiolite of the prepared product, wherein the prepared product is in powder form or unextruded.

35. The method according to claim 29, wherein the d of the particle size distribution of the product 50 is 10 - 25 microns or 11 - 22 microns or 12 - 21 microns.

36. The method according to claim 29, wherein when the loading of the product in each liter of the liquid is 0.5-2 g, the PFAS removal efficiency of the product for the at least one PFAS in the liquid is 70-100%, 80-100%, 90-100%, 95-100% or 97-100% within 12-25 hours.

37. A method for adsorbing at least one PFAS in a liquid, the method comprising: Contact the liquid with a product comprising sepiolite functionalized with the following: (a) a quaternary amine surface coating solution comprising a monoquaternary amine compound or a diquaternary amine compound, the monoquaternary amine compound comprising one or more monoquaternary amines attached to the sepiolite surface, the diquaternary amine compound comprising one or more diquaternary amines attached to the sepiolite surface, and (b) a surface coating agent comprising one or more thiol groups chemically bonded to the sepiolite surface; and Separate the product from the liquid to recover the resulting liquid, the PFAS content of which is lower than that of the liquid before mixing, wherein the composition of the product by weight percentage comprises: 76 - 97 wt% sepiolite, 1 - 16 wt% of (i) one or more monoquaternary amines or (ii) one or more diquaternary amines, and 0.5 - 8 wt% of a surface coating agent comprising one or more thiol groups; wherein when the quaternary amine surface coating solution comprises one or more monoquaternary amine compounds, the product does not contain diquaternary amine compounds, wherein when the quaternary amine surface coating solution comprises one or more diquaternary amine compounds, the product does not contain monoquaternary amine compounds, Among them, measured by the BET method, the surface area of the product is in the range of 76-276 m 2 / g. wherein when the loading of the product per liter of the liquid is 0.5 - 2 g, the removal efficiency of the product for PFAS is 10 - 100%.

38. The method according to claim 37, wherein the liquid comprises water, edible oil, wastewater, production water or a combination thereof.

39. The method according to claim 37, wherein the surface coating agent comprises mercapto silane.

40. The method according to claim 37, wherein when the contact lasts for 12-25 hours and the loading of the product in each liter of the liquid is 0.5-2 g, the PFAS removal efficiency of the product for the at least one PFAS is 70-100%, 80-100%, 90-100%, 95-100% or 97-100%.

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