Methods for removing perfluorinated and polyfluoroalkyl substances from complex water bodies

Abstract

This application proposes a method for removing perfluorinated and polyfluoroalkyl substances (PFAS) from complex water bodies. The method involves introducing a composite carbon material loaded with atomic-level metal sites into the complex water body to adsorb PFAS and PFAs. Specifically, the matrix of the composite carbon material captures PFAS and PFAs through hydrophobic interactions, while the atomic-level metal sites in the composite carbon material anchor PFAS and PFAs through electrostatic adsorption, binding and immobilizing them with the oxygen-containing head groups of the PFAS and PFAs.

Description

Technical Field

[0001] This application belongs to the field of new pollutant water treatment and adsorption material application technology, specifically relating to a method for removing perfluorinated and polyfluoroalkyl substances from complex water bodies. Background Technology

[0002] Per- and polyfluoroalkyl substances (PFAS) are a class of fluorinated organic pollutants with high stability, persistence, and environmental mobility. Due to the high strength of carbon-fluorine bonds in PFAS molecules, they are difficult to degrade in the natural environment and during conventional water treatment processes, and can persist for extended periods in water bodies, sediments, and organisms. Adsorption methods are considered one of the important technical routes for controlling PFAS pollution because of their relatively simple operation, low energy consumption, and ease of integration with existing water treatment processes.

[0003] In related technologies, materials used for PFAS adsorption mainly include activated carbon, ion exchange resins, metal oxides, metal-organic frameworks, and porous carbon materials. However, the adsorption behavior of PFAS in water is affected by various hydrochemical factors, such as pH, ionic strength, polyvalent metal ions, carbonates, phosphates, sulfates, natural organic matter, and particulate colloids. Many existing adsorbents exhibit high adsorption capacity in relatively simple laboratory water systems, but in real water bodies or complex systems with high salinity, multiple ions, and coexisting organic matter, they are prone to problems such as adsorption site competition, pore blockage, significant degradation of adsorption performance, and decreased regeneration efficiency. In addition, the regeneration process of some adsorbents is cumbersome, or the performance recovery after regeneration is not ideal, limiting their stable application in practical water treatment.

[0004] Therefore, developing a PFAS removal method that can maintain high adsorption efficiency under conditions of pH fluctuations, coexisting ions, natural organic matter, and actual water body disturbances is of great practical significance for improving the level of PFAS pollution control technology in complex water systems. Summary of the Invention

[0005] In view of this, in order to solve at least one technical problem in related technologies and other aspects, this application proposes a method for removing perfluorinated and polyfluoroalkyl substances from complex water bodies, comprising introducing a composite carbon material loaded with atomic-level metal sites into the complex water body to adsorb the perfluorinated and polyfluoroalkyl substances in the complex water body; wherein, the matrix of the composite carbon material captures the perfluorinated and polyfluoroalkyl substances through hydrophobic interactions, and the atomic-level metal sites in the composite carbon material anchor the perfluorinated and polyfluoroalkyl substances through electrostatic adsorption and bind and fix them with the oxygen-containing head groups of the perfluorinated and polyfluoroalkyl substances.

[0006] According to the embodiments of this application, the dosage of composite carbon material is 0.005~5.0 g / L.

[0007] According to embodiments of this application, the mass fraction of atomic-level metal sites is 0.1 to 15 wt% based on the total mass of the composite carbon material.

[0008] According to embodiments of this application, the material for the atomic-level metal sites includes at least one of iron, nickel, cobalt, and lanthanum.

[0009] According to embodiments of this application, in the composite carbon material, the matrix of the composite carbon material includes foamed carbon or porous carbon nitride; the specific surface area of ​​the matrix is ​​50~500m². 2 / g, pore volume 0.05~1.00cm³ 3 / g, with an average pore size of 2~20nm.

[0010] According to embodiments of this application, the types of perfluorinated and polyfluoroalkyl substances include at least one of perfluorocarboxylic acids, perfluorosulfonic acids, fluoropolymer sulfonic acids, fluorinated ether acids, perfluoropolyethers, disulfonamides, and perfluorosulfonamides; perfluorocarboxylic acids include at least one of perfluorobutyric acid, perfluorovaleric acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanic acid, perfluorotridecanoic acid, and perfluorotetradecanoic acid; perfluorosulfonic acids include perfluorobutyric acid... At least one of the following: sulfonic acid, perfluoropentanesulfonic acid, perfluorohexanesulfonic acid, perfluoroheptanesulfonic acid, perfluorooctanesulfonic acid, perfluorononanesulfonic acid, perfluorodecanesulfonic acid, and perfluorooctylsulfonamide; fluoropolymer sulfonic acids include at least one of 4:2 fluoropolymer sulfonic acid, 6:2 fluoropolymer sulfonic acid, 8:2 fluoropolymer sulfonic acid, and 10:2 fluoropolymer sulfonic acid; bissulfonylimides include lithium bis(trifluoromethanesulfonyl)imide and / or bisperfluoroalkylsulfonylimide; and perfluorosulfonamides include perfluorooctylsulfonamide.

[0011] According to embodiments of this application, the complex water body also includes coexisting ions or organic matter; coexisting ions include Na+. + Ca 2+ Mg 2+ Li + Ni 2+ Co 2+ Fe 3+ Al 3+ Cl - NO3 - SO4 2- HCO3 - CO3 2- H2PO4 - HPO4 2- F - PF6 - PO2F2 -At least one of the following; organic matter includes at least one of humic acid, dissolved organic matter, carbon black particles, metal oxide particles, and polyvinylidene fluoride particles.

[0012] According to embodiments of this application, the sources of complex water bodies include at least one of the following: natural water, groundwater, drinking water source water, domestic sewage, reclaimed water, industrial wastewater, fluoride-containing wastewater, fire-fighting foam contaminated water, landfill leachate, lithium battery recycling water, black powder washing liquid, acid leaching liquid, alkaline washing liquid, high-salt mother liquor, or residue leachate.

[0013] According to the embodiments of this application, the pH of the complex water body is 2~12, the adsorption time is 1min~48h, and the adsorption temperature is 5~60℃.

[0014] According to embodiments of this application, the aforementioned method for removing perfluorinated and polyfluoroalkyl substances from complex water bodies further includes: placing the adsorbed composite carbon material in an alkaline regeneration solution for regeneration; wherein the alkaline regeneration solution includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water; the concentration of the alkaline regeneration solution is 0.01~5.0 mol / L, and the regeneration time is 0.5~48 h.

[0015] According to embodiments of this application, a composite carbon material loaded with atomic-level metal sites is introduced into a complex aquatic body. The matrix of the composite carbon material captures perfluorinated and polyfluoroalkyl substances (PFAS) through hydrophobic interactions, enriching them on the surface of the composite carbon material. Simultaneously, the atomic-level metal sites loaded on the matrix carry localized charges, enabling them to further anchor PFAS molecules through electrostatic adsorption and specifically bind to the oxygen-containing head groups at the molecular ends. These two effects synergistically occur in a single material: hydrophobic capture increases local concentration, while electrostatic adsorption and head group binding enhance adsorption strength and selectivity. This synergistic mechanism allows for the effective removal of PFAS without relying on additional chemical reagents or complex operating conditions, making it particularly suitable for complex aquatic environments with a high proportion of coexisting components. Attached Figure Description

[0016] Figure 1 These are the morphology and metal dispersion diagrams of the composite carbon material in Example 2 of this application, where a is a transmission electron microscope (TEM) image of Fe-XPS@C, b is a metal dispersion diagram of Fe-XPS@C, c is a TEM image of Ni-XPS@C, d is a metal dispersion diagram of Ni-XPS@C, e is a TEM image of Ni-XPS@C, f is a metal dispersion diagram of Ni-XPS@C, g is a TEM image of La-XPS@C, and h is a metal dispersion diagram of La-XPS@C.

[0017] Figure 2 This is a test chart showing the removal rate and adsorption capacity of perfluorooctanoic acid (PFOA) in water in Example 3 of this application.

[0018] Figure 3 This is the adsorption curve for removing perfluorooctanoic acid from water in Example 3 of this application;

[0019] Figure 4 This is a test graph showing the removal rate and adsorption capacity of perfluorooctanoic acid (PFOA) in water in Example 4 of this application.

[0020] Figure 5 This is a comparison chart of the adsorption capacity of perfluorooctanoic acid (PFOA) in different water bodies (coexisting water chemical components) in Example 5 of this application. In the chart, a shows the adsorption of PFOA in water bodies containing coexisting cations, and b shows the adsorption in water bodies containing NO3. - and SO4 2- The adsorption of perfluorooctanoic acid (PFOA) in water bodies is shown in diagram c, where HCO3 is present. - CO3 2- and H2PO4 - / HPO4 2- d is a diagram showing the adsorption of perfluorooctanoic acid (PFOA) in water bodies containing humic acid.

[0021] Figure 6 This is a comparison chart of the adsorption capacity for removing perfluorooctanoic acid from different water bodies in Example 6 of this application;

[0022] Figure 7 This is a graph showing the removal rate results of the composite carbon material after recycling in Example 6 of this application;

[0023] Figure 8 This is a graph showing the leaching rate results of the composite carbon material in Example 6 of this application;

[0024] Figure 9 These are the infrared spectra of Fe-XPS@C before and after adsorption in Example 7 of this application;

[0025] Figure 10 These are XPS spectra of Fe-XPS@C before and after adsorption in Example 7 of this application, where a is the XPS spectrum of Fe-XPS@C before adsorption and b is the XPS spectrum of Fe-XPS@C after adsorption.

[0026] Figure 11 These are XPS spectra of different composite carbon materials after adsorption in Example 7 of this application;

[0027] Figure 12 This is a test graph showing the removal rate and adsorption capacity of perfluorooctane sulfonate in water in Example 9 of this application. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0029] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this application.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0031] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0032] Similarly, to simplify this application and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of this application, various features of this application are sometimes grouped together into a single embodiment, figure, or description thereof. The use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0033] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0034] In the process of realizing this application, it was discovered that perfluorinated and polyfluoroalkyl substances possess both hydrophobic fluorocarbon chains and hydrophilic oxygen-containing head groups (such as carboxylic acid, sulfonic acid, ether oxygen, or bissulfonylimide groups). This amphiphilic structure provides a potential dual-site synergistic approach for the design of adsorbent materials. In related technologies, conventional adsorbents such as activated carbon and ion exchange resins mainly rely on single interactions (such as hydrophobic partitioning or ion exchange) to capture perfluorinated and polyfluoroalkyl substances. While they can maintain a certain adsorption capacity in simple laboratory water systems, the single interaction is easily disturbed when there are high concentrations of coexisting ions, natural organic matter, or particulate matter in the water, leading to a significant decrease in adsorption performance. Further analysis revealed that if a composite material with both a hydrophobic interface and a metal active center can be constructed, where the hydrophobic interface is responsible for enriching the fluorocarbon chains and the metal center is responsible for recognizing and immobilizing the oxygen-containing head groups, it is expected to maintain stable capture efficiency under complex water chemistry conditions. Based on this idea, atomic-level metal sites are loaded onto a carbon matrix. By utilizing the hydrophobic effect of the matrix and the synergistic mechanism of electrostatic adsorption and coordination of the metal sites, the effective removal of perfluorinated and polyfluoroalkyl substances in complex water bodies can be achieved.

[0035] This application proposes a method for removing perfluorinated and polyfluoroalkyl substances from complex water bodies, comprising introducing a composite carbon material loaded with atomic-level metal sites into the complex water body to adsorb the perfluorinated and polyfluoroalkyl substances in the complex water body; wherein, the matrix of the composite carbon material captures the perfluorinated and polyfluoroalkyl substances through hydrophobic interactions, and the atomic-level metal sites in the composite carbon material anchor the perfluorinated and polyfluoroalkyl substances through electrostatic adsorption and bind and fix them with the oxygen-containing head groups of the perfluorinated and polyfluoroalkyl substances.

[0036] According to embodiments of this application, a composite carbon material loaded with atomic-level metal sites is introduced into a complex aquatic body. The matrix of the composite carbon material captures perfluorinated and polyfluoroalkyl substances (PFAS) through hydrophobic interactions, enriching them on the surface of the composite carbon material. Simultaneously, the atomic-level metal sites loaded on the matrix carry localized charges, enabling them to further anchor PFAS molecules through electrostatic adsorption and specifically bind to the oxygen-containing head groups at the molecular ends. These two effects synergistically occur in a single material: hydrophobic capture increases local concentration, while electrostatic adsorption and head group binding enhance adsorption strength and selectivity. This synergistic mechanism allows for the effective removal of PFAS without relying on additional chemical reagents or complex operating conditions, making it particularly suitable for complex aquatic environments with a high proportion of coexisting components.

[0037] According to the embodiments of this application, the dosage of composite carbon material is 0.005~5.0 g / L, for example, it can be 0.005 g / L, 0.1 g / L, 0.5 g / L, 1.0 g / L, 2.0 g / L, 3.0 g / L, 4.0 g / L, 5.0 g / L, or any range between two, preferably 0.01~1.0 g / L.

[0038] According to the embodiments of this application, if the dosage of the composite carbon material is less than 0.005 g / L, the adsorption sites provided by the composite carbon material are insufficient, making it difficult to fully capture perfluorinated and polyfluoroalkyl substances in the water, resulting in a low removal rate that fails to meet treatment requirements. If the dosage of the composite carbon material is higher than 5.0 g / L, on the one hand, it will cause material waste and a significant increase in treatment costs; on the other hand, excessive material may agglomerate, reducing the utilization efficiency per unit mass of material, while increasing the difficulty of solid-liquid separation, and even introducing additional suspended solids or metal leaching risks.

[0039] According to embodiments of this application, the mass fraction of atomic-level metal sites is 0.1 to 15 wt% based on the total mass of the composite carbon material. For example, it can be 0.1 wt%, 0.5 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, or any range between the two, preferably 1 to 10 wt%.

[0040] According to embodiments of this application, if the mass fraction is less than 0.1 wt%, the number of active sites provided on the material surface is too small, making it difficult to form effective electrostatic adsorption and head group binding for perfluorinated and polyfluoroalkyl substances, resulting in significantly insufficient adsorption capacity and removal rate. If the mass fraction is higher than 15 wt%, excessive metal loading can easily lead to the aggregation of metal atoms, forming nanoparticles or clusters, which cannot maintain an atomic-level dispersion state, thereby reducing atom utilization and site accessibility; at the same time, aggregated metal species may increase the risk of leaching, affecting the stability and regeneration performance of the material. Therefore, exceeding this range is not conducive to achieving efficient and stable adsorption effects.

[0041] According to embodiments of this application, the material for the atomic-level metal sites includes at least one of iron, nickel, cobalt, and lanthanum.

[0042] According to embodiments of this application, most of these metals are transition metals, which have high oxyphilicity and moderate Lewis acidity, and can effectively electrostatically adsorb or coordinate with oxygen-containing head groups (such as carboxylic acid groups, sulfonic acid groups, ether oxygen or disulfonamide groups) in perfluorinated and polyfluoroalkyl substances.

[0043] According to embodiments of this application, in the composite carbon material, the matrix of the composite carbon material includes foamed carbon or porous carbon nitride; the specific surface area of ​​the matrix is ​​50~500m². 2 / g, for example, can be 50m2 / g, 100m 2 / g, 150m 2 / g、200m 2 / g、250m 2 / g、300m 2 / g, 350m 2 / g、400m 2 / g、450m 2 / g、500m 2 / g or any combination thereof, with a pore volume of 0.05~1.00 cm³. 3 / g, for example, can be 0.05cm 3 / g, 0.1cm 3 / g, 0.5cm 3 / g, 1.00cm 3 / g or any range between the two, with an average pore size of 2~20nm, for example, 2nm, 5nm, 10nm, 15nm, 20nm or any range between the two.

[0044] According to embodiments of this application, the foamed carbon has a porous carbon framework with a hydrophobic surface, suitable for enriching fluorocarbon chains of perfluorinated and polyfluoroalkyl substances through hydrophobic interactions. The porous carbon nitride contains nitrogen-containing functional groups, which facilitates enhanced interactions with oxygen-containing head groups and improves the hydrophilicity balance. Within this size range, the matrix is ​​advantageous in balancing hydrophobic enrichment interfaces with pore accessibility.

[0045] In some specific embodiments, if the specific surface area of ​​the substrate is less than 50m² 2 / g, the hydrophobic interface provided by the composite carbon material is insufficient, making effective capture difficult; if it is higher than 500m 2 / g, may be accompanied by an excessively high micropore ratio, resulting in excessively small pore sizes, making it difficult for large molecular weight PFAS to enter the pores and for atomic-level metal sites to contact the water. If the pore volume of the matrix is ​​less than 0.05 cm³, 3 / g, adsorption capacity is limited; if it is higher than 1.00cm 3 / g, if the skeletal density is too low, the mechanical strength will decrease. If the average pore size of the matrix is ​​less than 2nm, PFAS molecules cannot enter effectively; if it is greater than 20nm, the specific surface area will decrease significantly, and the hydrophobic enrichment efficiency will decrease.

[0046] According to embodiments of this application, the types of perfluorinated and polyfluoroalkyl substances include at least one of perfluorocarboxylic acids, perfluorosulfonic acids, fluoropolymer sulfonic acids, fluorinated ether acids, perfluoropolyethers, disulfonamides, and perfluorosulfonamides; perfluorocarboxylic acids include perfluorobutyric acid (PFBA), perfluorovalerate (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUn). The following are included: DA), perfluorododecanic acid (PFDoDA), perfluorotridecanoic acid (PFTrDA), and perfluorotetradecanoic acid (PFTeDA); perfluorosulfonic acids include at least one of perfluorobutyric acid (PFBS), perfluoropentanesulfonic acid (PFPeS), perfluorohexanesulfonic acid (PFHxS), perfluoroheptanesulfonic acid (PFHpS), perfluorooctanesulfonic acid (PFOS), perfluorononanesulfonic acid (PFNS), and perfluorodecanesulfonic acid (PFDS); fluoropolymer sulfonic acids include at least one of 4:2 fluoropolymer sulfonic acid (4:2 FTS), 6:2 fluoropolymer sulfonic acid (6:2 FTS), 8:2 fluoropolymer sulfonic acid (8:2 FTS), and 10:2 fluoropolymer sulfonic acid (10:2 FTS); bissulfonylimides include lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and / or bis-perfluoroalkylsulfonylimide (bis-FASI); and perfluorosulfonamides include perfluorooctylsulfonamide (OBS).

[0047] According to embodiments of this application, the method can process perfluorinated and polyfluoroalkyl substances covering six common and novel PFAS, including short-chain to long-chain, carboxylic acid / sulfonic acid / bissulfonylimide and other head group structures, demonstrating its broad applicability to different PFAS in complex water bodies.

[0048] According to embodiments of this application, the complex water body also includes coexisting ions or organic matter; coexisting ions include Na+. + Ca 2+ Mg 2+ Li + Ni 2+ Co 2+ Fe 3+ Al 3+ Cl - NO3 - SO4 2- HCO3 - CO3 2- H2PO4 - HPO4 2- F - PF6 - PO2F2 -At least one of the following; organic matter includes at least one of humic acid, dissolved organic matter, carbon black particles, metal oxide particles, and polyvinylidene fluoride particles.

[0049] According to embodiments of this application, complex water bodies include typical interfering components, specifically covering common inorganic anions, cations, and various organic compounds. The method of this application can effectively adsorb target substances even in the presence of coexisting substances, demonstrating its adaptability to real-world complex water bodies.

[0050] According to embodiments of this application, the sources of complex water bodies include at least one of the following: natural water, groundwater, drinking water source water, domestic sewage, reclaimed water, industrial wastewater, fluoride-containing wastewater, fire-fighting foam contaminated water, landfill leachate, lithium battery recycling water, black powder washing liquid, acid leaching liquid, alkaline washing liquid, high-salt mother liquor, or residue leachate.

[0051] According to embodiments of this application, the method can treat complex water bodies including natural water bodies, municipal sewage, and industrial wastewater, with particular emphasis on various water samples (black powder washing solution, acid leaching solution, alkaline washing solution, high-salt mother liquor, and residue leachate) in the entire lithium battery recycling process. This indicates that the method of this application can adapt to complex matrices with different salinity, pH, and coexisting components, and has the potential to treat PFAS-containing wastewater from emerging industries.

[0052] According to embodiments of this application, the pH of the complex water body is 2 to 12, for example, it can be 2, 4, 6, 8, 10, 12, or any range between two, preferably 3 to 11, more preferably 3 to 9, the adsorption time is 1 min to 48 h, for example, it can be 1 min, 30 min, 1 h, 5 h, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 48 h, or any range between two, and the adsorption temperature is 5 to 60 °C, for example, it can be 5 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, or any range between two.

[0053] According to the embodiments of this application, the method can be implemented within a wide pH range and a broad temperature range, exhibiting strong adaptability to fluctuations in actual water quality and a wide operating window. Furthermore, its adsorption process shows a trend of rapid adsorption followed by gradual stabilization.

[0054] According to embodiments of this application, the aforementioned method for removing perfluorinated and polyfluoroalkyl substances from complex water bodies further includes: regenerating the adsorbed composite carbon material in an alkaline regeneration solution; wherein the alkaline regeneration solution includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water; the concentration of the alkaline regeneration solution is 0.01~5.0 mol / L, for example, it can be 0.01 mol / L, 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, etc. The concentration can be 1 / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, 3.5 mol / L, 4.0 mol / L, 4.5 mol / L, 5.0 mol / L, or any range between two of these, preferably 0.1 to 2.0 mol / L. The regeneration time is 0.5 to 48 hours, for example, 30 minutes, 1 hour, 5 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 48 ​​hours, or any range between two of these.

[0055] According to embodiments of this application, the regeneration of the adsorbed material utilizes an alkaline regeneration solution to desorb the captured perfluorinated and polyfluoroalkyl substances from the composite carbon material, restoring active sites. The regeneration solution encompasses common inorganic alkalis and weak base salts, with a wide concentration range and flexible regeneration time, adapting to different levels of pollution and treatment efficiency requirements. This regeneration step helps extend the material's lifespan, reduce treatment costs, and provides a workable reuse solution for practical engineering applications.

[0056] It should be noted that the described embodiments are merely some, not all, of the embodiments described in this application. Other embodiments obtained by those skilled in the art based on the embodiments described in this application without inventive effort are all within the scope of protection of this application.

[0057] Example 1

[0058] The composite carbon material with atomic-level metal sites used in Example 1 is denoted as M-XPS@C, where M is Fe, Ni, Co, or La. Specifically, its preparation method is as follows.

[0059] Using polystyrene foam as a carbon source, polystyrene foam boards were first pretreated at 230℃ to obtain a brittle solid, which was then pulverized into foam powder. FeCl3, NiCl2·6H2O, CoCl2·6H2O, or LaCl3·7H2O were weighed out and thoroughly dry-milled with the foam powder to obtain a metal salt / foam powder precursor mixture. The initial metal loading of the metal salt was 5 wt%.

[0060] The precursor mixture was placed in an oxygen-free atmosphere and heated to 450°C at a heating rate of 5°C / min and held for 2 hours to obtain an intermediate product. The intermediate product was washed three times with ethanol to remove weakly bound residues. Then, it was pyrolyzed at 550°C for 2 hours in an oxygen-free atmosphere to obtain composite carbon materials loaded with atomic-level metal sites, which were designated as Fe-XPS@C, Ni-XPS@C, Co-XPS@C, and La-XPS@C, respectively.

[0061] Example 2

[0062] The metal content in the composite carbon material loaded with atomic-level metal sites prepared in Example 1 was determined using inductively coupled plasma optical emission spectrometry (ICP-OES).

[0063] The pore structure of the N2 adsorption-desorption test material was used, and the test results of the matrix are shown in Table 1 below.

[0064] Table 1

[0065]

[0066] The morphology and metal dispersion state of the above composite carbon materials were observed using transmission electron microscopy (TEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM).

[0067] Figure 1 These are the morphology and metal dispersion diagrams of the composite carbon material in Example 2 of this application, where a is a transmission electron microscope (TEM) image of Fe-XPS@C, b is a TEM image of the metal dispersion state of Fe-XPS@C, c is a TEM image of Ni-XPS@C, d is a TEM image of the metal dispersion state of Ni-XPS@C, e is a TEM image of Ni-XPS@C, f is a TEM image of the metal dispersion state of Ni-XPS@C, g is a TEM image of La-XPS@C, and h is a TEM image of the metal dispersion state of La-XPS@C.

[0068] like Figure 1 As shown, the composite carbon material retains the wrinkled lamellar structure of foam-derived carbon, and no obvious large-sized metal particles or aggregates were observed. The metal elements are uniformly distributed in the carbon framework. Taking Fe-XPS@C as an example, a large number of isolated bright spots can be seen in the HAADF-STEM image, indicating that Fe species are anchored in the carbon framework in the form of highly dispersed atomic-level sites.

[0069] Example 3

[0070] In this Example 3, perfluorooctanoic acid (PFOA) was used as the target perfluorinated and polyfluoroalkyl substances to verify the effect of different composite carbon materials (M-XPS@C) on the removal of perfluorinated and polyfluoroalkyl substances from complex water bodies.

[0071] The standard adsorption conditions were as follows: initial PFOA concentration of 1 mg / L, adsorbent dosage of 0.1 g / L, temperature of 25℃, shaking rate of 180 rpm, contact time of 24 h, and initial pH of approximately 7. After adsorption, the sample was filtered through a 0.22 μm filter membrane, and the residual PFOA concentration was determined by UPLC-MS / MS. The removal rate and adsorption capacity were then calculated.

[0072] Figure 2 This is a test chart showing the removal rate and adsorption capacity of perfluorooctanoic acid (PFOA) in water in Example 3 of this application.

[0073] like Figure 2 As shown, under the condition of a dosage of 0.1 g / L, the removal rates of PFOA by Fe-XPS@C, Ni-XPS@C, Co-XPS@C and La-XPS@C were 97.01%, 94.29%, 91.49% and 75.79%, respectively; the corresponding metal normalized adsorption capacities were 405.65, 312.44, 167.61 and 114.49 mg / g, respectively.

[0074] Furthermore, adsorption kinetics experiments were conducted on the aforementioned composite carbon material.

[0075] The initial concentration of PFOA was 1 mg / L, the adsorbent dosage was 0.1 g / L, and the contact time ranged from 1 to 1440 min.

[0076] Figure 3 This is the adsorption curve for removing perfluorooctanoic acid from water in Example 3 of this application.

[0077] like Figure 3 As shown, all four materials exhibit a rapid adsorption followed by a slow equilibrium adsorption process. The pseudo-second-order kinetic model fits the experimental data better than the pseudo-first-order kinetic model. The pseudo-second-order equilibrium adsorption capacities of Fe-XPS@C, Ni-XPS@C, Co-XPS@C, and La-XPS@C are 416.68, 329.26, 179.77, and 139.66 mg / g, respectively, with the adsorption performance order being Fe-XPS@C>Ni-XPS@C>Co-XPS@C>La-XPS@C.

[0078] In summary, under the same foamed carbon framework conditions, the type of metal center significantly affects the adsorption capacity and site accessibility of PFOA, with Fe atomic-level sites exhibiting superior PFOA capture ability.

[0079] Example 4

[0080] In this Example 4, the effect of pH in the water body on the removal of perfluorinated and polyfluoroalkyl substances from complex water bodies was verified.

[0081] Specifically, the initial pH of the PFOA solution was adjusted to 3, 5, 7, 9 and 11, respectively, the initial concentration of PFOA was 1 mg / L, the adsorbent dosage was 0.1 g / L, the temperature was 25℃, the oscillation rate was 180 rpm, and the contact time was 24 h.

[0082] Figure 4 This is a test chart showing the removal rate and adsorption capacity of perfluorooctanoic acid (PFOA) in water in Example 4 of this application.

[0083] like Figure 4 As shown, Fe-XPS@C maintains a PFOA removal rate of 98-100% within a pH range of 3-9, and retains approximately 94% at pH 11. In contrast, Ni-XPS@C and La-XPS@C exhibit a more significant decrease in adsorption performance under strongly alkaline conditions. These results indicate that Fe-based atomic-level site foam carbon materials possess a more stable PFAS capture capacity over a wide pH range.

[0084] Example 5

[0085] In this Example 5, the effects of coexisting ions and organic matter in water on the removal of perfluorinated and polyfluoroalkyl substances from complex water bodies are verified.

[0086] NaCl, CaCl2, MgCl2, NaNO3, Na2SO4, NaHCO3, Na2CO3, NaH2PO4 / Na2HPO4, and humic acid were added to the PFOA solution, respectively. Unless otherwise specified, the initial concentration of PFOA was 1 mg / L, the adsorbent dosage was 0.1 g / L, the temperature was 25℃, the shaking rate was 180 rpm, and the contact time was 24 h. + Ca 2+ Mg 2+ NO3 - SO4 2- HCO3 - CO3 2- and H2PO4 / HPO4 2- The concentration was set to 0.5 mM, the humic acid concentration was set to 5 mg / L, and the initial pH of the system was adjusted to 7.3 ± 0.1.

[0087] Figure 5 This is a comparison chart of the adsorption capacity of perfluorooctanoic acid (PFOA) in different water bodies (coexisting water chemical components) in Example 5 of this application. In the chart, a shows the adsorption of PFOA in water bodies containing coexisting cations, and b shows the adsorption in water bodies containing NO3. - and SO4 2- The adsorption of perfluorooctanoic acid (PFOA) in water bodies is shown in diagram c, where HCO3 is present. - CO3 2- and H2PO4 - / HPO42- Figure 1 shows the adsorption of perfluorooctanoic acid (PFOA) in water bodies, and Figure 2 shows the adsorption of PFOA in water bodies containing humic acid.

[0088] like Figure 5 As shown, Na + Mg 2+ and NO3 - It has little effect on PFOA adsorption, Ca 2+ It has a slight promoting effect on PFOA removal; SO4 2- H2PO4 / HPO4 2- Phosphates and humic acids exhibit significant inhibitory effects on adsorption. Specifically, competition from oxygen anions and organic matter coverage reduce the effective accessibility of metal-related sites, while the type of atomic-level metal sites affects the material's resistance to interference in complex aqueous systems.

[0089] Example 6

[0090] In this Example 6, the effects of different water bodies on the removal of perfluorinated and polyfluoroalkyl substances from complex water bodies are verified.

[0091] Ultrapure water, tap water, surface water, and sewage were selected as actual water substrates. PFOA was added to each substrate to an initial concentration of 1 mg / L. The adsorbent dosage was 0.1 g / L, the contact time was 24 h, and no additional pH adjustment was performed.

[0092] Figure 6 This is a comparison chart of the adsorption capacity of perfluorooctanoic acid (PFOA) removed from different water bodies in Example 6 of this application.

[0093] like Figure 6 As shown, Fe-XPS@C maintained a high PFOA removal rate in tap water, surface water and sewage, reaching 98.56%, 96.21% and 94.31%, respectively.

[0094] The regeneration performance of the material was further investigated. The adsorbed material was regenerated by shaking in 1.0M NaOH solution at 25°C for 24 hours, then washed 2-3 times with ultrapure water, dried at 50°C, and reused for the next round of adsorption.

[0095] Figure 7 This is a graph showing the removal rate results of the composite carbon material after recycling in Example 6 of this application.

[0096] like Figure 7 As shown, after five adsorption-regeneration cycles, Fe-XPS@C still maintained a PFOA removal rate of 95.3%; the removal rates of Ni-XPS@C, Co-XPS@C and La-XPS@C after the fifth cycle were 92.4%, 91.7% and 86.7%, respectively.

[0097] Further analysis was conducted on metal leaching. After the material underwent one PFOA adsorption cycle in ultrapure water, tap water, surface water, and wastewater, the concentration of dissolved metals in the supernatant was determined using ICP-MS.

[0098] Figure 8 This is a graph showing the leaching rate results of the composite carbon material in Example 6 of this application.

[0099] like Figure 8 As shown, the metal leaching concentrations of the four materials were all low, approximately 0.01–0.03 mg / L, indicating that the metal sites have good stability in the foamed carbon skeleton.

[0100] Example 7

[0101] Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to analyze the changes in the surface structure of the material before and after adsorption. The specific analysis was carried out using Fe-XPS@C as an example.

[0102] Figure 9 These are the infrared spectra of Fe-XPS@C before and after adsorption in Example 7 of this application.

[0103] like Figure 9 As shown, the material before adsorption was at approximately 472 cm⁻¹. -1 Fe-C related vibrational peaks were observed at approximately 654 cm⁻¹; after PFOA adsorption, peaks were observed at approximately 654 cm⁻¹. -1 Fe-O related vibrational peaks appear at approximately 1450 cm⁻¹, and also at approximately 1450 cm⁻¹. -1 A carboxylate-related absorption peak appears at 950-1250 cm⁻¹, and the peak value is between 950-1250 cm⁻¹. -1 The range exhibits characteristic CF vibration peaks.

[0104] Figure 10 These are XPS spectra of Fe-XPS@C before and after adsorption in Example 7 of this application, where a is the XPS spectrum of Fe-XPS@C before adsorption and b is the XPS spectrum of Fe-XPS@C after adsorption. Figure 11 These are XPS spectra of different composite carbon materials after adsorption in Example 7 of this application.

[0105] like Figure 10 , Figure 11 As shown, an F1s signal appears on the material surface after PFOA adsorption, indicating that fluorine-containing substances are enriched on the material surface. The Fe2p binding energy of Fe-XPS@C undergoes a positive shift after adsorption, indicating a change in the local electronic environment of the Fe site. These results demonstrate that PFOA adsorption includes not only the enrichment of fluorocarbon chains at the hydrophobic interface of foamed carbon, but also the metal-oxygen interaction between the PFOA carboxylate head group and the metal-related site.

[0106] Furthermore, the hydrophilic and hydrophobic properties of the above-mentioned composite carbon material were tested, and the contact angles were recorded in Table 2 below.

[0107] Table 2

[0108]

[0109] As shown in Table 2, contact angle tests revealed that the M-XPS@C material exhibits strong hydrophobicity overall, providing an enrichment interface for PFAS fluorocarbon chains. Therefore, the removal of PFAS by the aforementioned composite carbon material can be attributed to the synergistic effect of hydrophobic enrichment of the foamed carbon framework and atomic-level metal site headgroup recognition.

[0110] Example 8

[0111] In this Example 8, the aforementioned composite carbon material is used to remove PFAS from lithium battery recycling water. The lithium battery recycling water includes one or more of the following: black powder washing solution, acid leaching solution, alkaline washing solution, high-salt mother liquor, and residue leaching solution. The water may contain Li. + Ni 2+ Co 2+ Fe 3+ Al 3+ F - PF6 - PO2F2 - It contains coexisting components such as carbon black particles, metal oxide particles, PVDF particles, and organic residues.

[0112] During processing, the aforementioned composite carbon material is added to lithium battery recovery water containing PFAS, with or without pH adjustment, and contacted at 5–60°C for 1 min–48 h. The adsorbed material is then separated by filtration, sedimentation, centrifugation, or membrane separation. The adsorbed material can be regenerated and reused using an alkaline regeneration solution.

[0113] This application scheme is suitable for removing traditional PFAS and novel battery-derived PFAS from lithium battery reclaimed water, including PFOA, PFOS, LiTFSI, and bis-FASI. For PFAS containing disulfonamide head groups, selective capture can be achieved through the interaction between Fe, Ni, Co, La, or other oxymetallic sites and S=O / O coordination sites.

[0114] Example 9

[0115] In Example 9, perfluorooctane sulfonate (PFOS) was used as a representative target of sulfonic acid perfluorinated and polyfluoroalkyl substances to verify the applicability of the aforementioned composite carbon material to different head groups of PFAS. The PFOS adsorption experiment was conducted in a simulated wastewater system with an initial PFOS concentration of 1 mg / L, an adsorbent dosage of 0.1 g / L, and an initial pH of approximately 7 (near neutral). After adsorption reached the set contact time, the sample was filtered through a 0.22 μm filter membrane, and the residual PFOS concentration was determined using UPLC-MS / MS.

[0116] Figure 12 This is a test graph showing the removal rate and adsorption capacity of perfluorooctane sulfonate in water in Example 9 of this application.

[0117] like Figure 12 As shown, in the method proposed in this application, the M-XPS@C material can remove not only carboxylic acid head PFAS but also sulfonic acid head PFAS. Different metal-centered materials exhibit differences in PFOS removal rates and adsorption capacities, indicating that the type of atomic-level metal sites affects the interfacial trapping behavior of PFOS. These results demonstrate that the method proposed in this application is not limited to PFOA but can be extended to perfluorosulfonic acid PFAS such as PFOS.

[0118] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for removing perfluorinated and polyfluoroalkyl substances from complex water bodies, comprising: Composite carbon materials loaded with atomic-level metal sites are introduced into complex water bodies to adsorb perfluorinated and polyfluoroalkyl substances in the water; wherein, The matrix of the composite carbon material captures the perfluorinated and polyfluoroalkyl substances through hydrophobic interactions. The atomic-level metal sites in the composite carbon material anchor the perfluorinated and polyfluoroalkyl substances through electrostatic adsorption and bind and fix them to the oxygen-containing head groups of the perfluorinated and polyfluoroalkyl substances.

2. The method of claim 1, wherein, The dosage of the composite carbon material is 0.005~5.0 g / L.

3. The method of claim 2, wherein, The mass fraction of the atomic-level metal sites is 0.1 to 15 wt% based on the total mass of the composite carbon material.

4. The method of claim 3, wherein, The material of the atomic-level metal sites includes at least one of iron, nickel, cobalt, and lanthanum.

5. The method of claim 2, wherein, In the composite carbon material, the matrix of the composite carbon material includes foamed carbon or porous carbon nitride; The specific surface area of ​​the substrate is 50~500m². 2 / g, pore volume 0.05~1.00cm³ 3 / g, with an average pore size of 2~20nm.

6. The method of claim 1, wherein, The types of perfluorinated and polyfluoroalkyl substances include at least one of perfluorinated carboxylic acids, perfluorinated sulfonic acids, fluoropolymer sulfonic acids, fluorinated ether acids, perfluorinated polyethers, disulfonamides, and perfluorinated sulfonamides. The perfluorocarboxylic acids include at least one of perfluorobutyric acid, perfluorovaleric acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanic acid, perfluorotridecanoic acid, and perfluorotetradecanoic acid. The perfluorosulfonic acids include at least one of perfluorobutyric acid, perfluoropentanesulfonic acid, perfluorohexanesulfonic acid, perfluoroheptanesulfonic acid, perfluorooctanesulfonic acid, perfluorononanesulfonic acid, perfluorodecanesulfonic acid, and perfluorooctylsulfonamide. The fluoropolymer sulfonic acids include at least one of 4:2 fluoropolymer sulfonic acid, 6:2 fluoropolymer sulfonic acid, 8:2 fluoropolymer sulfonic acid, and 10:2 fluoropolymer sulfonic acid. The bissulfonylimides include lithium bis(trifluoromethanesulfonyl)imide and / or bisperfluoroalkylsulfonylimides; The perfluorosulfonamides include perfluorooctylsulfonamides.

7. The method of claim 1, wherein, The complex water body also includes coexisting ions or organic matter; The coexisting ions include Na + Ca 2+ Mg 2+ Li + Ni 2+ Co 2+ Fe 3+ Al 3+ Cl - NO3 - SO4 2- HCO3 - CO3 2- H2PO4 - HPO4 2- F - PF6 - PO2F2 - At least one of them; The organic matter includes at least one of humic acid, dissolved organic matter, carbon black particles, metal oxide particles, and polyvinylidene fluoride particles.

8. The method according to claim 7, wherein, The sources of the complex water bodies include at least one of the following: natural water, groundwater, drinking water source water, domestic sewage, reclaimed water, industrial wastewater, fluoride-containing wastewater, fire-fighting foam contaminated water, landfill leachate, lithium battery recycling water, black powder washing solution, acid leaching solution, alkaline washing solution, high-salt mother liquor, or residue leachate.

9. The method of claim 7, wherein, The pH of the complex water body is 2~12, the adsorption time is 1min~48h, and the adsorption temperature is 5~60℃.

10. The method according to claim 1, further comprising: The adsorbed composite carbon material is then placed in an alkaline regeneration solution for regeneration; wherein... The alkaline regeneration solution includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water. The concentration of the alkaline regenerated solution is 0.01~5.0 mol / L, and the regeneration time is 0.5~48 h.

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