COF aerogel composite adsorption material for PFAS treatment as well as preparation method and application of COF aerogel composite adsorption material

Abstract

The invention discloses a COF aerogel composite material for PFAS treatment and a preparation method and application thereof, and relates to the field of pollutant adsorption, the COF aerogel composite material comprises the following components: 68.18%-70% of a COF material, 22.73%-90.91% of a CS solution, and 9.09% of a TP solution; the COF material is prepared from 0.0764 mmol of ETTA (Ethylene Terephthalic Acid), 30 mg of ETTA, 0.1528 mmol of a side functional monomer and 3 mL of an o-dichlorobenzene / n-butyl alcohol solvent. The volume ratio of orthodichlorobenzene to n-butanol in the orthodichlorobenzene / n-butanol solvent is 1: 1; and the side functional monomer comprises 0.025 mmol of TFTDA (Trifluorotoluene Diisocynate) / 0.127 mmol of BFB1M, and is named as COF-F1N5. A series of COF / aerogel synthesized by the method provided by the invention has the characteristics of ultralight weight, compression resistance, good stability and small specific surface area loss, overcomes the application limitation of COF powder, is easy to recover, and has better adsorption performance on PFAS.

Description

Technical Field

[0001] The present invention relates to the field of pollutant adsorption, in particular to a COF aerogel composite adsorption material for PFAS treatment, its preparation method and application. Background Art

[0002] Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic compounds characterized by the complete or partial replacement of hydrogen atoms directly connected to carbon atoms on the carbon chain, and are used in a variety of consumer and industrial products. Due to their carcinogenic and biotoxic properties, as well as persistence and bioaccumulation in the environment, they lead to widespread exposure in environmental media, especially water environments and foods, seriously threatening human health.

[0003] Covalent organic frameworks (COFs) are a type of porous organic nanomaterials that have been widely used for the adsorption treatment of PFAS pollutants due to their ordered porosity, stability, and function customization. However, in the actual application process of COF powders, they are often realized by directly filling columns. However, the powder form is prone to agglomeration in actual application scenarios, difficult to disperse in water, has low flux, is difficult to recycle, and environmental pollution and other problems greatly limit its application in water. Especially in the application background of PFAS adsorption treatment, due to the hydrophobicity of COF itself, it is difficult to disperse evenly in water, resulting in aggregation on the liquid surface and very poor permeability. This characteristic seriously restricts its application in fields such as water treatment and sample preparation extraction before detection. Combining COF with other functional materials to construct a hybrid material system to adjust the hydrophobicity of COF, improve the flux, and bridge the gap between COF from the laboratory to application.

[0004] Although some COF aerogel materials have been reported in the literature, most of them are in-situ synthesis, which cannot guarantee the function of COF in the composite material. At the same time, there is no report on the application of COF aerogels in PFAS treatment.

[0005] In addition, the COFs in the currently reported COF aerogels are all single-pore COFs. Heteroporous COFs or hierarchical porous COF nanomaterials have been widely used in fields such as catalysis, energy storage, and environment due to their unique two or more ordered porous network structures. The ordered pore sizes of hierarchical pores are potential adsorption platforms for PFAS with different chain lengths. However, heteroporous COFs also face the common application problems of COFs. Therefore, it is urgent to develop a COF aerogel composite material for PFAS treatment to bridge the inherent defects of COF in actual applications and expand the application scope of COF. By means of the macroporous environment provided by the aerogel and the mesoporous and microporous environments of the heteroporous COF material, a hierarchical pore structure is jointly constructed.

[0006] However, it is a great challenge to jointly construct COF aerogel with hetero-porous COF and aerogel, and there is no relevant report. Therefore, this patent describes a hierarchical porous COF / aerogel composite material for the simultaneous adsorption and removal of long-chain and short-chain PFAS. Summary of the Invention

[0007] To solve the above problems, the present application proposes a COF aerogel composite adsorption material for PFAS treatment, which includes the following components: COF material, CS solution, and TP solution;

[0008] The COF material includes 0.0382 - 0.0764 mmol of ETTA, 15 - 30 mg, 0.0764 - 0.1528 mmol of side functional monomer, and 1.5 - 3 mL of o-dichlorobenzene / n-butanol solvent;

[0009] In the o-dichlorobenzene / n-butanol solvent, the volume ratio of o-dichlorobenzene to n-butanol is 1:1;

[0010] The side functional monomer includes 0.0125 - 0.025 mmol of TFTDA; 0.0635 - 0.127 mmol of BFBlM, named COF-F1N5.

[0011] A preparation method of a COF aerogel composite material for PFAS treatment includes:

[0012] S1. Synthesize hetero-porous fluorine-doped cationic COF;

[0013] S2. Synthesize a COF / chitosan aerogel composite material based on the hetero-porous fluorine-doped cationic COF.

[0014] Preferably, the specific steps of S1 are:

[0015] S101. Mix ETTA, side functional monomer, and o-dichlorobenzene / n-butanol solvent to obtain a primary mixed solution;

[0016] S102. Add acetic acid as a catalyst to the primary mixed solution and mix to obtain a secondary mixed solution;

[0017] S103. Degas and seal the secondary mixed solution, and transfer it to a muffle furnace for reaction at room temperature to obtain a solid product;

[0018] S104. Wash and filter the solid product to obtain an initial material;

[0019] S105. Vacuum-dry the initial material overnight to obtain COF nanomaterials, and grind and screen them to obtain COF powder.

[0020] Preferably, the specific steps of S2 are:

[0021] S201. Dissolve chitosan CS in an aqueous acetic acid solution and shake to form a uniform and transparent CS solution;

[0022] S202. Add COF powder to the CS solution, shake and ultrasonically treat to obtain a uniformly dispersed solution;

[0023] S203. Add the TP solution to the dispersed solution, shake and then ultrasonically treat to form a hydrogel;

[0024] S204. Let the hydrogel stand undisturbed at room temperature to form a highly cross-linked and stable hydrogel;

[0025] S205. Freeze and vacuum dry the highly cross-linked and stable hydrogel to obtain a COF aerogel composite adsorbent material.

[0026] Preferably, the acetic acid content in S102 is 6 - 10 mol, 0.3 - 0.6 mL,

[0027] Preferably, the aqueous acetic acid solution in S201 is 800 - 1000 μL, 0.2 - 0.5 mol / L;

[0028] In S203, subsequently, the TP solution is 200 - 400 μL, 10 - 15 mg / L.

[0029] Preferably, in S101, ultrasonic treatment is used for 15 - 30 min during mixing;

[0030] In S102, ultrasonic treatment is used for 10 - 30 min during mixing;

[0031] In S103, the secondary mixed solution is degassed and sealed by using liquid nitrogen through three freeze - pump - thaw cycles for degassing;

[0032] The temperature of the muffle furnace is 120 - 140 °C, and the reaction is carried out for 72 - 96 hours;

[0033] In S104, the product solid is washed thoroughly with ultradry tetrahydrofuran by filtration 5 times, and then washed thoroughly with absolute ethanol by filtration 3 times;

[0034] In S105, the initial material is vacuum dried at 80 - 120 °C overnight to obtain a COF nanomaterial.

[0035] Preferably, in 201, shake for 10 - 20 s;

[0036] In S202, shake for 10 - 20 s and ultrasonically treat for 10 - 15 minutes to disperse uniformly;

[0037] In S204, let it stand for 12 - 18 hours;

[0038] In S205, put the hydrogel into a - 80 °C refrigerator and freeze for more than 12 h;

[0039] The hydrogel was vacuum freeze-dried for 36 h to obtain the COF aerogel composite adsorbent material.

[0040] Preferably, the ratio of COF to CS in S202 is 1:3 - 4:1.

[0041] Application of the COF aerogel composite material prepared by the described preparation method, wherein the COF aerogel composite material is applied to the adsorption of PFAS.

[0042] In summary, a COF aerogel composite adsorbent material for PFAS treatment, its preparation method and application according to the present invention. Compared with the traditional technology, a series of COF / aerogels synthesized by the present invention are ultra-light (26 mg / cm 3 ), compressive (able to support a pressure of 100 g while maintaining the original structure), good stability (maintaining the structure in water for 30 days), and have good adsorption performance for PFAS. In particular, COF / CS-4 has a fast adsorption kinetics, and the adsorption of short-chain PFAS is enhanced in the rapid treatment of PFAS in water, especially for the co-dissolution system of long-chain and short-chain PFAS. Compared with commercial adsorbents, the COF aerogel significantly enhances the adsorption treatment of PFAS in water while ensuring stability in the water environment.

[0043] The technical method of the present invention will be further described in detail below through the drawings and examples. Description of the Drawings

[0044] Figure 1 It is the morphology diagram of five aerogels in the examples, Figure 1 wherein a is the morphology diagram of the CS aerogel, Figure 1 b is the morphology diagram of the COF / CS-1 aerogel, Figure 1 c is the morphology diagram of the COF / CS-2 aerogel, Figure 1 d is the morphology diagram of the COF / CS-3 aerogel, Figure 1 e is the morphology diagram of the COF / CS-4 aerogel;

[0045] Figure 2 It is the state diagram of the aerogel placed on the fine hairs of setaria viridis in the examples, Figure 2 wherein a is the state diagram of the CS aerogel, Figure 2 b is the state diagram of the COF / CS-4 aerogel;

[0046] Figure 3 It is the change diagram of five aerogels placed in ultrapure water over time in the examples, Figure 3 wherein a is the state diagram of five aerogels at 24 h, Figure 3 b is the state diagram of five aerogels at 48 h, Figure 3Among them, c is the state diagram of five kinds of aerogels at 72 h, Figure 3 Among them, d is the state diagram of five kinds of aerogels at 96 h, Figure 3 Among them, e is the state diagram of five kinds of aerogels at 15 days, Figure 3 Among them, f is the state diagram of five kinds of aerogels at 30 days;

[0047] Figure 4 It is the diagram of COF / CS-4 in the embodiment that can withstand a weight of 100 g;

[0048] Figure 5 It is the diagram of the recovery process of COF / CS-4 under different proportions of pressure in the embodiment;

[0049] Figure 6 It is the isothermal adsorption and non-linear fitting diagram of five kinds of aerogels in the embodiment, Figure 6 Among them, a is the isothermal adsorption and non-linear fitting diagram of five kinds of aerogels for PFOA, Figure 6 Among them, b is the isothermal adsorption and non-linear fitting diagram of five kinds of aerogels for GenX;

[0050] Figure 7 It is the schematic diagram of the removal rate of different COF aerogels for PFOA in the embodiment;

[0051] Figure 8 It is the schematic diagram of the removal rate of different COF aerogels for GenX in the embodiment;

[0052] Figure 9 It is the comparison between COF / CS-4 and commercial adsorbents in the isothermal adsorption experiment in the embodiment, Figure 9 Among them, a is the comparison of the isothermal adsorption experiment between COF / CS-4 and commercial adsorbent for PFOA, Figure 9 Among them, b is the comparison of the isothermal adsorption experiment between COF / CS-4 and commercial adsorbent for GenX;

[0053] Figure 10 It is the comparison between COF / CS-4 and commercial adsorbents in the adsorption kinetics experiment in the embodiment, Figure 10 Among them, a is the comparison of the adsorption kinetics between COF / CS-4 and commercial adsorbent for PFOA, Figure 10 Among them, b is the comparison of the adsorption kinetics between COF / CS-4 and commercial adsorbent for GenX. Detailed implementation manners

[0054] The technical method of the present invention will be further described below through the accompanying drawings and embodiments. It should be noted that: unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values of the components and steps described in these embodiments do not limit the scope of the present application.

[0055] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0056] Technologies, systems, and devices known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, systems, and devices should be considered part of the specification.

[0057] In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0058] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0059] The three-dimensional network structure of aerogel is used to enhance the dispersibility and mechanical stability of COF in aqueous media to make up for the shortcomings of COF in practical applications. By integrating the biocompatibility of chitosan, the high specific surface area of COF and the multi-level pore structure of aerogel, it aims to break through the technical bottlenecks of low adsorption capacity, slow adsorption rate and high environmental risks of traditional materials for PFAS, and provide a new strategy for the green and efficient removal of PFAS in complex water systems.

[0060] A method for preparing a COF aerogel composite material for PFAS treatment, comprising:

[0061] S1. Synthesize heteroporous fluorine-doped cationic COF. The specific steps are as follows:

[0062] 0.0764mmol, 30mg ETTA was added to a glass tube, 0.1528mmol side functional monomer (0.025mmol TFTDA / 0.127mmol BFBlM, named COF-F1N5) was added to the tube, and then 3mL o-dichlorobenzene / n-butanol solvent (1:1, v / v) was added and ultrasonicated for 15min to mix them thoroughly. Then 6mol, 0.3mL acetic acid was added to each tube as a catalyst and immediately ultrasonicated for 10 minutes. Subsequently, liquid nitrogen was quickly used to degas and sealed after three freeze-pump-thaw cycles. When the system returned to room temperature, it was transferred to a muffle furnace at 120°C and reacted for 72 hours. After the reaction was completed, the product was fully washed and filtered 5 times with ultra-dry tetrahydrofuran, and then fully washed and filtered 3 times with anhydrous ethanol. Finally, the washed material was vacuum dried overnight at 80°C to obtain COF nanomaterials, and COF powder was obtained after grinding and sieving.

[0063] Table 1 Different COF and CS ratios according to

[0064]

[0065] S2. Synthesize COF / chitosan aerogel composites based on heteroaperture fluorine-doped cationic COF. The proportions of different COFs and CSs are shown in Table 1. The specific steps are shown in the following examples.

[0066] Example 1

[0067] First, dissolve 20 mg of chitosan (CS) in an acetic acid aqueous solution (800 μL, 0.2 mol / L), shake for 10 s to form a uniform and transparent CS solution. Subsequently, add the TP solution (200 μL, 10 mg / L), shake for 10 s, and then quickly transfer it to ultrasonic treatment until a hydrogel is formed, as shown in a of Figure 1 as shown.

[0068] Example 2

[0069] First, dissolve 15 mg of chitosan (CS) in an acetic acid aqueous solution (800 μL, 0.2 mol / L), shake for 10 s to form a uniform and transparent CS solution. Then, add 5 mg of the powdered COF material to the CS solution, shake for 10 s, and disperse it evenly by ultrasonic treatment for 10 minutes. Subsequently, add the TP solution (200 μL, 10 mg / L), shake for 10 s, and then quickly transfer it to ultrasonic treatment until a hydrogel is formed. Subsequently, let it stand undisturbed at room temperature for 12 hours to form a highly cross-linked and stable hydrogel. Then, put the hydrogel into a -80 °C refrigerator and freeze it for more than 12 h. Finally, vacuum freeze-dry the frozen COF aerogel for 36 h to obtain the COF aerogel composite adsorption material, as shown in b of Figure 1 as shown.

[0070] Example 3

[0071] First, dissolve 10 mg of chitosan (CS) in an acetic acid aqueous solution (800 μL, 0.2 mol / L), shake for 10 s to form a uniform and transparent CS solution. Then, add 10 mg of the powdered COF material to the CS solution, shake for 10 s, and disperse it evenly by ultrasonic treatment for 10 minutes. Subsequently, add the TP solution (200 μL, 10 mg / L), shake for 10 s, and then quickly transfer it to ultrasonic treatment until a hydrogel is formed. Subsequently, let it stand undisturbed at room temperature for 12 hours to form a highly cross-linked and stable hydrogel. Then, put the hydrogel into a -80 °C refrigerator and freeze it for more than 12 h. Finally, vacuum freeze-dry the frozen COF aerogel for 36 h to obtain the COF aerogel composite adsorption material, as shown in c of Figure 1 as shown.

[0072] Example 4

[0073] First, dissolve 6.67 mg of chitosan (CS) in an aqueous acetic acid solution (800 μL, 0.2 mol / L), shake for 10 s to form a uniform and transparent CS solution. Then, add 13.33 mg of powdered COF material to the CS solution, shake for 10 s, and disperse it evenly by ultrasonic treatment for 10 minutes. Subsequently, add the TP solution (200 μL, 10 mg / L), shake for 10 s, and then quickly transfer it to ultrasonic treatment until a hydrogel is formed. Then, let it stand undisturbed at room temperature for 12 hours to form a highly cross-linked and stable hydrogel. Next, place the hydrogel in a -80 °C refrigerator and freeze it for more than 12 h. Finally, vacuum freeze-dry the frozen COF aerogel for 36 h to obtain the COF aerogel composite adsorbent material, as Figure 1 shown in d of

[0074] Example 5

[0075] First, dissolve 5 mg of chitosan (CS) in an aqueous acetic acid solution (800 μL, 0.2 mol / L), shake for 10 s to form a uniform and transparent CS solution. Then, add 15 mg of powdered COF material to the CS solution, shake for 10 s, and disperse it evenly by ultrasonic treatment for 10 minutes. Subsequently, add the TP solution (200 μL, 10 mg / L), shake for 10 s, and then quickly transfer it to ultrasonic treatment until a hydrogel is formed. Then, let it stand undisturbed at room temperature for 12 hours to form a highly cross-linked and stable hydrogel. Next, place the hydrogel in a -80 °C refrigerator and freeze it for more than 12 h. Finally, vacuum freeze-dry the frozen COF aerogel for 36 h to obtain the COF aerogel composite adsorbent material, as Figure 1 shown in e of

[0076] The morphologies of the five aerogels are as Figure 1 shown: The CS aerogel is white, and as the proportion of COF incorporated gradually increases, the color of the COF / CS aerogel gradually becomes darker.

[0077] The COF / CS aerogel has a low density (22.27 - 26 mg / cm 3 ), with the characteristic of being ultra-light, as Figure 2 shown:

[0078] As Figure 3 shown, a series of synthesized aerogels are placed in ultrapure water and can still maintain their original morphology after 30 days, and always float on the liquid surface by virtue of their low-density characteristics.

[0079] As Figure 4 - 5 shown, it has certain compressive and self-recovery properties.

[0080] A series of synthesized COF / aerogels are ultra-light, compressive, stable, have a small specific surface area loss, and have good adsorption performance for PFAS. In particular, COF / CS-4 has a fast adsorption kinetics and has certain application potential for the rapid treatment of PFAS in water.

[0081] Adsorption performance for PFAS

[0082] The adsorption performance of 5 COF aerogels was evaluated through isothermal adsorption experiments and adsorption kinetics experiments. The adsorption capacity and adsorption rate were calculated using the following formulas:

[0083]

[0084] C0 and C e (mg / L) represent the initial concentration and equilibrium concentration of PFAS, respectively, and C t represents the PFAS concentration at time t. m (mg) and V (mL) represent the mass of the adsorbent and the volume of the solution, respectively. At the same time, the Langmuir and Freundlich adsorption isotherm models were used to fit the adsorption processes of two PFAS by the mesoporous COF to describe the adsorption processes of the COF materials in this study.

[0085] The Langmuir adsorption isotherm equation is as follows:

[0086]

[0087] The Freundlich adsorption isotherm equation is as follows:

[0088]

[0089] q m (mg / g) is the maximum adsorption capacity, K L is the Langmuir constant, and K F is the Freundlich constant, and C e (mg / L) is the concentration of PFAS at the adsorption equilibrium.

[0090] First, as Figure 6 shown, the CS aerogel without loaded COF also has a high adsorption capacity for PFOA. With the increase of COF loading, q e further increases, and COF / CS-2 reaches the maximum adsorption capacity; then it tends to be stable.

[0091] The isothermal adsorption results and non-linear fitting results of five COF aerogels for GenX (perfluoroalkyl substances) are as Figure 7As shown, similar to PFOA, the CS aerogel without loaded COF also has a certain adsorption capacity for GenX, but it is relatively low. With the increase of COF loading, qe increases significantly, and COF / CS-2 also reaches the maximum adsorption capacity; then it tends to be stable. The fitting results show that the Langmuir model can better describe the adsorption process.

[0092] Adsorption kinetics test method: Add 30 mL of aqueous solution of PFOA or Gen X (1 mg / L) into the bottle. Then add the COF aerogel material and mix well. Subsequently, process it on a shaker at 250 rpm at different time intervals (2 min, 5 min, 10 min, 15 min, 30 min, 1 h, 2 h) at room temperature. Filter the mixture of all samples through a 0.2 μm membrane filter, and then analyze the filtrate using UHPLC-MS / MS to determine the remaining content of PFOA and Gen X. All batch tests were repeated three times. The removal rate, pseudo-first-order kinetic model, and pseudo-second-order kinetic model were used to fit the process of the kinetic adsorption test to describe the adsorption process of the COF material in this study. The calculation formulas of the pseudo-first-order kinetic model and the pseudo-second-order kinetic model are shown as follows:

[0093] In(q e -q t )=Inq e -k1t;

[0094]

[0095] q t (mg / g) and q e (mg / g) represent the adsorption capacity of the adsorbent at time t (min) and at equilibrium, respectively. In addition, the pseudo-first-order rate constant and the pseudo-second-order rate constant are represented by k1 (min -1 ) and k2 (g mg -1 min -1 ), respectively.

[0096] According to Figure 7 , it can be seen that although the CS aerogel has a good adsorption capacity, the kinetics of the pure CS aerogel is poor, and it reaches a removal rate close to 100% within 120 min. With the incorporation of COF, the adsorption kinetics of COF / CS aerogel shows a similar linear improvement, especially COF / CS-4 reaches a removal rate of more than 90% within 10 min.

[0097] As Figure 8, for short-chain GenX, the pure CS aerogel shows poor kinetic results for ultra-short-chain PFAS. However, with the incorporation of COF, the adsorption kinetics of COF / CS aerogel also shows a similar linear improvement. In particular, COF / CS-4 reaches a removal rate of over 80% within 2 min and over 90% within 5 min.

[0098] Comparison with commercial adsorbents:

[0099] Activated carbon and β-cyclodextrin are among the most common adsorbents. COF / CS-4 and other commercial adsorbents were selected for comparison of adsorption performance. Isothermal adsorption experiments and adsorption kinetics were carried out under the same conditions, and the results are as Figure 9 - 10 shown. Compared with commercial adsorbents activated carbon and β-cyclodextrin, the adsorption capacity of the COF / CS-4 aerogel is increased by 6-7 times, and the adsorption equilibrium can be reached within 15 minutes instead of 120 minutes in terms of adsorption kinetics.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical method of the present invention or make equivalent replacements, and these modifications or equivalent replacements cannot make the modified technical method deviate from the spirit and scope of the technical method of the present invention.

Claims

1. A COF aerogel composite for PFAS treatment, characterized in that, It includes the following components: 68.18% - 70% of COF material, 22.73% - 90.91% of CS solution, and 9.09% of TP solution; The COF material includes 0.0382 - 0.0764 mmol of ETTA, 15 - 30 mg, 0.0764 - 0.1528 mmol of side functional monomer, and 1.5 - 3 mL of o-dichlorobenzene / n-butanol solvent; In the o-dichlorobenzene / n-butanol solvent, the volume ratio of o-dichlorobenzene to n-butanol is 1:1; The side functional monomer includes 0.0125 - 0.025 mmol of TFTDA; 0.0635 - 0.127 mmol of BFBlM, named COF-F1N5.

2. A preparation method of a COF aerogel composite material for PFAS treatment, characterized in that, It includes: S1. Synthesize hetero-porous fluorine-doped cationic COF; S2. Synthesize COF / chitosan aerogel composite material based on hetero-porous fluorine-doped cationic COF.

3. The preparation method of a COF aerogel composite material for PFAS treatment according to claim 2, characterized in that, The specific steps of S1 are: S101. Mix ETTA, side functional monomer, and o-dichlorobenzene / n-butanol solvent to obtain a primary mixed solution; S102. Add acetic acid as a catalyst to the primary mixed solution and mix to obtain a secondary mixed solution; S103. Degas and seal the secondary mixed solution, and transfer it to a muffle furnace for reaction at room temperature to obtain a solid product after it returns to room temperature; S104. Wash and filter the solid product to obtain an initial material; S105. Vacuum dry the initial material overnight to obtain COF nano-material, and obtain COF powder after grinding and sieving.

4. The preparation method of a COF aerogel composite material for PFAS treatment according to claim 1, characterized in that, The specific steps of S2 are: S201. Dissolve chitosan CS in an acetic acid aqueous solution and shake to form a uniform and transparent CS solution; S202. Add COF powder to the CS solution, shake and ultrasonically treat to obtain a uniformly dispersed solution; S203. Add TP solution to the dispersed solution, shake and then ultrasonically treat to form a hydrogel; S204. Let the hydrogel stand undisturbed at room temperature to form a highly cross-linked and stable hydrogel; S205. Freeze and vacuum dry the highly cross-linked and stable hydrogel to obtain a COF aerogel composite adsorption material.

5. The preparation method of a COF aerogel composite material for PFAS treatment according to claim 3, characterized in that, The acetic acid content in S102 is 6 - 10 mol, 0.3 - 0.6 mL.

6. The preparation method of a COF aerogel composite material for PFAS treatment according to claim 1, characterized in that, The acetic acid aqueous solution in S201 is 800 - 1000 μL, 0.2 - 0.5 mol / L; Subsequently, the TP solution in S203 is 200 - 400 μL, 10 - 15 mg / L.

7. The preparation method of a COF aerogel composite material for PFAS treatment according to claim 6, characterized in that, In S101, the mixing is carried out by ultrasonic treatment for 15 - 30 min; In S102, the mixing is carried out by ultrasonic treatment for 10 - 30 min; In S103, the degassing and sealing of the secondary mixed solution is carried out by the method of degassing through three freeze-pump-thaw cycles with liquid nitrogen; The muffle furnace temperature is 120 - 140 °C, and the reaction is for 72 - 96 hours; In S104, the solid product is washed and filtered 5 times with ultra-dry tetrahydrofuran and then washed and filtered 3 times with absolute ethanol; In S105, the initial material is vacuum dried overnight at 80 - 120 °C to obtain COF nano-material.

8. The preparation method of a COF aerogel composite material for PFAS treatment according to claim 1, characterized in that, In S201, shake for 10 - 20 s; In S202, shake for 10 - 20 s and ultrasonically treat for 10 - 15 minutes to uniformly disperse; In S204, let it stand for 12 - 18 hours; The hydrogel is placed in a -80 °C refrigerator and frozen for 12 - 18 h; The aerogel is vacuum freeze-dried for 36 h to obtain a COF aerogel composite adsorbent material.

9. The preparation method of a COF aerogel composite material for PFAS treatment according to claim 1, characterized in that, In S202, the ratio of COF to CS is 1:3 - 4:

1.

10. Use of the COF aerogel composite material prepared by the preparation method according to any one of claims 1 to 9, characterized in that, The COF aerogel composite material is applied to the adsorption of short-chain PFAS in the co-solvent system of long-chain and short-chain PFAS.

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