Three-dimensional reticular porous MOFs / MXene cellulose composite aerogel as well as preparation method and application thereof

Abstract

The invention discloses three-dimensional reticular porous MOFs / MXene cellulose composite aerogel as well as a preparation method and application thereof, and belongs to the technical field of aerogel. The preparation method comprises the following steps: adding divalent metal salt into an MXene aqueous dispersion to obtain a mixed dispersion I; sequentially adding the mixed dispersion liquid I and a borax aqueous solution into the mixed dispersion liquid of cellulose nanofibers and polyvinyl alcohol under a heating condition, stirring and dispersing, cooling, and freeze-drying to obtain double-crosslinked network aerogel; the preparation method comprises the following steps: preparing a bi-crosslinked network aerogel, immersing the bi-crosslinked network aerogel into a solution containing imidazole ligands for an in-situ reaction, and then washing and drying to obtain the three-dimensional network porous MOFs / MXene cellulose composite aerogel which has high MOFs loading capacity and excellent stability, can realize efficient adsorption of antibiotics, and is simple in preparation method and suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of aerogel technology, and in particular to a three-dimensional mesh porous MOFs / MXene cellulose composite aerogel and a preparation method and application thereof. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] In recent years, a new class of porous materials—metal-organic frameworks (MOFs)—has been discovered as separation materials for water treatment and organic solution separation. As adsorbents, they can quickly and efficiently adsorb dyes from water, with separation performance superior to that of traditional polymer resins. However, their crystalline nature and powdery morphology make MOFs difficult to manipulate and process. For example, the MOF powder is difficult to quickly and easily recover after adsorption, and the poor dispersion of hydrophobic MOF powder in aqueous solutions hinders its full adsorption performance. Macroscaling MOFs is the best approach to addressing this challenge. Currently, the primary approach to expanding their application is to grow MOFs on or within various substrates to construct novel composite separation materials that combine the advantages of both materials.

[0004] Cellulose aerogels, with their abundant and inexpensive raw materials, good biocompatibility, and high specific surface area, have become one of the most sought-after porous materials in recent years. They not only possess the low density, high porosity, and narrow pore size distribution of traditional aerogels, but also offer the advantages of cellulose, such as biodegradability, biocompatibility, and enhanced mechanical elasticity. Furthermore, cellulose's layered porous structure and ease of processing make it an excellent support for the construction of novel hybrid materials, with significant potential for application in adsorption and separation. Distributing MOFs within the three-dimensional network of aerogels effectively mitigates the vulnerability of MOFs to decomposition, improving their stability, processability, and recyclability. Therefore, the composite of cellulose aerogels with MOFs represents a strategy for effectively combining rigid and flexible materials, potentially improving the properties of both, and thus offering potential applications in adsorption and separation. However, the dispersion of MOF particles in cellulose solutions is difficult to control, leading to prone aggregation and sedimentation. Furthermore, their interaction with the gel matrix is primarily physical, resulting in low MOF particle loading, low adhesion, and poor stability. Therefore, how to provide a MOFs / cellulose composite aerogel with good stability and uniform MOFs distribution and its preparation method is an urgent problem to be solved. Summary of the Invention

[0005] In view of this, the present invention provides a three-dimensional network porous MOFs / MXene cellulose composite aerogel and its preparation method and application. The composite aerogel provided by the present invention has a high MOFs loading capacity, high mechanical strength and excellent stability, and exhibits good application performance in antibiotic adsorption.

[0006] In a first aspect, the present invention provides a method for preparing a three-dimensional porous MOFs / MXene cellulose composite aerogel, comprising the following steps: Adding a divalent metal salt to the MXene aqueous dispersion to obtain a mixed dispersion 1; Adding the mixed dispersion liquid 1 and the borax aqueous solution to the mixed dispersion liquid of cellulose nanofibers and polyvinyl alcohol in sequence under heating conditions, stirring and dispersing, cooling and freeze-drying to obtain a double-crosslinked network aerogel; The double-crosslinked network aerogel is immersed in an aqueous solution containing imidazole ligands for in-situ reaction, and then washed and dried to obtain a three-dimensional network porous MOFs / MXene cellulose composite aerogel.

[0007] In a second aspect, the present invention provides a three-dimensional network porous MOFs / MXene cellulose composite aerogel prepared by the above preparation method.

[0008] In a third aspect, the present invention provides the role of the above-mentioned three-dimensional network porous MOFs / MXene cellulose composite aerogel in the adsorption of antibiotics.

[0009] Compared with the prior art, the present invention has achieved the following beneficial effects: The present invention utilizes MXene nanosheets to modify double-crosslinked network cellulose aerogels, and based on the "nano-confinement" effect of the aerogel pores, realizes the in-situ embedding, firm anchoring and uniform distribution of MOFs particles, and improves the adhesion between MOFs and the substrate, thereby constructing a three-dimensional porous double-crosslinked network MOFs / MXene cellulose composite aerogel with high MOFs loading and excellent stability, which can achieve efficient adsorption of antibiotics, and the preparation method is simple, suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute undue limitations thereon. It is obvious that one of ordinary skill in the art could derive other drawings based on these drawings without inventive effort.

[0011] Figure 1 The three-dimensional porous ZIF-67 / MXene / CNF of Example 2 of the present invention -4Scanning electron microscope image of composite aerogel; Figure 2 This is a scanning electron microscope image of the double-crosslinked network CNF aerogel of Comparative Example 1 of the present invention; Figure 3 is a scanning electron microscope image of the ZIF-67 / CNF aerogel of Comparative Example 2 of the present invention; Figure 4 3 is a comparison chart of the tetracycline adsorption capacity of the aerogels of Example 2 of the present invention and Comparative Examples 1-2.

[0012] Figure 5 The three-dimensional porous ZIF-67 / MXene / CNF of Example 2 of the present invention -4 Figure 2 shows the recycling results of tetracycline adsorbed on composite aerogel. DETAILED DESCRIPTION

[0013] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0014] The present invention provides a method for preparing a three-dimensional network porous MOFs / MXene cellulose composite aerogel, comprising the following steps: Adding a divalent metal salt to the MXene aqueous dispersion to obtain a mixed dispersion 1; Adding the mixed dispersion liquid 1 and the borax aqueous solution to the mixed dispersion liquid of cellulose nanofibers and polyvinyl alcohol in sequence under heating conditions, stirring and dispersing, cooling and freeze-drying to obtain a double-crosslinked network aerogel; The double-crosslinked network aerogel is immersed in an aqueous solution containing imidazole ligands for in-situ reaction, and then washed and dried to obtain a three-dimensional network porous MOFs / MXene cellulose composite aerogel.

[0015] In the present invention, polyvinyl alcohol and cellulose nanofibers can form a dual-crosslinked network hydrogel. The surface of the MXene nanosheets contains abundant terminal groups, such as hydroxyl (-OH), oxygen (-O-), or fluorine (-F). These hydroxyl and oxygen-containing functional groups act as binding sites for metal ions, altering the nucleation and growth equilibrium of MOFs, thereby increasing their loading capacity. They also participate in the assembly of the dual-crosslinked network MOFs / cellulose composite aerogel through hydrogen bonding. Furthermore, the MXene nanosheets effectively enhance the interaction between the MOFs and the cellulose dual-network aerogel, significantly overcoming the drawbacks of MOFs' rapid crystal growth and aggregation. This also results in smaller and more dispersed MOFs within the aerogel, significantly improving the mechanical properties of the composite. Furthermore, the MXene loaded with MOF particles acts as a secondary crosslinker in the composite system, further optimizing the network structure and mechanical strength of the composite aerogel. The three-dimensional, porous MOFs / MXene cellulose composite aerogel prepared by the above method exhibits excellent compression recovery and superior antibiotic adsorption and separation properties, and can be applied in water treatment.

[0016] In the present invention, the divalent metal salt is selected from at least one of sulfates, nitrates, acetates, or hydrochlorides of zirconium, iron, copper, zinc, or cobalt. In one or more embodiments of the present invention, the divalent metal salt is selected from cobalt nitrate hexahydrate.

[0017] The present invention does not impose any special restrictions on the preparation method of the MXene aqueous dispersion, and the preparation method of the MXene aqueous dispersion commonly used in the art can be used. The present invention preferably uses LiF and hydrochloric acid solution to etch the MAX phase material. The present invention does not impose any special restrictions on the selected MAX phase material. The molecular formula of the MAX phase material is M n+1 AX n , wherein M comprises one or more of scandium, titanium, vanadium, chromium, zirconium, niobium, molybdenum, hafnium, and tantalum, A is selected from Group III or Group IV elements, X is one or more of carbon, nitrogen, and boron, and n is 1, 2, 3, or 4. In one or more embodiments of the present invention, the MAX phase material is selected from Ti3AlC2.

[0018] In the MXene aqueous dispersion of the present invention, the concentration of MXene is 1 to 5 mg / mL, for example, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, etc.; the mass ratio of MXene to divalent metal salt is 1: (2 to 6), more preferably 1: (3 to 5), and most preferably 1:4.

[0019] In the mixed dispersion of cellulose nanofibers and polyvinyl alcohol described in the present invention, the concentration of the cellulose nanofibers is 0.5-2wt%, and the concentration of the polyvinyl alcohol is 3-8wt%. The volume ratio of the mixed dispersion of cellulose nanofibers and polyvinyl alcohol to the mixed dispersion is 1:(1-3), preferably 1:2. The present invention does not impose any particular limitation on the method for preparing the mixed dispersion of cellulose nanofibers and polyvinyl alcohol. The cellulose nanofibers can be added to the aqueous dispersion of cellulose nanofibers, to the aqueous polyvinyl alcohol solution, or both into water and dissolved and dispersed uniformly under heating and stirring conditions.

[0020] In the present invention, the concentration of the borax aqueous solution is 2-6 wt %, and the mass ratio of polyvinyl alcohol to borax is (3-8):1. Polyvinyl alcohol (PVA) is a water-soluble polymer compound containing a large number of hydroxyl (-OH) groups in its molecules. When the polyvinyl alcohol aqueous solution is mixed with borax (sodium borate), the borate ions in the borax undergo a cross-linking reaction with the hydroxyl groups in the polyvinyl alcohol molecules, forming a three-dimensional network structure.

[0021] In the present invention, the heating condition is 80-100° C., more preferably 90-100° C. Heating conditions are more conducive to uniform stirring and dispersion. The present invention does not impose any particular limitation on the stirring and dispersion time, as long as uniform mixing is ensured.

[0022] In the present invention, the imidazole ligand is selected from one or both of 2-methylimidazole and benzimidazole; in one or more embodiments of the present invention, the imidazole ligand is selected from 2-methylimidazole. The concentration of the imidazole ligand in the solution containing the imidazole ligand is 2-10 wt%, more preferably 4-8 wt%, and even more preferably 5-7 wt%. The present invention does not impose any particular limitation on the specific amount of the solution containing the imidazole ligand, as long as the double-crosslinked network aerogel can be immersed in the solution.

[0023] In the present invention, the in-situ reaction time is 8 to 20 hours, and the temperature is 10 to 40°C, preferably at room temperature. During the in-situ reaction, the abundant hydrophilic groups of MXene interact with the hydroxyl groups of PVA and cellulose through hydrogen bonding, connecting the MXene to the tough PVA network and the rigid cellulose network. In addition, the divalent metal ions on the MXene surface can serve as nucleation centers within the aerogel matrix to synthesize MOFs particles in situ, and can act as strong crosslinkers to enhance the entanglement between polymer chains, significantly improving the mechanical properties and compressive resistance of the aerogel.

[0024] The present invention also provides a three-dimensional mesh porous MOFs / MXene cellulose composite aerogel prepared by the above preparation method, which has the advantages of high MOFs loading, high mechanical strength and excellent stability.

[0025] The present invention also provides the role of the above-mentioned three-dimensional network porous MOFs / MXene cellulose composite aerogel in the adsorption of antibiotics, wherein the antibiotics include one or more of tetracycline, levofloxacin hydrochloride, penicillin or azithromycin. In one or more embodiments of the present invention, the antibiotic is selected from tetracycline.

[0026] The technical solution of the present invention is further described below with reference to specific examples. The present invention has no particular limitation on the sources of the reagents in the following examples, and commercially available products known to those skilled in the art can be used; "room temperature" in the following examples refers to a temperature of 25±3°C.

[0027] In the following examples, the MXene material was prepared as follows: 1.5 g of Ti3AlC2MAX phase material was added to 1.5 g of LiF and 20 ml of a 6 M HCl solution. The reaction was stirred at a constant temperature for a period of time. The etched product was rinsed with deionized water, then centrifuged and rinsed repeatedly until the pH of the supernatant reached ≥ 6. The rinsed product was then mixed with deionized water and sonicated. The resulting solution was centrifuged and the precipitate was collected to obtain the MXene material. This preparation was repeated multiple times to obtain the desired amount.

[0028] Example 1 This embodiment provides a method for preparing a three-dimensional network porous MOFs / MXene cellulose composite aerogel.

[0029] (1) Disperse 60 mg of MXene material in 20 mL of deionized water, add 120 mg of cobalt nitrate hexahydrate and stir for 2 h to obtain a uniformly mixed dispersion, namely, M-MXene dispersion.

[0030] (2) Polyvinyl alcohol (PVA) was added to 10 mL of 1 wt% cellulose nanofiber (CNF) solution at 95 °C and stirred continuously. The amount of PVA added was controlled to be 5 wt% to obtain a PVA / CNF mixed dispersion.

[0031] (3) The M-MXene dispersion and the PVA / CNF mixed dispersion were evenly mixed at 95 °C, and a 4 wt% borax aqueous solution (the mass ratio of borax to PVA was 1:5) was added dropwise, and stirred vigorously until a well-dispersed M-MXene / PVA / CNF uniform dispersion was formed. When the temperature was cooled to room temperature, a double-cross-linked network hydrogel was obtained, which was freeze-dried to obtain a double-cross-linked network structure aerogel.

[0032] (4) At room temperature, the double-crosslinked network aerogel obtained in step (3) was immersed in 20 mL of an aqueous solution containing 6 wt% 2-methylimidazole and reacted at room temperature (25 ± 3 ° C) for 12 h. MOFs nanoparticles were controllably grown in the three-dimensional network aerogel by the in situ growth method. After multiple washing and drying, a three-dimensional porous ZIF-67 / MXene / CNF was obtained. -2 Composite aerogel.

[0033] In this embodiment, the loading amount of MOFs nanoparticles is 1.22 wt %.

[0034] The scanning electron microscope image of the three-dimensional porous MOFs / MXene cellulose composite aerogel obtained in this example is shown in FIG. Figure 1 As shown, the material exhibits a typical three-dimensional porous network structure, with interconnected pores forming a continuous network. This indicates a high specific surface area and good mass transfer pathways, which are beneficial for adsorption applications. The MXene sheets and MOF particles are uniformly dispersed within the cellulose matrix, with no apparent agglomeration observed, demonstrating that the composite process effectively achieves a homogeneous multi-component composite. The flexibility of the cellulose backbone likely mitigates the rigid stress of the MXene and MOFs, thereby maintaining the stability of the porous structure.

[0035] Example 2 This embodiment provides a method for preparing a three-dimensional network porous MOFs / MXene cellulose composite aerogel.

[0036] (1) 60 mg of MXene material was dispersed in 20 mL of deionized water, and 240 mg of cobalt nitrate hexahydrate was added under stirring conditions and stirred for 2 h to obtain a uniformly mixed dispersion, namely, M-MXene dispersion.

[0037] (2) Polyvinyl alcohol (PVA) was added to 10 mL of 1 wt% cellulose nanofiber (CNF) solution at 95 °C and stirred continuously. The amount of PVA added was controlled to be 5 wt% to obtain a PVA / CNF mixed dispersion.

[0038] (3) The M-MXene dispersion and the PVA / CNF mixed dispersion were evenly mixed at 95 °C, and a 4 wt% borax aqueous solution (the mass ratio of borax to PVA was 1:5) was added dropwise, and stirred vigorously until a well-dispersed M-MXene / PVA / CNF uniform dispersion was formed. When the temperature was cooled to room temperature, a double-cross-linked network hydrogel was obtained, which was freeze-dried to obtain a double-cross-linked network structure aerogel.

[0039] (4) The double-crosslinked network aerogel obtained in step (3) was immersed in 20 mL of an aqueous solution containing 6 wt% 2-methylimidazole and reacted at room temperature (25 ± 3 ° C) for 12 h. MOFs nanoparticles were controllably grown in the three-dimensional network aerogel by the in situ growth method. After multiple washing and drying, a three-dimensional porous ZIF-67 / MXene / CNF was obtained. -4 Composite aerogel.

[0040] In this embodiment, the loading amount of MOFs nanoparticles is 1.37%.

[0041] Example 3 This embodiment provides a method for preparing a three-dimensional network porous MOFs / MXene cellulose composite aerogel.

[0042] (1) 60 mg of MXene material was dispersed in 20 mL of deionized water, and 360 mg of cobalt nitrate hexahydrate was added under stirring conditions and stirred for 2 h to obtain a uniformly mixed dispersion, namely, M-MXene dispersion.

[0043] (2) Polyvinyl alcohol (PVA) was added to 10 mL of 1 wt% cellulose nanofiber (CNF) solution at 95 °C and stirred continuously. The amount of PVA added was controlled to be 5 wt% to obtain a PVA / CNF mixed dispersion.

[0044] (3) The M-MXene dispersion and the PVA / CNF mixed dispersion were evenly mixed at 95 °C, and a 4 wt% borax aqueous solution (the mass ratio of borax to PVA was 1:5) was added dropwise, and stirred vigorously until a well-dispersed M-MXene / PVA / CNF uniform dispersion was formed. When the temperature was cooled to room temperature, a double-cross-linked network hydrogel was obtained, which was freeze-dried to obtain a double-cross-linked network structure aerogel.

[0045] (4) The double-crosslinked network aerogel obtained in step (3) was immersed in 20 mL of an aqueous solution containing 6 wt% 2-methylimidazole and reacted at room temperature (25 ± 3 ° C) for 12 h. MOFs nanoparticles were controllably grown in the three-dimensional network aerogel by the in situ growth method. After multiple washing and drying, a three-dimensional porous ZIF-67 / MXene / CNF was obtained. -6 Cellulose composite aerogels.

[0046] In this embodiment, the loading amount of MOFs nanoparticles is 1.99%.

[0047] Comparative Example 1 The difference between this comparative example and Example 2 is that the aerogel in this comparative example does not contain MXene and MOFs nanoparticles. The specific preparation method is as follows: Polyvinyl alcohol (PVA) was added to 10 mL of a 1 wt% cellulose nanofiber (CNF) solution at 95°C and stirred continuously. The amount of PVA added was controlled to 5 wt% to obtain a PVA / CNF mixed dispersion. Then, a 4 wt% borax aqueous solution (the mass ratio of borax to PVA was 1:5) was added dropwise to the PVA / CNF mixed dispersion and stirred vigorously until a well-dispersed PVA / CNF / borax uniform dispersion was formed. When the temperature was cooled to room temperature, a double-cross-linked network hydrogel was obtained, which was freeze-dried to obtain a double-cross-linked network CNF aerogel.

[0048] The scanning electron microscope image of the double cross-linked network CNF aerogel prepared in this comparative example is as follows: Figure 2 As shown, the material exhibits a typical three-dimensional porous network structure with a wide pore size distribution (visible pores ranging from a few microns to tens of microns). On the pore walls, CNF nanofibers with diameters of approximately 50-100 nm are visible, forming an interwoven network. These fibers are tightly bonded to the PVA matrix, forming continuous, open pores, indicating the material's high porosity.

[0049] Comparative Example 2 The difference between this comparative example and Example 2 is that the aerogel in this comparative example does not contain MXene. The specific preparation method is as follows: (1) Polyvinyl alcohol (PVA) was added to 10 mL of 1 wt% cellulose nanofiber (CNF) solution at 95 °C and stirred continuously. The amount of PVA added was controlled to be 5 wt% to obtain a PVA / CNF mixed dispersion.

[0050] 240 mg of cobalt nitrate hexahydrate was added to the PVA / CNF mixed dispersion at 95°C and mixed. A 4 wt% borax aqueous solution (borax to PVA mass ratio of 1:5) was added dropwise and stirred vigorously until a well-dispersed M-MXene / PVA / CNF uniform dispersion was formed. When the temperature was lowered to room temperature, a double cross-linked network hydrogel was obtained. After freeze-drying, a double cross-linked network aerogel was obtained. (3) The double cross-linked network aerogel obtained in step (2) was immersed in 20 mL of an aqueous solution containing 6 wt% 2-methylimidazole and reacted at room temperature (25±3°C) for 12 h. ZIF-67 nanoparticles were controllably grown in the three-dimensional network aerogel by the in situ growth method. After multiple washing and drying, a three-dimensional porous ZIF-67 / CNF composite aerogel was obtained.

[0051] The scanning electron microscope image of the ZIF-67 / CNF composite aerogel prepared in this comparative example is shown in FIG. Figure 3As shown, it can be seen that the material presents a highly interconnected three-dimensional porous network structure. The ZIF-67 particles are sparsely distributed and unevenly sized and are embedded in the gel skeleton in larger sizes. In some areas, micron-sized agglomerates (1-5 μm) even appear, indicating that in the absence of MXene support, the nucleation process of ZIF-67 is restricted, resulting in uneven particle distribution and structural defects.

[0052] Test example 1. Determination of tetracycline adsorption performance: 10 mg of ZIF-67 / MXene / CNF of Example 1, ZIF-67 / CNF of Comparative Example 2, and CNF aerogel of Comparative Example 1 were added to 10 mL of 20 mg / L tetracycline solution, respectively. The color change was observed after adsorption for different times, the absorbance was measured, and the adsorption amount was calculated according to the following formula: formula:

[0053] Where, q is the adsorption capacity, unit is mg / g; C 0 is the initial concentration of tetracycline solution before adsorption, in mg / L; C t is the final concentration of tetracycline solution after adsorption, in mg / L; V is the volume of tetracycline solution consumed, in mL; M is the mass of the adsorbent, in mg.

[0054] The above formula was used to calculate the adsorption capacity of the composite aerogel, and the results were as follows: Figure 4 As shown, the adsorption capacity of all three materials increases with time, but the kinetic behavior differs significantly. The adsorption capacity of the ZIF-67 / MXene / CNF composite aerogel rapidly increases to 28 mg / g within the first 4 hours, then slows down, reaching an equilibrium adsorption capacity of 43 mg / g after 12 hours. The rapid adsorption phase indicates abundant active sites on the material surface, while the slow equilibrium phase is likely dominated by diffusion of tetracycline molecules into the material's pores and chemical adsorption. The ZIF-67 / CNF aerogel reaches an adsorption capacity of 20 mg / g within 6 hours and ultimately reaches an equilibrium adsorption capacity of 30 mg / g, exhibiting lower adsorption rates and capacities than the MXene-containing sample. The CNF aerogel exhibits the lowest adsorption capacity (only 10 mg / g after 12 hours) and exhibits a slow growth rate throughout the entire process, indicating that adsorption relies primarily on physical entrapment and lacks specific chemical adsorption sites.

[0055] 2. Cyclic stability determination: The cyclic stability of the ZIF-67 / MXene / CNF composite aerogel of Example 1 was studied by ethanol desorption. The aerogel after tetracycline adsorption was recovered by squeezing and washing with deionized water. The regenerated aerogel was dried at 80°C and then subjected to three repeated 12-h adsorption experiments. Figure 5 As shown in the figure, the adsorption capacity remained at a high level throughout three cycles with no apparent downward trend, demonstrating the aerogel's excellent regeneration and structural durability. This result can be attributed to the synergistic effect of the aerogel's multi-component system: the porous framework of ZIF-67 provides abundant active sites, the high surface area and surface functional groups of MXene enhance adsorption capacity, and the cross-linked network of CNF and PVA ensures the mechanical strength of the material during cycling, preventing pore collapse or structural damage caused by repeated adsorption and desorption. Furthermore, slight fluctuations in adsorption capacity during cycling (e.g., a slight decrease after the first cycle) may be related to temporary deactivation of some active sites due to physical blockage or chemical passivation. However, the overall stable adsorption performance indicates that the material can recover most of its adsorption capacity through simple regeneration (e.g., solvent elution or thermal treatment).

[0056] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a three-dimensional porous MOFs / MXene cellulose composite aerogel, characterized in that: The steps include: Adding a divalent metal salt to the MXene aqueous dispersion to obtain a mixed dispersion 1; Adding the mixed dispersion liquid 1 and the borax aqueous solution to the mixed dispersion liquid of cellulose nanofibers and polyvinyl alcohol in sequence under heating conditions, stirring and dispersing, cooling and freeze-drying to obtain a double-crosslinked network aerogel; The double-crosslinked network aerogel is immersed in a solution containing imidazole ligands for in-situ reaction, and then washed and dried to obtain a three-dimensional network porous MOFs / MXene cellulose composite aerogel.

2. The preparation method according to claim 1, wherein The divalent metal salt is selected from at least one of sulfates, nitrates, acetates or hydrochlorides of metal zirconium, iron, copper, zinc or cobalt.

3. The preparation method according to claim 1, wherein In the MXene aqueous dispersion, the concentration of MXene is 1-5 mg / mL; and the mass ratio of MXene to divalent metal salt is 1:(2-6).

4. The preparation method according to claim 1, wherein In the mixed dispersion of cellulose nanofibers and polyvinyl alcohol, the concentration of cellulose nanofibers is 0.5~2wt%, and the concentration of polyvinyl alcohol is 3~8wt%; the volume ratio of the mixed dispersion of cellulose nanofibers and polyvinyl alcohol to the mixed dispersion is 1:(1~3).

5. The preparation method according to claim 1, wherein The concentration of the borax aqueous solution is 2-6 wt %; the mass ratio of the polyvinyl alcohol to borax is (3-8):

1.

6. The preparation method according to claim 1, wherein The heating condition is 80-100°C.

7. The preparation method according to claim 1, wherein The imidazole ligand is selected from one or both of 2-methylimidazole and benzimidazole; and the concentration of the imidazole ligand in the solution containing the imidazole ligand is 2-10 wt %.

8. The preparation method according to claim 1, wherein The in-situ reaction time is 8-20 hours, and the temperature is 10-40°C.

9. A three-dimensional network porous MOFs / MXene cellulose composite aerogel prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the three-dimensional network porous MOFs / MXene cellulose composite aerogel according to claim 9 in the adsorption of antibiotics.

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