An amine oxime functionalized defective metal organic framework material, and a preparation method and application thereof

Abstract

The application discloses a kind of amine oxime functionalized defective metal organic framework material and its preparation method and application, belong to the preparation technical field of functional MOFs material.The preparation steps of the amine oxime functionalized defective metal organic framework material include: with metal salt, adjusting agent ligand and terephthalic acid as reactant, by solvothermal reaction, preparation obtains cyanated defective MOFs material;Amine oxime functionalization is carried out to the cyanated defective MOFs material, and the amine oxime functionalized defective MOFs material is obtained.The amine oxime functionalized defective metal organic framework material provided in the application has excellent adsorption and selection capacity to hexavalent uranium, which is further combined with graphene / cellulose aerogel, based on solving the problem of MOFs particle agglomeration, using the excellent photo-thermal conversion performance of graphene / cellulose aerogel, the adsorption capacity of the composite material to hexavalent uranium is further improved.

Description

Technical Field

[0001] This invention belongs to the field of preparation technology of functional MOFs materials, specifically relating to a metal-organic framework material with a methylamine oxime functionalization defect type, its preparation method and application. Background Technology

[0002] Nuclear energy, with its exceptionally high energy density and extremely low carbon emissions, has emerged as a powerful alternative to fossil fuels. Uranium is the primary raw material for nuclear reactors, and its ample supply is crucial for the continued healthy development and sustainable future of the nuclear energy industry. However, uranium resources face significant challenges. It is estimated that there are only about 4.5 million tons of uranium ore remaining on land globally, and the ore grade is low, insufficient to meet global energy demand. Fortunately, uranium resources in the ocean are abundant. It is estimated that there are approximately 4.5 billion tons of usable uranium in the ocean. This potential uranium source is sufficient to support the vigorous development of the nuclear energy industry for thousands of years, providing strong support for alleviating the global energy crisis and exploring a green and sustainable energy future.

[0003] However, the extremely low concentration of uranium (3.3 ppb) in seawater and the immense complexity of the marine environment pose significant challenges to the effective extraction of uranium. Among various methods for extracting uranium from seawater, selective adsorption using functional materials is considered the most feasible approach for recovering marine uranium resources due to its wide availability, ease of operation, and environmental friendliness.

[0004] However, existing adsorbents still suffer from problems such as slow adsorption rate, low adsorption efficiency, and poor recyclability. It is crucial to develop a uranium adsorbent that is highly efficient, structurally stable, safe, and environmentally friendly. Summary of the Invention

[0005] The purpose of this invention is to provide a defective metal-organic framework (MOF) material functionalized with amine oxime, its preparation method, and its applications. The provided defective MOF material exhibits excellent adsorption and selectivity for hexavalent uranium. Further combining it with graphene / cellulose aerogel solves the problem of MOF particle aggregation and, by utilizing the excellent photothermal conversion properties of graphene / cellulose aerogel, further enhances the adsorption capacity of the composite material for hexavalent uranium.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] One of the technical solutions of this invention is to provide a method for preparing a defective metal-organic framework material functionalized with amine oxime, comprising the following steps:

[0008] A cyano-defective MOF material was prepared by a solvothermal reaction using metal salts, modifier ligands, and terephthalic acid as reactants.

[0009] The cyano-defective MOF material is functionalized with a amine oxime to obtain the amine oxime-functionalized defective MOF material.

[0010] The regulator ligand is 3-cyanobenzoic acid, 4-cyanobenzoic acid, or cyanoacetic acid.

[0011] The second technical solution of this invention provides a method for preparing a metal-organic framework@graphene / cellulose aerogel composite material functionalized with amine oxime, comprising the following steps:

[0012] Using graphene / cellulose aerogel as a carrier, it was immersed in a solution containing metal salts and stirred to obtain metal ion-loaded graphene / cellulose aerogel.

[0013] Using the metal ion-supported graphene / cellulose aerogel, regulator ligands, and terephthalic acid as reactants, a cyano-defective MOFs@graphene / cellulose aerogel composite material was prepared by solvothermal reaction.

[0014] The cyano-defective MOFs@graphene / cellulose aerogel composite material was functionalized with amine oxime to obtain the defective metal-organic framework@graphene / cellulose aerogel composite material.

[0015] The regulator ligand is 3-cyanobenzoic acid, 4-cyanobenzoic acid, or cyanoacetic acid.

[0016] The metal-organic framework (MOFs) in this invention are porous materials formed by coordination between metal centers (clusters or metal ions) and an organic framework. They possess ordered porous scaffolds, high specific surface area, controllable functionality, and structural diversity. MOFs exhibit porous structures, precise construction, and ease of functionalization, enabling them to interact with uranyl ions in multiple dimensions, such as precise recognition and adsorption, thus making them stand out in the field of uranium removal. This invention further enhances adsorption performance by controlling the internal defects of MOFs, thereby expanding pores and increasing adsorption active sites. The cleverly embedded amine oxime groups significantly optimize the pore structure and specific surface area of ​​MOFs, substantially increasing selective active sites and thus greatly improving their adsorption performance and selectivity. This effectively overcomes the problems of pore size limitations, scarce and low utilization of adsorption sites, and insufficient selectivity for hexavalent uranium inherent in traditional MOF materials.

[0017] The graphene / cellulose aerogel in this invention has advantages such as ultralight weight, high mechanical strength, and excellent photothermal conversion performance, making it a very promising material in the field of adsorption. This invention uses in-situ growth technology to firmly anchor the defective metal-organic framework material functionalized with amylopectin onto the graphene / cellulose aerogel matrix. While effectively avoiding the aggregation of MOF particles, the excellent photothermal conversion performance of graphene-based aerogel is utilized to make the composite material have better adsorption performance.

[0018] Preferably, the metal ions in the metal salt include Zr. 4+ Ce 3+ Ni 2+ or Cu 2+ .

[0019] Preferably, the molar ratio of the regulator ligand to the terephthalic acid is 1 to 30:1.

[0020] Preferably, the solvent for the solvothermal reaction is N,N-dimethylformamide, the temperature is 100-120°C, and the time is 12-48 hours.

[0021] Preferably, the step of functionalizing the amylopyrime includes: mixing the raw material to be functionalized with hydroxylamine hydrochloride and anhydrous potassium carbonate in a mixed solvent of ethanol and water, and reacting under an inert atmosphere to complete the functionalization of the amylopyrime.

[0022] More preferably, the mass ratio of the raw material to be functionalized, the hydroxylamine hydrochloride, and the anhydrous potassium carbonate is 0.2–1:1:1; the volume ratio of ethanol to water in the mixed solvent is 9:1–3; the reaction temperature is 60–90°C, and the reaction time is 8–12 h.

[0023] Preferably, the mass ratio of the metal ions in the metal salt to the graphene / cellulose aerogel is 27.3:5 to 20.

[0024] Preferably, the preparation steps of the graphene / cellulose aerogel include: using graphene oxide and cellulose as reactants, and ethylenediamine as a crosslinking agent, and performing a hydrothermal reaction to obtain the graphene / cellulose aerogel.

[0025] More preferably, the mass ratio of graphene oxide to cellulose is 1:0.1-2; the amount ratio of graphene oxide to ethylenediamine is 0.05-0.2g:20μL; and the hydrothermal reaction temperature is 100-120℃ and the time is 6-10h.

[0026] The third technical solution of the present invention provides a metal-organic framework material with a amine oxime functionalization defect type prepared according to the above preparation method.

[0027] The fourth technical solution of the present invention provides a metal-organic framework@graphene / cellulose aerogel composite material functionalized with a amine oxime according to the above preparation method.

[0028] Fifth technical solution of the present invention: to provide an application of the above-mentioned amine oxime functionalized defective metal-organic framework material in the enrichment of hexavalent uranium.

[0029] The sixth technical solution of this invention provides an application of the above-mentioned amine oxime-functionalized defective metal-organic framework@graphene / cellulose aerogel composite material in the enrichment of hexavalent uranium.

[0030] The beneficial technical effects of the present invention are as follows:

[0031] The metal-organic framework material or metal-organic framework@graphene / cellulose aerogel composite material provided by this invention not only has excellent adsorption performance and uranium selectivity, but also uses environmentally friendly, non-toxic and harmless raw materials, and is low in cost. Attached Figure Description

[0032] Figure 1 The images shown are SEM images of the samples prepared in Examples 1, 4 and 5, where a is the SEM image of UiO-66-3BA-AO prepared in Example 1, b is the SEM image of UiO-66-4BA-AO prepared in Example 4, and c is the SEM image of UiO-66-AA-AO prepared in Example 5.

[0033] Figure 2 The image shows the SEM images of UiO-66-3BA-AO / GCA prepared in Example 3, where a is a low-magnification image and b is a high-magnification image.

[0034] Figure 3 The X-ray diffraction patterns are of the samples prepared in Examples 1, 4 and 5.

[0035] Figure 4 The images show the infrared spectra of the samples prepared in Examples 1, 4, and 5. Specifically, a is the infrared spectrum of UiO-66-3BA-AO and the intermediate product before oxime hydride preparation in Example 1, b is the infrared spectrum of UiO-66-4BA-AO and the intermediate product before oxime hydride preparation in Example 4, and c is the infrared spectrum of UiO-66-AA-AO and the intermediate product before oxime hydride preparation in Example 5.

[0036] Figure 5The nitrogen adsorption-desorption isotherms and pore size distribution diagrams of the samples prepared in Examples 1, 4, 5 and Comparative Example 2 are shown, where a is the nitrogen adsorption-desorption isotherm and b is the pore size distribution diagram.

[0037] Figure 6 The adsorption performance of hexavalent uranium on the samples prepared in Examples 1, 3, 4, 5, 6, 7, 8, 9, 10, 11 and Comparative Example 2 is shown in the figure.

[0038] Figure 7 The graph shows the relationship between the amount of hexavalent uranium adsorbed by the sample prepared in Example 1 and time.

[0039] Figure 8 The graph shows the relationship between the amount of uranium adsorbed by the sample prepared in Example 3 and time under darkness and light.

[0040] Figure 9 The graph shows the relationship between the amount of hexavalent uranium adsorbed by the sample prepared in Example 1 and temperature.

[0041] Figure 10 The graph shows the performance of the sample prepared in Example 1 in cyclic adsorption of hexavalent uranium.

[0042] Figure 11 The graph shows the selective adsorption performance of hexavalent uranium in the sample prepared in Example 1. Detailed Implementation

[0043] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0044] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0045] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0046] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0047] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0048] Example 1

[0049] Preparation of defective metal-organic framework materials functionalized with amine oxime:

[0050] S1. Disperse 0.3 mmol of ZrCl4 in 10 mL of DMF and sonicate for 10 min to obtain a homogeneous solution, denoted as solution A.

[0051] S2. Disperse 0.3 mmol of terephthalic acid and 6 mmol of 3-cyanobenzoic acid into 10 mL of DMF, sonicate for 5 min, and record as solution B.

[0052] S3. Mix solutions A and B and sonicate for 10 min. Then transfer the mixture to a high-pressure reactor lined with polytetrafluoroethylene and react at 120 °C for 24 h. After naturally cooling to room temperature, collect the solid product by centrifugation and wash it three times with N,N-dimethylformamide and ethanol respectively. Finally, vacuum dry the product at 60 °C for 24 h to obtain cyano-defective MOF materials.

[0053] S4. Disperse 0.2 g of cyano-defective MOF material, 0.4 g of hydroxylamine hydrochloride, and 0.4 g of potassium carbonate in 60 mL of 90 vol.% ethanol solution. React at 80 °C for 8 h under nitrogen protection. After cooling, collect the sample, wash it three times with water and ethanol respectively, and finally vacuum dry it at 60 °C for 12 h to obtain the amine oxime-functionalized defective metal-organic framework material, denoted as UiO-66-3BA-AO.

[0054] Example 2

[0055] Preparation of graphene / cellulose aerogels:

[0056] S1. Take 0.05g of graphene oxide and add it to 5mL of ultrapure water. Sonicate for 2h to obtain a graphene oxide dispersion solution.

[0057] S2. Add 0.005g of cellulose to 5mL of ultrapure water and stir for 1h to obtain a cellulose dispersion.

[0058] S3. Mix the graphene oxide dispersion and the cellulose dispersion, then add 10 μL of ethylenediamine and stir for 15 min. Pour the mixture into a high-pressure reactor lined with polytetrafluoroethylene and react at 120 °C for 8 h. After cooling to room temperature, soak in a 15 vol.% ethanol solution for 24 h, then freeze in a refrigerator for 24 h, and finally freeze-dry in a freeze dryer for 72 h to obtain graphene / cellulose aerogel (GCA).

[0059] Example 3

[0060] Preparation of defective metal-organic frameworks@graphene / cellulose aerogel composites functionalized with amine oxime:

[0061] S1. Weigh 0.3 mmol of ZrCl4 and disperse it in 10 mL of DMF. After sonication for 10 min, obtain a homogeneous solution. Then add 10 mg of GCA prepared in Example 2 and stir at 25 °C for 24 h.

[0062] S2. Weigh 0.3 mmol of terephthalic acid and 6 mmol of 3-cyanobenzoic acid and disperse them in 10 mL of DMF. Sonicate for 5 min to obtain a homogeneous solution.

[0063] S3. Mix and stir the solutions obtained from S1 and S2 for 10 min, then transfer them to a high-pressure reactor lined with polytetrafluoroethylene and react at 120 °C for 24 h. After cooling, collect the solid product and wash it three times each with N,N-dimethylformamide and ethanol. Finally, vacuum dry the product at 60 °C for 24 h to obtain the cyano-defective MOFs@graphene / cellulose aerogel composite material, denoted as UiO-66-3BA-CN / GCA.

[0064] S4. 0.2 g of UiO-66-3BA-CN / GCA, 0.4 g of hydroxylamine hydrochloride, and 0.4 g of potassium carbonate were dispersed in 60 mL of 90 vol.% ethanol solution and reacted at 80 °C for 8 h under nitrogen protection. After cooling, the sample was collected, washed three times sequentially with water and ethanol, and finally vacuum dried at 60 °C for 12 h to obtain a methylamine oxime-functionalized defective metal-organic framework@graphene / cellulose aerogel composite material, denoted as UiO-66-3BA-AO / GCA.

[0065] Example 4

[0066] Compared with Example 1, the only difference is that 3-cyanobenzoic acid is replaced with an equimolar amount of 4-cyanobenzoic acid, and the resulting sample is denoted as UiO-66-4BA-AO.

[0067] Example 5

[0068] Compared with Example 1, the only difference is that 3-cyanobenzoic acid is replaced with an equimolar amount of cyanoacetic acid, and the resulting sample is denoted as UiO-66-AA-AO.

[0069] Example 6

[0070] Compared to Example 1, the only difference is that the amount of 3-cyanobenzoic acid was adjusted to 3 mmol.

[0071] Example 7

[0072] Compared with Example 1, the only difference is that the amount of 3-cyanobenzoic acid was adjusted to 4.5 mmol.

[0073] Example 8

[0074] Compared with Example 1, the only difference is that the amount of 3-cyanobenzoic acid was adjusted to 7.5 mmol.

[0075] Example 9

[0076] Compared to Example 1, the only difference is that the amount of 3-cyanobenzoic acid was adjusted to 9 mmol.

[0077] Example 10

[0078] Compared to Example 3, the only difference is that the dosage of GCA is adjusted to 5 mg.

[0079] Example 11

[0080] Compared to Example 3, the only difference is that the dosage of GCA is adjusted to 15 mg.

[0081] Comparative Example 1

[0082] Preparation of cyano-defective MOF materials:

[0083] S1. Disperse 0.3 mmol of ZrCl4 in 10 mL of DMF and sonicate for 10 min to obtain a homogeneous solution, denoted as solution A.

[0084] S2. Disperse 0.3 mmol of terephthalic acid and 6 mmol of 3-cyanobenzoic acid into 10 mL of DMF, sonicate for 5 min, and record as solution B.

[0085] S3. Mix solutions A and B and sonicate for 10 min. Then transfer the mixture to a high-pressure reactor lined with polytetrafluoroethylene and react at 120℃ for 24 h. After naturally cooling to room temperature, collect the solid product by centrifugation and wash it three times with N,N-dimethylformamide and ethanol respectively. Finally, vacuum dry the product at 60℃ for 24 h to obtain the cyano-defective MOF material, denoted as UiO-66-3BA-CN.

[0086] Comparative Example 2

[0087] Preparation of defect-free MOF materials:

[0088] S1. Disperse 0.3 mmol of ZrCl4 in 10 mL of DMF and sonicate for 10 min to obtain a homogeneous solution, denoted as solution A.

[0089] S2. Disperse 0.3 mmol of terephthalic acid into 10 mL of DMF and sonicate for 5 min. This solution is called solution B.

[0090] S3. Mix solutions A and B and sonicate for 10 min. Then transfer the mixture to a high-pressure reactor lined with polytetrafluoroethylene and react at 120°C for 24 h. After naturally cooling to room temperature, collect the solid product by centrifugation and wash it three times with N,N-dimethylformamide and ethanol respectively. Finally, vacuum dry the product at 60°C for 24 h to obtain defect-free MOFs material, denoted as UiO-66.

[0091] Figure 1 SEM images of the samples prepared in Examples 1, 4, and 5 are shown below. Figure 1 In the figure, a is the SEM image of UiO-66-3BA-AO prepared in Example 1, b is the SEM image of UiO-66-4BA-AO prepared in Example 4, and c is the SEM image of UiO-66-AA-AO prepared in Example 5.

[0092] Figure 1 The results show that all three samples exhibit uniform octahedrons, indirectly proving that the sample preparation was successful.

[0093] The SEM image of UiO-66-3BA-AO / GCA prepared in Example 3 is shown below. Figure 2 Where a is a low-magnification image and b is a high-magnification image.

[0094] Figure 2 The results show that UiO-66-3BA-AO / GCA has a polyhedral structure, and UiO-66-3BA-AO was successfully grown in situ and uniformly dispersed on the surface of GCA.

[0095] The X-ray diffraction patterns of the samples prepared in Examples 1, 4, and 5 are shown below. Figure 3 .

[0096] Figure 3 The results showed that the bee emergence locations of the three samples were basically consistent with those of the simulated sample, indicating that all three samples were successfully prepared.

[0097] The infrared spectra of the samples prepared in Examples 1, 4, and 5 are shown below. Figure 3 In the figure, a is the infrared spectrum of UiO-66-3BA-AO and the intermediate product before oxime hydration prepared in Example 1, b is the infrared spectrum of UiO-66-4BA-AO and the intermediate product before oxime hydration prepared in Example 4, and c is the infrared spectrum of UiO-66-AA-AO and the intermediate product before oxime hydration prepared in Example 5.

[0098] Figure 4 The presence of the cyano group indicates that the modifier ligand was successfully introduced. After the amylopyroxylation reaction, the disappearance of the cyano group and the appearance of C=N, CN and NO indicate that the amylopyroxylation was successful and the material was successfully prepared.

[0099] The nitrogen adsorption-desorption isotherms and pore size distribution diagrams of the samples prepared in Examples 1, 4, 5 and Comparative Example 2 are shown in the figure. Figure 5 , where a is the nitrogen adsorption-desorption isotherm diagram and b is the pore size distribution diagram.

[0100] Figure 5 The results show that the prepared samples all have a large specific surface area and a microporous structure, which is conducive to the adsorption of uranium.

[0101] The adsorption performance of different samples was tested. The experimental procedure was as follows: 2 mg of each sample was added to a solution containing hexavalent uranium, with a uranium concentration of 100 mg / L. The adsorption time was 180 min, the adsorption pH was 6, and the adsorption temperature was 25 °C. The adsorption performance of the samples prepared in Examples 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, and Comparative Example 2 for hexavalent uranium is shown in the figure. Figure 6 .

[0102] Figure 6 The results show that, compared with defect-free MOFs (Comparative Example 2), defective MOFs and their composites exhibit superior adsorption performance, which confirms that the introduction of structural defects effectively promotes the adsorption capacity of materials for uranium.

[0103] The adsorption performance of the sample prepared in Example 1 was investigated in relation to time. The experimental procedure was as follows: 2 mg of the sample was added to a solution containing hexavalent uranium, with a uranium concentration of 100 mg / L. The adsorption pH was 6, and the adsorption temperature was 25 °C. The relationship between the amount of hexavalent uranium adsorbed by the sample prepared in Example 1 and time is shown in the figure. Figure 7 .

[0104] Figure 7The results showed that UiO-66-3BA-AO reached adsorption equilibrium in 90 minutes and had an adsorption capacity of up to 666.7 mg / g for uranium, indicating that UiO-66-3BA-AO has extremely fast adsorption kinetics and excellent adsorption performance.

[0105] The adsorption performance of the sample prepared in Example 3 under light and dark conditions was investigated. The experimental procedure was as follows: 2 mg of sample was added to a solution containing hexavalent uranium, with a uranium concentration of 100 mg / L. Adsorption was carried out under both dark and light conditions for 150 min, with an adsorption pH of 6. The relationship between the amount of uranium adsorbed by the sample prepared in Example 3 under dark and light conditions and time is shown in the figure. Figure 8 .

[0106] Figure 8 The results showed that under dark conditions, the equilibrium adsorption capacity of UiO-66-3BA-AO / GCA for uranium was 415.6 mg / L, and adsorption equilibrium was reached in 45 min. The abundant adsorption sites and more dispersed MOFs endowed the adsorbent with excellent adsorption performance. Under light conditions, the adsorption capacity of UiO-66-3BA-AO / GCA for uranium increased to 545.5 mg / g, indicating that UiO-66-3BA-AO / GCA has excellent photothermal conversion performance.

[0107] The adsorption performance of the sample prepared in Example 1 was investigated in relation to temperature. The experimental procedure was as follows: 2 mg of sample was added to a solution containing hexavalent uranium (uranium concentration: 100 mg / L), the adsorption time was 3 h, and the adsorption pH was 6. The relationship between the adsorption capacity of the sample prepared in Example 1 for hexavalent uranium and temperature is shown in the figure below. Figure 9 .

[0108] Figure 9 The results showed that the uranium adsorption capacity of the UiO-66-3BA-AO sample gradually increased with increasing temperature, reaching as high as 796.1 mg / g at 313 K, indicating that the adsorption process was endothermic.

[0109] The cyclic adsorption performance of the sample prepared in Example 1 was investigated. The experimental procedure was as follows: 2 mg of sample was added to a solution containing hexavalent uranium, with a uranium concentration of 100 mg / L. The adsorption time was 3 h, the adsorption pH was 6, and the adsorption temperature was 25 °C. After adsorption, desorption was performed using 0.1 M hydrochloric acid solution for 3 h. After desorption, the sample was washed with ultrapure water and dried in a vacuum oven. The next adsorption experiment was then performed after drying. The cycle was repeated ten times. The performance graph of the cyclic adsorption of hexavalent uranium by the sample prepared in Example 1 is shown in the figure. Figure 10 .

[0110] Figure 10The results showed that after ten cycles of regeneration, the regeneration performance of the sample was still as high as 87.2% (reaching 87.2% of the initial adsorption amount), proving that the UiO-66-3BA-AO structure is stable and has excellent cyclic regeneration performance.

[0111] The selective adsorption performance of the sample prepared in Example 1 for hexavalent uranium was investigated. The experimental procedure was as follows: 2 mg of adsorbent was added to simulated seawater containing hexavalent uranium, and the adsorption time was 24 h. After adsorption, the concentration changes of each ion in the simulated seawater before and after adsorption were measured by ICP-MS. The initial concentrations of Na, Mg, V, Mn, Co, Cu, Zn, Ba, Ca, and U before adsorption were 1149.1, 455.5, 180.7, 244.4, and 238.4, respectively. The adsorption capacities of the adsorbents for each ion were calculated. The selectivity of the sample prepared in Example 1 for hexavalent uranium is shown in the figure. (The initial concentrations of Na, Mg, V, Mn, Co, Cu, Zn, Ba, Ca, and U after adsorption were 239.4, 259.1, 232.8, 510.7, and 295.8 μg / L, respectively.) Figure 11 .

[0112] Figure 11 The results show that, in a simulated seawater environment, the UiO-66-3BA-AO material prepared in Example 1 exhibits excellent selective adsorption performance of hexavalent uranium, with a maximum adsorption capacity of 125.4 mg / L. This significant adsorption effect indicates that the material has important practical application value in the treatment of uranium-containing wastewater and uranium extraction from seawater.

[0113] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing an amidoamine-functionalized defective metal-organic framework material, characterized in that, The method comprises the following steps: The cyano-defective MOFs material is prepared by using metal salt, adjusting agent ligand and terephthalic acid as reactants through solvothermal reaction; The cyano-defective MOFs material is subjected to amidoxime functionalization to obtain the amidoxime functionalized defective metal organic framework material; The adjusting agent ligand is 3-cyanobenzoic acid, 4-cyanobenzoic acid or cyanoacetic acid; The step of the amidoxime functionalization comprises the following steps: the cyano-defective MOFs material is blended with hydroxylamine hydrochloride and anhydrous potassium carbonate in a mixed solvent of ethanol and water, and is subjected to reaction under inert atmosphere to complete the amidoxime functionalization; The mass ratio of the cyano-defective MOFs material, the hydroxylamine hydrochloride and the anhydrous potassium carbonate is 0.2-1:1:1; the volume ratio of ethanol to water in the mixed solvent is 9:1-3; the reaction temperature is 60-90 DEG C, and the reaction time is 8-12h; The metal ion in the metal salt includes Zr 4+ , Ce 3+ , Ni 2+ or Cu 2+ ; the molar ratio of the adjusting agent ligand to the terephthalic acid is 1-30:1; the solvent of the solvothermal reaction is N,N-dimethylformamide, the temperature is 100-120℃, and the time is 12-48h.

2. A method for preparing a co-amidoxime functionalized defective metal-organic framework@graphene / cellulose aerogel composite material, characterized in that, The method comprises the following steps: The metal ion loaded graphene / cellulose aerogel is obtained by immersing the graphene / cellulose aerogel into a solution containing metal salt and stirring; The cyano-defective MOFs@graphene / cellulose aerogel composite material is prepared by using the metal ion loaded graphene / cellulose aerogel, adjusting agent ligand and terephthalic acid as reactants through solvothermal reaction; The cyano-defective MOFs@graphene / cellulose aerogel composite material is subjected to amidoxime functionalization to obtain the amidoxime functionalized defective metal organic framework@graphene / cellulose aerogel composite material; The adjusting agent ligand is 3-cyanobenzoic acid, 4-cyanobenzoic acid or cyanoacetic acid; The step of the amidoxime functionalization comprises the following steps: the cyano-defective MOFs@graphene / cellulose aerogel composite material is blended with hydroxylamine hydrochloride and anhydrous potassium carbonate in a mixed solvent of ethanol and water, and is subjected to reaction under inert atmosphere to complete the amidoxime functionalization; The mass ratio of the cyano-defective MOFs@graphene / cellulose aerogel composite material, the hydroxylamine hydrochloride and the anhydrous potassium carbonate is 0.2-1:1:1; the volume ratio of ethanol to water in the mixed solvent is 9:1-3; the reaction temperature is 60-90 DEG C, and the reaction time is 8-12h; The metal ion in the metal salt includes Zr 4+ , Ce 3+ , Ni 2+ or Cu 2+ ; the molar ratio of the adjusting agent ligand to the terephthalic acid is 1-30:1; the solvent of the solvothermal reaction is N,N-dimethylformamide, the temperature is 100-120℃, and the time is 12-48h.

3. The preparation method according to claim 2, characterized in that, The mass ratio of the metal ion in the metal salt to the graphene / cellulose aerogel is 27.3:5-20.

4. The production method according to claim 2, characterized by, The preparation step of the graphene / cellulose aerogel comprises the following steps: graphene oxide and cellulose are used as reactants, and ethylenediamine is used as crosslinking agent to prepare the graphene / cellulose aerogel through hydrothermal reaction. 5.An amidoxime functionalized defective metal organic framework material prepared by the preparation method in claim 1. 6.An amidoxime functionalized defective metal organic framework@graphene / cellulose aerogel composite material prepared by the preparation method in any one of claims 2-4. 7.The use of the amidoxime functionalized defective metal organic framework material in claim 5 or the amidoxime functionalized defective metal organic framework@graphene / cellulose aerogel composite material in claim 6 in enriching hexavalent uranium.

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