MOF-loaded tobacco cellulose aerogel material as well as preparation method and application thereof

Abstract

The invention discloses an MOF-loaded tobacco cellulose aerogel material as well as a preparation method and application thereof, and relates to the technical field of composite materials. Wherein the MOF-loaded tobacco cellulose aerogel material presents a loose and porous appearance, and comprises tobacco cellulose aerogel and an MOF material coated on the surface of the tobacco cellulose aerogel. According to the preparation method, the MOF material is generated on the surface of the tobacco cellulose aerogel in situ, so that a large amount of MOF material is exposed on the surface of the tobacco cellulose aerogel. Through specific adsorption of the MOF material, the effect of efficiently removing the organic dye Congo red by the MOF-loaded tobacco cellulose aerogel material is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and particularly relates to a tobacco cellulose aerogel material loaded with MOF, a preparation method thereof, and an application thereof. Background Art

[0002] China is a major producer of dyes, and organic dyes are widely used in industries such as food, textiles, leather, and papermaking. Water pollution caused by dye wastewater has become one of the most challenging environmental problems. Every year, 80,000 - 90,000 tons of dyes are released into the environment during production and use globally, causing the color of water areas to deepen, which not only reduces the quality of drinking water but also affects the beauty of cities and people's lives. In particular, organic dyes account for a large part of the total industrial dyes. Due to their good water solubility, high toxicity, and carcinogenicity, they have caused serious ecological and environmental problems, such as methyl violet, rhodamine B, methylene blue, congo red, etc. Therefore, it is crucial to develop simple and efficient dye wastewater treatment technologies to remove these organic pollutants.

[0003] China has a large tobacco planting area and high output. Currently, mainly high-quality tobacco leaves are used for cigarettes, and more than 10 times the amount of tobacco stems, tobacco veins, and tobacco dust are piled up or burned as waste, which not only causes waste of resources but also environmental pollution, becoming one of the problems affecting the development of the tobacco industry. Moreover, tobacco stems, tobacco veins, and tobacco dust all contain abundant cellulose.

[0004] Cellulose aerogel is a green and biodegradable porous material. It has low density, high specific surface area, high porosity, etc., and at the same time has the unique properties of natural cellulose aerogel itself, which makes cellulose aerogel have good application value in fields such as catalysis, adsorption, fuel cells, and thermal insulation. Metal-organic framework materials (MOF) have shown broad application prospects in the field of adsorption and separation in recent years due to their advantages such as high porosity, large specific surface area, highly adjustable pore size, and diverse structures. However, MOF materials are not easy to form, and their powder form limits their large-scale use. Summary of the Invention

[0005] The purpose of the present invention is to combine the advantages of tobacco cellulose and MOF materials to prepare an aerogel material with excellent adsorption performance for organic dyes.

[0006] To this end, the present invention provides a tobacco cellulose aerogel material loaded with MOF, a preparation method thereof, and an application thereof. The preparation method has the advantages of simple process and low cost. Using the tobacco cellulose aerogel material loaded with MOF to remove the organic dye congo red achieves the effect of efficiently removing congo red.

[0007] In the first aspect of the present invention, a tobacco cellulose aerogel material loaded with MOF is provided. The tobacco cellulose aerogel material loaded with MOF includes a tobacco cellulose aerogel and an MOF material coated on the surface of the tobacco cellulose aerogel. The tobacco cellulose aerogel material loaded with MOF presents a loose and porous appearance.

[0008] Further, the mass ratio of the tobacco cellulose to the MOF material is (3 - 5):1; the MOF material is a metal-organic framework material formed by zinc ions and 2-methylimidazole ligands.

[0009] In the second aspect of the present invention, a preparation method of a tobacco cellulose aerogel material loaded with MOF is provided. The preparation method of the above-mentioned tobacco cellulose aerogel material loaded with MOF includes:

[0010] Pre-freeze the NaOH / urea aqueous solution;

[0011] Put the tobacco cellulose and polyethyleneimine into the pre-frozen NaOH / urea aqueous solution, and stir at high speed in an ice bath to obtain a uniformly dispersed mixed solution;

[0012] Slowly add epichlorohydrin to the mixed solution, stir in an ice bath, and then pour it into a mold and carry out a cross-linking reaction at 50°C - 70°C to obtain a hydrogel;

[0013] Soak the hydrogel repeatedly in deionized water until the pH value is neutral, and then freeze-dry it to obtain a tobacco cellulose aerogel block;

[0014] Cut the tobacco cellulose aerogel block into small pieces, put them into a methanol solution, add a metal source and an organic ligand, stir at 20°C - 30°C, and let it stand for 10h - 15h;

[0015] Take out the aerogel small pieces, wash them with anhydrous methanol and air-dry them to obtain the tobacco cellulose aerogel material loaded with MOF.

[0016] Further, in the mixed solution, the mass concentration of the tobacco cellulose is 2% - 10%.

[0017] Further, in the mixed solution, the mass ratio of the tobacco cellulose to the polyethyleneimine is 1:1 - 5:1.

[0018] Further, for the cross-linking reaction, the reaction time is 2h - 5h; for the freeze-drying, the time is 36h - 60h.

[0019] Further, the metal source is a methanol solution of zinc nitrate hexahydrate, and the organic ligand is a methanol solution of 2-methylimidazole.

[0020] The third aspect of the present invention provides an application of a MOF-loaded tobacco cellulose aerogel material in removing the organic dye Congo Red.

[0021] Further, when applying the MOF-loaded tobacco cellulose aerogel material to remove the organic dye Congo Red, the concentration of the organic dye Congo Red is controlled at 20 mg / L - 50 mg / L, 450 mg - 550 mg of the MOF-loaded tobacco cellulose aerogel material is added to each liter of Congo Red dye wastewater, and the adsorption time is 60 h - 70 h.

[0022] Further, the removal rate of the organic dye Congo Red is between 83% and 90%.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] The MOF-loaded tobacco cellulose aerogel material provided by the present invention has a loose and porous structure. By in-situ generating MOF materials on the surface of the tobacco cellulose aerogel, the problem of difficult shaping of MOF powders is solved, so that a large amount of MOF materials are exposed on the surface of the tobacco cellulose aerogel. Moreover, the raw material is waste tobacco cellulose, turning waste into treasure, with low cost and simple operation. Through the specific adsorption of MOF materials, the MOF-loaded tobacco cellulose aerogel material can efficiently remove the organic dye Congo Red. Description of the Drawings

[0025] Figure 1 Morphologies of MOF-loaded tobacco cellulose aerogel materials prepared from tobacco cellulose at different concentrations in Example 1 of the present invention.

[0026] Figure 2 Removal rates of Congo Red by MOF-loaded tobacco cellulose aerogel materials prepared from tobacco cellulose at different concentrations in Example 1 of the present invention.

[0027] Figure 3 Morphologies of aerogel materials prepared with different mass ratios of tobacco cellulose and polyvinyl imidazole in Example 2 of the present invention.

[0028] Figure 4 Removal rates of Congo Red by aerogel materials prepared with different mass ratios of tobacco cellulose and polyvinyl imidazole in Example 2 of the present invention.

[0029] Figure 5 The physical object and SEM images of the MOF-loaded tobacco cellulose aerogel material provided in Example 3 of the present invention; wherein, a is a photo of the physical object, b is the front SEM image, and c is the cross-section SEM image.

[0030] Figure 6UV spectrum of Congo red adsorbed by tobacco cellulose aerogel loaded with MOF provided in Example 3 and Example 4 of the present invention.

[0031] Figure 7 Adsorption kinetic model of the aerogel material provided in Example 3 of the present invention; wherein, the left figure is the change curve of the adsorption capacity of the tobacco cellulose aerogel material loaded with MOF with time; the right figure is the quasi-second-order adsorption kinetic fitting curve of the tobacco cellulose aerogel material loaded with MOF.

[0032] Figure 8 Adsorption kinetic model of the aerogel material provided in Example 4 of the present invention; wherein, the left figure is the change curve of the adsorption capacity of the tobacco cellulose aerogel material loaded with MOF with time; the right figure is the quasi-second-order adsorption kinetic fitting curve of the tobacco cellulose aerogel material loaded with MOF.

[0033] Figure 9 Isothermal adsorption model of the aerogel material provided in Example 3 (left) and Example 4 (right) of the present invention.

[0034] Figure 10 Results of cyclic adsorption of the aerogel material provided in Example 3 (left) and Example 4 (right) of the present invention. Detailed implementation manners

[0035] In order to better understand the above technical solutions, the technical solutions of the present invention will be described in detail through specific examples below.

[0036] In the first aspect of the embodiments of the present invention, a tobacco cellulose aerogel material loaded with MOF is provided, which includes a tobacco cellulose aerogel and an MOF material coated on the surface of the tobacco cellulose aerogel. The tobacco cellulose aerogel material loaded with MOF presents a loose and porous appearance.

[0037] The tobacco cellulose aerogel material loaded with MOF provided in the embodiments of the present invention uses waste tobacco cellulose as the raw material, turning waste into treasure with low cost. Coating the MOF material on the surface of the tobacco cellulose aerogel solves the problem of difficult shaping of MOF powder.

[0038] In some embodiments, the mass ratio of tobacco cellulose to the MOF material is (3 - 5):1; the MOF material is a metal-organic framework material formed by zinc ions and 2-methylimidazole ligands.

[0039] Specifically, the mass ratio of cellulose to the MOF material is controlled by controlling the mass ratio of tobacco cellulose to the metal source. The ZIF-8 MOF material formed by zinc ions and 2-methylimidazole ligands has a stable structure, certain pore size and specific surface area, which is beneficial to adsorption, and can be in-situ grown on the surface of tobacco cellulose at room temperature.

[0040] In the second aspect of the embodiments of the present invention, there is provided a method for preparing the above-mentioned tobacco cellulose aerogel material loaded with MOF, comprising:

[0041] Pre-freezing the NaOH / urea aqueous solution;

[0042] Putting tobacco cellulose and polyethyleneimine into the pre-frozen NaOH / urea aqueous solution, and stirring at high speed in an ice bath to obtain a uniformly dispersed mixed solution;

[0043] Slowly adding epichlorohydrin to the mixed solution, stirring in an ice bath, and then pouring it into a mold for cross-linking reaction at 50°C - 70°C to obtain a hydrogel;

[0044] Repeatedly soaking the hydrogel in deionized water until the pH value is neutral, and then freeze-drying to obtain a tobacco cellulose aerogel block;

[0045] Cutting the tobacco cellulose aerogel block into small pieces, putting them into a methanol solution, adding a metal source and an organic ligand, stirring at 20°C - 30°C, and standing for 10h - 15h;

[0046] Fishing out the small aerogel pieces, washing them with anhydrous methanol and air-drying to obtain the tobacco cellulose aerogel material loaded with MOF.

[0047] The method for preparing the tobacco cellulose aerogel material loaded with MOF provided by the embodiments of the present invention has the advantages of simple preparation process and low cost. The MOF material is in-situ grown on the surface of the tobacco cellulose aerogel, solving the problem of difficult shaping of MOF powder.

[0048] Preferably, in the mixed solution, the mass concentration of tobacco cellulose is 2% - 10%.

[0049] Preferably, in the mixed solution, the mass ratio of tobacco cellulose to the polyethyleneimine is 1:1 - 5:1.

[0050] In some embodiments, the reaction time of the cross-linking reaction is 2h - 5h; the freeze-drying time is 36h - 60h.

[0051] Specifically, when the cross-linking time is less than 2h, the aerogel is not well formed. When the cross-linking time is longer than 5h, the aerogel becomes too hard and is prone to form a large-particle state. When the freeze-drying time is less than 36h, incomplete drying occurs, affecting the mechanical properties of the aerogel. When the freezing time is longer than 60h, it is not conducive to energy conservation.

[0052] In some embodiments, the metal source is a methanol solution of zinc nitrate hexahydrate, and the organic ligand is a methanol solution of 2-methylimidazole.

[0053] Optionally, zinc ions are provided by the metal source zinc nitrate hexahydrate. Compared with other MOF materials, it has the advantages that it can be prepared at room temperature and can grow in-situ on the surface of tobacco cellulose.

[0054] In the third aspect of the embodiments of the present invention, there is provided an application of a MOF-loaded tobacco cellulose aerogel material in removing the organic dye Congo red.

[0055] In some embodiments, the application method is as follows: put the MOF-loaded tobacco cellulose aerogel material into the wastewater containing the organic dye Congo red, adjust the concentration of the organic dye Congo red to be 20 mg / L - 50 mg / L, add 450 mg - 550 mg of the MOF-loaded tobacco cellulose aerogel material per liter of Congo red dye wastewater, the adsorption time is 60 h - 70 h, and the removal rate of the organic dye Congo red is between 83% and 90%.

[0056] Example 1 Determination of the concentration of tobacco cellulose during the preparation of the MOF-loaded tobacco cellulose aerogel material

[0057] (I) Preparation method

[0058] The preparation of the MOF-loaded tobacco cellulose aerogel material includes the following steps:

[0059] (1) Prepare a 7 wt% NaOH / 14 wt% urea aqueous solution and place it in a refrigerator at -14 °C for pre-freezing.

[0060] (2) Put a certain amount of tobacco cellulose and a certain amount (50% aqueous solution, MW = 70000) of polyethyleneimine into 50 mL of the pre-frozen urea aqueous solution, and stir at high speed (3200 r / min) in an ice bath for 1 h to obtain a uniformly dispersed mixed solution. Among them, keep the mass ratio of tobacco cellulose to polyethyleneimine unchanged at 1:1, and the mass concentrations of tobacco cellulose in the prepared mixed solution are 1%, 2%, 4%, 6%, 8%, 10%, and 12% respectively.

[0061] (3) Slowly add 5 mL of epichlorohydrin to the mixed solution in step (2), stir in the ice bath for 1 h, and then directly pour it into a mold. The mold is heated at 60 °C for cross-linking reaction for 2 h to successfully prepare a hydrogel.

[0062] (4) Soak the hydrogel repeatedly in deionized water until the pH value reaches neutral. Then, freeze-dry for 48 h to successfully prepare a tobacco cellulose aerogel block.

[0063] (5) Cut the tobacco cellulose aerogel block obtained in step (4) into small cubes of 1×1×1 cm, put the small cubes into 35 mL of methanol solution, then add 0.75 g of zinc nitrate hexahydrate, and stir at room temperature for 1 h to obtain a precursor solution.

[0064] (6) Dissolve 1.65 g of 2-methylimidazole in 35 mL of methanol, and then slowly pour it into the precursor solution in step (5). Continue to stir at room temperature for 1 h, and let it stand for 12 h after stirring.

[0065] (7) Fish out the small cube aerogel blocks, wash them repeatedly with anhydrous methanol and air-dry them at room temperature to successfully prepare tobacco cellulose aerogel materials loaded with MOF with different tobacco cellulose concentrations.

[0066] (II) Characterization

[0067] The prepared tobacco cellulose aerogel materials loaded with MOF with different tobacco cellulose concentrations were characterized by scanning electron microscopy for their morphology. The results are shown in Figure 2 .

[0068] The prepared tobacco cellulose aerogel materials loaded with MOF with different tobacco cellulose concentrations were put into a congo red dye solution with a concentration of 20 mg / mL. After standing at room temperature for 60 h, the absorbance value of the solution at 490 nm was measured using a UV-visible spectrophotometer, and the removal rate of the tobacco cellulose aerogel materials loaded with MOF for the congo red dye was calculated. The results are shown in Figure 3 .

[0069] It can be seen from the experimental results that when the mass concentration of tobacco cellulose is between 2% and 10%, the prepared tobacco cellulose aerogel materials loaded with MOF have a uniform pore-like and layered structure and have a better removal rate for congo red dye.

[0070] Determination of the ratio of tobacco cellulose to polyethyleneimine during the preparation of tobacco cellulose aerogel materials loaded with MOF in Example 2

[0071] (I) Preparation method

[0072] The preparation of tobacco cellulose aerogel materials loaded with MOF includes the following steps:

[0073] (1) Prepare a 7 wt% NaOH / 14 wt% urea aqueous solution and pre-freeze it in a refrigerator at -14 °C.

[0074] (2) Put 3 g of tobacco cellulose and a certain amount (50% aqueous solution, MW = 70000) of polyethyleneimine into 50 mL of the pre-frozen urea aqueous solution respectively, and stir at high speed (3200 r / min) in an ice bath for 1 h to obtain a uniformly dispersed mixed solution. Among them, the mass ratios of cellulose to polyethyleneimine are 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, and 6:1 respectively.

[0075] (3) Slowly add 5 mL of epichlorohydrin to the mixed solution in step (2), stir for another 1 h in an ice bath, and then directly pour it into a mold. The mold is heated at 60 °C for cross-linking reaction for 2 h to successfully prepare the hydrogel.

[0076] (4) Soak the hydrogel repeatedly in deionized water until it reaches a neutral pH value. Then, freeze-dry it for 48 h to successfully prepare the tobacco cellulose aerogel block.

[0077] (5) Cut the tobacco cellulose aerogel block obtained in step (4) into small cubes of 1×1×1 cm, put the small cubes into 35 mL of methanol solution, then add 0.75 g of zinc nitrate hexahydrate, and stir at room temperature for 1 h to obtain the precursor solution.

[0078] (6) Dissolve 1.65 g of 2-methylimidazole in 35 mL of methanol, then slowly pour it into the precursor solution in step (5), continue to stir at room temperature for 1 h, and let it stand for 12 h after stirring.

[0079] (7) Fish out the small cube aerogel blocks, wash them repeatedly with anhydrous methanol and air-dry them at room temperature to successfully prepare the tobacco cellulose aerogel material loaded with MOF with different mass ratios of tobacco cellulose and polyethyleneimine.

[0080] (II) Characterization

[0081] The tobacco cellulose aerogel materials loaded with MOF with different mass ratios of tobacco cellulose and polyethyleneimine were characterized by scanning electron microscopy, and the results are shown in Figure 4 .

[0082] The tobacco cellulose aerogel materials loaded with MOF with different mass ratios of tobacco cellulose and polyethyleneimine were put into a congo red dye solution with a concentration of 20 mg / mL. After standing at room temperature for 60 h, the absorbance value of the solution at 490 nm was measured by a UV-visible spectrophotometer, and the removal rate of the tobacco cellulose aerogel material loaded with MOF for the congo red dye was calculated. The results are shown in Figure 5 .

[0083] It can be seen from the experimental results that when the mass ratio of tobacco cellulose to polyethyleneimine is between 1:1 and 5:1, the prepared tobacco cellulose aerogel material loaded with MOF has a relatively uniform porous and layered structure and has a better removal rate for congo red dye. It should be noted that when the mass ratio of the two is 6:1, it is difficult for the aerogel material to form.

[0084] Example 3 Preparation of Tobacco Cellulose Aerogel Material Loaded with MOF

[0085] The preparation of the tobacco cellulose aerogel material loaded with MOF includes the following steps:

[0086] (1) Prepare 200 mL of 7 wt% NaOH / 14 wt% urea aqueous solution and place it in a refrigerator at -14 °C for pre-freezing.

[0087] (2) Put 2 g of tobacco cellulose and 2 mL (50% aqueous solution, MW = 70000) of polyethyleneimine into 50 mL of the pre-frozen urea aqueous solution, and stir vigorously (3200 r / min) in an ice bath for 1 h to obtain a uniformly dispersed mixed solution.

[0088] (3) Slowly add 5 mL of epichlorohydrin to the mixed solution in step (2), stir for another 1 h in an ice bath, and then pour it directly into a mold. The mold is heated at 60 °C for cross-linking reaction for 2 h to successfully prepare the hydrogel.

[0089] (4) Soak the hydrogel repeatedly in deionized water until it reaches a neutral pH value. Then, freeze-dry it for 48 h to successfully prepare tobacco cellulose aerogel blocks.

[0090] (5) Cut the tobacco cellulose aerogel blocks obtained in step (4) into small cubes of 1×1×1 cm, put the small cubes into 35 mL of methanol solution, then add 0.75 g of zinc nitrate hexahydrate, and stir at room temperature for 1 h to obtain a precursor solution.

[0091] (6) Dissolve 1.65 g of 2-methylimidazole in 35 mL of methanol, and then slowly pour it into the precursor solution in step (5), continue to stir at room temperature for 1 h, and let it stand for 12 h after stirring.

[0092] (7) Fish out the small cube aerogel blocks, wash them repeatedly with anhydrous methanol and air-dry them at room temperature to successfully obtain the tobacco cellulose aerogel material loaded with MOF.

[0093] The physical object and SEM image of the tobacco cellulose aerogel material loaded with MOF prepared in Example 3 are as Figure 5 shown.

[0094] Preparation of the tobacco cellulose aerogel material loaded with MOF in Example 4

[0095] The preparation of the tobacco cellulose aerogel material loaded with MOF includes the following steps:

[0096] (1) Prepare 200 mL of 7 wt% NaOH / 14 wt% urea aqueous solution and place it in a refrigerator at -14 °C for pre-freezing.

[0097] (2) Put 2 g of tobacco cellulose and 2 mL (50% aqueous solution, MW = 70000) of polyethyleneimine into 50 mL of the pre-frozen urea aqueous solution, and stir vigorously (3200 r / min) in an ice bath for 1 h to obtain a uniformly dispersed mixed solution.

[0098] (3) Slowly add 5 mL of epichlorohydrin to the mixed solution in step (2), stir for another 1 h in an ice bath, and then directly pour it into a mold. The mold is heated at 60 °C for cross-linking reaction for 2 h to successfully prepare the hydrogel.

[0099] (4) Immerse the hydrogel repeatedly in deionized water until it reaches a neutral pH value. Then, freeze-dry it for 48 h to successfully prepare the tobacco cellulose aerogel block.

[0100] (5) Cut the tobacco cellulose aerogel block obtained in step (4) into small cubes of 1×1×1 cm, put the small cubes into 35 mL of methanol solution, then add 1.65 g of 2-methylimidazole, and stir at room temperature for 1 h to obtain the precursor solution.

[0101] (6) Dissolve 0.75 g of zinc nitrate hexahydrate in 35 mL of methanol, then slowly pour it into the precursor solution in step (5), continue to stir at room temperature for 1 h, and let it stand for 12 h after stirring.

[0102] (7) Take out the small cube aerogel blocks, wash them repeatedly with anhydrous methanol and air-dry them at room temperature to successfully prepare the tobacco cellulose aerogel material loaded with MOF.

[0103] Application of the tobacco cellulose aerogel material loaded with MOF prepared in Example 3 and Example 4

[0104] (I) Adsorption of the organic dye Congo red

[0105] Put the tobacco cellulose aerogel materials loaded with MOF prepared in Example 3 and Example 4 into the Congo red dye solution with a concentration of 20 mg / mL. After standing at room temperature for 150 h, use a UV-visible spectrophotometer to measure the absorbance curve of the solution between 200 nm and 800 nm, and use the Congo red solution with the initial concentration as a control. The results are shown in Figure 6 . It can be seen from the figure that the tobacco cellulose aerogel material loaded with MOF has a significant effect on removing the organic dye Congo red.

[0106] (II) Adsorption kinetics

[0107] Put the tobacco cellulose aerogel materials loaded with MOF prepared in Example 3 and Example 4 into the Congo red solutions with concentrations of 5 mg / L, 10 mg / L, 20 mg / L, and 50 mg / L respectively. Then, take samples at different adsorption time periods, measure the absorbance values of the solutions at a wavelength of 490 nm, calculate the remaining mass concentration and adsorption amount of the Congo red solution, and establish an adsorption kinetic model. The results are shown in Figure 7 and Table 1, and Figure 8And Table 2. From the trend of the adsorption amount changing with time, it can be seen that the adsorption quickly reaches equilibrium, and the aerogel material shows a relatively fast adsorption rate, which helps to shorten the time for dye removal. From the kinetic simulation curve, it can be seen that the adsorption of the aerogel material is mainly chemical adsorption. The special structure of the aerogel provides a larger specific surface area and porosity, and at the same time exposes more adsorption sites, promoting the migration and diffusion of Congo red to the surface active sites, thus strengthening its chemical adsorption on the surface of the aerogel.

[0108] Table 1

[0109]

[0110] Table 2

[0111]

[0112] (III) Isothermal adsorption situation

[0113] The tobacco cellulose aerogel materials loaded with MOF prepared in Example 3 and Example 4 were respectively put into Congo red solutions with concentrations of 5mg / L, 10mg / L, 20mg / L, 30mg / L, 40mg / L, 50mg / L, and 60mg / L. The absorbance value of the solution after adsorption was measured at a wavelength of 490nm, the remaining mass concentration and adsorption amount of the Congo red solution were calculated, and an isothermal adsorption model was established. The results are shown in Figure 9 and Table 3. The isothermal adsorption model simulation can calculate the maximum theoretical adsorption amount of the aerogel material, further characterizing the adsorption performance of the material. It can be seen that the adsorption capacity of the aerogel adsorbent increases with the increase of the equilibrium concentration, and shows a trend of rapid growth in the early stage and slow growth in the later stage. As the equilibrium concentration continues to increase, the adsorption capacity of the adsorbent gradually tends to be stable. The results of the adsorption isotherm fitting show that the adsorption process of the tobacco cellulose aerogel material loaded with MOF for Congo red conforms to the Langmuir model, and its adsorption process belongs to monolayer adsorption.

[0114] Table 3

[0115]

[0116] (IV) Recycling adsorption situation

[0117] 10mg of the tobacco cellulose aerogel materials loaded with MOF in Example 3 and Example 4 were put into a Congo red solution with a mass concentration of 30mg / L. After adsorption for 240min, the aerogel materials were separated, rinsed with anhydrous ethanol to remove Congo red, and then reused in the recycling adsorption experiment of Congo red after freeze-drying. The results are shown in Figure 10As can be seen from the data in the figure, after 4 adsorption-desorption cycles, the MOF-loaded tobacco cellulose aerogel material still has stable adsorption performance for Congo red, indicating its good reusability.

[0118] The above embodiments verify the effectiveness and practicality of the present invention.

[0119] It is easy for those skilled in the art to understand that, on the premise of no conflict, the above advantageous ways can be freely combined and superimposed. The above are only the preferred embodiments of the present application, and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application. The above is only the preferred implementation manner of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present application, several improvements and modifications can also be made, and these improvements and modifications should also be regarded as the protection scope of the present application.

Claims

1. A tobacco cellulose aerogel material loaded with MOF, characterized in that, The MOF-loaded tobacco cellulose aerogel material includes tobacco cellulose aerogel and MOF material coated on the surface of the tobacco cellulose aerogel, and the MOF-loaded tobacco cellulose aerogel material presents a loose and porous appearance.

2. The tobacco cellulose aerogel material loaded with MOF according to claim 1, wherein The mass ratio of the tobacco cellulose to the MOF material is (3-5):1; The MOF material is a metal-organic framework material formed by zinc ions and 2-methylimidazole ligands.

3. A preparation method of a tobacco cellulose aerogel material loaded with MOF, characterized in that, The preparation method of the MOF-loaded tobacco cellulose aerogel material according to claim 1 or 2 includes: Pre-freezing the NaOH / urea aqueous solution; Putting the tobacco cellulose and polyethyleneimine into the pre-frozen NaOH / urea aqueous solution and stirring at high speed in an ice bath to obtain a uniformly dispersed mixed solution; Slowly adding epichlorohydrin to the mixed solution, stirring in an ice bath, and then pouring it into a mold to carry out a cross-linking reaction at 50°C - 70°C to obtain a hydrogel; Repeatedly soaking the hydrogel in deionized water until the pH value is neutral, and then freeze-drying to obtain a tobacco cellulose aerogel block; Cutting the tobacco cellulose aerogel block into small pieces, putting them into a methanol solution, adding a metal source and an organic ligand, stirring at 20°C - 30°C, and standing for 10h - 15h; Fishing out the aerogel small pieces, washing them with anhydrous methanol and air-drying to obtain the MOF-loaded tobacco cellulose aerogel material.

4. The preparation method of the tobacco cellulose aerogel material loaded with MOF according to claim 3, characterized in that, In the mixed solution, the mass concentration of the tobacco cellulose is 2% - 10%.

5. The preparation method of the tobacco cellulose aerogel material loaded with MOF according to claim 3, characterized in that, In the mixed solution, the mass ratio of the tobacco cellulose to the polyethyleneimine is 1:1 - 5:

1.

6. The preparation method of the tobacco cellulose aerogel material loaded with MOF according to claim 3, characterized in that, For the cross-linking reaction, the reaction time is 2h - 5h; for the freeze-drying, the time is 36h - 60h.

7. The preparation method of the tobacco cellulose aerogel material loaded with MOF according to claim 3, characterized in that, The metal source is a methanol solution of zinc nitrate hexahydrate, and the organic ligand is a methanol solution of 2-methylimidazole.

8. Application of a MOF-loaded tobacco cellulose aerogel material, characterized in that, The application of the MOF-loaded tobacco cellulose aerogel material according to claim 1 or 2 in removing the organic dye Congo red.

9. Use of the tobacco cellulose aerogel material loaded with MOF according to claim 8, characterized in that, When applying the MOF-loaded tobacco cellulose aerogel material to remove the organic dye Congo red, the concentration of the organic dye Congo red is controlled at 20mg / L - 50mg / L, 450mg - 550mg of the MOF-loaded tobacco cellulose aerogel material is added to each liter of Congo red dye wastewater, and the adsorption time is 60h - 70h.

10. Use of the tobacco cellulose aerogel material loaded with MOF according to claim 9, characterized in that, The removal rate of the organic dye Congo red is between 83% - 90%.

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