A three-dimensional asymmetric infiltrated cellulose aerogel, its preparation method and application

Abstract

This invention belongs to the field of cellulose aerogel technology. It discloses a three-dimensional asymmetric wettable cellulose aerogel, its preparation method, and its applications. The preparation method includes the following steps: mixing cellulose with an alkaline solution to obtain a cellulose sol; soaking a portion of the cellulose sol in anhydrous ethanol, followed by sequential standing and modification to obtain a modified hydrogel; pouring the remaining cellulose sol onto the modified hydrogel and immersing it in anhydrous ethanol, followed by sequential standing, drying, and thermal curing to obtain a three-dimensional asymmetric wettable cellulose aerogel. The three-dimensional asymmetric wettable cellulose aerogel material prepared by this invention has the following advantages: controllable structure, allowing the thickness of the hydrophilic and hydrophobic phases to be changed by adjusting the amount of hydrophilic and hydrophobic hydrogel; simultaneous adsorption and filtration functions and good recyclability, enabling the separation of various oil-water mixtures and oil-water emulsions.

Description

Technical Field

[0001] This invention relates to the field of cellulose aerogel technology, and more particularly to a three-dimensional asymmetric wettable cellulose aerogel, its preparation method, and its applications. Background Technology

[0002] Crude oil spills, illegal discharge of factory wastewater, and indiscriminate discharge of oily wastewater from restaurants cause serious oil and water pollution, which in turn damages the natural environment on which humans depend for survival. Traditional oil-water separation methods, such as skimming, flotation, sedimentation, centrifugation, ultrasonic separation, bioremediation, in-situ combustion, and coagulation-flocculation, have significant limitations due to their low efficiency, high energy consumption, complex separation equipment, and the potential for secondary pollution.

[0003] Asymmetric wettable materials, due to their unique structure and composition, facilitate the directional transport of liquids and the separation of various oil-water emulsions, and have great application prospects in the field of oil-water separation. At present, there are still many challenges in the development of asymmetric materials, such as complex preparation processes, poor asymmetric bonding strength, difficulty in scaling up, and poor reusability. Moreover, existing asymmetric wettable oil-water separation materials often neglect the environmental friendliness of the materials themselves.

[0004] Cellulose, as the world's most abundant natural polymer, is being widely used in various fields due to its environmental friendliness, high biocompatibility, and low cost. Cellulose-based oil-water separation materials are also being continuously developed and applied. Developing oil-water separation materials using cellulose as a raw material has significant ecological benefits and promising application prospects.

[0005] Therefore, it is of great significance to study an environmentally friendly three-dimensional asymmetric infiltrated cellulose aerogel with adsorption, filtration and reusability and its preparation method. Summary of the Invention

[0006] In view of this, the present invention provides a three-dimensional asymmetric wettable cellulose aerogel, its preparation method and application, the purpose of which is to provide an environmentally friendly oil-water separation material that has both adsorption and filtration functions and can be reused.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a method for preparing three-dimensional asymmetric infiltrated cellulose aerogel, comprising the following steps:

[0009] 1) Cellulose is mixed with an alkaline solution to prepare cellulose sol;

[0010] 2) After soaking a portion of the cellulose sol in anhydrous ethanol, it was subjected to static standing and modification in sequence to obtain a modified hydrogel;

[0011] 3) After pouring the remaining cellulose sol onto the modified hydrogel, immerse it in anhydrous ethanol, and then sequentially allow it to stand, dry, and heat-cur it to obtain a three-dimensional asymmetric wettable cellulose aerogel.

[0012] Preferably, the cellulose in step 1) is plant cellulose and / or biological cellulose.

[0013] Preferably, the alkaline solution in step 1) includes urea, NaOH and water, and the mass ratio of urea, NaOH and water is 6-14:5-13:80-82.

[0014] Preferably, the mass of cellulose in step 1) is 2-6% of the mass of the cellulose sol.

[0015] Preferably, the modifier used in step 2) is a silane modifier, which comprises a mixed solution of methyltrimethoxysilane, tetraethyl silicate and anhydrous ethanol in a volume ratio of 1-3:1-3:2-6.

[0016] Preferably, the settling time in steps 2) and 3) is 45-50 hours; the volume ratio of the partial cellulose sol in step 2) to the remaining cellulose sol in step 3) is 1-2:1-2.

[0017] Preferably, the drying in step 3) is vacuum freeze drying, with a drying temperature of -70 to -50°C, a drying pressure of 1 to 10 Pa, and a drying time of 45 to 50 hours;

[0018] Preferably, the temperature for heat curing in step 3) is 100–160°C, and the heat curing time is 2.5–3.5 h.

[0019] This invention provides a method for preparing three-dimensional asymmetric infiltrated cellulose aerogels, resulting in three-dimensional asymmetric infiltrated cellulose aerogels.

[0020] The present invention also provides the application of the aforementioned three-dimensional asymmetric wettable cellulose aerogel in oil-water separation.

[0021] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) The raw material cellulose used in this invention is an environmentally friendly natural polymer material with the characteristics of wide availability, renewability, and easy degradation. The three-dimensional asymmetric wettable cellulose aerogel material prepared by this invention conforms to the current mainstream of social development, and its excellent comprehensive performance gives it broad application prospects.

[0023] (2) The “similar phase self-assembly” method used in this invention has the advantages of being simple, easy to operate, having high combined strength, being easy to manufacture in large sizes, and being environmentally friendly.

[0024] (3) The three-dimensional asymmetric wettable cellulose aerogel material prepared by the present invention has the following advantages: the structure is controllable, and the thickness of the hydrophilic and hydrophobic phases can be changed by adjusting the amount of hydrophilic and hydrophobic hydrogel; it also has adsorption and filtration functions as well as good recycling performance, and can separate a variety of oil-water mixtures and oil-water emulsions; it is economical and environmentally friendly, and can treat oil and water pollution in a simple and efficient manner. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 SEM image of the three-dimensional asymmetric infiltrated cellulose aerogel obtained in Example 3;

[0027] Figure 2 This is a graph showing the oil adsorption capacity of the three-dimensional asymmetric wettable cellulose aerogel obtained in Example 3.

[0028] Figure 3 The graph shows the separation performance of the three-dimensional asymmetric wettable cellulose aerogel obtained in Example 3 for oil-water mixtures.

[0029] Figure 4 The graph shows the separation performance of the three-dimensional asymmetric wetting cellulose aerogel obtained in Example 3 on a surfactant-free water-in-oil emulsion.

[0030] Figure 5 The graph shows the separation performance of the three-dimensional asymmetric wetting cellulose aerogel obtained in Example 3 on surfactant-stabilized water-in-oil emulsions.

[0031] Figure 6 The graph shows the cyclic separation performance of the three-dimensional asymmetric wettable cellulose aerogel obtained in Example 3 on the water-in-oil emulsion. Detailed Implementation

[0032] This invention provides a method for preparing three-dimensional asymmetric infiltrated cellulose aerogel, comprising the following steps:

[0033] 1) Cellulose is mixed with an alkaline solution to prepare cellulose sol;

[0034] 2) After soaking a portion of the cellulose sol in anhydrous ethanol, it was subjected to static standing and modification in sequence to obtain a modified hydrogel;

[0035] 3) After pouring the remaining cellulose sol onto the modified hydrogel, immerse it in anhydrous ethanol, and then sequentially allow it to stand, dry, and heat-cur it to obtain a three-dimensional asymmetric wettable cellulose aerogel.

[0036] In this invention, the cellulose mentioned in step 1) is preferably plant cellulose and / or biological cellulose, and more preferably one or more of cotton linter cellulose, bacterial cellulose, bagasse cellulose, pulp cellulose, coconut husk cellulose and banana stem cellulose.

[0037] In this invention, the alkaline solution in step 1) preferably includes urea, NaOH and water, and the mass ratio of urea, NaOH and water is preferably 6-14:5-13:80-82, more preferably 8-12:6-11:80.5-81.5, and even more preferably 9-10:8-9:81.

[0038] In this invention, the alkaline solution described in step 1) is preferably allowed to stand before being mixed with cellulose. The standing temperature is preferably -15 to -20°C, more preferably -16 to -19°C, and even more preferably -17 to -18°C. The standing time is preferably 25 to 35 minutes, more preferably 27 to 33 minutes, and even more preferably 29 to 32 minutes.

[0039] In this invention, the mixing speed in step 1) is preferably 1000-1500 rpm, more preferably 1100-1400 rpm, and even more preferably 1200-1300 rpm. The mixing time is preferably 18-23 min, more preferably 19-22 min, and even more preferably 20-21 min.

[0040] In this invention, the mixing process in step 1) further includes ultrasound, and the ultrasound time is preferably 15-25 min, more preferably 18-22 min, and even more preferably 19-21 min.

[0041] In this invention, the mass of cellulose in step 1) is preferably 2-6% of the mass of cellulose sol, more preferably 3-5% of the mass of cellulose sol, and even more preferably 4-4.5% of the mass of cellulose sol.

[0042] In this invention, the cellulose sol soaking in anhydrous ethanol in steps 2) and 3) is preferably done by slowly pouring anhydrous ethanol along the container wall until the cellulose sol is submerged.

[0043] In this invention, the modifier used in step 2) is preferably a silane modifier, which includes methyltrimethoxysilane, tetraethyl silicate and anhydrous ethanol. The volume ratio of methyltrimethoxysilane, tetraethyl silicate and anhydrous ethanol is preferably 1-3:1-3:2-6, more preferably 1-3:2:3-5, and even more preferably 2:2:3.5-4.

[0044] In this invention, the modification in step 2) is preferably to soak the cellulose sol after it has been left to stand in a silane modifier for a soaking time of 22-26 hours, more preferably 23-24 hours.

[0045] In this invention, the settling time in steps 2) and 3) is preferably 45-50 h, more preferably 46-49 h, and even more preferably 47-48 h; the settling temperature is preferably 23-28 °C, more preferably 24-27 °C, and even more preferably 25-26 °C; the volume ratio of the partial cellulose sol in step 2) to the remaining cellulose sol in step 3) is preferably 1-2:1-2, more preferably 1-2:1.5, and even more preferably 1.2-1.6:1.5.

[0046] In this invention, after the settling process described in steps 2) and 3), washing is also performed independently. The washing process is preferably performed by washing the cellulose sol with water until it is neutral.

[0047] In this invention, the drying in step 3) is preferably vacuum freeze drying, the drying temperature is preferably -70 to -50°C, more preferably -68 to -54°C, and even more preferably -64 to -58°C, the drying pressure is preferably 1 to 10 Pa, more preferably 2 to 8 Pa, and even more preferably 4 to 6 Pa, and the drying time is preferably 45 to 50 h, more preferably 46 to 49 h, and even more preferably 47 to 48 h; the heat curing temperature is preferably 100 to 160°C, more preferably 110 to 150°C, and even more preferably 120 to 130°C, and the heat curing time is preferably 2.5 to 3.5 h, more preferably 2.8 to 3.4 h, and even more preferably 3 to 3.2 h.

[0048] This invention provides a method for preparing three-dimensional asymmetric infiltrated cellulose aerogels, resulting in three-dimensional asymmetric infiltrated cellulose aerogels.

[0049] In this invention, the three-dimensional asymmetric infiltrated cellulose aerogel has a rich three-dimensional network structure.

[0050] In this invention, one side of the three-dimensional asymmetric wettable cellulose aerogel is a hydrophilic and oleophilic side, and the other side is a hydrophobic and oleophilic side, and the thickness of the hydrophilic layer and the hydrophobic layer can be adjusted.

[0051] In this invention, the porosity of the three-dimensional asymmetric wettable cellulose aerogel is preferably greater than or equal to 95%, more preferably greater than or equal to 96%, and even more preferably greater than or equal to 97%.

[0052] The present invention also provides the application of the aforementioned three-dimensional asymmetric wettable cellulose aerogel in oil-water separation.

[0053] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1

[0055] 1) Prepare an alkaline solution by mixing urea, sodium hydroxide and deionized water in a mass ratio of 7:12:81. Let the alkaline solution stand at -18℃ for 30 min to obtain a low-temperature alkaline solution. Mix the low-temperature alkaline solution with dried cotton linter cellulose at a speed of 1250 rpm for 20 min and then sonicate (input power 200W, ultrasonic frequency 40KHZ) for 20 min to obtain cellulose sol (in which the mass of cotton linter cellulose accounts for 3% of the mass of cellulose sol).

[0056] 2) Place half the volume of cellulose sol in a mold, and slowly pour anhydrous ethanol along the mold wall until the cellulose sol is submerged. Let it stand at 25°C for 48 hours, then wash with deionized water until neutral. Mix methyltrimethoxysilane, tetraethyl silicate, and anhydrous ethanol in a volume ratio of 1:1:2 to prepare a silane modifier. Then, soak the neutralized cellulose sol in the silane modifier for 24 hours to obtain a modified hydrogel.

[0057] 3) Pour the remaining cellulose sol onto the modified hydrogel, slowly pour anhydrous ethanol along the mold wall until it covers the cellulose sol, let it stand for 48 hours, and then wash it with deionized water until it is neutral to obtain a neutral asymmetric wetting hydrogel. Dry the obtained neutral asymmetric wetting hydrogel under vacuum at -60℃ and 8Pa for 48 hours, and then heat-cur it at 100℃ for 3 hours to obtain a three-dimensional asymmetric wetting cellulose aerogel.

[0058] Example 2

[0059] 1) Prepare an alkaline solution by mixing urea, sodium hydroxide and deionized water in a mass ratio of 8:11:81. After standing the alkaline solution at -17℃ for 28 min, a low-temperature alkaline solution is obtained. Mix the low-temperature alkaline solution with dried coconut shell cellulose at a speed of 1300 rpm for 18 min and then sonicate (input power 200W, ultrasonic frequency 40KHZ) for 18 min to obtain cellulose sol (where the mass of coconut shell cellulose accounts for 5% of the mass of cellulose sol).

[0060] 2) Place two-thirds of the cellulose sol in a mold, and slowly pour anhydrous ethanol along the mold wall until it covers the cellulose sol. Let it stand at 26°C for 46 hours, then wash with deionized water until neutral. Mix methyltrimethoxysilane, tetraethyl silicate, and anhydrous ethanol in a volume ratio of 1:2:5 to prepare a silane modifier. Then, soak the neutralized cellulose sol in the silane modifier for 22 hours to obtain a modified hydrogel.

[0061] 3) Pour the remaining cellulose sol onto the modified hydrogel, and slowly pour anhydrous ethanol along the mold wall until it covers the cellulose gel. After standing for 46 hours, wash with deionized water until neutral to obtain a neutral asymmetric wetting hydrogel. Dry the obtained neutral asymmetric wetting hydrogel under vacuum at -65℃ and 6 Pa for 47 hours, and then heat-cur it at 120℃ for 2.8 hours to obtain a three-dimensional asymmetric wetting cellulose aerogel.

[0062] Example 3

[0063] 1) Prepare an alkaline solution by mixing urea, sodium hydroxide and deionized water in a mass ratio of 7:12:81. Let the alkaline solution stand at -18℃ for 30 min to obtain a low-temperature alkaline solution. Mix the low-temperature alkaline solution with dried cotton linter cellulose at a speed of 1300 rpm for 20 min and then sonicate (input power 200W, ultrasonic frequency 40KHZ) for 20 min to obtain cellulose sol (in which the mass of cotton linter cellulose accounts for 2% of the mass of cellulose sol).

[0064] 2) Place one-third of the volume of cellulose sol in a mold, and slowly pour anhydrous ethanol along the mold wall until it covers the cellulose sol. Let it stand at 25°C for 48 hours, then wash with deionized water until neutral. Mix methyltrimethoxysilane, tetraethyl silicate, and anhydrous ethanol in a volume ratio of 1:2:3 to prepare a silane modifier. Then, soak the neutralized cellulose sol in the silane modifier for 24 hours to obtain a modified hydrogel.

[0065] 3) Pour the remaining cellulose sol onto the modified hydrogel, slowly pour anhydrous ethanol along the mold wall until it covers the cellulose gel, let it stand for 48 hours, and then wash it with deionized water until it is neutral to obtain a neutral asymmetric wetting hydrogel. Dry the obtained neutral asymmetric wetting hydrogel under vacuum at -60℃ and 6Pa for 48 hours, and then heat-cur it at 150℃ for 3 hours to obtain a three-dimensional asymmetric wetting cellulose aerogel.

[0066] Example 4

[0067] 1) Prepare an alkaline solution by mixing urea, sodium hydroxide and deionized water in a mass ratio of 9:10:81. After standing the alkaline solution at -19℃ for 32 min, a low-temperature alkaline solution is obtained. Mix the low-temperature alkaline solution with dried bagasse cellulose at a speed of 1450 rpm for 22 min and then sonicate (input power 200W, ultrasonic frequency 40KHZ) for 22 min to obtain cellulose sol (of which the mass of bagasse cellulose accounts for 4% of the mass of cellulose sol).

[0068] 2) Place half the volume of cellulose sol in a mold, and slowly pour anhydrous ethanol along the mold wall until it covers the cellulose sol. Let it stand at 26°C for 50 hours, then wash with deionized water until neutral. Mix methyltrimethoxysilane, tetraethyl silicate, and anhydrous ethanol in a volume ratio of 2:2:4 to prepare a silane modifier. Then, soak the neutralized cellulose sol in the silane modifier for 25 hours to obtain a modified hydrogel.

[0069] 3) Pour the remaining cellulose sol onto the modified hydrogel, slowly pour anhydrous ethanol along the mold wall until it covers the cellulose gel, let it stand for 46 hours, and then wash it with deionized water until it is neutral to obtain a neutral asymmetric wetting hydrogel. Dry the obtained neutral asymmetric wetting hydrogel under vacuum at -65℃ and 6 Pa for 47 hours, and then heat-cur it at 140℃ for 3.2 hours to obtain a three-dimensional asymmetric wetting cellulose aerogel.

[0070] Example 5

[0071] 1) Prepare an alkaline solution by mixing urea, sodium hydroxide and deionized water in a mass ratio of 12:7:81. After standing the alkaline solution at -17℃ for 28 min, a low-temperature alkaline solution is obtained. Mix the low-temperature alkaline solution with dried bacterial cellulose at a speed of 1400 rpm for 18 min and then sonicate (input power 200W, ultrasonic frequency 40KHZ) for 18 min to obtain a cellulosic sol (in which the mass of bacterial cellulose accounts for 6% of the mass of the cellulosic sol).

[0072] 2) Place half the volume of cellulose sol in a mold, and slowly pour anhydrous ethanol along the mold wall until the cellulose sol is submerged. Let it stand at 26°C for 46 hours, then wash with deionized water until neutral. Mix methyltrimethoxysilane, tetraethyl silicate, and anhydrous ethanol in a volume ratio of 3:2:5 to prepare a silane modifier. Then, soak the neutralized cellulose sol in the silane modifier for 22 hours to obtain a modified hydrogel.

[0073] 3) Pour the remaining cellulose sol onto the modified hydrogel, slowly pour anhydrous ethanol along the mold wall until it covers the cellulose gel, let it stand for 46 hours, and then wash it with deionized water until it is neutral to obtain a neutral asymmetric wetting hydrogel. Dry the obtained neutral asymmetric wetting hydrogel under vacuum at -65℃ and 6Pa for 47 hours, and then heat-cur it at 110℃ for 2.8 hours to obtain a three-dimensional asymmetric wetting cellulose aerogel.

[0074] Figure 1 This is a SEM image of the three-dimensional asymmetric infiltrated cellulose aerogel obtained in Example 3. Figure 1 As can be seen, the three-dimensional asymmetric wetted cellulose aerogel obtained in Example 3 is a three-dimensional fluffy porous structure with cellulose fibers as the skeleton, and there is no obvious difference in the microstructure on both sides of the asymmetry, which illustrates the uniformity of the three-dimensional asymmetric wetted cellulose aerogel structure obtained in this invention.

[0075] Figure 2 This is a graph showing the oil adsorption capacity of the three-dimensional asymmetric wettable cellulose aerogel obtained in Example 3. The oil adsorption capacity was determined by immersing the fully dried three-dimensional asymmetric wettable cellulose aerogel in different types of oil at 25°C. After adsorption saturation, the aerogel was weighed, and the oil adsorption capacity was calculated according to Formula I. Figure 2 As can be seen, the three-dimensional asymmetric wettable cellulose aerogel prepared in this invention exhibits adsorption capacities for different oils ranging from 15.13 to 34.38 g / g, particularly for carbon tetrachloride, where the adsorption capacity reaches as high as 34.38 g / g. These results confirm the excellent oil adsorption capacity of the three-dimensional asymmetric wettable cellulose aerogel, demonstrating its potential for oil removal from water.

[0076]

[0077] Figure 3 The graph shows the separation performance of the three-dimensional asymmetric wettable cellulose aerogel obtained in Example 3 for oil-water mixtures. Figure 3 The separation flux and separation efficiency shown are calculated according to Equations II and III, respectively. Figure 3 It can be seen that the three-dimensional asymmetric wettable cellulose aerogel obtained by the present invention can effectively separate oil-water mixtures and has high throughput and high efficiency, which further illustrates that the three-dimensional asymmetric wettable cellulose aerogel obtained by the present invention has good oil-water separation performance.

[0078]

[0079]

[0080] Figure 4 The graph shows the separation performance of the three-dimensional asymmetric wetting cellulose aerogel obtained in Example 3 on a surfactant-free water-in-oil emulsion. Figure 4 The separation flux and separation efficiency shown are calculated according to Equations II and IV, respectively. Figure 4 It is evident that the three-dimensional asymmetric wettable cellulose aerogel obtained in this invention can effectively separate various surfactant-free water-in-oil emulsions, with a maximum separation flux and separation efficiency reaching 3111 L·m⁻¹, respectively. -2 ·h -1 And 99.51%.

[0081]

[0082] Figure 5 The graph shows the separation performance of the three-dimensional asymmetric wetting cellulose aerogel obtained in Example 3 on surfactant-stabilized water-in-oil emulsions. Figure 5 The separation flux and separation efficiency shown are calculated according to Equations II and IV, respectively. Figure 5 It is evident that the three-dimensional asymmetric wettable cellulose aerogel obtained in this invention can effectively separate various water-in-oil emulsions containing surfactants, with a maximum separation flux and separation efficiency reaching 2596 L·m⁻¹, respectively. -2 ·h -1 And 99.2%.

[0083] Figure 6 This is a graph showing the cyclic separation performance of the three-dimensional asymmetric wetting cellulose aerogel obtained in Example 3 on the n-hexane-in-water emulsion. Figure 6 It can be seen that after 10 separations, the separation flux of the three-dimensional asymmetric wettable cellulose aerogel obtained in this invention for n-hexane-in-water emulsion without surfactant and n-hexane-in-water emulsion with surfactant stabilized only decreased by 15.32% and 16.70%, respectively. The overall separation flux can still be maintained at a high level, which shows that the three-dimensional asymmetric wettable cellulose aerogel has excellent reusability.

[0084] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a three-dimensional asymmetric infiltrated cellulose aerogel, characterized in that, Includes the following steps: 1) Cellulose is mixed with an alkaline solution to prepare cellulose sol; 2) After soaking a portion of the cellulose sol in anhydrous ethanol, it was subjected to static standing and modification in sequence to obtain a modified hydrogel; 3) After pouring the remaining cellulose sol onto the modified hydrogel, immerse it in anhydrous ethanol, and then sequentially allow it to stand, dry, and heat-cur it to obtain a three-dimensional asymmetric wettable cellulose aerogel. The modifier used in step 2) is a silane modifier, which contains methyltrimethoxysilane, tetraethyl silicate and anhydrous ethanol in a volume ratio of 1-3:1-3:2-6. Step 3) The drying is vacuum freeze drying, the drying temperature is -70 to -50℃, the drying pressure is 1 to 10 Pa, and the drying time is 45 to 50 h.

2. The method for preparing a three-dimensional asymmetric infiltrated cellulose aerogel according to claim 1, characterized in that, The cellulose mentioned in step 1) is plant cellulose and / or biological cellulose.

3. The method for preparing a three-dimensional asymmetric infiltrated cellulose aerogel according to claim 2, characterized in that, The alkaline solution in step 1) includes urea, NaOH and water, and the mass ratio of urea, NaOH and water is 6-14:5-13:80-82.

4. A method for preparing a three-dimensional asymmetric infiltrated cellulose aerogel according to claim 2 or 3, characterized in that, The mass of cellulose mentioned in step 1) is 2-6% of the mass of the cellulose sol.

5. The method for preparing a three-dimensional asymmetric infiltrated cellulose aerogel according to claim 1, characterized in that, The settling time in steps 2) and 3) is 45-50 hours; the volume ratio of the partial cellulose sol in step 2) to the remaining cellulose sol in step 3) is 1-2:1-2.

6. The method for preparing a three-dimensional asymmetric infiltrated cellulose aerogel according to claim 1, characterized in that, The temperature for heat curing in step 3) is 100-160℃, and the heat curing time is 2.5-3.5h.

7. The three-dimensional asymmetric infiltrated cellulose aerogel prepared by the method of any one of claims 1 to 6.

8. The application of the three-dimensional asymmetric wettable cellulose aerogel of claim 7 in oil-water separation.

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