A method for preparing a corn straw-based cellulose skeleton with a core-shell structure

Abstract

The application relates to a preparation method of a corn straw-based cellulose skeleton with a core-shell structure and belongs to the field of cellulose skeleton preparation methods. In order to solve the technical problem that the inherent defects of cellulose make the mechanical performance of the cellulose skeleton extracted from straw weak in the current treatment process, the following method is adopted: firstly, the stem pith is subjected to hydrothermal treatment; secondly, delignification treatment is carried out, and the cellulose skeleton is preserved in a solvent; thirdly, the cellulose skeleton is soaked in a replacement liquid, then frozen, and then continuously subjected to freeze drying. Alternatively, the corn stem pith after the hydrothermal treatment in the first step is directly subjected to high-temperature drying in an oven. The application adopts a surface densification process to make the hydrogen bond combination on the surface of the cellulose skeleton, so that a highly directional macroscopic core-shell structure straw cellulose skeleton from the micro-macro is formed. The application is used for preparing a corn straw-based cellulose skeleton with a core-shell structure.

Description

Technical Field

[0001] This invention relates to the field of methods for preparing cellulose skeletons. Background Technology

[0002] Petroleum-based materials are typically difficult to biodegrade and have limited resources. Their production involves significant carbon emissions and high production costs, contradicting the principles of sustainable development. Developing biomass materials is considered a crucial approach to addressing the energy crisis and achieving carbon neutrality. Corn stalks, a major agricultural byproduct, are expected to reach an annual output of approximately 330 million tons in my country in 2024, urgently requiring effective resource utilization. Direct burning easily causes air pollution, while simply returning them to the field may lead to pest and disease problems. Therefore, developing environmentally friendly straw-based materials and achieving their high-value utilization has become an urgent technological direction that needs to be promoted.

[0003] In terms of physical structure, corn stalks are similar to bamboo, which also belongs to the Poaceae family, both mainly consisting of an epidermis and a pith. The chemical composition of the corn pith is similar to that of most biomass materials, primarily composed of cellulose, hemicellulose, and lignin. Structurally, it is mainly composed of parenchyma and vascular bundles. The basic tissue of the corn pith consists of loosely arranged, nearly circular parenchyma cells, exhibiting a porous structure resembling foam. The vascular bundles embedded in this tissue are responsible for the transport of water, minerals, and organic matter, and provide mechanical support for the stalk. Overall, the corn pith has a continuous three-dimensional multi-level network structure, rich in porosity, and its apparent density can be as low as 0.04 g / cm³. 3 The typical density range of cellulose-based aerogels is 0.02~0.05 g / cm³. 3 While the aforementioned multi-level structure and component combination endow straw with excellent mechanical properties, current main utilization methods are still limited to crushing it as a substitute for wood flour or extracting components such as cellulose through chemical means. These conventional methods all destroy the inherent structural integrity of straw, making it difficult to effectively retain and transform its inherent multi-level structural advantages into the final product. On the other hand, extracting cellulose from straw and reconstructing it into three-dimensional nanomaterials usually requires first deconstructing its natural cell walls. This process is energy-intensive and cumbersome, essentially a resource-intensive processing method that is difficult to meet the requirements of sustainable development. In summary, existing technological approaches cannot effectively utilize the exquisite macroscopic structural characteristics of straw, and the development of new utilization solutions faces significant challenges.

[0004] Corn stalks, as an agricultural waste, possess a good cellulose structure, low thermal conductivity, and low density, making them an excellent raw material for constructing lightweight cushioning materials based on a cellulose skeleton. However, the cellulose skeleton extracted directly from stalks has very weak mechanical properties, crumbling easily under light pressure, making it difficult to meet practical application requirements. Summary of the Invention

[0005] In order to solve the technical problem of weak mechanical properties of cellulose skeletons extracted from straw, this invention provides a method for preparing corn straw-based cellulose skeletons with a core-shell structure and high adsorption and strength.

[0006] To broaden the utilization of straw, this invention designs a core-shell structured corn stalk pith material with a hard outer shell and a porous interior, which not only maintains high adsorption capacity but also has high compressive strength and buffers external impact.

[0007] A method for preparing a corn stalk-based cellulose skeleton with a core-shell structure, the method comprising the following steps:

[0008] 1. Peel the corn stalks to obtain the pith, cut the pith into small sections evenly, and then soak them in deionized water for hydrothermal treatment.

[0009] 2. The small stem pith segments treated in step one are soaked in a buffer solution for delignification treatment, then washed with water multiple times to remove residual chemicals, and then stored in a solvent.

[0010] The buffer solution is a sodium chlorite-acetic acid buffer solution, a formic acid-hydrogen peroxide buffer solution, or a sodium sulfite-sodium hydroxide buffer solution.

[0011] 3. Remove the pith from the solvent after step 2 and soak it directly in a replacement solution, such as anhydrous ethanol, acetone, or dimethyl sulfoxide; then freeze it and continue to freeze-dry it to obtain a corn stalk-based cellulose skeleton with a core-shell structure, thus completing the process.

[0012] Furthermore, the buffer solution described in step two has a pH of 3-5 and a mass fraction of 1-5%.

[0013] Furthermore, the delignification treatment in step two is carried out at a temperature of 70-90°C for a duration of 1-6 hours.

[0014] Furthermore, in step two, the solvent is preserved as water.

[0015] Furthermore, in step three, the sample is soaked in the replacement solution for 0.1 to 10 minutes.

[0016] Furthermore, in step three, the mixture is frozen at a temperature of -10℃ to -30℃ for 2 to 12 hours, and then freeze-dried.

[0017] Furthermore, in step three, the freeze-drying temperature is -20~-55℃, and the product is dried until the moisture content is below 10%.

[0018] In addition, a method for preparing a corn stalk-based cellulose skeleton with a core-shell structure is provided, the method comprising the following steps:

[0019] 1. Peel the corn stalks to obtain the pith, cut the pith into small sections evenly, and then soak them in deionized water for hydrothermal treatment.

[0020] 2. The small stem pith segments processed in step one are directly dried in an oven at a high temperature of 103℃~150℃ until the moisture content is below 10%, thus obtaining a corn stalk-based cellulose skeleton with a core-shell structure, completing the process.

[0021] Furthermore, in step one, the stem pith is evenly cut into small segments with a size of 0.5~5.0m.

[0022] Furthermore, the temperature of the hydrothermal treatment in step one is 50~90℃, and the treatment time is 0.5~8h.

[0023] Beneficial effects of this invention:

[0024] After lignin is removed, the rigid structure of the corn pith is broken. The adhesion between cell walls weakens, and the pith becomes soft. At this point, the pith is filled with water. Immersing the water-filled, lignin-free corn pith in ethanol, acetone, or dimethyl sulfoxide allows the solvents, such as ethanol, to gradually penetrate and "displace" the water from the cell walls and cell cavities surrounding the pith. Under different immersion times, the liquid in the pores on the outer surface of the pith changes from water (high surface tension) to alcohol, acetone, or dimethyl sulfoxide (low surface tension). Due to the very low surface tension and freezing point of solvents like alcohol, the core of the pith freezes solid during sample freezing and freeze-drying, while the surface layer of the pith, due to the presence of solvents like ethanol, cannot freeze and dries slowly and gently at low temperatures. The capillary force generated when solvents like ethanol evaporate from the microstructure of the pith surface is very small. This weak force is insufficient to stretch the soft cell walls to collapse, but it allows a large number of cellulose nanofibers to come into close contact with each other. Cellulose molecules have numerous hydroxyl groups (-OH), which form strong hydrogen bonds, creating a robust, self-supporting nanofiber network. The water in the core pith is not replaced by alcohol, and after freeze-drying, it retains a relatively loose structure. High-temperature drying was employed, with a drying temperature range of 103°C to 150°C. 103°C is the boiling point of water at normal pressure, significantly accelerating the drying rate. Water rapidly vaporizes, increasing the internal vapor pressure. This rapid drying rate causes the sample surface to quickly dry and shrink, forming a "hard shell," but this shell is not yet completely undeformable. The pressure generated by the vaporization of internal water is sufficient to support this shell, allowing it to expand uniformly or maintain its shape while still retaining plasticity, thus avoiding significant local collapse or bulging, ultimately forming a relatively symmetrical cylinder. At ultra-high temperature drying of 150°C, water vaporizes rapidly. The sample surface loses water instantly, forming a hard, dense shell that almost completely loses its plasticity. This resulted in the construction of a high-strength "core-shell" cellulose skeleton.

[0025] This invention employs a surface densification process to enable hydrogen bonding on the surface of the cellulose skeleton, thereby forming a macroscopic core-shell structure straw cellulose skeleton that is highly oriented from both the microscopic and macroscopic levels.

[0026] This invention removes non-cellulose components from corn pith without damaging its overall structure, following the growth advantages of straw and thus utilizing its structural orientation. Furthermore, by controlling the drying process, corn pith can be transformed into a high-strength cellulose three-dimensional framework, retaining extremely strong adsorption capacity, which has great potential in areas such as cushioning, packaging, heat insulation, and flame retardancy.

[0027] This invention is used to prepare a corn straw-based cellulose skeleton with a core-shell structure. Attached Figure Description

[0028] Figure 1 This is a photograph of the corn stalk-based cellulose skeleton with a core-shell structure in Example 1;

[0029] Figure 2 This is a cross-sectional SEM image of the corn stalk-based cellulose skeleton with a core-shell structure in Example 1;

[0030] Figure 3 This is a cross-sectional SEM image of the corn stalk-based cellulose skeleton in Comparative Example 3;

[0031] Figure 4 Compressive stress-strain diagrams of corn straw-based cellulose skeletons obtained in the examples and comparative examples;

[0032] Figure 5 This is an image of a corn stalk-based cellulose skeleton with a core-shell structure stained in Example 1;

[0033] Figure 6 This is a photograph of the corn stalk-based cellulose skeleton with a core-shell structure in Example 5. Detailed Implementation

[0034] Specific Implementation Method 1: This implementation method provides a method for preparing a corn stalk-based cellulose skeleton with a core-shell structure, which is carried out according to the following steps:

[0035] 1. Peel the corn stalks to obtain the pith, cut the pith into small sections evenly, and then soak them in deionized water for hydrothermal treatment.

[0036] 2. The small stem pith segments treated in step one are soaked in a buffer solution for delignification treatment, then washed with water multiple times to remove residual chemicals, and then stored in a solvent.

[0037] The buffer solution is a sodium chlorite-acetic acid buffer solution, a formic acid-hydrogen peroxide buffer solution, or a sodium sulfite-sodium hydroxide buffer solution.

[0038] 3. Remove the pith from the solvent after step 2 and soak it directly in a replacement solution, such as anhydrous ethanol, acetone, or dimethyl sulfoxide; then freeze it and continue to freeze-dry it to obtain a corn stalk-based cellulose skeleton with a core-shell structure, thus completing the process.

[0039] Specific Implementation Method Two: This implementation method provides a method for preparing a corn stalk-based cellulose skeleton with a core-shell structure, which is carried out according to the following steps:

[0040] 1. Peel the corn stalks to obtain the pith, cut the pith into small sections evenly, and then soak them in deionized water for hydrothermal treatment.

[0041] 2. The small stem pith segments processed in step one are directly dried in an oven at a high temperature of 103℃~150℃ until the moisture content is below 10%, thus obtaining a corn stalk-based cellulose skeleton with a core-shell structure, completing the process.

[0042] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that: in step one, the stem pith is evenly cut into small segments of 0.5~5.0cm in size. Everything else is the same as in Specific Implementation Method 1 or 2.

[0043] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the hydrothermal treatment temperature in step one is 50~90℃, and the treatment time is 0.5~8h. Everything else is the same as in Specific Implementation Methods One to Three.

[0044] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the sodium chlorite-acetic acid buffer solution described in step two has a pH of 3-5 and a mass fraction of 1-5%. Everything else is the same as in Specific Implementation Methods One to Four.

[0045] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the delignification treatment temperature in step two is 70~90℃, and the treatment time is 1~6 hours. Everything else is the same as in Specific Implementation Methods One to Five.

[0046] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the solvent for preservation in step two is water. Everything else is the same as in Specific Implementation Methods One to Six.

[0047] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that step three involves soaking in anhydrous ethanol for 0.1 to 10 minutes. Everything else is the same as in Specific Implementation Methods One to Seven.

[0048] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: in step three, the mixture is frozen at a temperature of -10 to -30°C for 2 to 12 hours, followed by freeze-drying. Everything else is the same as in Specific Implementation Methods One to Eight.

[0049] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: the freeze-drying temperature in step three is -20 to -55°C, and the drying is carried out until the moisture content is below 10%. Everything else is the same as in Specific Implementation Methods One to Nine.

[0050] The scope of this invention is not limited to the above-described embodiments; a combination of one or more specific embodiments can also achieve the purpose of the invention.

[0051] Example 1

[0052] This embodiment describes a method for preparing a corn stalk-based cellulose skeleton with a core-shell structure, which is carried out according to the following steps:

[0053] 1. Cut the corn pith into 2cm lengths and soak it in 50℃ deionized water for 2 hours;

[0054] 2. The small stem pith segments treated in step one are soaked in an acidic buffer solution with a NaClO2 mass fraction of 2% at 85°C for delignification treatment for 6 hours, and then washed repeatedly with water to remove residual chemical substances on the surface, and then stored in water; the acidic buffer solution is a sodium chlorite-acetic acid buffer solution with pH=4.6.

[0055] 3. Remove the stem pith treated in step 2 from the water and soak it in anhydrous ethanol for 3 minutes. Then freeze it in a -20°C freezer for 2 hours. After that, dry it in a -55°C freeze dryer until it is completely dry to obtain a high-strength, macroscopic corn stalk-based cellulose skeleton (D-3E) with a core-shell structure.

[0056] The corn stalk-based cellulose skeleton with a core-shell structure in this embodiment can be further dyed, coated with waterproof materials, and used as a photothermal conversion material.

[0057] Example 2

[0058] This embodiment describes a method for preparing a corn stalk-based cellulose skeleton with a core-shell structure, which is carried out according to the following steps:

[0059] 1. Cut the corn pith into 3cm lengths and soak it in deionized water at 80℃ for 2 hours;

[0060] 2. The small stem pith segments treated in step one are soaked in an acidic buffer solution with a NaClO2 mass fraction of 2% at 85°C for delignification treatment for 6 hours, and then washed repeatedly with water to remove residual chemical substances on the surface, and then stored in water; the acidic buffer solution is a sodium chlorite-acetic acid buffer solution with pH=4.6.

[0061] 3. Remove the stem pith treated in step 2 from the water and soak it in anhydrous ethanol for 7 minutes. Then freeze it in a -20°C freezer for 3 hours. After that, dry it in a -55°C freeze dryer until it is completely dry to obtain a high-strength, macroscopic corn stalk-based cellulose skeleton (D-7E) with a core-shell structure.

[0062] The corn stalk-based cellulose skeleton with a core-shell structure in this embodiment can be further dyed, coated with waterproof materials, and used as a photothermal conversion material.

[0063] Comparative Example 1

[0064] This comparative example is conducted according to the following steps:

[0065] 1. Cut the corn pith into 2cm lengths and soak it in deionized water at 80℃ for 2 hours;

[0066] 2. The small stem pith segments treated in step one are soaked in an acidic buffer solution with a NaClO2 mass fraction of 2% at 85°C for delignification treatment for 6 hours, and then washed repeatedly with water to remove residual chemical substances on the surface, and then stored in water; the acidic buffer solution is a sodium chlorite-acetic acid buffer solution with pH=4.6.

[0067] 3. Remove the pith from the water after step 2 and dry it in a 60℃ oven until completely dry to obtain the corn stalk-based cellulose skeleton.

[0068] Comparative Example 2

[0069] This comparative example is conducted according to the following steps:

[0070] 1. Cut the corn pith into 2cm lengths and soak it in deionized water at 80℃ for 2 hours;

[0071] 2. The small stem pith segments treated in step one are soaked in an acidic buffer solution with a NaClO2 mass fraction of 2% at 85°C for delignification treatment for 6 hours, and then washed repeatedly with water to remove residual chemical substances on the surface, and then stored in water; the acidic buffer solution is a sodium chlorite-acetic acid buffer solution with pH=4.6.

[0072] 3. Remove the pith from the water after step 2 and dry it in an oven at 105℃ until it is completely dry to obtain the corn stalk-based cellulose skeleton.

[0073] Comparative Example 3

[0074] This comparative example is conducted according to the following steps:

[0075] 1. Cut the corn pith into 2cm lengths and soak it in deionized water at 80℃ for 2 hours;

[0076] 2. The small stem pith segments treated in step one are soaked in an acidic buffer solution with a NaClO2 mass fraction of 2% at 85°C for delignification treatment for 6 hours, and then washed repeatedly with water to remove residual chemical substances on the surface, and then stored in water; the acidic buffer solution is a sodium chlorite-acetic acid buffer solution with pH=4.6.

[0077] 3. Remove the pith from the water after step 2, freeze it directly in a refrigerator, and then freeze-dry it to obtain the corn stalk-based cellulose skeleton (D).

[0078] Example 3

[0079] This embodiment describes a method for preparing a corn stalk-based cellulose skeleton with a core-shell structure, which is carried out according to the following steps:

[0080] 1. Cut the corn pith into 2cm lengths and soak it in deionized water at 80℃ for 2 hours;

[0081] 2. The small stem pith segments treated in step one are soaked in an acidic buffer solution with a NaClO2 mass fraction of 2% at 85°C for delignification treatment for 6 hours, and then washed repeatedly with water to remove residual chemical substances on the surface, and then stored in water; the acidic buffer solution is a sodium chlorite-acetic acid buffer solution with pH=4.6.

[0082] 3. Remove the stem pith treated in step 2 from the water and soak it in anhydrous ethanol for 5 minutes. Then freeze it in a -20°C freezer for 8 hours. After that, dry it in a -55°C freeze dryer until it is completely dry to obtain a high-strength, macroscopic corn stalk-based cellulose skeleton (D-5E) with a core-shell structure.

[0083] The corn stalk-based cellulose skeleton with a core-shell structure in this embodiment can be further dyed, coated with waterproof materials, and used as a photothermal conversion material.

[0084] Example 4

[0085] This embodiment describes a method for preparing a corn stalk-based cellulose skeleton with a core-shell structure, which is carried out according to the following steps:

[0086] 1. Cut the corn pith into 4cm lengths and soak it in 80℃ deionized water for 2 hours;

[0087] 2. The small stem pith segments treated in step one are soaked in an acidic buffer solution with a NaClO2 mass fraction of 2% at 85°C for delignification treatment for 5 hours, and then washed repeatedly with water to remove residual chemical substances on the surface, and then stored in water; the acidic buffer solution is a sodium chlorite-acetic acid buffer solution with pH=5.

[0088] 3. Remove the stem pith treated in step 2 from the water and soak it in anhydrous ethanol for 10 minutes. Then freeze it in a -20°C freezer for 12 hours. After that, dry it in a -45°C freeze dryer until it is completely dry to obtain a high-strength, macroscopic corn stalk-based cellulose skeleton (D-10E) with a core-shell structure.

[0089] The corn stalk-based cellulose skeleton with a core-shell structure in this embodiment can be further dyed, coated with waterproof materials, and used as a photothermal conversion material.

[0090] Comparative Example 4

[0091] This comparative example is conducted according to the following steps:

[0092] 1. Cut the corn pith into 5cm lengths and soak it in 50℃ deionized water for 2 hours;

[0093] 2. The small stem pith segments treated in step one are soaked in an acidic buffer solution with a NaClO2 mass fraction of 2% at 85°C for delignification treatment for 6 hours, and then washed repeatedly with water to remove residual chemical substances on the surface, and then stored in water; the acidic buffer solution is a sodium chlorite-acetic acid buffer solution with pH=4.2.

[0094] 3. Remove the pith from the water after step 2 and soak it in acetone for 24 hours, then let it air dry to obtain the corn stalk-based cellulose skeleton.

[0095] Example 5

[0096] This embodiment is performed according to the following steps:

[0097] 1. Cut the corn pith into 5cm lengths and soak it in 50℃ deionized water for 2 hours;

[0098] 2. The small stem pith segments processed in step one are subjected to hydrothermal treatment at 85℃ for 0.5 hours;

[0099] 3. The pith treated in step two is directly dried in an oven at 150℃ until the moisture content is below 10%, yielding a corn stalk-based cellulose skeleton. (150℃)

[0100] Example 6

[0101] This embodiment is performed according to the following steps:

[0102] 1. Cut the corn pith into 2cm lengths and soak it in deionized water at room temperature for 2 hours;

[0103] 2. The small stem pith segment processed in step one is subjected to hydrothermal treatment at 75℃ for 2 hours;

[0104] 3. The pith treated in step two is directly dried in an oven at 103℃ until the moisture content is below 10%, yielding a corn stalk-based cellulose skeleton. (103℃)

[0105] Figure 1 The image shows a physical diagram of the corn stalk-based cellulose skeleton with a core-shell structure in Example 1. As can be seen from the image, the surface of the straw is relatively dense, while the core is relatively loose, forming a standard core-shell structure.

[0106] Figure 2 The image shows a cross-sectional SEM image of the corn stalk-based cellulose skeleton with a core-shell structure in Example 1. As can be seen from the image, at the microscopic level, the cell diameter near the outer surface is significantly smaller than that of the core cells.

[0107] Figure 3 This is a cross-sectional SEM image of the corn stalk-based cellulose skeleton in Comparative Example 3; and... Figure 2 In contrast, the parenchyma cells of the maize stalk pith in Comparative Example 3 were evenly distributed, but no "nucleoshell" structure was produced.

[0108] Figure 4 The figures show the compressive stress-strain diagrams of the corn stalk-based cellulose skeletons obtained in the examples and comparative examples. The figures show that the compression test results indicate a positive correlation between the alcohol soaking time and the compressibility of the material in the alcohol-soaked treatment group. That is, the longer the soaking time, the stronger the material's resistance to compression. The group that was directly freeze-dried without alcohol replacement had the lowest compressive strength and was prone to collapse under pressure. Group D-10E exhibited the best compressive performance, with significantly higher compressive strength and elastic modulus than other groups. In the oven-drying treatment group, the compressive strength of the group dried at 103℃ was better than that dried at 150℃. The drying process at 150℃ was too fast, potentially leading to internal defects, while the drying process at 103℃ was slower than at 150℃, resulting in a more uniform product with higher compressive strength. The figures also show that the compressive strength of the corn stalk pith after "core-shell" treatment is significantly improved, indicating that this invention can significantly improve the mechanical strength of the cellulose skeleton.

[0109] Figure 5 The image shows the stained corn stalk-based cellulose skeleton with a core-shell structure, as described in Example 1. The image shows that the treated corn stalk has good loading capacity and can serve as a basis for the cellulose skeleton. Its good loading capacity allows for further functionalization.

[0110] Figure 6 The image shows a physical diagram of the corn stalk-based cellulose skeleton with a core-shell structure in Example 5. As can be seen from the image, after high-temperature drying, a shell layer forms on the surface of the corn stalk pith, while the core retains a loose and porous structure.

Claims

1. A method for preparing a corn stalk-based cellulose skeleton with a core-shell structure, characterized in that... This method is performed in the following steps:

1. Peel the corn stalks to obtain the pith, cut the pith into small sections evenly, and then soak them in deionized water for hydrothermal treatment.

2. The small stem pith segments treated in step one are soaked in a buffer solution for delignification treatment, then washed with water multiple times to remove residual chemicals, and then stored in a solvent, with water as the storage solvent. The buffer solution is a sodium chlorite-acetic acid buffer solution or a formic acid-hydrogen peroxide buffer solution; 3. Remove the pith from the solvent after step 2 and soak it directly in a replacement solution, which is anhydrous ethanol or acetone; then freeze it and then freeze-dry it to obtain a corn stalk-based cellulose skeleton with a core-shell structure, thus completing the process.

2. The method for preparing a corn stalk-based cellulose skeleton with a core-shell structure according to claim 1, characterized in that... Step 1: Cut the stem pith into small segments of 0.5-5.0 cm in size.

3. The method for preparing a corn stalk-based cellulose skeleton with a core-shell structure according to claim 1, characterized in that... The temperature of the hydrothermal treatment in step one is 50~90℃, and the treatment time is 0.5~8h.

4. The method for preparing a corn stalk-based cellulose skeleton with a core-shell structure according to claim 1, characterized in that... The buffer solution described in step two has a pH of 3-5 and a mass fraction of 1-5%.

5. The method for preparing a corn stalk-based cellulose skeleton with a core-shell structure according to claim 1, characterized in that... The delignification treatment in step two is carried out at a temperature of 70-90℃ for 1-6 hours.

6. The method for preparing a corn stalk-based cellulose skeleton with a core-shell structure according to claim 1, characterized in that... Step 3: Soak in the replacement solution for 3-10 minutes.

7. The method for preparing a corn stalk-based cellulose skeleton with a core-shell structure according to claim 1, characterized in that... Step 3: Freeze at a temperature of -10℃ to -30℃ for 2 to 12 hours, and then freeze-dry.

8. The method for preparing a corn stalk-based cellulose skeleton with a core-shell structure according to claim 1, characterized in that... Step 3: Freeze-dry at -20~-55℃ until the moisture content is below 10%.

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