2D wood cell wall thin layer batch preparation method

Abstract

The invention belongs to a 2D wood cell wall thin layer batch preparation method which comprises the following steps: sequentially treating wood powder with an alkaline solution and a sodium hypochlorite solution, then putting the wood powder in a wet state into a kneading machine, carrying out mechanical shear mixing treatment for 4-5 hours, adding low-amount cellulase during the period, and promoting cell wall separation by cooperating with the mechanical shear mixing effect, so as to obtain the 2D wood cell wall thin layer. The 2D wood cell wall thin layer batch preparation material is obtained. According to the method, the 2D wood cell wall thin layer material can be obtained through high-yield, high-efficiency, low-cost and industrial-grade expansion, TEMPO treatment and ultrasonic treatment which are high in energy consumption and have environmental burden are not included in the method, large-scale preparation of the material is achieved through the kneading technology, the stripping yield of the 2D cell wall thin layer can be greatly increased, and the method is suitable for large-scale production of the 2D wood cell wall thin layer material. The stripping yield of the 2D cell wall thin layer can reach about 75%, the obtaining rate is high, and the requirement of large-scale application can be met.

Description

Technical Field

[0001] The invention belongs to a method for batch preparing 2D wood cell wall thin layers. Background Art

[0002] The development of graphene has led to extensive research on other two-dimensional materials with unique properties besides graphene, such as insulating hexagonal boron nitride (h-BN), semiconducting transition metal dichalcogenides (TMDCs) and black phosphorus (BP) with tunable band gaps, and conductive transition metal carbides and / or nitrides (MXene). In addition, emerging two-dimensional materials such as metal oxides and layered double hydroxides (LDHs) have also attracted increasing attention due to their unique physical and chemical properties. These two-dimensional materials are of various types and have common characteristics such as high specific surface area, good mechanical flexibility, and ultra-thinness. They have broad application prospects in a variety of application fields such as energy storage and conversion devices, flexible sensors, and electromagnetic shielding.

[0003] Cell wall 2D sheet materials (or two-dimensional nanosheet materials; nanosheet materials) usually have unique microstructures such as layers, sheets, and ribbons, which give two-dimensional nanomaterials excellent optical, electrical, mechanical and other properties. In the future, they can be widely used in energy storage, adsorption, catalysis, high-performance biomass materials, sensing and other fields.

[0004] Chinese Patent No. 201910427999.0 introduces a method for preparing a 2D sheet material of wood cell wall, which peels off the natural 2D material of wood cell wall thin layer, and uses this structure to prepare SEI and apply it to energy storage materials as an attractive solution to solve the short life of LMB. In addition, it can be used as a platform material to load various heteroatoms, and different properties can be improved according to the doping substances. By further carbonizing it, its surface defects are increased, and the active sites are expanded, so that the performance after doping is improved. Studies have shown that the application potential of the carbonized thin layer as an electrode material and good dye degradation performance. And through the curling of the two-dimensional structure, using two-dimensional cellulose as a medium, different powdered materials can be processed into micro / nano particles. This material has huge market potential.

[0005] However, in practical applications, large-scale production of two-dimensional materials is a prerequisite for their scalability and commercialization, and must meet the requirements of high yield, high efficiency, low cost and industrial-grade expansion. However, the yield of this wood 2D material preparation is low, and the TEMPO and ultrasonic treatments, which are energy-intensive and environmentally burdensome, have a low yield, and the yield of wood cell wall 2D sheet materials is only about 15%, which is difficult to meet large-scale applications.

[0006] Therefore, there is an urgent need for a green, environmentally friendly, low-cost, simple and easy method for batch preparation of 2D wood cell wall thin layers, which can provide the possibility for batch preparation of wood 2D thin layer materials. Summary of the invention

[0007] The purpose of the present invention is to design a method for batch preparation of 2D wood cell wall thin layers, which has the advantages of being green, environmentally friendly, low cost, high yield, and simple and easy to operate.

[0008] To this end, a method for batch preparing 2D wood cell wall thin layers of the present invention comprises the following steps: (1) Use wood powder with a particle size of 0.1 to 0.5 mm and dry it in an oven until it is absolutely dry; (2) Weigh the dried wood powder, add 50 mL of 2 wt% to 4 wt% alkaline solution per 1 g of wood powder, stir at 200 rpm for 3.5 h to 4.5 h at 90 to 100 °C, and after the reaction, repeatedly wash the wood powder with distilled water until the pH is neutral; (3) Add 25 ml of 3-4% sodium hypochlorite solution to every 1 g of wood powder, and adjust the solution pH to 4-5 with glacial acetic acid. Stir at 70-90°C for 4-5 hours. After the reaction, wash the wood powder repeatedly with distilled water until the pH is neutral. (4) The wet wood powder is placed in a kneader for mechanical shearing and mixing for 4 to 5 hours, during which a low amount of cellulase is added to promote cell wall separation in coordination with the mechanical shearing and mixing effect, thereby obtaining a 2D wood cell wall thin layer batch preparation material.

[0009] As a further description of the above technical solution: the wood can be any kind of wood, including bamboo.

[0010] As a further description of the above technical solution: the fiber concentration of the wet wood powder is 30% to 40%.

[0011] As a further description of the above technical solution: the alkaline solution is any one of potassium hydroxide, sodium hydroxide and lithium hydroxide.

[0012] As a further description of the above technical solution: the low amount of cellulase is 0.015-0.020 g per gram of dry weight fiber, and the added amount is 0.8-3% of the weight of the wet wood powder.

[0013] As a further description of the above technical solution: the mechanical shearing and mixing treatment time in the kneading machine can be appropriately adjusted according to the concentration and quality of the fiber slurry.

[0014] The present invention has the following beneficial effects: 1. The present invention adopts a top-down peeling method to peel off the 2D wood cell wall thin layer, and the peeled thin layer has good mechanical properties and anisotropy, the dispersion form has good rheological properties, and the freeze-dried material has good thermal insulation properties.

[0015] 2. The present invention can obtain 2D wood cell wall thin layer materials with high yield, high efficiency, low cost and industrial expansion. The method of the present invention does not contain TEMPO treatment and ultrasonic treatment that consumes a lot of energy and has an environmental burden. The kneading technology is used to achieve large-scale preparation of the material, which can greatly improve the peeling yield of the 2D cell wall thin layer. The peeling yield of the 2D cell wall thin layer of the present invention can reach about 75%, and the acquisition rate is high. The present invention greatly reduces energy consumption and reduces costs by 90% compared to traditional methods. It can also adjust the process and parameters, change the morphology of the peeled thin layer, and make the product more suitable for specific applications, providing possibilities for the industrial application of this wood 2D thin layer.

[0016] 3. The preparation method provided by the present invention is simple and easy to implement, the raw materials are easy to obtain, and it is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the 2D wood cell wall thin layer optical image in Example 1 of the present invention; Figure 2 This is a 2D wood cell wall thin layer SEM image in Example 1 of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described in conjunction with specific embodiments below, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work all belong to the protection scope of the present invention. The construction methods in the following embodiments, unless otherwise specified, are all conventional methods. The materials, devices, equipment, etc. used in the following embodiments, unless otherwise specified, can all be obtained from commercial channels.

[0019] Example 1: Figure 1 and Figure 2As shown, a method for preparing 2D wood cell wall thin layers in batches comprises the following steps: weighing 80g of dry wood fiber with a particle size of 0.1-0.5mm, immersing it in 2L of 2wt% potassium hydroxide solution, and stirring it at 200rmp / min at 90°C for 3.5h. After the reaction, the wood fiber is repeatedly washed with distilled water until the pH is neutral; 2L of 3%-4% sodium hypochlorite solution is added, and the pH of the solution is adjusted to about 4.6 with glacial acetic acid, and reacted at 70°C for 4h. After the reaction, the wood fiber is repeatedly washed with distilled water until the pH is neutral; the wet wood fiber with a fiber concentration of 30%-40% is placed in a kneader for mechanical treatment for 4h, during which 1.2g of low-amount cellulase of 0.015-0.020g per gram of dry weight fiber is added, and the mechanical action promotes cell wall separation, so as to obtain a liquid 2D wood cell wall thin layer batch preparation material.

[0020] Example 2: A method for preparing 2D wood cell wall thin layers in batches: 200 g of dry wood powder with a particle size of 0.1-0.5 mm was weighed and immersed in 5L of 2wt% potassium hydroxide solution, and stirred at 90°C and 200 rpm for 3.5 hours. After the reaction, the wood fiber was repeatedly washed with distilled water until the pH was neutral; 5L of 3%-4% sodium hypochlorite solution was added, and the pH of the solution was adjusted to about 4.6 with glacial acetic acid, and reacted at 70°C for 4 hours. After the reaction, the wood powder was repeatedly washed with distilled water until the pH was neutral; the wet wood powder with a fiber concentration of 35% was placed in a kneader for mechanical treatment for 6 hours, during which 3g of low-amount cellulase of 0.015-0.020g per gram of dry weight fiber was added to promote cell wall separation with synergistic mechanical action, and a 2D wood cell wall thin layer batch preparation material was obtained.

[0021] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for batch preparation of 2D wood cell wall thin layers, characterized in that: The steps include: (1) Use wood powder with a particle size of 0.1 to 0.5 mm and dry it in an oven until it is absolutely dry; (2) Weigh the dried wood powder, add 50 mL of 2 wt% to 4 wt% alkaline solution per 1 g of wood powder, stir at 200 rpm for 3.5 h to 4.5 h at 90 to 100 °C, and after the reaction, repeatedly wash the wood powder with distilled water until the pH is neutral; (3) Add 25 ml of 3-4% sodium hypochlorite solution to every 1 g of wood powder, and adjust the solution pH to 4-5 with glacial acetic acid. Stir at 70-90°C for 4-5 hours. After the reaction, wash the wood powder repeatedly with distilled water until the pH is neutral. (4) The wet wood powder is placed in a kneader for mechanical shearing and mixing for 4 to 5 hours, during which a low amount of cellulase is added to promote cell wall separation in coordination with the mechanical shearing and mixing effect, thereby obtaining a 2D wood cell wall thin layer batch preparation material.

2. A method for batch preparation of 2D wood cell wall thin layers according to claim 1, characterized in that: The wood can be any kind of wood, including bamboo.

3. A method for batch preparation of 2D wood cell wall thin layers according to claim 1, characterized in that: The wet wood powder has a fiber concentration of 30% to 40%.

4. The method for batch preparation of 2D wood cell wall thin layers according to claim 1, characterized in that: The alkaline solution is any one of potassium hydroxide, sodium hydroxide and lithium hydroxide.

5. The method for batch preparation of 2D wood cell wall thin layers according to claim 1, characterized in that: The low-amount cellulase is 0.015-0.020 g per gram of dry weight fiber, and the added amount is 0.8-3% of the weight of the wet wood powder.

6. The method according to claim 1, characterized in that: The mechanical shearing and mixing treatment time in the kneader can be appropriately adjusted according to the concentration and quality of the fiber slurry.

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