Nano-cellulose preparation device, wood nano-cellulose and preparation method of wood nano-cellulose

Abstract

The invention relates to a nano-cellulose preparation device, wood nano-cellulose and a preparation method of the wood nano-cellulose. The nanocellulose preparation device comprises a pretreatment assembly, a micro-nanocrystallization assembly, a nanocrystallization assembly and a finished product collection part which are connected in sequence; the pretreatment assembly comprises a first storage part and a pretreatment part which are connected in sequence; the micro-nanocrystallization assembly comprises a second material storage part and a micro-nanocrystallization treatment part which are connected in sequence; the nanocrystallization assembly comprises at least three homogenizing components which are connected in series; the continuous mass production of the nanocellulose is realized, the nanocrystallization treatment times are reduced, the production energy consumption and the abrasion to equipment are reduced, and the production cost is reduced; according to the lignin-containing wood nanocellulose prepared by the preparation method, the diameter is as small as 10-90 nm, the content of the nanocellulose with the length smaller than or equal to 3 microns and the diameter smaller than 100 nm is larger than or equal to 85%, the lignin content is larger than or equal to 5 wt%, the lignin-containing wood nanocellulose has the excellent performance of both lignin and nanocellulose, and the preparation process is simple, environmentally friendly and free of pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of nanocellulose preparation, and particularly to a nanocellulose preparation device, lignin nanocellulose and a preparation method thereof. Background Art

[0002] The raw material of nanocellulose is plant fiber, and the preparation methods are mainly divided into mechanical method and chemical method. A representative chemical method is the TEMPO (2,2,6,6 - tetramethylpiperidine - 1 - oxyl radical) oxidation method. Although this method can effectively obtain nanocellulose, the chemical reagent TEMPO used has characteristics such as very high toxicity and difficult recovery, so the production cost of this method is very high. The mechanical method mainly uses mechanical treatments such as crushing and grinding to nanofibrillate high - purity plant fibers. Currently, the equipment used for nanofibrillation in the market is mainly a high - pressure homogenizer or a microfluidic high - pressure homogenizer. Since it needs to carry out nanofibrillation under high pressure (generally between 800 bar and 1500 bar), the requirements and wear on equipment accessories are extremely high, and nanofibrillation needs to be carried out multiple times. Therefore, the energy consumption is high, the mechanical strength is large, and the production cost is also very high. In addition, currently, the nanocellulose in the market is generally prepared by chemical and mechanical methods using bleached fibers, and the prepared nanocellulose basically does not contain lignin, resulting in the inability to fully utilize the high mechanical properties, strong anti - aging property and antioxidant property of lignin.

[0003] For example, CN118087301A discloses a preparation method of lignin nanocellulose, which specifically includes carrying out one - pot acid pretreatment on lignocellulose biomass raw materials by mixing with two organic acids, citric acid and maleic acid, and then carrying out mechanical nanofibrillation treatment by using a high - pressure homogenizer; the pre - decomposition treatment step of this preparation method has a complex operation process, and still uses a high - pressure homogenizer for mechanical nanofibrillation treatment, with a large number of homogenization times and high pressure, which causes great wear on the high - pressure homogenizer, and the energy consumption and cost are high.

[0004] For example, CN110130136B discloses a preparation method of lignocellulose nanofibers, which specifically includes heating a delignified lignocellulose raw material by mixing with a deep eutectic solvent to obtain a swollen, delignified and surface - esterified lignocellulose mixture, and then carrying out mechanical treatment on the obtained mixture to obtain a surface - esterified lignocellulose nanofiber dispersion; finally, filtering, washing, separating and drying the dispersion to obtain lignocellulose nanofibers; this preparation method has a complex preparation process, consumes a large amount of reagents, and the nanofibrillation effect on lignocellulose still needs to be improved.

[0005] Therefore, how to develop a new nanocellulose preparation device and a preparation method of lignin nanocellulose to achieve low - cost preparation of small - size nanocellulose and lignin - containing nanocellulose is an urgent technical problem to be solved in the current field. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a nanocellulose preparation device, lignin-based nanocellulose and a preparation method thereof. On the one hand, it solves the problem that the traditional device for preparing nanofibers needs to be carried out under high pressure, which has extremely high requirements and wear on the equipment. On the other hand, it avoids the problem of harm to the human body and the environment caused by the traditional method of preparing nanocellulose using toxic reagents; it successfully prepares nanocellulose containing lignin at low cost.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a nanocellulose preparation device, which includes a pretreatment component, a micro-nanoization component, a nanoization component and a finished product collection component connected in sequence;

[0009] The pretreatment component includes a first storage component and a pretreatment component connected in sequence;

[0010] The micro-nanoization component includes a second storage component and a micro-nanoization processing component connected in sequence;

[0011] The nanoization component includes at least 3 homogenization components connected in series (for example, it can be 3, 4, 5 or 6, etc., preferably 3 to 5).

[0012] The nanocellulose device of the present invention connects the pretreatment component, the micro-nanoization component and the nanoization component to gradually degrade cellulose. First, it is initially degraded by the pretreatment component, then degraded to the micro-nano level by the micro-nanoization component, and finally degraded to the nano level by the nanoization component; it not only realizes the continuous mass production of nanocellulose, but also compared with the traditional method of preparing nanocellulose using a high-pressure homogenizer or a microfluidic high-pressure homogenizer, the pretreatment component, the micro-nanoization component and the nanoization component including at least 3 homogenization components in the present invention greatly reduce the number of nanoization times, reduce energy consumption and wear on the equipment, thereby reducing the preparation cost.

[0013] Preferably, the pretreatment component includes a trough beater.

[0014] The present invention further preferably includes a trough beater in the pretreatment component. The trough beater has the functions of separating, dispersing, cutting and refining cellulose, and realizes the preliminary degradation of cellulose.

[0015] Preferably, a first monitoring component is arranged at the bottom of the pretreatment component.

[0016] The present invention further preferably provides that a first monitoring component is provided at the bottom of the pretreatment component, and the first monitoring component is used for on-line monitoring of the plant cellulose in the pretreatment component, and the beating times of the pretreatment component, i.e., the trough beater, are determined according to different materials and different processing requirements.

[0017] Preferably, a first feeding component is provided between the first storage component and the pretreatment component.

[0018] Preferably, a first stirring member is provided at the bottom of the first storage component.

[0019] The present invention further preferably provides that a first stirring member is provided at the bottom of the first storage component, and the first stirring member is used for the preliminary dispersion of the plant cellulose raw material in the first storage component.

[0020] Preferably, the nano-cellulose preparation device includes at least 2 groups of micro-nanoization components connected in parallel, such as 2 groups, 3 groups, 4 groups or 5 groups, etc., preferably 2 to 4 groups.

[0021] The present invention further preferably provides that the nano-cellulose preparation device includes 2 to 4 groups of micro-nanoization components connected in parallel, which are used for simultaneous micro-nanoization treatment and nanoization treatment. Specifically, for example, when the nano-cellulose preparation device includes 2 groups of micro-nanoization components connected in parallel, when one group of micro-nanoization components conveys the material to the subsequent nanoization component for nanoization treatment, the other set performs micro-nanoization treatment on the new raw material, so as to ensure the production continuity and the operation stability of the homogenization component.

[0022] Preferably, the micro-nanoization treatment component includes a colloid pump.

[0023] The present invention further preferably provides that the micro-nanoization treatment component includes a colloid pump, which can perform repeated grinding, dispersion, homogenization and emulsification to realize the micro-nanoization treatment of the cellulose after preliminary degradation so that its size reaches the micro-nano level.

[0024] Preferably, a second feeding component is provided between the second storage component and the micro-nanoization treatment component.

[0025] Preferably, the second feeding component includes a diaphragm pump.

[0026] In the present invention, the second feeding component and the micro-nanoization treatment component operate in series, and the second feeding component provides a stable flow rate for the micro-nanoization treatment component, and this part is circulated until the cellulose size reaches the micro-nano level and the circulation stops.

[0027] Preferably, a second monitoring component is provided at the bottom of the second storage component.

[0028] The present invention further preferably provides that a second monitoring component is provided at the bottom of the second storage component. The second monitoring component is used to on-line monitor the size of the cellulose in the second storage component, that is, whether the size of the cellulose in the micro-nano cycle treatment process reaches the micro-nano level, and judge the operation of the micro-nano component based on this.

[0029] Preferably, a second stirring member is provided at the bottom of the second storage component.

[0030] In the present invention, it is preferred that a second stirring member is provided at the bottom of the second storage component to prevent the cellulose from precipitating and cross-linking into clusters.

[0031] Preferably, the nano-sizing component further includes a buffer component provided between two adjacent homogenizing components.

[0032] The present invention preferably provides that the nano-sizing component further includes a buffer component provided between two adjacent homogenizing components. The buffer component is used to provide stable feeding for the homogenizing components, avoid unstable pressure caused by discontinuous feeding of subsequent homogenizing components, thereby affecting the nano-sizing treatment effect, and causing wear to the homogenizing components, increasing energy consumption and costs.

[0033] Preferably, a third feeding component is provided between the homogenizing component and the buffer component.

[0034] In a second aspect, the present invention provides a method for preparing wood nano-cellulose, and the preparation method includes the following steps:

[0035] (1) The plant fiber raw material is successively subjected to first hydrolysis and first solid-liquid separation to obtain a first fiber solid;

[0036] (2) The first fiber solid obtained in step (1) is successively subjected to second hydrolysis and second solid-liquid separation to obtain a second fiber solid;

[0037] (3) The second fiber solid obtained in step (2) is processed by the nano-cellulose preparation device described in the first aspect to obtain wood nano-cellulose.

[0038] In the preparation method of the present invention, by first performing first hydrolysis and second hydrolysis on the plant fiber raw material, selectively separating hemicellulose and part of lignin in the plant fiber raw material respectively to obtain the second fiber solid, and then using the nano-cellulose device in the first aspect to pre-treat, micro-nano-size and nano-size the second fiber solid successively to obtain nano-cellulose containing lignin with a longer length and a smaller diameter. The reagents used in the preparation method are all easily obtainable and non-toxic, and the preparation method does not require complex equipment and is easy to mass-produce on a large scale.

[0039] Preferably, based on the mass percentage of the plant fiber raw material described in step (1) being 100 wt%, the plant fiber raw material described in step (1) includes 20 - 40 wt% hemicellulose, 10 - 35 wt% lignin, and 30 - 50 wt% cellulose.

[0040] Among them, 20 - 40 wt% hemicellulose can be, for example, 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt% etc.; 10 - 35 wt% lignin can be, for example, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, or 35 wt% etc.; 30 - 50 wt% cellulose can be, for example, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt% etc.

[0041] Preferably, the plant fiber raw material described in step (1) includes woody biomass and / or herbaceous biomass.

[0042] Preferably, the woody biomass includes any one or a combination of at least two of hardwood, softwood, or shrub. Typical but non - limiting combinations include combinations of hardwood and softwood, combinations of hardwood and shrub, or combinations of softwood and shrub, etc.

[0043] Preferably, the herbaceous biomass includes any one or a combination of at least two of bagasse, bamboo, rice straw, wheat straw, corn straw, or reed. Typical but non - limiting combinations include combinations of bagasse and bamboo, combinations of bamboo and rice straw, or combinations of rice straw and wheat straw, etc.

[0044] Preferably, the first hydrolysis in step (1) includes mixing the plant fiber raw material and a first acetic acid solution for the first hydrolysis.

[0045] Preferably, the mass ratio of the plant fiber raw material to the first acetic acid solution is 1:(4 - 10), which can be, for example, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10 etc., and preferably 1:(5 - 7).

[0046] Preferably, the mass concentration of the first acetic acid solution is 5 wt% - 30 wt%, which can be, for example, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, 28 wt%, or 30 wt% etc.

[0047] The present invention further preferably has the mass concentration of the first acetic acid solution being 5wt% - 30wt%. That is, a lower concentration of acetic acid solution is used for the first hydrolysis. The acetic acid solution with a lower concentration has a high selectivity for hemicellulose and a poor selectivity for lignin, and can effectively separate the hemicellulose and lignin with smaller size and lower molecular weight. If the mass concentration of the first acetic acid solution is too low, the separation of the hemicellulose will be incomplete, resulting in a large amount of hemicellulose still remaining in the final product. If the mass concentration of the first acetic acid solution is too high, the separation effect on lignin will be better, while hemicellulose still remains in the product.

[0048] Preferably, a first hydrolysis solution is also obtained after the first solid-liquid separation.

[0049] Preferably, the first hydrolysis solution includes hemicellulose and lignin.

[0050] Preferably, the present invention also includes concentrating the first hydrolysis solution and then extracting with an ester extractant to obtain nano-lignin.

[0051] Preferably, the concentration multiple is 5 - 30 times, for example, it can be 5 times, 8 times, 10 times, 12 times, 15 times, 18 times, 20 times, 22 times, 25 times, 28 times or 30 times, etc.

[0052] Preferably, the ester extractant includes any one or a combination of at least two of ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, tert-butyl acetate, ethyl n-valerate or glycerol acetate. Typical but non-limiting combinations include the combination of ethyl acetate and n-propyl acetate, the combination of n-propyl acetate and isopropyl acetate, or the combination of n-butyl acetate and isobutyl acetate, etc.

[0053] Preferably, the particle size of the nano-lignin is 50 - 500nm, for example, it can be 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm or 500nm, etc.

[0054] Preferably, the temperature of the first hydrolysis is 100 - 140°C, and typical but non-limiting combinations include 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C or 140°C, etc.

[0055] Preferably, the pressure of the first hydrolysis is 0.1 - 0.6MPa, for example, it can be 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa or 0.6MPa, etc.

[0056] Preferably, the time of the first hydrolysis is 1 to 5 h, for example, it can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h, etc.

[0057] Preferably, based on the mass percentage of the first fiber solid being 100 wt%, the first fiber solid comprises 5 to 10 wt% of hemicellulose, 10 to 25 wt% of lignin, and 65 to 85 wt% of cellulose.

[0058] Among them, 5 to 10 wt% of hemicellulose, for example, can be 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt% or 10 wt%, etc.; 10 to 25 wt% of lignin, for example, can be 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt% or 25 wt%, etc.; 65 to 85 wt% of cellulose, for example, can be 65 wt%, 70 wt%, 75 wt%, 80 wt% or 85 wt%, etc.

[0059] Preferably, the second hydrolysis in step (2) includes mixing the first fiber solid and a second acetic acid solution for the second hydrolysis.

[0060] Preferably, the mass ratio of the first fiber solid to the second acetic acid solution is 1:(4 to 12), for example, it can be 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11 or 1:12, etc., and preferably 1:(5 to 8).

[0061] Preferably, the mass concentration of the second acetic acid solution is 70 wt% to 90 wt%, for example, it can be 70 wt%, 72 wt%, 75 wt%, 78 wt%, 80 wt%, 82 wt%, 85 wt%, 88 wt% or 90 wt%, etc.

[0062] Preferably, the temperature of the second hydrolysis is 120 to 160 °C, for example, it can be 120 °C, 125 °C, 130 °C, 135 °C, 140 °C, 145 °C, 150 °C, 155 °C or 160 °C, etc.

[0063] Preferably, the pressure of the second hydrolysis is 0.2 to 0.8 MPa, for example, it can be 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa or 0.8 MPa, etc.

[0064] Preferably, the time of the second hydrolysis is 1 to 5 h, for example, it can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h, etc.

[0065] Preferably, based on the mass percentage of the second fiber solid being 100 wt%, the second fiber solid comprises 5 - 10 wt% hemicellulose, 5 - 15 wt% lignin, and 75 - 90 wt% cellulose.

[0066] Among them, 5 - 10 wt% hemicellulose can be, for example, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%, etc.; 5 - 15 wt% lignin can be, for example, 5 wt%, 8 wt%, 10 wt%, 12 wt%, or 15 wt%, etc.; 75 - 90 wt% cellulose can be, for example, 75 wt%, 80 wt%, 85 wt%, or 90 wt%, etc.

[0067] Preferably, step (2) further includes acid - treating the second fiber solid.

[0068] Preferably, the acid solution used for the acid - treatment includes sulfuric acid.

[0069] Preferably, the mass concentration of the acid solution used for the acid - treatment is 1 wt% - 5 wt%, and can be, for example, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, or 5 wt%, etc.

[0070] Preferably, the time of the acid - treatment is 30 - 60 min, and can be, for example, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min, etc.

[0071] Preferably, after the acid - treatment, it further includes performing alkali neutralization and secondary water - washing. Preferably, step (3) includes mixing the second fiber solid and water to obtain a mixed solution; the mixed solution is successively subjected to pretreatment, micro - nano - sizing treatment, and nano - sizing treatment to obtain the native nano - cellulose.

[0072] Preferably, the mass concentration of the second fiber solid in the mixed solution is 1 wt% - 5 wt%, and can be, for example, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, or 5 wt%, etc.

[0073] Preferably, when performing the pretreatment, the rotational speed of the beating roller of the trough - type beater is 490 - 510 r / min, and can be, for example, 490 r / min, 495 r / min, 500 r / min, 505 r / min, or 510 r / min, etc.

[0074] The present invention does not limit the time of the pretreatment, as long as the cellulose in the second fiber solid is preliminarily degraded.

[0075] Preferably, during the micro-nano processing, the rotational speed of the rotor of the colloid pump is 200-800 r / min, for example, it can be 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min or 800 r / min, etc.

[0076] The present invention does not limit the time of the micro-nano processing, as long as micro-nano scale cellulose can be obtained.

[0077] Preferably, during the nano processing, the working pressure of the first homogenization component is 200-500 bar, for example, it can be 200 bar, 220 bar, 250 bar, 280 bar, 300 bar, 320 bar, 350 bar, 380 bar, 400 bar, 420 bar, 450 bar, 480 bar or 500 bar, etc.

[0078] The present invention further preferably sets the working pressure of the first homogenization component during the nano processing to be 200-500 bar, that is, the low-pressure homogenization component is used for pre-nano processing first, combined with the aforementioned pretreatment and micro-nano processing, and they work together to reduce the burden of the subsequent high-pressure homogenization component for nano processing, reduce the overall number of times of nano processing of the homogenization components, thereby reducing the wear and energy consumption of the homogenization components.

[0079] Among them, the first homogenization component refers to the homogenization component connected to the micro-nano component, that is, the first homogenization component that works first.

[0080] Preferably, during the nano processing, the working pressure of the homogenization components other than the first homogenization component is 800-1300 bar, for example, it can be 800 bar, 900 bar, 1000 bar, 1100 bar, 1200 bar or 1300 bar, etc.

[0081] The present invention does not limit the time of the nano processing, as long as wood nano cellulose with the target nano size can be obtained.

[0082] Preferably, before the acid treatment in step (2), washing the second fiber solid is also included.

[0083] Preferably, the washing includes pickling and the first water washing in sequence.

[0084] Preferably, the pickling is carried out with a third acetic acid solution.

[0085] Preferably, the mass concentration of the third acetic acid solution is 70 wt% - 90 wt%, for example, it can be 70 wt%, 75 wt%, 80 wt%, 85 wt% or 90 wt%, etc.

[0086] Preferably, the number of pickling times is 2 to 10 times, for example, it can be 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times or 10 times, etc.

[0087] Preferably, the temperature of the first water washing is 70 to 90 °C, for example, it can be 70 °C, 75 °C, 80 °C, 85 °C or 90 °C, etc.

[0088] Preferably, the number of the first water washing times is 2 to 10 times, for example, it can be 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times or 10 times, etc.

[0089] As a further preferred technical solution of the present invention, the preparation method includes the following steps:

[0090] (1) Mix the plant fiber raw material and the first acetic acid solution with a mass concentration of 5wt% - 30wt% at a mass ratio of 1:(4 - 10), and perform the first hydrolysis at 100 - 140 °C and 0.1 - 0.6 MPa for 1 - 5 h, and then obtain the first fiber solid through the first solid-liquid separation;

[0091] (2) Mix the second acetic acid solution with a mass concentration of 70wt% - 90wt% and the first fiber solid obtained in step (1) at a mass ratio of 1:(4 - 12), and perform the second hydrolysis at 120 - 160 °C and 0.2 - 0.8 MPa for 1 - 5 h, and then obtain the second fiber solid through the second solid-liquid separation; the second fiber solid is first pickled with the third acetic acid solution with a mass concentration of 70wt% - 90wt% for 2 - 10 times, then first water washed with water at 70 - 90 °C for 2 - 10 times, then acid-treated with sulfuric acid with a mass concentration of 1wt% - 5wt% for 30 - 60 min, and then alkali-neutralized and second water washed;

[0092] (3) Mix the second fiber solid after water washing in step (2) and water to obtain a mixed solution with a mass concentration of 1wt% - 5wt%; the mixed solution is successively subjected to pretreatment, micro-nanoization treatment and nanoization treatment by the nano-cellulose preparation device described in the first aspect to obtain the essential nano-cellulose;

[0093] Among them, when performing the pretreatment in step (3), the rotation speed of the beating roller of the trough beater is 490 - 510 r / min; when performing the micro-nanoization treatment, the rotation speed of the rotor of the colloid pump is 200 - 800 r / min; when performing the nanoization treatment, the working pressure of the first homogenization component is 200 - 500 bar; when performing the nanoization treatment, the working pressure of the homogenization components other than the first homogenization component is 800 - 1300 bar.

[0094] In a third aspect, the present invention provides a lignocellulose nanofiber, which is prepared by the preparation method described in the second aspect.

[0095] The lignocellulose nanofiber of the present invention has a smaller diameter and a longer length. It not only has the properties of high strength, high thermal stability, and excellent biocompatibility of nanofiber, but also has excellent mechanical properties, heat resistance, weather resistance, anti-aging property, and antioxidant property of lignin. It has a lower production cost and a wider application field.

[0096] Preferably, the diameter distribution of the lignocellulose nanofiber is 10 - 90 nm, and it can be, for example, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, or 90 nm, etc.

[0097] Preferably, the length of the lignocellulose nanofiber ≤ 3 μm, and it can be, for example, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm, etc.

[0098] Preferably, the content of lignin in the lignocellulose nanofiber is 5 - 15 wt%, and it can be, for example, 5 wt%, 8 wt%, 10 wt%, 12 wt%, or 15 wt%, etc.

[0099] Compared with the prior art, the present invention has at least the following beneficial effects:

[0100] (1) The nanofiber preparation device provided by the present invention connects the pretreatment component, the micro-nanoization component, and the nanoization component in sequence, gradually degrades the cellulose, including preliminary degradation, degradation to the micro-nano level, and degradation to the nano level, and can be processed cyclically to achieve continuous production of nanofiber. Compared with the traditional high-pressure homogenizer or microfluidic high-pressure homogenizer, the nanofiber device of the present invention greatly reduces the number of nanoizations, reduces energy consumption and wear on the high-pressure homogenizer, and has a lower preparation cost.

[0101] (2) The preparation method of the lignocellulose nanofiber provided by the present invention effectively separates hemicellulose and part of lignin by first performing the first hydrolysis and the second hydrolysis on the plant fiber raw material in sequence, and then uses the nanofiber preparation device described in the first aspect for nanoization to prepare a nanofiber with a longer length, a smaller diameter, and containing lignin, which combines the excellent properties of both nanofiber and lignin; compared with the TEMPO oxidation method and the traditional mechanical method, the reagent used in the preparation method of the present invention is non-toxic and environmentally friendly, has fewer nanoizations, less equipment loss, lower energy consumption, lower production cost, and is easy to scale up production.

[0102] (3) The wood-based nanocellulose provided by the present invention has a diameter of the nanocellulose as small as 10-90 nm, a length ≤ 3 μm, the content of nanocellulose with a diameter < 100 nm ≥ 85%, and the content of lignin ≥ 5 wt%. It not only has the properties of high strength, high thermal stability and excellent biocompatibility of nanocellulose, but also has excellent mechanical properties, heat resistance, weather resistance, anti-aging property and antioxidant property of lignin, with lower production cost and wider application fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] Figure 1 is a schematic diagram of the structure and connection relationship of the nanocellulose preparation device provided in Embodiment 1 of the present invention;

[0104] Figure 2 is the SEM image of the nano-lignin provided in Embodiment 1 of the present invention;

[0105] Figure 3 is the SEM image of the wood-based nanocellulose provided in Embodiment 1 of the present invention;

[0106] In the figure, 1 is the first storage tank; 2 is the first diaphragm pump; 3 is the trough beater; 4 is the second storage tank; 5 is the second diaphragm pump; 6 is the colloid pump; 7 is the first homogenizer; 8 is the buffer tank; 9 is the third diaphragm pump; 10 is the second homogenizer; 11 is the third homogenizer; 12 is the fourth homogenizer; 13 is the finished product collection tank. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0107] The technical solution of the present invention will be further described below with reference to the drawings and through specific embodiments. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention is subject to the claims.

[0108] I. Embodiment

[0109] Embodiment 1

[0110] This embodiment provides a nanocellulose preparation device, as Figure 1 shown, the nanocellulose preparation device includes a pretreatment component, two groups of micro-nanoization components connected in parallel, a nanoization component and a finished product collection tank 13 connected in sequence; the pretreatment component is the trough beater 3; a first monitoring component is arranged at the bottom of the pretreatment component;

[0111] The pretreatment component includes a first storage tank 1, a first diaphragm pump 2 and a trough beater 3 connected in sequence; a first stirring component is arranged at the bottom of the first storage tank 1;

[0112] The micro-nano component includes a second storage tank 4, a second diaphragm pump 5, and a colloid pump 6 connected in sequence; a second monitoring component is provided at the bottom of the second storage tank 4; a second stirring member is provided at the bottom of the second storage tank 4.

[0113] The nano component includes 4 homogenizers connected in series, a buffer tank 8 provided between two adjacent homogenizers, and a third diaphragm pump 9 provided between the homogenizer and the buffer tank 8, where the 4 homogenizers connected in series are the first homogenizer 7, the second homogenizer 10, the third homogenizer 11, and the fourth homogenizer 12 in sequence.

[0114] This embodiment also provides a preparation method of wood nano cellulose, and the preparation method includes the following steps:

[0115] (1) Mix the plant fiber raw material and the first acetic acid solution with a mass concentration of 20 wt% at a mass ratio of 1:8, and perform the first hydrolysis at 120 °C and 0.3 MPa for 2.5 h, and then filter to obtain the first fiber solid.

[0116] (2) Mix the second acetic acid solution with a mass concentration of 80 wt% and the first fiber solid in step (1) at a mass ratio of 1:10, and perform the second hydrolysis at 140 °C and 0.5 MPa for 3 h, and then filter to obtain the second fiber solid; the second fiber solid is first pickled with the third acetic acid solution with a mass concentration of 80 wt% for 6 times, then washed with water at 80 °C for the first time for 6 times, then acid-treated with sulfuric acid with a mass concentration of 3 wt% for 40 min, and then neutralized with sodium hydroxide and washed with water for the second time for 3 times.

[0117] (3) Mix the second fiber solid after washing with water in step (2) and water to obtain a mixed solution with a mass concentration of 3 wt%; the mixed solution is sequentially subjected to pretreatment, micro-nano treatment, and nano treatment by the above nano cellulose preparation device to obtain the essential nano cellulose.

[0118] Among them, when performing the pretreatment in step (3), the rotational speed of the beating roller of the trough beater 3 is 500 r / min; when performing the micro-nano treatment, the rotational speed of the rotor of the colloid pump 6 is 600 r / min; when performing the nano treatment, the working pressure of the first homogenizer 7 is 350 bar; when performing the nano treatment, the working pressure of the homogenizers other than the first homogenizer 7 is 1000 bar.

[0119] In this embodiment, the plant fiber raw material is eucalyptus wood, including 20 wt% hemicellulose, 25 wt% lignin, and 45 wt% cellulose.

[0120] This embodiment also provides a wood nano cellulose, which is prepared by the above preparation method, as Figure 3As shown, the diameter distribution of the lignocellulose nanofibers is 10 - 90 nm, and the length is ≤ 1 μm.

[0121] In this example, the lignin content in the lignocellulose nanofibers is 8.31 wt%.

[0122] This example also provides a method for preparing nano-lignin. The preparation method includes the following steps:

[0123] Concentrate the first hydrolysis solution obtained after filtration in step (1) above by 20 times, and then extract it with ethyl acetate to obtain nano-lignin.

[0124] As Figure 2 shown, the nano-lignin obtained by the above preparation method is of nano size, with a particle size of 50 - 500 nm, thus having abundant active sites, and its application effect in epoxy resin is more excellent than that of the lignin (1 - 200 μm) on the current market.

[0125] Example 2

[0126] This example provides a nano-cellulose preparation device. The nano-cellulose preparation device includes a pretreatment component, three groups of micro-nanoization components connected in parallel, a nanoization component, and a finished product collection tank connected in sequence; the pretreatment component is a trough beater; a first monitoring component is arranged at the bottom of the pretreatment component;

[0127] The pretreatment component includes a first storage tank, a first diaphragm pump, and a trough beater connected in sequence; a first stirring member is arranged at the bottom of the first storage tank;

[0128] The micro-nanoization component includes a second storage tank, a second diaphragm pump, and a colloid pump connected in sequence; a second monitoring component is arranged at the bottom of the second storage tank; a second stirring member is arranged at the bottom of the second storage tank;

[0129] The nanoization component includes three homogenizers connected in series, a buffer tank arranged between two adjacent homogenizers, and a third diaphragm pump arranged between the homogenizer and the buffer tank.

[0130] This example also provides a method for preparing lignocellulose nanofibers. The preparation method includes the following steps:

[0131] (1) Mix the plant fiber raw material and the first acetic acid solution with a mass concentration of 30 wt% at a mass ratio of 1:4, and carry out the first hydrolysis at 100 °C and 0.1 MPa for 5 h, and then filter to obtain the first fiber solid;

[0132] (2) Mix the second acetic acid solution with a mass concentration of 70 wt% and the first fiber solid described in step (1) in a ratio of 1:5 by mass, and perform a second hydrolysis at 120 °C and 0.2 MPa for 5 h, and then filter to obtain a second fiber solid; the second fiber solid is first pickled 8 times with a third acetic acid solution with a mass concentration of 70 wt%, then washed 8 times with water at 70 °C, then acid-treated with sulfuric acid with a mass concentration of 5 wt% for 30 min, and then neutralized with sodium hydroxide and washed a second time 5 times;

[0133] (3) Mix the second fiber solid after washing in step (2) and water to obtain a mixed solution with a mass concentration of 1 wt%; the mixed solution is successively subjected to pretreatment, micro-nanoization treatment and nanoization treatment by the above-mentioned nano-cellulose preparation device to obtain the essential nano-cellulose;

[0134] Among them, when performing the pretreatment in step (3), the rotational speed of the beating roller of the trough beater is 490 r / min; when performing the micro-nanoization treatment, the rotational speed of the rotor of the colloid pump is 200 r / min; when performing the nanoization treatment, the working pressure of the first homogenizer is 200 bar; when performing the nanoization treatment, the working pressure of the homogenizer other than the first homogenizer is 1300 bar.

[0135] In this embodiment, the plant fiber raw material is masson pine, including 22 wt% hemicellulose, 26 wt% lignin and 40 wt% cellulose.

[0136] This embodiment also provides a lignin nano-cellulose, which is prepared by the above preparation method. The diameter distribution of the lignin nano-cellulose is 10 - 90 nm, the length ≤ 3 μm, and the content of lignin in the lignin nano-cellulose is 12.05 wt%.

[0137] Example 3

[0138] This embodiment provides a nano-cellulose preparation device, which includes a pretreatment component, 2 groups of micro-nanoization components connected in parallel, a nanoization component and a finished product collection component connected in sequence; the pretreatment component is a trough beater; a first monitoring component is arranged at the bottom of the pretreatment component;

[0139] The pretreatment component includes a first storage component, a first feeding component and a pretreatment component connected in sequence; a first stirring member is arranged at the bottom of the first storage component;

[0140] The micro-nanoization component includes a second storage component, a second feeding component and a micro-nanoization treatment component connected in sequence; the micro-nanoization treatment component is a colloid pump; a second monitoring component is arranged at the bottom of the second storage component; a second stirring member is arranged at the bottom of the second storage component;

[0141] The nanosized component includes 5 homogeneous components connected in series, a buffer component disposed between two adjacent homogeneous components, and a third feeding component disposed between the homogeneous component and the buffer component.

[0142] This embodiment also provides a method for preparing lignocellulose nanocrystals. The preparation method includes the following steps:

[0143] (1) Mix the plant fiber raw material and the first acetic acid solution with a mass concentration of 5 wt% at a mass ratio of 1:10, and perform the first hydrolysis at 140 °C and 0.6 MPa for 1 h, and then filter to obtain the first fiber solid;

[0144] (2) Mix the second acetic acid solution with a mass concentration of 90 wt% and the first fiber solid in step (1) at a mass ratio of 1:12, and perform the second hydrolysis at 160 °C and 0.8 MPa for 1 h, and then filter to obtain the second fiber solid; the second fiber solid is first pickled 4 times with the third acetic acid solution with a mass concentration of 90 wt%, then washed 4 times with water at 90 °C, then acid-treated with sulfuric acid with a mass concentration of 1 wt% for 60 min, and then neutralized with sodium hydroxide and washed a second time 3 times;

[0145] (3) Mix the second fiber solid after washing in step (2) and water to obtain a mixed solution with a mass concentration of 5 wt%; the mixed solution is sequentially subjected to pretreatment, micro-nanosizing treatment, and nanosizing treatment by the above-mentioned lignocellulose nanocrystals preparation device to obtain the native lignocellulose nanocrystals;

[0146] Among them, when performing the pretreatment in step (3), the rotational speed of the beating roller of the trough beater is 510 r / min; when performing the micro-nanosizing treatment, the rotational speed of the rotor of the colloid pump is 800 r / min; when performing the nanosizing treatment, the working pressure of the first homogenizer is 500 bar; when performing the nanosizing treatment, the working pressure of the homogenizer other than the first homogenizer is 800 bar.

[0147] In this embodiment, the plant fiber raw material is moso bamboo, including 21 wt% hemicellulose, 23 wt% lignin, and 43 wt% cellulose.

[0148] This embodiment also provides a lignocellulose nanocrystal, which is prepared by the above preparation method. The diameter distribution of the lignocellulose nanocrystal is 10-90 nm, the length ≤ 1 μm, and the content of lignin in the lignocellulose nanocrystal is 5.02 wt%.

[0149] Example 4

[0150] This embodiment provides a nano-cellulose preparation device. Except for only one set of micro-nanoization components being provided, the rest are the same as those in Embodiment 1.

[0151] This embodiment also provides a method for preparing lignocellulose nano-cellulose. Except for using the nano-cellulose preparation device described in this embodiment, the rest are the same as those in Embodiment 1.

[0152] This embodiment also provides a lignocellulose nano-cellulose, which is prepared by the preparation method provided in this embodiment.

[0153] Since only one set of micro-nanoization components is provided in the nano-cellulose preparation device in this embodiment, when the micro-nanoization treatment component transports the cellulose after micro-nanoization treatment to the nanoization component, it is impossible to simultaneously perform the micro-nanoization treatment of new raw materials, that is, it is impossible to realize the continuous production of nano-cellulose, reducing the production efficiency.

[0154] Embodiment 5

[0155] This embodiment provides a nano-cellulose preparation device. Except for not having a buffer tank, the rest are the same as those in Embodiment 1.

[0156] This embodiment also provides a method for preparing lignocellulose nano-cellulose. Except for using the nano-cellulose preparation device described in this embodiment, the rest are the same as those in Embodiment 1.

[0157] This embodiment also provides a lignocellulose nano-cellulose, which is prepared by the preparation method provided in this embodiment.

[0158] Since the nano-cellulose preparation device in this embodiment does not have a buffer tank, the material transportation between homogenizers is unstable and the feeding is discontinuous, resulting in unstable pressure in the homogenizer, thus affecting the nanoization treatment effect and causing wear to the homogenizer, increasing the treatment energy consumption and cost.

[0159] Embodiment 6

[0160] This embodiment provides a method for preparing lignocellulose nano-cellulose. Except that the mass concentration of the first acetic acid solution used in the first hydrolysis in step (1) is 35 wt%, the rest are the same as those in Embodiment 1.

[0161] Embodiment 7

[0162] This embodiment provides a method for preparing lignocellulose nano-cellulose. Except that the mass concentration of the first acetic acid solution used in the first hydrolysis in step (1) is 4 wt%, the rest are the same as those in Embodiment 1.

[0163] Example 8

[0164] This example provides a method for preparing wood-based nanocellulose. Except that the working pressure of the first homogenizer in step (3) is 180 bar, the rest are the same as those in Example 1.

[0165] Example 9

[0166] This example provides a method for preparing wood-based nanocellulose. Except that the working pressure of the first homogenizer in step (3) is 1000 bar, that is, the working pressure of all homogenizers is high pressure, the rest are the same as those in Example 1.

[0167] II. Comparative Examples

[0168] Comparative Example 1

[0169] This comparative example provides a nanocellulose preparation device. Except that the nanosizing component has only 1 homogenizer, the rest are the same as those in Example 1.

[0170] This comparative example also provides a method for preparing wood-based nanocellulose. Except that the method uses the nanocellulose preparation device described in this comparative example in step (3), and the working pressure of the only 1 homogenizer is set to 1000 bar, the rest are the same as those in Example 1.

[0171] Comparative Example 2

[0172] This comparative example provides a nanocellulose preparation device. Except that the micro-nanosizing component is not provided, the rest are the same as those in Example 1.

[0173] This comparative example also provides a method for preparing wood-based nanocellulose. Except that the method uses the nanocellulose preparation device described in this comparative example, that is, directly performing nanosizing treatment after the pretreatment in step (3), the rest are the same as those in Example 1.

[0174] In this comparative example, since the micro-nanosizing component is not provided in the nanocellulose preparation device, the particles are too large and the high-pressure homogenizer cannot work.

[0175] Comparative Example 3

[0176] This comparative example provides a method for preparing wood-based nanocellulose. Except that step (1) is not carried out, that is, directly performing step (2) and step (3), the rest are the same as those in Example 1.

[0177] III. Tests and Their Results

[0178] ① Test the diameter distribution range, length distribution range of the prepared lignocellulose nanofibers obtained by the preparation methods provided in the above examples or comparative examples, and the content of nanofibers with a diameter < 100 nm. The results are shown in Table 1;

[0179] Table 1

[0180]

[0181]

[0182] Note: "-" in the table indicates no relevant data.

[0183] ② Test the contents of hemicellulose, lignin and cellulose in the lignocellulose nanofibers obtained by the preparation methods provided in Example 1, Example 6, Example 7 and Comparative Example 3 above respectively. The results are shown in Table 2;

[0184] Table 2

[0185]

[0186] It can be seen from the data in Table 1 and Table 2 that:

[0187] (1) It can be seen from Examples 1 to 3: The nanofiber preparation device and the preparation method of lignocellulose nanofibers provided by the present invention can prepare lignocellulose nanofibers with a diameter of 10 - 90 nm, a length ≤ 3 μm, a relatively narrow distribution range, good dispersion, a content of nanofibers with a diameter < 100 nm ≥ 85 wt%, and a lignin content ≥ 5 wt%, combining the excellent properties of nanofibers and lignin.

[0188] (2) From the comprehensive comparison of Example 1 with Example 4, Example 5, Comparative Example 1 and Comparative Example 2, it can be seen that in Example 4, only one set of micro-nano components is provided. The diameter distribution range of the obtained lignocellulose nanocrystals is as wide as 10 - 1000 nm, the content of nanocellulose with a diameter < 100 nm is reduced to ≥ 70%, and continuous production cannot be achieved, resulting in low production efficiency. In Example 5, no buffer tank is set, resulting in poor nanonization effect, a relatively wide diameter distribution range of the obtained lignocellulose nanocrystals, and a low content of nanocellulose with a diameter < 100 nm. In Comparative Example 1, only one homogenizer is set, resulting in insufficient nanonization, a relatively large diameter of the obtained lignocellulose nanocrystals, and a low content of nanocellulose with a diameter < 100 nm. In Comparative Example 2, no micro-nano components are set, resulting in the raw material not being micro-nanonized after pretreatment, and the particles being too large to be directly nanonized by a high-pressure homogenizer. Thus, it is shown that the nanocellulose device of the present invention connects the pretreatment component, the micro-nano component and the nano component in sequence, and the nano component is set to include at least two homogenizing components connected in series, enabling the cellulose to be gradually degraded. Further, at least two sets of micro-nano components connected in parallel and buffer components between adjacent two homogenizing components are provided, significantly improving the nanonization effect, reducing the number of nanonization treatments, and reducing the wear on the high-pressure homogenizing components.

[0189] (3) From the comprehensive comparison of Example 1 with Example 6, Example 7 and Comparative Example 3, it can be seen that in Example 6, the mass concentration of the first acetic acid solution used in the first hydrolysis is relatively high, resulting in a weakened selective separation effect on hemicellulose, thereby reducing the lignin content in the subsequent obtained lignocellulose nanocrystals and resulting in relatively large particle sizes of the obtained nano-lignin. In Example 7, the mass concentration of the first acetic acid solution used in the first hydrolysis is relatively low, resulting in a poor separation effect on hemicellulose and lignin, and the structures among hemicellulose, cellulose and lignin cannot be fully destroyed, resulting in high hemicellulose and lignin contents in the obtained lignocellulose nanocrystals. In Comparative Example 3, no first hydrolysis is carried out, resulting in the remaining hemicellulose during the nanonization treatment, resulting in high hemicellulose and lignin contents in the obtained lignocellulose nanocrystals, and at the same time, nano-lignin cannot be separated out. Thus, it is shown that the preparation method of the lignocellulose nanocrystals of the present invention first carries out the first hydrolysis and the second hydrolysis in sequence before the treatment in step (3), and further preferably, the mass concentration of the first acetic acid solution used in the first hydrolysis is 5 wt% - 30 wt%, further reducing the burden of the nanonization treatment and improving the nanonization effect.

[0190] (4) It can be seen from the comprehensive implementation of Example 1, Example 8 and Example 9 that in Example 8, the working pressure of the first homogenizer is too low, resulting in a poor nanosizing effect at this stage, affecting the overall diameter of the finally obtained lignocellulose nanocrystals to be relatively large, and the content of nanocellulose with a diameter < 100 nm is relatively low; in Example 9, the working pressure of the first homogenizer is the same as that of the other homogenizers, which does not significantly improve the nanosizing effect, but instead increases the energy consumption and wear of the homogenizer, thus increasing the preparation cost.

[0191] In summary, the nanocellulose preparation device provided by the present invention can not only achieve a good nanosizing effect, but also reduce the number of nanosizing times, relieve the burden on the high-pressure homogenizer, and achieve continuous mass production; the preparation method of the lignocellulose nanocrystals provided by the present invention first performs the first hydrolysis and the second hydrolysis on the plant fiber raw material, and then uses the nanocellulose preparation device provided by the present invention for nanosizing treatment to prepare high-performance lignocellulose nanocrystals with a small diameter, a long length and containing lignin. The preparation method is simple, the process is short, and it is easy to achieve large-scale mass production.

[0192] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A nano-cellulose preparation device, characterized in that, The nanocellulose preparation device comprises a pretreatment component, a micro-nano component, a nano component and a finished product collection component connected in sequence; The pretreatment component includes a first material storage component and a pretreatment component connected in sequence; The micro-nano component includes a second material storage component and a micro-nano processing component connected in sequence; The nanostructured component comprises at least three homogeneous components connected in series.

2. The nanofibrillated cellulose preparation device according to claim 1, characterized in that, The pretreatment component includes a trough beater; Preferably, a first monitoring component is provided at the bottom of the pretreatment component; Preferably, a first material feeding component is provided between the first material storage component and the pre-processing component; Preferably, a first stirring member is provided at the bottom of the first material storage component.

3. The nanofibrillated cellulose preparation device according to claim 1 or 2, characterized in that, The nanocellulose preparation device comprises at least two groups of micro-nano components connected in parallel; Preferably, the micro-nano processing component includes a colloid pump; Preferably, a second material feeding component is provided between the second material storage component and the micro-nano processing component; Preferably, a second monitoring component is provided at the bottom of the second storage component; Preferably, a second stirring member is provided at the bottom of the second material storage component.

4. The nanofibrillated cellulose preparation device according to any one of claims 1 to 3, characterized in that, The nanostructured component further includes a buffer component disposed between two adjacent homogeneous components; Preferably, a third feeding component is provided between the homogenizing component and the buffer component.

5. A method for preparing wood-based nanocellulose, characterized in that, The preparation method comprises the following steps: (1) The plant fiber raw material is sequentially subjected to a first hydrolysis and a first solid-liquid separation to obtain a first fiber solid; (2) in step (1), the first fiber solid is subjected to a second hydrolysis and a second solid-liquid separation to obtain a second fiber solid; (3) In step (2), the second fiber solid is processed by the nanocellulose preparation device according to any one of claims 1 to 4 to obtain wood nanocellulose.

6. The preparation method according to claim 5, characterized in that, Step (1) the first hydrolysis comprises mixing the plant fiber raw material and a first acetic acid solution to perform a first hydrolysis; Preferably, the mass ratio of the plant fiber raw material to the first acetic acid solution is 1:(4-10), preferably 1:(5-7); Preferably, the mass concentration of the first acetic acid solution is 5wt% to 30wt%; Preferably, the temperature of the first hydrolysis is 100-140°C; Preferably, the pressure of the first hydrolysis is 0.1-0.6 MPa; Preferably, the first hydrolysis time is 1 to 5 hours.

7. The preparation method according to any one of claims 5 or 6, characterized in that, Step (2) the second hydrolysis comprises mixing the first fiber solid and a second acetic acid solution to perform a second hydrolysis; Preferably, the mass ratio of the first fiber solid to the second acetic acid solution is 1:(4-12), preferably 1:(5-8); Preferably, the mass concentration of the second acetic acid solution is 70wt% to 90wt%; Preferably, the temperature of the second hydrolysis is 120-160°C; Preferably, the pressure of the second hydrolysis is 0.2-0.8 MPa; Preferably, the second hydrolysis time is 1 to 5 hours; Preferably, step (2) further comprises subjecting the second fiber solid to acid treatment; Preferably, the mass concentration of the acid solution used in the acid treatment is 1wt% to 5wt%; Preferably, the acid treatment time is 30 to 60 minutes.

8. The preparation method according to any one of claims 5 to 7, characterized in that Step (3) includes mixing the second fibrous solid and water to obtain a mixed solution; the mixed solution is successively subjected to pretreatment, micro-nanometerization treatment, and nanometerization treatment to obtain the essential nanocellulose; Preferably, the mass concentration of the second fibrous solid in the mixed solution is 1 wt% to 5 wt%; Preferably, the rotational speed of the beating roller of the trough beater during the pretreatment is 490 to 510 r / min; Preferably, the rotational speed of the rotor of the colloid pump during the micro-nanometerization treatment is 200 to 800 r / min; Preferably, the working pressure of the first homogenization component during the nanometerization treatment is 200 to 500 bar; Preferably, the working pressure of the homogenization components other than the first homogenization component during the nanometerization treatment is 800 to 1300 bar.

9. A wood-based nanocellulose, characterized in that, The lignocellulose nanocellulose is prepared by the preparation method according to any one of claims 5 to 8.

10. The wood nano-cellulose according to claim 9, wherein The diameter distribution of the lignocellulose nanocellulose is 10 to 90 nm; Preferably, the length of the lignocellulose nanocellulose ≤ 3 μm; Preferably, the lignin content in the lignocellulose nanocellulose is 5 to 15 wt%.

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