Method for separating all components of bamboo biomass

Abstract

The invention provides a method for separating all components of bamboo biomass. The method comprises the following steps: preparing a low-concentration eutecticevaporate solvent aqueous solution with the mass fraction of 0.1%-1% and a high-concentration eutecticevaporate solvent aqueous solution with the mass fraction of 50%-100%; the method comprises the following steps: mixing bamboo biomass with a low-concentration eutectic solvent aqueous solution, carrying out a heating reaction, removing hemicellulose, and then carrying out solid-liquid separation to obtain solid residues; and mixing the solid residues with a high-concentration eutectic solvent aqueous solution, carrying out a heating reaction, removing lignin, and then carrying out solid-liquid separation to obtain cellulose residues. By means of the method, the hemicellulose removal rate of the bamboo biomass is larger than or equal to 90%, the lignin removal rate is larger than or equal to 90%, and the cellulose retention rate is larger than or equal to 85%; meanwhile, the reaction conditions are mild, the cost is low, the energy consumption is low, equipment corrosion is not caused, the method is environment-friendly, and the method has important significance on all-component high-value utilization of bamboo organisms.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass pretreatment, and particularly relates to a method for separating all components of bamboo biomass. Background Art

[0002] Lignocellulose is the most abundant and cheapest biomass resource on the earth. Among them, bamboo has the advantages of fast growth rate, high biomass density, strong carbon sequestration ability, low cultivation cost and wide distribution, and is considered to be one of the important biomass raw materials in the future.

[0003] Generally, the cellulose content in bamboo is 40% - 60%, the hemicellulose content is 19% - 23%, the lignin content is 20% - 25%, and there are also a small amount of ash, starch, etc. Through biomass refining, the comprehensive utilization of all components of biomass can be realized, the production cost can be reduced, and high-value-added products can be obtained. However, affected by factors such as the strong compactness of the bamboo cell wall and the high degree of polymerization of cellulose, it is difficult to efficiently disassemble and separate the hemicellulose, lignin and cellulose components in the bamboo cell wall, which hinders the effective utilization of bamboo. Existing bamboo biomass pretreatment methods often cannot simultaneously achieve the high-efficiency separation and retention of each component, and in most cases, it is at the expense of sacrificing one of the components, and at the same time, the required reaction conditions are harsh.

[0004] Therefore, how to achieve the efficient disassembly and separation of the three major components in bamboo under relatively mild conditions is the key to realizing the high-value utilization of all components of bamboo. Summary of the Invention

[0005] The main object of the present invention is to provide a method for separating all components of bamboo biomass, which can achieve the efficient disassembly and separation of the three major components of hemicellulose, lignin and cellulose in bamboo, so that the all components of bamboo can be highly valued and utilized, and thus it is more suitable for practical use.

[0006] The object of the present invention and the solution to its technical problems are achieved by the following technical solutions. A method for separating all components of bamboo biomass proposed according to the present invention includes the following steps:

[0007] (1) Prepare a low-concentration deep eutectic solvent aqueous solution and a high-concentration deep eutectic solvent aqueous solution; the mass fraction of the deep eutectic solvent in the aforementioned low-concentration deep eutectic solvent aqueous solution is 0.1% - 1%, and the mass fraction of the deep eutectic solvent in the aforementioned high-concentration deep eutectic solvent aqueous solution is 50% - 100%;

[0008] (2) Mix the bamboo biomass with the aforementioned low-concentration deep eutectic solvent aqueous solution, heat and react to remove hemicellulose, and then perform solid-liquid separation to obtain a solid residue;

[0009] (3) Mix the aforementioned solid residue with an aqueous solution of a high-concentration deep eutectic solvent, heat and react to remove lignin, and then perform solid-liquid separation to obtain a cellulose residue.

[0010] The object of the present invention and the technical problems to be solved can also be further achieved by the following technical measures.

[0011] Preferably, according to the method for separating all components of bamboo biomass described above, in the deep eutectic solvent in the aqueous solution of the low-concentration deep eutectic solvent, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (1-10):(1-10); and / or,

[0012] In the deep eutectic solvent in the aqueous solution of the high-concentration deep eutectic solvent, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (1-10):(1-10).

[0013] Preferably, according to the method for separating all components of bamboo biomass described above, in step (2), the temperature of the heating reaction is 120-200 °C, and the time is 1-6 h.

[0014] Preferably, according to the method for separating all components of bamboo biomass described above, in step (2), the solid-liquid ratio of the bamboo biomass to the aqueous solution of the low-concentration deep eutectic solvent is 1:4-10 kg / L.

[0015] Preferably, according to the method for separating all components of bamboo biomass described above, in step (3), the temperature of the heating reaction is 100-160 °C, and the time is 2-6 h.

[0016] Preferably, according to the method for separating all components of bamboo biomass described above, in step (3), the solid-liquid ratio of the solid residue to the aqueous solution of the high-concentration deep eutectic solvent is 1:5-15 kg / L.

[0017] Preferably, according to the method for separating all components of bamboo biomass described above, in the aqueous solution of the low-concentration deep eutectic solvent and the aqueous solution of the high-concentration deep eutectic solvent, the hydrogen bond donor is at least one of formic acid, oxalic acid, acetic acid, citric acid, propionic acid, 2,3-dihydroxybutanedioic acid, L-hydroxybutanedioic acid, ethylene glycol, propylene glycol, glycerol, and butanediol.

[0018] Preferably, according to the method for separating all components of bamboo biomass described above, in the aqueous solution of the low-concentration deep eutectic solvent and the aqueous solution of the high-concentration deep eutectic solvent, the hydrogen bond acceptor is at least one of choline chloride, betaine, benzyltriethylammonium chloride, acetamide, diethanolamine, and triethanolamine.

[0019] Preferably, according to the method for separating all components of bamboo biomass described above, the particle size of the bamboo biomass is 40-80 mesh.

[0020] Preferably, according to the method for separating all components of bamboo biomass described above, the bamboo biomass is Neosinocalamus affinis and / or Phyllostachys edulis.

[0021] By means of the above technical solution, a method for separating all components of bamboo biomass proposed by the present invention has at least the following advantages:

[0022] The present invention proposes a method for separating all components of bamboo biomass based on a coupling strategy. By using an aqueous solution of a low-concentration deep eutectic solvent with a mass fraction of 0.1% to 1% to react with bamboo biomass by heating, hemicellulose in the bamboo biomass is efficiently removed, and a solid residue is obtained by filtration; then, by using an aqueous solution of a high-concentration deep eutectic solvent with a mass fraction of 50% to 100% to react with the aforementioned solid residue, lignin in the solid residue is efficiently removed, and a cellulose residue is obtained. The method proposed by the present invention realizes the efficient disassembly of all components of bamboo biomass under mild conditions, can efficiently selectively remove hemicellulose and lignin from bamboo biomass resources, and at the same time improve the retention rate of cellulose. It can achieve a hemicellulose removal rate of ≥90%, a lignin removal rate of ≥90%, and a cellulose retention rate of ≥85% in bamboo biomass. The method proposed by the present invention is low in cost, low in energy consumption, does not cause equipment corrosion, and is environmentally friendly, and is of great significance for the high-value utilization of all components of bamboo biomass.

[0023] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly and to be implemented in accordance with the content of the specification, the following describes in detail with preferred embodiments of the present invention as follows. Detailed implementation manners

[0024] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following, in combination with preferred embodiments, details the specific implementation manners, structures, features and effects of a method for separating all components of bamboo biomass proposed by the present invention as follows.

[0025] A method for separating all components of bamboo biomass proposed by the present invention includes the following steps:

[0026] (1) Prepare an aqueous solution of a low-concentration deep eutectic solvent and an aqueous solution of a high-concentration deep eutectic solvent; the mass fraction of the deep eutectic solvent in the aforementioned aqueous solution of the low-concentration deep eutectic solvent is 0.1% to 1%, and the mass fraction of the deep eutectic solvent in the aforementioned aqueous solution of the high-concentration deep eutectic solvent is 50% to 100%;

[0027] (2) Mix bamboo biomass with the aforementioned aqueous solution of the low-concentration deep eutectic solvent, heat and react to remove hemicellulose, and then perform solid-liquid separation to obtain a solid residue;

[0028] (3) Mix the aforementioned solid residue with an aqueous solution of a high-concentration deep eutectic solvent, heat and react to remove lignin, and then perform solid-liquid separation to obtain a cellulose residue.

[0029] Specifically, a deep eutectic solvent is a low-eutectic-point liquid formed by a hydrogen bond donor and a hydrogen bond acceptor in a certain proportion, and has the advantages of low toxicity, biodegradability, easy recovery, etc. Compared with traditional solvents, deep eutectic solvents have higher selectivity and can efficiently dissolve lignin and hemicellulose in biomass under mild conditions without significantly damaging the structure of cellulose.

[0030] One or more hydrogen bond donors can be selected in the deep eutectic solvent. Preferably, the hydrogen bond donor is at least one of formic acid, oxalic acid, acetic acid, citric acid, propionic acid, 2,3-dihydroxybutanedioic acid, L-hydroxybutanedioic acid, ethylene glycol, propylene glycol, glycerol, and butanediol.

[0031] One or more hydrogen bond acceptors can be selected in the deep eutectic solvent. Preferably, the hydrogen bond acceptor is at least one of choline chloride, betaine, benzyltriethylammonium chloride, acetamide, diethanolamine, and triethanolamine.

[0032] The deep eutectic solvents in the aqueous solution of low-concentration deep eutectic solvent and the aqueous solution of high-concentration deep eutectic solvent can be the same or different. Preferably, the aqueous solution of low-concentration deep eutectic solvent and the aqueous solution of high-concentration deep eutectic solvent use the same deep eutectic solvent, which is convenient for the formulation of the two solutions.

[0033] Based on the mass of the aqueous solution of low-concentration deep eutectic solvent being 100%, the mass fraction of the deep eutectic solvent in the aqueous solution of low-concentration deep eutectic solvent is 0.1% - 1%. Based on the mass of the aqueous solution of high-concentration deep eutectic solvent being 100%, the mass fraction of the deep eutectic solvent in the aqueous solution of high-concentration deep eutectic solvent is 50% - 100%.

[0034] Preferably, in the deep eutectic solvent in the aqueous solution of low-concentration deep eutectic solvent, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (1 - 10)∶(1 - 10). In the deep eutectic solvent in the aqueous solution of high-concentration deep eutectic solvent, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (1 - 10)∶(1 - 10). Within this range, the hydrogen bond donor and the hydrogen bond acceptor in the deep eutectic solvent can form a strong coupling effect, and more efficiently remove hemicellulose and lignin in bamboo biomass.

[0035] Bamboo biomass can be whole bamboo or bamboo scraps, etc. Preferably, whole bamboo can be prepared into bamboo biomass after removing bamboo joints and bamboo leaves. The raw materials of bamboo biomass can be selected from moso bamboo, Neosinocalamus affinis, or Dendrocalamus giganteus, etc., preferably moso bamboo or Neosinocalamus affinis. Moso bamboo accounts for 70% of the bamboo forest area in China, has a short growth cycle, grows rapidly, has strong reproductive ability, grows into timber quickly, and has a high yield. Neosinocalamus affinis is widely distributed in the southwestern provinces of China.

[0036] The bamboo biomass can be in the form of flakes, filaments or powders to facilitate subsequent reactions. For example, a chipper can be used to chip the bamboo. After chipping, the bamboo chips are screened to remove broken bamboo joints, bamboo chips and unchipped bamboo strips. After screening, the bamboo chips are washed with a drum washer to remove impurities such as stones, sediment and metal mixed in the bamboo chips. After washing, the bamboo chips are dehydrated to remove the free water carried by the bamboo chips. The dehydrated bamboo chips can then be crushed into filaments or powders. Preferably, the particle size of the bamboo biomass is 40 - 80 mesh. If the particle size of the bamboo biomass is greater than 40 mesh, the required reaction time is longer and the removal rates of hemicellulose and lignin will decrease; if the particle size of the bamboo biomass is less than 80 mesh, the preparation cost of the bamboo biomass will increase significantly and it has little effect on the removal rates of hemicellulose and lignin.

[0037] In step (2), the bamboo biomass reacts with an aqueous solution of a low - concentration deep eutectic solvent by heating to remove hemicellulose. The mass fraction of the deep eutectic solvent in the aqueous solution of the low - concentration deep eutectic solvent is 0.1% - 1%. If the mass fraction of the deep eutectic solvent is less than 0.1%, the hemicellulose removal rate is low, affecting the subsequent lignin removal effect; if the mass fraction of the deep eutectic solvent is greater than 1%, there are more side reactions, affecting the further utilization of the hemicellulose removed by the reaction. For example, it will reduce the yield of hemicellulose degraded into monosaccharides.

[0038] Preferably, in step (2), the temperature of the heating reaction is 120 - 200 °C and the time is 1 - 6 h. If the reaction temperature is lower than 120 °C, the removal efficiency of hemicellulose is low and the required reaction time is too long; if the reaction temperature is higher than 200 °C, there are more side reactions, affecting the further utilization of the hemicellulose removed by the reaction. For example, it will reduce the yield of hemicellulose degraded into monosaccharides; therefore, the reaction temperature is controlled at 120 - 200 °C. If the reaction time is less than 1 h, the hemicellulose removal rate is low; if the reaction time is greater than 6 h, the production efficiency is low; therefore, the reaction time is controlled at 1 - 6 h.

[0039] Preferably, in step (2), the solid - liquid ratio of the bamboo biomass to the aforementioned aqueous solution of the low - concentration deep eutectic solvent is 1∶4 - 10 kg / L. When calculating the solid - liquid ratio, the mass of the solid is based on the dry weight. If the solid - liquid ratio is less than 1∶10 kg / L, the bamboo biomass is relatively less and the production efficiency is low; if the solid - liquid ratio is greater than 1∶4 kg / L, the bamboo biomass is relatively more, and there may be incomplete reactions, reducing the hemicellulose removal rate.

[0040] In step (3), the solid residue obtained in step (2) is heated with an aqueous solution of a high-concentration deep eutectic solvent for lignin removal reaction. The mass fraction of the deep eutectic solvent in the aqueous solution of the high-concentration deep eutectic solvent is 50% - 100%. If the mass fraction of the deep eutectic solvent is less than 50%, the lignin removal rate is low.

[0041] Preferably, in step (3), the temperature of the heating reaction is 100 - 160 °C, and the time is 2 - 6 h. If the reaction temperature is lower than 100 °C, the removal efficiency of hemicellulose is low, and the required reaction time is too long; if the reaction temperature is higher than 160 °C, there are more side reactions, which affect the quality of the lignin product; therefore, the reaction temperature is controlled at 120 - 200 °C. If the reaction time is less than 2 h, the removal rate of hemicellulose is low, and if the reaction time is greater than 6 h, the production efficiency is low; therefore, the reaction time is controlled at 2 - 6 h.

[0042] Preferably, in step (3), the solid-liquid ratio of the solid residue to the aqueous solution of the high-concentration deep eutectic solvent is 1:5 - 15 kg / L. When calculating the solid-liquid ratio, the mass of the solid is based on the dry weight. If the solid-liquid ratio is less than 1:15 kg / L, the amount of solid residue is relatively small, and the production efficiency is low; if the solid-liquid ratio is greater than 1:5 kg / L, the amount of solid residue is relatively large, and the reaction may not be sufficient, reducing the lignin removal rate.

[0043] The present invention creatively proposes a method for separating all components of bamboo biomass based on a coupling strategy, which combines hydrothermal pretreatment catalyzed by a low-concentration deep eutectic solvent solution with a lignin removal step using a high-concentration deep eutectic solvent solution, realizing the efficient disassembly of all components of bamboo biomass under mild conditions, selectively removing hemicellulose and lignin from bamboo biomass, and simultaneously increasing the retention rate of cellulose.

[0044] The technical solution of the present invention will be described in more detail below with more specific examples. Among them, the raw materials and reagents used, unless otherwise specified, are all arbitrary commercially available products; the performance detection methods adopted are all conventional detection methods in the art.

[0045] In Examples 1 - 10, the hemicellulose removal rate, lignin removal rate, and cellulose retention rate are calculated as follows:

[0046] Hemicellulose removal rate = 1 - (mass of solid residue × hemicellulose proportion in solid residue) / (mass of raw material × hemicellulose proportion in raw material);

[0047] Lignin removal rate = 1 - (mass of cellulose residue × lignin proportion in cellulose residue) / (mass of raw material × lignin proportion in raw material);

[0048] Cellulose retention rate = (mass of cellulose residue × cellulose proportion) / (mass of raw material × cellulose proportion in raw material).

[0049] Example 1

[0050] Prepare an aqueous solution of a eutectic solvent with a concentration of 0.13 wt% and an aqueous solution of a eutectic solvent with a concentration of 85 wt%; wherein, the eutectic solvent is composed of choline chloride, ethylene glycol and formic acid, and the molar ratio of choline chloride, ethylene glycol and formic acid is 1:5:0.1; during preparation, stir at 85 °C for 1.5 h until a colorless transparent solution is obtained.

[0051] Mix 1 kg of bamboo raw material with a particle size of 40 - 60 mesh and a dry weight with 8 L of an aqueous solution of a eutectic solvent with a concentration of 0.13 wt%, heat at 190 °C for 4.5 h, and then perform solid-liquid separation to obtain a solid residue;

[0052] Take 0.5 kg of the solid residue and mix it with 5 L of an aqueous solution of a eutectic solvent with a concentration of 85 wt%, heat at 120 °C for 5 h, and then perform solid-liquid separation to obtain a cellulose residue.

[0053] Detect the obtained cellulose residue, and the measured hemicellulose removal rate is 91.2%, the lignin removal rate is 93.6%, and the cellulose retention rate is 90.4%.

[0054] Example 2

[0055] Prepare an aqueous solution of a eutectic solvent with a concentration of 0.35 wt% and an aqueous solution of a eutectic solvent with a concentration of 55 wt%; wherein, the eutectic solvent is composed of betaine, glycerol and oxalic acid, and the molar ratio of betaine, glycerol and oxalic acid is 1:1:0.5; during preparation, stir at 85 °C for 1.5 h until a colorless transparent solution is obtained.

[0056] Mix 1 kg of moso bamboo raw material with a particle size of 40 - 60 mesh and a dry weight with 10 L of an aqueous solution of a eutectic solvent with a concentration of 0.35 wt%, heat at 140 °C for 3.5 h, and then perform solid-liquid separation to obtain a solid residue;

[0057] Take 0.5 kg of the solid residue, mix it with 3.5 L of an aqueous solution of a eutectic solvent with a concentration of 55 wt%, heat at 150 °C for 2.5 h, and then perform solid-liquid separation to obtain a cellulose residue.

[0058] Detect the obtained cellulose residue, and the measured hemicellulose removal rate is 90.8%, the lignin removal rate is 96.2%, and the cellulose retention rate is 95.1%.

[0059] Example 3

[0060] Prepare an aqueous solution of a eutectic solvent with a concentration of 0.26 wt% and an aqueous solution of a eutectic solvent with a concentration of 56 wt%; wherein, the eutectic solvent is composed of benzyltriethylammonium chloride, butanediol and acetic acid, and the molar ratio of benzyltriethylammonium chloride, butanediol and acetic acid is 2:2:5; during preparation, stir at 85 °C for 1.5 h until a colorless transparent solution is obtained.

[0061] Mix 1 kg of bamboo raw materials with a particle size of 40 - 60 mesh and a dry weight with 7 L of an aqueous solution of a eutectic solvent with a concentration of 0.26 wt%, heat at 180 °C for 2.5 h, and then perform solid-liquid separation to obtain a solid residue;

[0062] Take 0.5 kg of the solid residue and mix it with 7 L of an aqueous solution of a eutectic solvent with a concentration of 56 wt%, heat at 160 °C for 2 h, and then perform solid-liquid separation to obtain a cellulose residue.

[0063] Detect the obtained cellulose residue, and the measured hemicellulose removal rate is 96.4%, the lignin removal rate is 97.3%, and the cellulose retention rate is 90.1%.

[0064] Example 4

[0065] Prepare an aqueous solution of a eutectic solvent with a concentration of 0.46 wt% and an aqueous solution of a eutectic solvent with a concentration of 83 wt%; wherein, the eutectic solvent is composed of acetamide, butanediol and triethanolamine, and the molar ratio of acetamide, butanediol and triethanolamine is 2:3:0.9; during preparation, stir at 85 °C for 1.5 h until a colorless transparent solution is obtained.

[0066] Mix 1 kg of bamboo raw materials with a particle size of 40 - 60 mesh and a dry weight with 5 L of an aqueous solution of a eutectic solvent with a concentration of 0.46 wt%, heat at 190 °C for 5.5 h, and then perform solid-liquid separation to obtain a solid residue;

[0067] Take 0.5 kg of the solid residue and mix it with 7.5 L of an aqueous solution of a eutectic solvent with a concentration of 83 wt%, heat at 110 °C for 5.7 h, and then perform solid-liquid separation to obtain a cellulose residue.

[0068] Detect the obtained cellulose residue, and the measured hemicellulose removal rate is 95.8%, the lignin removal rate is 97.2%, and the cellulose retention rate is 94.5%.

[0069] Example 5

[0070] Prepare an aqueous solution of a eutectic solvent with a concentration of 0.37 wt% and an aqueous solution of a eutectic solvent with a concentration of 52 wt%; wherein, the eutectic solvent is composed of ammonium chloride, ethylene glycol and propionic acid, and the molar ratio of ammonium chloride, ethylene glycol and propionic acid is 2:3:0.9; during preparation, stir at 85 °C for 1.5 h until a colorless transparent solution is obtained.

[0071] Mix 1 kg of bamboo raw materials with a particle size of 40 - 60 mesh and a dry weight with 8 L of an aqueous solution of a eutectic solvent with a concentration of 0.37 wt%. Heat at 170 °C for 4.5 h and then perform solid-liquid separation to obtain solid residues.

[0072] Take 0.5 kg of the solid residues and mix them with 4 L of an aqueous solution of a eutectic solvent with a concentration of 52 wt%. Heat at 130 °C for 3.2 h and then perform solid-liquid separation to obtain cellulose residues.

[0073] Detect the obtained cellulose residues. The hemicellulose removal rate is measured to be 92.3%, the lignin removal rate is 93.2%, and the cellulose retention rate is 95.4%.

[0074] Example 6

[0075] Prepare an aqueous solution of a eutectic solvent with a concentration of 0.34 wt% and an aqueous solution of a eutectic solvent with a concentration of 75 wt%. Among them, the eutectic solvent is composed of betaine, butanediol, and triethanolamine, and the molar ratio of betaine, butanediol, and triethanolamine is 2:4:0.1. Stir at 85 °C for 1.5 h until a colorless transparent solution is obtained during preparation.

[0076] Mix 1 kg of bamboo raw materials with a particle size of 40 - 60 mesh and a dry weight with 9 L of an aqueous solution of a eutectic solvent with a concentration of 0.34 wt%. Heat at 160 °C for 5.8 h and then perform solid-liquid separation to obtain solid residues.

[0077] Take 0.5 kg of the solid residues and mix them with 3 L of an aqueous solution of a eutectic solvent with a concentration of 75 wt%. Heat at 140 °C for 3 h and then perform solid-liquid separation to obtain cellulose residues.

[0078] Detect the obtained cellulose residues. The hemicellulose removal rate is measured to be 94.1%, the lignin removal rate is 95.2%, and the cellulose retention rate is 96.6%.

[0079] Example 7

[0080] Prepare an aqueous solution of a eutectic solvent with a concentration of 0.88 wt% and an aqueous solution of a eutectic solvent with a concentration of 65 wt%. Among them, the eutectic solvent is composed of choline chloride, propylene glycol, and triisopropanolamine, and the molar ratio of choline chloride, propylene glycol, and triisopropanolamine is 2:1:2. Stir at 85 °C for 1.5 h until a colorless transparent solution is obtained during preparation.

[0081] Mix 1 kg of bamboo raw materials with a particle size of 40 - 60 mesh and a dry weight with 7 L of an aqueous solution of a eutectic solvent with a concentration of 0.88 wt%. Heat at 140 °C for 4.6 h and then perform solid-liquid separation to obtain solid residues.

[0082] Take 0.5 kg of solid residue by dry weight, mix it with 7 L of an aqueous solution of a deep eutectic solvent with a concentration of 65 wt%, heat it at 150 °C for 2.2 h, and then perform solid-liquid separation to obtain cellulose residue.

[0083] Detect the obtained cellulose residue, and the measured hemicellulose removal rate is 96.9%, the lignin removal rate is 97.4%, and the cellulose retention rate is 91.3%.

[0084] Example 8

[0085] Prepare an aqueous solution of a deep eutectic solvent with a concentration of 0.69 wt% and an aqueous solution of a deep eutectic solvent with a concentration of 81 wt%; among them, the deep eutectic solvent is composed of acetamide, formic acid and propylene glycol, and the molar ratio of acetamide, formic acid and propylene glycol is 1:0.5:3; during preparation, stir at 85 °C for 1.5 h until a colorless transparent solution is obtained.

[0086] Mix 1 kg of bamboo raw material with a particle size of 40 - 60 mesh by dry weight with 10 L of an aqueous solution of a deep eutectic solvent with a concentration of 0.69 wt%, heat it at 160 °C for 3.3 h, and then perform solid-liquid separation to obtain solid residue;

[0087] Take 0.5 kg of solid residue by dry weight, mix it with 4 L of an aqueous solution of a deep eutectic solvent with a concentration of 81 wt%, heat it at 140 °C for 2.5 h, and then perform solid-liquid separation to obtain cellulose residue.

[0088] Detect the obtained cellulose residue, and the measured hemicellulose removal rate is 91.6%, the lignin removal rate is 93.8%, and the cellulose retention rate is 92.6%.

[0089] Example 9

[0090] Prepare an aqueous solution of a deep eutectic solvent with a concentration of 0.72 wt% and an aqueous solution of a deep eutectic solvent with a concentration of 54 wt%; among them, the deep eutectic solvent is composed of benzyltriethylammonium chloride, propionic acid and diethanolamine, and the molar ratio of benzyltriethylammonium chloride, propionic acid and diethanolamine is 3:0.5:1; during preparation, stir at 85 °C for 1.5 h until a colorless transparent solution is obtained.

[0091] Mix 1 kg of bamboo raw material with a particle size of 40 - 60 mesh by dry weight with 8 L of an aqueous solution of a deep eutectic solvent with a concentration of 0.72 wt%, heat it at 180 °C for 4.2 h, and then perform solid-liquid separation to obtain solid residue;

[0092] Take 0.5 kg of solid residue by dry weight, mix it with 4.5 L of an aqueous solution of a deep eutectic solvent with a concentration of 54 wt%, heat it at 160 °C for 2 h, and then perform solid-liquid separation to obtain cellulose residue.

[0093] The obtained cellulose residue was detected, and the hemicellulose removal rate was measured to be 95.4%, the lignin removal rate was 93.9%, and the cellulose retention rate was 97.1%.

[0094] Example 10

[0095] An aqueous solution of a deep eutectic solvent with a concentration of 0.55 wt% and an aqueous solution of a deep eutectic solvent with a concentration of 93 wt% were prepared; wherein, the deep eutectic solvent was composed of choline chloride, acetic acid and diisopropanol, and the molar ratio of choline chloride, acetic acid to diisopropanol was 6:0.5:3; during the preparation, it was stirred at 85 °C for 1.5 h until a colorless transparent solution was obtained.

[0096] 1 kg of bamboo raw materials with a particle size of 40 - 60 mesh and a dry weight were mixed with 10 L of an aqueous solution of a deep eutectic solvent with a concentration of 0.55 wt%, heated at 190 °C for 4.9 h, and then subjected to solid-liquid separation to obtain a solid residue;

[0097] 0.5 kg of the obtained solid residue was taken and mixed with 5 L of an aqueous solution of a deep eutectic solvent with a concentration of 93 wt%, heated at 150 °C for 2.5 h, and then subjected to solid-liquid separation to obtain a cellulose residue.

[0098] The obtained cellulose residue was detected, and the hemicellulose removal rate was measured to be 95.5%, the lignin removal rate was 95.7%, and the cellulose retention rate was 94.2%.

[0099] The technical features in the claims and / or the specification of the present invention can be combined, and the combination method is not limited to the combination obtained through the citation relationship in the claims. The technical solutions obtained by combining the technical features in the claims and / or the specification also fall within the protection scope of the present invention.

[0100] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solutions of the present invention.

Claims

1. A method for separating all components of bamboo biomass, characterized in that: The steps include: (1) preparing a low-concentration deep eutectic solvent aqueous solution and a high-concentration deep eutectic solvent aqueous solution, wherein the mass fraction of the deep eutectic solvent in the low-concentration deep eutectic solvent aqueous solution is 0.1% to 1%, and the mass fraction of the deep eutectic solvent in the high-concentration deep eutectic solvent aqueous solution is 50% to 100%; (2) mixing the bamboo biomass with the low-concentration deep eutectic solvent aqueous solution, heating the mixture for reaction, removing hemicellulose, and then performing solid-liquid separation to obtain a solid residue; and, (3) mixing the solid residue with a high-concentration low eutectic solvent aqueous solution, heating for reaction, removing lignin, and then performing solid-liquid separation to obtain a cellulose residue.

2. The method for separating all components of bamboo biomass according to claim 1, characterized in that: In the low eutectic solvent in the low concentration deep eutectic solvent aqueous solution, the molar ratio of hydrogen bond acceptor to hydrogen bond donor is (1-10): (1-10); and / or, In the deep eutectic solvent in the high-concentration deep eutectic solvent aqueous solution, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (1-10):(1-10).

3. The method for separating all components of bamboo biomass according to claim 1, characterized in that: In step (2), the heating reaction temperature is 120 to 200° C. and the time is 1 to 6 hours.

4. The method for separating all components of bamboo biomass according to claim 1, characterized in that: In step (2), the solid-to-liquid ratio of the bamboo biomass to the low-concentration deep eutectic solvent aqueous solution is 1:4-10 kg / L.

5. The method for separating all components of bamboo biomass according to claim 1, characterized in that: In step (3), the heating reaction temperature is 100 to 160° C. and the time is 2 to 6 hours.

6. The method for separating all components of bamboo biomass according to claim 1, characterized in that: In step (3), the solid-to-liquid ratio of the solid residue to the high-concentration deep eutectic solvent aqueous solution is 1:5-15 kg / L.

7. The method for separating all components of bamboo biomass according to claim 1, characterized in that: In the low-concentration deep eutectic solvent aqueous solution and the high-concentration deep eutectic solvent aqueous solution, the hydrogen bond donor is at least one of formic acid, oxalic acid, acetic acid, citric acid, propionic acid, 2,3-dihydroxysuccinic acid, L-hydroxysuccinic acid, ethylene glycol, propylene glycol, glycerol and butanediol.

8. The method for separating all components of bamboo biomass according to claim 1, characterized in that: In the low-concentration deep eutectic solvent aqueous solution and the high-concentration deep eutectic solvent aqueous solution, the hydrogen bond acceptor is at least one of choline chloride, betaine, benzyltriethylammonium chloride, acetamide, diethanolamine and triethanolamine.

9. The method for separating all components of bamboo biomass according to claim 1, characterized in that: The particle size of the bamboo biomass is 40 to 80 meshes.

10. The method for separating all components of bamboo biomass according to claim 1, characterized in that: The bamboo biomass is Phyllostachys edulis and / or Phyllostachys pubescens.