Cellulose-based thickening stabilizer extracted by eutectic solvent and preparation method of cellulose-based thickening stabilizer

Abstract

The invention discloses a cellulose-based thickening stabilizer extracted by a deep-eutectic solvent and a preparation method thereof. The preparation method comprises the following steps: preparation of the deep-eutectic solvent, pretreatment of raw materials, heating extraction, filter pressing, washing, defibrating and drying. The thickening efficiency of the prepared cellulose-based thickening stabilizer is superior to that of various commercial thickening stabilizers, and the thickening effect can still be achieved under the conditions of more lignin residues and poor fiber particle size consistency. The deep-eutectic solvent extraction method is simple and easy to implement, cellulose can be efficiently defibrillated in the presence of lignin, pollution possibly caused when lignin is removed through other chemical methods is avoided, and better environmental protection benefits are achieved; the eutectic solvent provided by the invention has the advantages of recoverability, low cost and good economic benefit.

Description

Technical Field

[0001] The present invention belongs to the technical field of comprehensive utilization of biomass, and particularly relates to a cellulose-based thickening and stabilizing agent extracted by a deep eutectic solvent and a preparation method thereof. Background Art

[0002] Cellulose-based biomass from non-wood sources, such as herbaceous plants and straw, contains a large amount of short fibers due to its cell composition and structural characteristics. This characteristic not only limits its application in traditional fields such as papermaking, but also poses challenges to the pretreatment process in other new material fields, such as the preparation of nanocellulose. In addition, in addition to cellulose, cellulose-based biomass usually contains a relatively large amount of lignin and hemicellulose. The structure of lignin is complex, and its main structural units include phenylpropenols (such as vanillyl alcohol, guaiacyl alcohol, etc.), which are connected together by strong chemical bonds such as phenolic ether bonds and ether bonds. Even under the pretreatment conditions of strong acids or strong bases, these chemical bonds cannot be completely broken. The difficulty in removing lignin and its inhibitory effect on the subsequent processing of cellulose also become a major difficulty in biomass utilization.

[0003] At present, the utilization idea of cellulose-based biomass is usually to separate hemicellulose, lignin, and cellulose and then utilize them separately. Hemicellulose is usually used for hydrolysis to produce ethanol or monosaccharides and derivatives; cellulose is also widely used in the preparation of biofuels or nanocellulose; the efficient utilization of lignin is still in the development stage. At present, the cost of separating the three components of non-wood cellulose biomass is still relatively high, and there are many challenges in large-scale commercialization due to the inconsistent fiber lengths. There is an urgent need for a simple, easy-to-implement, and low-cost method to process cellulose-based biomass without considering lignin removal and obtain good commercial application effects.

[0004] In the field of commercial cellulose-based thickening and stabilizing agents, currently common products include colloidal microcrystalline cellulose, citrus fiber, etc. The key to their thickening effect lies in the fact that the hydroxyl groups rich in cellulose can form hydrogen bonds with water and form a hydrogen bond network at a certain concentration, thereby providing excellent thickening effects and gel structures. The strength of the hydrogen bond network is mainly determined by the number of hydroxyl groups that can participate in hydration in cellulose. Can the thickening efficiency be further improved by enhancing the cellulose hydrogen bond network without completely removing lignin?

[0005] Deep eutectic solvents are liquid solvents formed by the eutectic action of two or more components (usually including a hydrogen bond donor and a hydrogen bond acceptor). Due to the strong hydrogen bond interaction between the components, the melting point of the eutectic is usually lower than the melting point of the single component, and even presents a liquid state at room temperature. Some studies have shown that it can defibrillate cellulose in the presence of lignin, and can remove hemicellulose and part of lignin, showing great application potential in the field of biomass conversion.

[0006] In summary, the difficult removal of lignin and the poor consistency of fibers are two important technical difficulties in realizing the commercial application of cellulose-based biomass. The present invention provides a cellulose-based thickening and stabilizing agent extracted by a deep eutectic solvent and a preparation method thereof. The thickening efficiency of the fiber is superior to that of a variety of commercially available thickening and stabilizing agents, and it can still exert a thickening effect in the case of more lignin residues and poor consistency of fiber particle size. Summary of the Invention

[0007] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the specification of this application, to avoid obscuring the purpose of this part, the abstract of the specification, and the title of the invention, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0008] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0009] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a preparation method of a cellulose-based thickening and stabilizing agent extracted by a deep eutectic solvent.

[0010] To solve the above technical problems, the present invention provides the following technical solutions, including,

[0011] Mix a hydrogen bond donor, a hydrogen bond acceptor, and water, and heat to prepare a deep eutectic solvent; mix the deep eutectic solvent with a cellulose raw material and heat for extraction; subject the extracted cellulose raw material to pressure filtration, washing, suction filtration, defibration, and drying to obtain a cellulose-based thickening and stabilizing agent.

[0012] As a preferred embodiment of the preparation method of the cellulose-based thickening and stabilizing agent extracted by the deep eutectic solvent of the present invention, wherein: the hydrogen bond donor includes one or more of amino compounds, carboxylic acids with one or more carboxyl groups, alcohol compounds with one or more hydroxyl groups, or compounds containing both amino and carboxyl groups; the hydrogen bond acceptor includes one or more of ammonium chloride, sodium chloride, and choline chloride.

[0013] As a preferred embodiment of the preparation method of the cellulose-based thickening and stabilizing agent extracted by the deep eutectic solvent of the present invention, wherein: the amino compound includes urea; the carboxylic acids with one or more carboxyl groups include acetic acid, oxalic acid, citric acid, tartaric acid, lactic acid, malic acid, and phenylacetic acid; the alcohol compounds with one or more hydroxyl groups include glycerol, ethylene glycol, and propylene glycol; the compounds containing both amino and carboxyl groups include glycine and glutamic acid.

[0014] As a preferred embodiment of the preparation method of the cellulose-based thickening and stabilizing agent extracted by the deep eutectic solvent of the present invention, wherein: the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:11 to 11:1; the addition ratio of water is 0 to 80% of the total mass.

[0015] As a preferred embodiment of the preparation method of the cellulose-based thickening and stabilizing agent extracted by the eutectic solvent of the present invention, wherein: the cellulose raw material is a cellulose-based biomass raw material with a cellulose content > 20%, including one or more of pretreated straw, bagasse, wood powder, corncob, fruit peel, and plant leaf stems;

[0016] Among them, the pretreatment includes one or several of crushing, sieving, high-pressure steam explosion, microwave pretreatment, hot water pretreatment, lignin peroxidase or laccase pretreatment, and acid pretreatment.

[0017] As a preferred embodiment of the preparation method of the cellulose-based thickening and stabilizing agent extracted by the eutectic solvent of the present invention, wherein: the temperature of the heating extraction is 30 - 300 °C, the extraction time is 0.1 - 480 h, and the mass ratio of the cellulose raw material to the eutectic solvent is 1:100 - 2:1.

[0018] As a preferred embodiment of the preparation method of the cellulose-based thickening and stabilizing agent extracted by the eutectic solvent of the present invention, wherein: the temperature of the heating extraction is 50 - 150 °C, the extraction time is 0.5 - 48 h, and the mass ratio of the cellulose raw material to the eutectic solvent is 1:10.

[0019] As a preferred embodiment of the preparation method of the cellulose-based thickening and stabilizing agent extracted by the eutectic solvent of the present invention, wherein: the defibrillation method includes one or more of ultrasonic, microwave, homogenization, emulsification, and grinding.

[0020] As a preferred embodiment of the preparation method of the cellulose-based thickening and stabilizing agent extracted by the eutectic solvent of the present invention, wherein: the drying method includes one or several of drum drying, spray drying, freeze drying, and microwave drying.

[0021] As a preferred embodiment of the preparation method of the cellulose-based thickening and stabilizing agent extracted by the eutectic solvent of the present invention, wherein: in the spray drying, the mass ratio of the drying aid to the cellulose-based thickening and stabilizing agent is 0:1 - 10:1.

[0022] Another object of the present invention is to overcome the deficiencies in the prior art and provide a cellulose-based thickening and stabilizing agent extracted by a eutectic solvent, including,

[0023] Cellulose 20 - 100%, lignin 0 - 50%, hemicellulose 0 - 20%, ash 0 - 5%, other polysaccharides 0 - 50%.

[0024] The third object of the present invention is to overcome the deficiencies in the prior art and provide an application of a cellulose-based thickening and stabilizing agent extracted by a deep eutectic solvent, wherein the viscosity of the cellulose-based thickening and stabilizing agent is 39.6 to 235 Pa·s; the cellulose-based thickening and stabilizing agent can also be compounded with other polysaccharides or colloids to enhance the application effect.

[0025] Advantages of the present invention:

[0026] (1) The deep eutectic solvent selected in the present invention has specificity. Its principle of acting on cellulose-based biomass is as follows: First, it breaks the chemical bonds and hydrogen bond connections between some cellulose, hemicellulose, and lignin, removes most of the hemicellulose and a small amount of lignin. Second, it breaks the hydrogen bonds between cellulose molecules, causing cellulose fibrillation and exposing more fine fibers. After the fine fibers are fully hydrated, they can form a hydrogen bond network to provide viscosity.

[0027] (2) The preparation method of the cellulose-based thickening and stabilizing agent extracted by the deep eutectic solvent of the present invention has low requirements for the consistency of raw materials, has a defibrillation effect on both long fibers and fine fibers, and can also play a thickening effect under a wide particle size range. Therefore, it has universality in the comprehensive utilization of cellulose-based biomass.

[0028] (3) The preparation method of the cellulose-based thickening and stabilizing agent extracted by the deep eutectic solvent of the present invention is simple and easy to operate, can efficiently defibrillate cellulose in the presence of lignin, and avoids the possible pollution caused by other chemical methods for removing lignin, having better environmental protection.

[0029] (4) The use of a drying aid in the present invention can increase the drying yield and reduce costs.

[0030] (5) The deep eutectic solvent in the present invention is recyclable, has a low cost, and has good economic benefits. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0032] Figure 1 SEM image (A) and partial enlarged view (B) of the bagasse raw material used in Example 1 of the present invention;

[0033] Figure 2 AFM image of the cellulose-based thickening and stabilizing agent extracted in Example 1 of the present invention, wherein the scanning range of (A) is 10 μm, the scanning range of (B) is 3 μm, and the scanning range of (C) is 1 μm;

[0034] Figure 3 Images after rehydration of the cellulose-based thickening and stabilizing agent prepared in Example 1 of the present invention at different concentrations;

[0035] Figure 4 Viscosity comparison chart of the cellulose-based thickening and stabilizing agent prepared in Example 1 of the present invention and other commercial thickening and stabilizing agents;

[0036] Figure 5 Fiber diameter comparison chart of Example 1 and Example 6 of the present invention;

[0037] Figure 6 Application effects of Example 1 of the present invention in thickening and suspending and emulsifying and stabilizing;

[0038] Figure 7 Pictures of the dispersion solvent of the cellulose-based thickening and stabilizing agent prepared in Examples 7 to 9 and the determination results of apparent viscosity;

[0039] Figure 8 Comparison chart of fiber diameter (A) of Example 15 and Control Example 9 and morphology (B) of Control Example 9. Detailed implementation manners

[0040] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following describes the detailed implementation manners of the present invention in conjunction with the embodiments of the specification.

[0041] Many specific details are set forth in the following description to facilitate a thorough understanding of the present invention, but the present invention may be practiced in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0042] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation manner of the present invention. The appearances of "in one embodiment" in different places in this specification do not all refer to the same embodiment, nor are they separate or alternative embodiments that exclude each other with other embodiments.

[0043] Unless otherwise specified, the raw materials used in the present invention are all commercially available.

[0044] The materials prepared in the embodiments of the present invention are tested for performance according to the following methods:

[0045] Determination of component content: It is determined by the method described in NY / T 3494-2019 "Determination of Cellulose, Hemicellulose, and Lignin in Agricultural Biomass Raw Materials".

[0046] Scanning electron microscopy (SEM) measurement: The bagasse raw materials used in Examples 1-6 were fixed on a cross-section sample stage with conductive glue, sprayed with gold after sufficient purging, and photographed under a scanning electron microscope (SU8220, Hitachi, Japan). The acceleration voltage for scanning the samples was 3 kV. The cellulose-based thickening and stabilizing agent obtained in Comparative Example 1 was rehydrated, dropped onto a silicon wafer, air-dried at room temperature, sprayed with gold, and photographed under a scanning electron microscope (SU8220, Hitachi, Japan). The acceleration voltage for scanning the samples was also 3 kV.

[0047] Atomic force microscopy (AFM) measurement: After diluting the fiber sample to 50 mg / L, 10 μL was taken and dropped onto a mica sheet, and observed under an atomic force microscope (Dimension FastScan, Bruker, Germany). NanoScope Analysis 1.7 was used to process and analyze the images.

[0048] Particle size measurement: The particle size of the fibers was measured using a laser particle size analyzer (Bettersize 2600, Dandong BETTER, China) in the wet mode. A 0.25% mass concentration of the fibers was dropped into the sample cell, and the sample particle size was detected after the obscuration reached the detection range of 8-15%.

[0049] Viscosity (viscometer method) measurement: A cellulose-based thickener sample with a mass concentration of 0.25% was prepared, homogenized twice at 180 MPa, and the viscosity of each sample at a mass concentration of 0.25% was measured using a rapid viscometer (Brookfield DV2T, Brookfield, USA). The test conditions were: rotor No. 13, rotation speed 60 rpm.

[0050] Viscosity (rheometer method) measurement: A cellulose-based thickener sample with a mass concentration of 0.25% was prepared, homogenized twice at 180 MPa, and 1 mL - 2 mL of the sample was loaded onto the test bench of a rotational rheometer (Discovery DHR-3, TA Instruments, USA). A 40 mm, 2° cone plate was selected, and the gap value was set to 1000 μm. The shear viscosity test procedure was: the apparent viscosity at a shear rate of 0.001 - 1000 / s at 25 °C, and the zero-shear viscosity was fitted through the Carreau-Yasuda model.

[0051] Example 1

[0052] This example provides a preparation method of a cellulose-based thickening and stabilizing agent, specifically:

[0053] (1) Preparation of deep eutectic solvent: Take 126 g of oxalic acid dihydrate and 139.5 g of choline chloride, stir at 80 °C for 2 h to obtain a clear and transparent deep eutectic solvent, that is, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1, and the water content in the deep eutectic solvent is 13.5%;

[0054] (2) Pretreatment of cellulose-based biomass raw materials: Pulverize the bagasse and sieve it through a 60-mesh sieve;

[0055] (3) Extraction of cellulose-based thickening and stabilizing agent: Mix 100 g of deep eutectic solvent with 10 g of bagasse, and stir and extract at 70 °C for 4 h;

[0056] (4) Pressure filtration and washing: Separate the extracted bagasse from the deep eutectic solvent by pressure filtration, and wash the obtained bagasse extract with clear water until the pH of the filtrate > 5;

[0057] (5) Defibrillation: Subject the above-mentioned bagasse extract to high-pressure homogenization at 180 MPa;

[0058] (6) Drying: Spray-dry the bagasse fibers obtained in (5), with an inlet air temperature of 180 °C and an outlet air temperature of 65 °C. Adjust the flow rate according to the outlet air temperature, and then obtain the cellulose-based thickening and stabilizing agent after granulation.

[0059] Comparative Example 1

[0060] The difference between this comparative example and Example 1 is that the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is adjusted to 1:11, and the rest of the preparation processes are the same as those in Example 1, to obtain a cellulose-based thickening and stabilizing agent.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 1 is that the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is adjusted to 11:1, and the rest of the preparation processes are the same as those in Example 1, to obtain a cellulose-based thickening and stabilizing agent.

[0063] Perform performance tests on the materials obtained in the above examples and comparative examples, and the comparison results with Example 1 are shown in Table 1.

[0064] Table 1

[0065] Hydrogen bond donor mass Hydrogen bond acceptor mass Molar ratio Zero-shear viscosity Example 1 126g 139.5g 1∶1 235 Pa·s Comparative Example 1 126g 1534.5g 1∶11 1.25 Pa·s Comparative Example 2 1386g 139.5g 11∶1 10.26 Pa·s

[0066] As can be seen from the above table, adjusting the ratio of the hydrogen bond donor to the hydrogen bond acceptor of the raw materials has a significant impact on the performance of the cellulose-based thickening and stabilizing agent. This is because the formation of the deep eutectic solvent requires a suitable ratio of the hydrogen bond donor to the hydrogen bond acceptor. When one of the components is excessive, the other component does not have enough hydrogen bond acceptors / donors to pair with it, resulting in an unstable structure of the solvent system and reducing the defibrillation ability. According to the results in the above table, the best technical effect can be obtained when the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor in the present invention is 1:1.

[0067] Example 2

[0068] The difference between this example and Example 1 lies in that the hydrogen bond donor is adjusted to an amino compound - urea, and the remaining preparation processes are the same as those in Example 1, resulting in a cellulose-based thickening and stabilizing agent.

[0069] Example 3

[0070] The difference between this example and Example 1 lies in that the hydrogen bond donor is adjusted to an alcohol - glycerol, and the remaining preparation processes are the same as those in Example 1, resulting in a cellulose-based thickening and stabilizing agent.

[0071] Example 4

[0072] The difference between this example and Example 1 lies in that the hydrogen bond donor is adjusted to another carboxylic acid compound - citric acid, and the remaining preparation processes are the same as those in Example 1, resulting in a cellulose-based thickening and stabilizing agent.

[0073] The materials prepared in the above examples were subjected to performance tests, and the comparison results with Example 1 are shown in Table 2.

[0074] Table 2

[0075] Hydrogen bond donor Zero-shear viscosity Example 1 Oxalic acid (carboxylic acid compound) 235 Pa·s Example 2 Urea (amino compound) 39.6 Pa·s Example 3 Glycerol (alcohol) 12.6 Pa·s Example 4 Citric acid (carboxylic acid compound) 128 Pa·s

[0076] As can be seen from the above table, adjusting the type of hydrogen bond donor of the raw materials has a significant impact on the performance of the cellulose-based thickening and stabilizing agent. This is because the acidic deep eutectic solvent has a higher hydrogen bond acidity compared to other types of deep eutectic solvents, has a stronger ability to break the hydrogen bonds between fiber molecules, is not easily directly hydrolyzed or dissolve crystalline cellulose, and has a higher retention of cellulose. According to the results in the above table, the best technical effect can be obtained when the type of hydrogen bond donor in the present invention is a carboxylic acid compound.

[0077] Example 5

[0078] The difference between this example and Example 1 lies in that anhydrous oxalic acid is used to adjust the water content in the deep eutectic solvent to 0, and the remaining preparation processes are the same as those in Example 1, resulting in a cellulose-based thickening and stabilizing agent.

[0079] Example 6

[0080] The difference between this example and Example 1 lies in that the water content in the deep eutectic solvent is adjusted to 80%, the extraction temperature is 100 °C, and the extraction time is 5 h, and the remaining preparation processes are the same as those in Example 1, resulting in a cellulose-based thickening and stabilizing agent.

[0081] Comparative Example 3

[0082] The difference between this comparative example and Example 1 lies in that the water content in the deep eutectic solvent is adjusted to 80%, and the remaining preparation processes are the same as those in Example 1, resulting in a cellulose-based thickening and stabilizing agent.

[0083] Comparative Example 4

[0084] This comparative example is different from Example 1 in that the water content in the eutectic solvent is adjusted to 90%, the extraction temperature is 110 °C, and the extraction time is 6 h. The remaining preparation processes are the same as those in Example 1, and a cellulose-based thickening and stabilizing agent is prepared.

[0085] The materials prepared in the above examples and comparative examples were subjected to performance tests, and the comparison results with Example 1 are shown in Table 3.

[0086] Table 3

[0087] Water content Extraction temperature Time Zero-shear viscosity Example 1 13.5％ 70℃ 4h 235 Pa·s Example 5 0 70℃ 4h 159 Pa·s Example 6 80％ 100℃ 5h 165.2 Pa·s Comparative Example 3 80％ 70℃ 4h 0.49 Pa·s Comparative Example 4 90％ 110℃ 6h 1.56 Pa·s

[0088] As can be seen from the above table, adjusting the water content in the eutectic solvent has a significant impact on the performance of the cellulose-based thickening and stabilizing agent. This is because water will change key indicators such as the viscosity, solvent polarity, hydrogen bond acidity, and hydrogen bond basicity of the eutectic solvent. Appropriate water can reduce the viscosity of the eutectic solvent and promote the defibrillation process. Within a certain water content (Example 6, 80% water content), the defibrillation effect can be ensured by increasing the treatment temperature or treatment time. When the water content exceeds 80%, it will damage the eutectic system composed of hydrogen bond donors and acceptors, resulting in a decline in the extraction effect. According to the results in the above table, the best technical effect can be obtained when the water content in the eutectic solvent in the present invention is 0-80%.

[0089] Example 7

[0090] This example is different from Example 1 in that the cellulose raw material is adjusted to pineapple leaves, and the remaining preparation processes are the same as those in Example 1, and a cellulose-based thickening and stabilizing agent is prepared.

[0091] Example 8

[0092] This example is different from Example 1 in that the cellulose raw material is adjusted to corncobs, and the remaining preparation processes are the same as those in Example 1, and a cellulose-based thickening and stabilizing agent is prepared.

[0093] Example 9

[0094] This example is different from Example 1 in that the cellulose raw material is adjusted to carrot residue, and the remaining preparation processes are the same as those in Example 1, and a cellulose-based thickening and stabilizing agent is prepared.

[0095] Comparative Example 5

[0096] This example is different from Example 1 in that the cellulose raw material is adjusted to coffee grounds, and the remaining preparation processes are the same as those in Example 1, and a cellulose-based thickening and stabilizing agent is prepared.

[0097] The materials prepared in the above examples and comparative examples were subjected to performance tests, and the comparison results with Example 1 are shown in Table 4.

[0098] Table 4

[0099] Raw material cellulose content Raw material Zero-shear viscosity Example 1 39.4％ Bagasse 235 Pa·s Example 7 70.2％ Pineapple leaves 127 Pa·s Example 8 34.1％ Corncobs 226 Pa·s Example 9 69.1％ Carrot residue 104 Pa·s Comparative Example 5 20.0％ Coffee grounds 0.75 Pa·s

[0100] As can be seen from the above table, adjusting the cellulose raw material has a significant impact on the performance of the cellulose-based thickening and stabilizing agent. This is because the coffee grounds have a relatively low cellulose content compared to other raw materials, with the hemicellulose and lignin content being more than 60% of the dry weight, while the cellulose only accounts for 20%. This results in insufficient cellulose content in the extracted thickening and stabilizing agent, making it difficult to form a hydrogen bond network in water. According to the results of the above table, in the present invention, a better technical effect can be obtained when the cellulose content in the waste raw material is greater than 20%.

[0101] Comparative Example 6

[0102] The difference between this comparative example and Example 1 is that the temperature of the heating extraction is adjusted to 50°C, and the remaining preparation processes are the same as those in Example 1, to obtain a cellulose-based thickening and stabilizing agent.

[0103] Example 10

[0104] The difference between this example and Example 1 is that the temperature of the heating extraction is adjusted to 50°C and the heating extraction time is adjusted to 24 h, and the remaining preparation processes are the same as those in Example 1, to obtain a cellulose-based thickening and stabilizing agent.

[0105] Comparative Example 7

[0106] The difference between this comparative example and Example 1 is that the temperature of the heating extraction is adjusted to 150°C, and the remaining preparation processes are the same as those in Example 1, to obtain a cellulose-based thickening and stabilizing agent.

[0107] Example 11

[0108] The difference between this example and Example 1 is that the temperature of the heating extraction is adjusted to 150°C and the heating extraction time is adjusted to 0.5 h, and the remaining preparation processes are the same as those in Example 1, to obtain a cellulose-based thickening and stabilizing agent.

[0109] Comparative Example 8

[0110] The difference between this comparative example and Example 1 is that the heating extraction time is adjusted to 0.5 h, and the remaining preparation processes are the same as those in Example 1, to obtain a cellulose-based thickening and stabilizing agent.

[0111] Example 12

[0112] The difference between this example and Example 1 is that the heating extraction time is adjusted to 48 h, and the remaining preparation processes are the same as those in Example 1, to obtain a cellulose-based thickening and stabilizing agent.

[0113] The materials prepared in the above examples and comparative examples were subjected to performance tests, and the comparison results with Example 1 are shown in Table 5.

[0114] Table 5

[0115] Extraction temperature Extraction time Zero-shear viscosity Color Example 1 70℃ 4h 235 Pa·s Light yellow Comparative Example 6 50℃ 4h 0.11 Pa·s Light yellow Example 10 50℃ 24h 181 Pa·s Light yellow Comparative Example 7 150℃ 4h 10.5 Pa·s Black Example 11 150℃ 0.5h 126 Pa·s Light yellow Comparative Example 8 70℃ 0.5h 0.25 Pa·s Light yellow Example 12 70℃ 48h 66.5 Pa·s Black

[0116] If the extraction temperature is too low or the extraction time is too short, the degree of defibrillation of cellulose is insufficient, and a high-viscosity hydrocolloid cannot be formed. If the extraction temperature is too high or the time is too long, the cellulose undergoes excessive hydrolysis, resulting in a decrease in the hydrodynamic radius and viscosity; the lignin structure undergoes depolymerization and condensation, leading to a darker color and limited application. According to the results in the above table, in the present invention, when the heating extraction temperature range is 50-150 °C and the extraction time range is 0.5-48 h, better technical effects can be obtained.

[0117] Example 13

[0118] The difference between this example and Example 1 is that in step (6), the cellulose-based thickening and stabilizing agent is mixed with 0.5 parts of pectin and then spray-dried, and the rest of the preparation process is the same as that of Example 1, to obtain the cellulose-based thickening and stabilizing agent.

[0119] Example 14

[0120] The difference between this example and Example 1 is that in step (6), the cellulose-based thickening and stabilizing agent is mixed with 0.5 parts of maltodextrin and 0.5 parts of pectin and then spray-dried, and the rest of the preparation process is the same as that of Example 1, to obtain the cellulose-based thickening and stabilizing agent.

[0121] Example 15

[0122] In this example, the eutectic solvent obtained by pressure filtration was recycled and reused to obtain the cellulose-based thickening and stabilizing agent. Specifically:

[0123] (1) Preparation of eutectic solvent: Take 126 parts of oxalic acid and 139.5 parts of choline chloride, stir at 80 °C for 2 h to obtain a clear and transparent eutectic solvent;

[0124] (2) Pretreatment of cellulose-based biomass raw material: Place bagasse in a reaction kettle at 200 °C and a pressure of 5 MPa for steam explosion treatment for 5 min, and after pulverization, pass through a 60-mesh sieve;

[0125] (3) Extraction of cellulose-based thickening and stabilizing agent: Mix 100 parts of the eutectic solvent prepared in (1) with 10 parts of bagasse, and stir and extract at 70 °C for 4 h;

[0126] (4) Pressure filtration and washing: Separate the extracted bagasse from the eutectic solvent by pressure filtration to obtain the recycled eutectic solvent;

[0127] (5) Extraction of cellulose-based thickening and stabilizing agent: Mix 100 parts of the recycled deep eutectic solvent obtained in (4) with 10 parts of the pretreated bagasse obtained in (2), and stir and extract at 70 °C for 4 h;

[0128] (6) Filter pressing and washing: Separate the extracted bagasse from the deep eutectic solvent again by filter pressing, and wash the obtained cellulose-based extract with clear water until the pH of the filtrate > 5;

[0129] (7) Defibrillation: Subject the bagasse extract prepared in (6) to high-pressure homogenization at 180 MPa;

[0130] (8) Drying: Spray-dry the bagasse extract obtained in (7), with an inlet air temperature of 180 °C, an outlet air temperature of 60 - 70 °C, and the flow rate adjusted according to the outlet air temperature. After granulation, a cellulose-based thickening and stabilizing agent is obtained.

[0131] Perform performance tests on the materials prepared in the above examples, and the comparison results with Example 1 are shown in Table 6.

[0132] Table 6

[0133] Rehydration conditions Zero-shear viscosity Yield Example 1 Homogenize at 180 MPa for 2 times 235 Pa·s 50％ Example 13 Homogenize at 150 MPa for 1 time 202 Pa·s 71％ Example 14 Homogenize at 150 MPa for 1 time 218 Pa·s 98％ Example 15 Homogenize at 180 MPa for 2 times 221 Pa·s 50％

[0134] Note: Only when the drying method is spray drying, the yield of the cellulose-based thickening and stabilizing agent needs to be tested, and the yields of other drying methods are all 100%.

[0135] As can be seen from the above table, when the cellulose-based thickening and stabilizing agent is dried after being compounded with other polysaccharides, the homogenization pressure and number of times required for rehydration can be reduced, because other polysaccharides enhance the dispersibility of the cellulose-based colloid. Compounding the prepared cellulose-based thickening and stabilizing agent with a drying aid can significantly increase the drying yield. Compounding the cellulose in the present invention with other colloids and a drying aid to enhance dispersibility and increase the drying yield should be covered by the protection scope of the present invention. During the cellulose extraction process, the sample after sufficient homogenization treatment has obtained good thickening effects, and whether or not it includes a drying step, it should be included in the protection scope of the present invention. Pretreating the raw materials to remove part of the hemicellulose or amorphous cellulose, as well as acid-soluble lignin can ensure the recovery effect of the deep eutectic solvent. The cellulose-based thickening and stabilizing agent extracted with a deep eutectic solvent after various pretreatments of the raw materials should also be covered by the protection scope of the present invention.

[0136] Comparative Example 9

[0137] (1) Pretreatment of cellulose-based biomass raw materials: Place the bagasse in a reaction kettle at 200 °C and a pressure of 5 MPa for steam explosion treatment for 5 min, and after pulverization, pass through a 60-mesh sieve;

[0138] (2) Extraction of cellulose-based thickening and stabilizing agent: Mix 10 parts of bagasse prepared in (1) with 100 parts of water, and stir at 70 °C for 4 h;

[0139] (3) Pressure filtration and washing: Separate the bagasse after extraction in (2) from water by pressure filtration, and wash the obtained bagasse extract with clear water until the pH of the filtrate is 5 - 9;

[0140] (4) Defibrillation: Subject the bagasse extract prepared in (3) to high-pressure homogenization at 180 MPa;

[0141] (5) Drying: Spray-dry the bagasse fibers obtained in (4), with an inlet air temperature of 180 °C, an outlet air temperature of 60 - 70 °C, and the flow rate adjusted according to the outlet air temperature. After granulation, the cellulose-based thickening and stabilizing agent of the control example is obtained.

[0142] Comparative Example 10

[0143] (1) Preparation of deep eutectic solvent: Take 126 g of oxalic acid dihydrate and 139.5 g of choline chloride, stir at 80 °C for 2 h to obtain a clear and transparent deep eutectic solvent, that is, the molar ratio of hydrogen bond donor to hydrogen bond acceptor is 1.4∶1;

[0144] (2) Extraction of cellulose-based thickening and stabilizing agent: Mix 100 g of deep eutectic solvent with 10 g of untreated bagasse, and stir and extract at 70 °C for 4 h;

[0145] (3) Pressure filtration and washing: Separate the extracted bagasse from the deep eutectic solvent by pressure filtration, and wash the obtained bagasse extract with clear water until the pH of the filtrate > 5;

[0146] (4) Defibrillation: Disperse the above bagasse extract by ultrasonic wave at 600 W for 30 min;

[0147] (5) Drying: Spray-dry the bagasse fibers obtained in (4), with an inlet air temperature of 180 °C, an outlet air temperature of 65 °C, and the flow rate adjusted according to the outlet air temperature. After granulation, the cellulose-based thickening and stabilizing agent is obtained.

[0148] Perform performance tests on the materials prepared in the above comparative examples, and the comparison results with Example 1 are shown in Table 7.

[0149] Table 7

[0150] Zero-shear viscosity Example 1 235 Pa·s Comparative Example 9 0.05 Pa·s Comparative Example 10 0.15 Pa·s

[0151] As can be seen from the above table analysis, when bagasse is only subjected to crushing, sieving, and steam explosion pretreatment without extraction by deep eutectic solvents, the viscosity of cellulose is very low and cannot achieve the thickening effect. This is because the pretreatment cannot fully defibrate cellulose, and there are not enough hydroxyl groups to participate in hydration and form a hydrogen bond network to contribute to viscosity. For some materials with strong intermolecular hydrogen bonding in cellulose, without pretreatment such as crushing and sieving, the accessibility of deep eutectic solvents to the materials is poor, resulting in poor treatment effects.

[0152] The component contents of the cellulose-based thickening and stabilizing agents prepared from the above partial examples and comparative examples were measured, and the results are shown in Table 8.

[0153] Table 8

[0154] Lignin content Hemicellulose content Cellulose content Ash content Bagasse 27.4±1.2％ 26.8±1.8％ 39.4±2.6％ 3.53±0.12％ Example 1 32.2±2.4％ 6.15±0.53％ 56.0±1.9％ 2.92±0.25％ Example 2 48.2±1.6％ 4.10±1.15％ 45.9±1.8％ 3.25±0.21％ Example 4 33.2±1.8％ 5.30±0.51％ 55.2±2.3％ 3.25±0.36％ Example 15 33.8±2.5％ 2.15±0.5％ 58.1±1.6％ 3.10±0.22％ Control Example 9 36.8±1.5％ 4.75±0.55％ 55.4±1.1％ 2.92±0.25％

[0155] As can be seen from the above table, the treatment methods of Examples 1-6 and Comparative Example 9 can all remove hemicellulose, but the effect of removing lignin is not good. The retention rates of the components of the deep eutectic solvents with carboxylic acids as hydrogen bond donors in Examples 1 and 4 are similar. However, the retention rate of cellulose by the deep eutectic solvent used in Example 2 is significantly reduced. In Example 15, the steam explosion pretreatment of bagasse raw materials was increased, resulting in a better removal effect of hemicellulose. Comparative Example 9 further shows that although steam explosion can remove hemicellulose and obtain a component composition similar to that of Example 1, due to the lack of defibrating cellulose by deep eutectic solvents, its thickening effect is not good.

[0156] Figure 1 SEM images (A) and partial enlarged views (B) of the bagasse raw materials used in Example 1 can be seen that the consistency of bagasse fibers is poor, which is mainly due to the cell structure characteristics during the growth of sugarcane and the existence of bagasse pith.

[0157] Figure 2 AFM image of the cellulose-based thickening and stabilizing agent after extraction in Example 1, from Figure 2 It can be seen that the cellulose in Example 1 was defibrated into fine fibers of 4-10 nm, and the links between the fine fibers were not broken. Combining the component content data of the bagasse and the cellulose-based thickening and stabilizing agent prepared in Example 1 in Table 8, it can be seen that the lignin-carbohydrate complex that was not removed may be the one connecting the fine fibers. Most of the hemicellulose in bagasse was removed and most of the lignin was retained during the treatment in Example 1. The defibrated nanofibers can provide sufficient hydrogen bond hydration to form a hydrogen bond network; while the in-situ retained lignin plays a linking role and provides a relatively large hydrodynamic radius.

[0158] Figure 3 Images of the cellulose-based thickening and stabilizing agent prepared in Example 1 after rehydration at different concentrations, from Figure 3It can be seen that the cellulose-based thickening and stabilizing agent obtained in Example 1 can form a semi-solid with strong water retention after sufficient shearing at a concentration of 2.5-5%; it can form a stable gel at a concentration of 0.5%; and it can form a highly viscous dispersion that is relatively transparent and has certain gel properties at a concentration of 0.25%.

[0159] Figure 4 This is a viscosity comparison chart of the cellulose-based thickening and stabilizing agent prepared in Example 1 of the present invention and other commercial thickening and stabilizing agents. From Figure 4 It can be seen that the viscosity of the cellulose-based thickening and stabilizing agent obtained in Example 1 is superior to that of various commercial thickening and stabilizing agents on the market at the same concentration.

[0160] Figure 5 This is a comparison chart of the fiber particle sizes of Example 1 and Example 6 of the present invention. From Figure 5 It can be seen that by adjusting the treatment temperature and time, the eutectic solvent with high water content can achieve a defibrillation effect similar to that of the eutectic solvent with low water content, so as to obtain a cellulose-based thickening and stabilizing agent with a similar degree of defibrillation.

[0161] Figure 6 This is the usage effect of the thickening and stabilizing agent prepared in Example 1. It can be seen that it has good performance in thickening, suspending, emulsifying and stabilizing.

[0162] Figure 7 These are the pictures of the dispersed solvents of the cellulose-based thickening and stabilizing agents prepared in Examples 7-9 and the measured results of the apparent viscosity. From Figure 7 It can be seen that the method for extracting cellulose-based thickening and stabilizing agents with eutectic solvents in the present invention has universality in biomass treatment.

[0163] Figure 8 This is the comparison of the fiber particle sizes of Example 15 and Control Example 9 ( Figure 8 A) and the apparent morphology diagram of Control Example 9 ( Figure 8 B). From Figure 8 the results in Table 6 and Table 7, it can be seen that compared with the pure steam explosion treatment extraction in Control Example 9, the eutectic solvent treatment in Example 15 is the key for the fiber to obtain high viscosity and high degree of defibrillation.

[0164] In summary, the preparation method of the cellulose-based thickening and stabilizing agent extracted with eutectic solvents in the present invention has low requirements for the consistency of raw materials, has a defibrillation effect on both long fibers and fine fibers, and can also play a thickening effect under a wide range of particle size conditions. Therefore, it has universality in the comprehensive utilization of cellulose-based biomass. This method is simple and easy to operate, can efficiently defibrillate cellulose in the presence of lignin, and avoids the possible pollution caused by other chemical methods for removing lignin, and has better environmental protection.

[0165] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a cellulose-based thickening stabilizer extracted by a deep eutectic solvent, characterized in that: include, A hydrogen bond donor, a hydrogen bond acceptor and water are mixed and heated to prepare a low eutectic solvent; the low eutectic solvent is mixed with a cellulose raw material and heated for extraction; the extracted cellulose raw material is subjected to pressure filtration, washing, suction filtration, defibration and drying to obtain a cellulose-based thickening stabilizer.

2. The method for preparing a cellulose-based thickening stabilizer extracted by a deep eutectic solvent according to claim 1, characterized in that: The hydrogen bond donor includes one or more of amino compounds, monovalent or higher carboxylic acids, monovalent or higher alcohol compounds, or compounds containing both amino groups and carboxyl groups; the hydrogen bond acceptor includes one or more of ammonium chloride, sodium chloride, and choline chloride.

3. The method for preparing a cellulose-based thickening stabilizer extracted by a deep eutectic solvent according to claim 2, characterized in that: The amino compound includes urea; the monovalent or higher carboxylic acids include acetic acid, oxalic acid, citric acid, tartaric acid, lactic acid, malic acid, and phenylacetic acid; the monovalent or higher alcohol compounds include glycerol, ethylene glycol, and propylene glycol; the compound containing both amino and carboxyl groups includes glycine and glutamic acid.

4. The method for preparing a cellulose-based thickening stabilizer extracted by a deep eutectic solvent according to claim 2, characterized in that: The molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:11 to 11:1; and the added amount of water is 0 to 80% of the total mass of the low eutectic solvent.

5. The method for preparing a cellulose-based thickening stabilizer extracted by a deep eutectic solvent according to claim 1, characterized in that: The cellulose raw material is a cellulose-based biomass raw material with a cellulose content greater than 20%, including one or more of pretreated straw, bagasse, wood powder, corn cobs, fruit peels, and plant stems; The pretreatment comprises one or more of crushing, screening, high-pressure steam explosion, microwave pretreatment, hot water pretreatment, lignin peroxidase or laccase pretreatment, and acid pretreatment.

6. The method for preparing a cellulose-based thickening stabilizer extracted by a deep eutectic solvent according to claim 1, characterized in that: The temperature of the heating extraction is 30-300° C., the extraction time is 0.1-480 hours, and the mass ratio of the cellulose raw material to the low eutectic solvent is 1:100-2:

1.

7. The method for preparing a cellulose-based thickening stabilizer extracted by a deep eutectic solvent according to claim 6, characterized in that: The heating extraction temperature is 50-150° C., the extraction time is 0.5-48 hours, and the mass ratio of the cellulose raw material to the low eutectic solvent is 1:

10.

8. The method for preparing a cellulose-based thickening stabilizer extracted by a deep eutectic solvent according to claim 1, characterized in that: The defibration method includes one or more of ultrasound, microwave, homogenization, emulsification, and grinding; the drying method includes one or more of drum drying, spray drying, freeze drying, and microwave drying.

9. A cellulose-based thickening stabilizer extracted from a deep eutectic solvent prepared by the method of any one of claims 1 to 8, characterized in that: In terms of weight percentage, it includes: Cellulose 20-100%, lignin 0-50%, hemicellulose 0-20%, ash 0-5%, other polysaccharides 0-50%.

10. A use of a cellulose-based thickening stabilizer extracted from a deep eutectic solvent as claimed in claim 9, characterized in that: The viscosity of the cellulose-based thickening stabilizer is 39.6-235 Pa·s; the cellulose-based thickening stabilizer can also be compounded with other polysaccharides or colloids to enhance the application effect.

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