Biomass nanofiber and preparation method thereof
By using sodium chlorite-glacial acetic acid solution treatment and mechanical defibrillation during the preparation of nanocellulose, combined with the electrostatic repulsion of pectin and hemicellulose components, the problem of poor redispersibility of nanocellulose was solved, and nanocellulose with high aspect ratio and excellent redispersibility was prepared.
Patent Information
- Application Number
- CN202511254846.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-04
- Publication Date
- 2025-11-07
AI Technical Summary
In existing technologies, nanocellulose exhibits poor redispersibility, is prone to agglomeration, and lacks synergistic effects among non-cellulose components.
The original fiber samples were treated with a sodium chlorite-glacial acetic acid solution at 60-70℃, and then mechanically defibriled to prepare biomass nanofibers. The pectin and hemicellulose components were retained, and their electrostatic repulsion on the surface of the nanocellulose was used to inhibit agglomeration.
It improves the redispersibility of nanocellulose, reduces production costs, maintains the original structure, obtains nanocellulose with a high aspect ratio, inhibits agglomeration, and enhances material properties.
Smart Images
Figure CN120905933A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of nanocellulose, in particular to a biomass nanofiber and a preparation method thereof. BACKGROUND
[0002] Uniformly dispersed nanocellulose can form a "uniform stress network" through intermolecular or intermatrix interaction. For example, in a composite material, well-dispersed nanocellulose can uniformly bear external force as a "nanoscale reinforcing unit", significantly improving the tensile strength, elastic modulus, etc. of the material; and agglomerates will become "weak points" in the material, which not only cannot be reinforced, but also can cause the material to be prone to breakage due to stress concentration.
[0003] Nanocellulose with good dispersibility can be flexibly adapted to different processing systems (such as aqueous phase, organic phase, molten polymer, etc.). For example, in an aqueous phase system (such as preparing a water-based coating), uniformly dispersed nanocellulose can form a stable colloidal solution, which is convenient for construction by coating, spraying, etc.; in an organic phase or polymer melting system (such as preparing a plastic-based composite material), well-dispersed nanocellulose can be fully mixed with the matrix, avoiding the problem of "local incompatibility" caused by agglomeration.
[0004] In the prior art, nanocellulose containing hemicellulose is prepared from bamboo fibers, and it is found that the presence of hemicellulose can endow nanocellulose with certain redispersion performance. After redispersion, the particle size of nanocellulose increases from 15 nm to 100 nm, and partial agglomeration occurs.
[0005] In the above-mentioned nanocellulose preparation technology containing non-cellulose components, the following common problems exist: the redispersion performance of nanofiber needs to be further improved; and the non-cellulose components do not form a synergistic effect. SUMMARY
[0006] The present application aims to overcome the above technical deficiencies, and provides a biomass nanofiber and a preparation method thereof, which solve the technical problems of poor redispersion and easy agglomeration of nanofiber in the prior art.
[0007] To achieve the above technical purpose, the technical scheme of the present application provides a preparation method of a biomass nanofiber, comprising the following steps: soaking the fibers as they are in a sodium chlorite-glacial acetic acid solution at 60-70℃ for treatment, and then obtaining the biomass nanofiber through mechanical defibration.
[0008] In any embodiment, the mass concentration of sodium chlorite in the sodium chlorite-glacial acetic acid solution is 3-4wt%, and the mass concentration of glacial acetic acid is 2-3wt%.
[0009] In any embodiment, the treatment time is 12-15 hours.
[0010] In any embodiment, the sodium chlorite and the glacial acetic acid are supplemented every 4-5 hours during the treatment process.
[0011] In any embodiment, the amount of sodium chlorite supplemented each time is 3-4wt% of the mass of the sodium chlorite-glacial acetic acid solution, and the amount of glacial acetic acid supplemented each time is 2-3wt% of the mass of the sodium chlorite-glacial acetic acid solution.
[0012] In any embodiment, the fiber sample is prepared by the following steps: stripping the fiber from the fiber crop, rinsing with water and drying, cutting the dried sample to 1-2cm to obtain the fiber sample.
[0013] In any embodiment, the fiber crop is one or more of ramie, flax, kenaf, jute, industrial hemp and Russian hemp.
[0014] In any embodiment, the mechanical defiberization is one or more of high-pressure homogenization, grinding, extrusion, high-speed shearing, ultrasonic treatment, steam explosion and ball milling.
[0015] In any embodiment, before the fiber sample is immersed in the sodium chlorite-glacial acetic acid solution at 60-70°C for treatment, the fiber sample is further immersed in boiling water for treatment, then immersed in an ammonium oxalate solution for treatment, and then immersed in a sodium carbonate solution for treatment.
[0016] In any embodiment, the fiber sample is immersed in boiling water for 4-5h for treatment; and / or, the fiber sample is further immersed in the ammonium oxalate solution for 24-26h for treatment; and / or, the fiber sample is further immersed in the sodium carbonate solution for 24-26h for treatment; and / or, the concentration of the ammonium oxalate solution is 50-55mmol / L; and / or, the concentration of the sodium carbonate solution is 50-55mmol / L.
[0017] In addition, the present application also provides a biomass nanofiber prepared by the above preparation method.
[0018] Compared with the prior art, the present application has the beneficial effects including: the fiber is soaked in a sodium chlorite-glacial acetic acid solution at 60-70 DEG C for treatment, and then mechanically defibrillated to obtain biomass nanofiber, and high aspect ratio nanofiber containing pectin and hemicellulose is obtained. The softening of the dense structure of the plant cell wall by delignification treatment improves the defibrillation efficiency of the biomass fiber, and high aspect ratio nanocellulose is obtained. Strong steric hindrance is formed during the drying process of the nanofiber, which inhibits the agglomeration of the nanocellulose; the residual pectin component and hemicellulose component both contain carboxyl groups, which are attached to the surface of the nanocellulose, and strong electrostatic repulsion is formed during the drying process of the nanofiber, which further inhibits the agglomeration of the nanocellulose. The process of the present application is simple and environmentally friendly, greatly reduces the production cost of nanocellulose, retains the original structure of nanocellulose, and at the same time endows the nanofiber with excellent redispersion performance. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 is a schematic diagram of the redispersion of biomass nanofiber of the present application.
[0020] Figure 2 is an atomic force microscope (AFM) image of the nanofiber prepared in Example 1, Example 3 and each of the comparative examples.
[0021] Figure 3 is a photo of the 0-day sample of the redispersed nanofiber suspension of Example 1, Example 3 and each of the comparative examples.
[0022] Figure 4 is a photo of the 30-day sample of the redispersed nanofiber suspension of Example 1, Example 3 and each of the comparative examples. DETAILED DESCRIPTION
[0023] "RANGES" disclosed herein are defined, for each range by its upper and lower limit, as an amount that can be "greater than (or greater than or equal to) " (or "less than" (or "less than or equal to")) that lim it. It is specifically intended that the descriptions set forth herein include "gaps", unless otherwise indicated. For example, a description of "a range between 60 and 120" is specifically intended to include "60 to 70", "70 to 80", "80 to 90", "90 to 100", "100 to 110", "110 to 120", etc. In other words, other genera tions of "a range between 60 and 120" are also intended in this disclosure. Furthermore, other ranges such as "less than 120" or "greater than 60", are intended to include the "gaps", as would be interpreted by one skilled in the art. For example, a range of "less than 120" is specifically intended to include less than 60, less than 80, less than 100, less than 120, etc. In other words, other genera tions of "less than 120" are also intended in this disclosure. Moreover, although versions have been described with certain types of components, compositions, or methods, other versions can employ adjunct components, other compositions, or other methods, and certain therapeutics can have different uses. Note that, as used in this application, "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless specified otherwise, or clear from context, "X employs A or B" means that X employs A or B or both. Further, unless expressly stated to the contrary, "a or an" means "one or more" and "at least one", and "one", "an", and "the" means "at least one" and / or "one or more".
[0024] The terms "comprise", "comprising", "include", "including", "contain", "containing", "have", "having", "maintain", "maintaining", "carry", "carrying", "hold", "holding", "provide", "providing", "carry", "carrying", "hold", "holding", "provide", "providing" and the like are open-ended, and each of the terms are intended to mean that the named item is necessarily present, but that other items can also be present, unless otherwise indicated.
[0025] The term "or" is inclusive, meaning and / or, unless otherwise indicated. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following satisfy the condition "A or B": A is true (or present) and B is false (or not present); A is false (or not present) and B is true (or present); or both A and B are true (or present).
[0026] The embodiment provides a preparation method of biomass nanofiber, comprising the following steps: soaking the fiber in a sodium chlorite-glacial acetic acid solution at 60-70 DEG C for 12-15 hours, and then mechanically defibrating to obtain the biomass nanofiber; the mass concentration of sodium chlorite in the sodium chlorite-glacial acetic acid solution is 3-4 wt%, and the mass concentration of glacial acetic acid is 2-3 wt%.
[0027] In some embodiments, during the treatment process, the sodium chlorite and the glacial acetic acid are supplemented every 4-5 hours; the amount of sodium chlorite supplemented each time is 3-4 wt% of the mass of the sodium chlorite-glacial acetic acid solution, and the amount of glacial acetic acid supplemented each time is 2-3 wt% of the mass of the sodium chlorite-glacial acetic acid solution.
[0028] In some embodiments, the fiber is prepared by the following steps: stripping the fiber from the fiber crop, rinsing with water and drying, cutting the dried sample to 1-2 cm to obtain the fiber as is; the fiber crop is preferably one or more of ramie, flax, kenaf, jute, industrial hemp and Russian hemp.
[0029] In some embodiments, the mechanical defibrillation is one or more of high-pressure homogenization, grinding, extrusion, high-speed shearing, ultrasonic treatment, steam explosion and ball milling.
[0030] In some embodiments, before the fiber as is is soaked in a sodium chlorite-glacial acetic acid solution at 60-70℃ for treatment, the fiber as is is further soaked in boiling water for 4-5h, then soaked in an ammonium oxalate solution for 24-26h, and then soaked in a sodium carbonate solution for 24-26h; the concentration of the ammonium oxalate solution is 50-55mmol / L; the concentration of the sodium carbonate solution is 50-55mmol / L.
[0031] The specific embodiment further provides a biomass nanofiber prepared by the above preparation method.
[0032] In combination Figure 1 , the biomass nanofiber provided by the present application contains pectin, and the pectin component contains a large number of carboxyl groups, which are adsorbed on the surface of nanocellulose together with hemicellulose to synergistically provide strong electrostatic repulsion to inhibit the agglomeration of nanocellulose; after mild delignification pretreatment and mechanical defibrillation, the aspect ratio of nanocellulose reaches 200 or more, and strong steric hindrance is formed during the drying of nanofiber to inhibit the agglomeration of nanocellulose, thereby improving the redispersion of nanofiber.
[0033] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.
[0034] In the present application, "some embodiments", "the present embodiment" and the like are described, which describe a subset of all possible embodiments, but it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict.
[0035] If the application file contains similar descriptions of "first / second", the following description is added. In the following description, the terms "first / second / third" are only used to distinguish similar objects, and do not represent a specific order of the objects. Understandably, "first / second / third" can be interchanged in a specific order or sequence as allowed, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.
[0036] In this embodiment, the term "and / or" is only used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, object A and / or object B, which means that object A exists alone, object A and object B exist together, and object B exists alone.
[0037] The following describes the embodiments of the present application. The embodiments described below are exemplary and are used only to explain the present application and cannot be understood as limiting the present application. If the specific technology or condition is not specified in the embodiments, it is performed according to the technology or condition described in the literature in the art or according to the product manual. If the reagent or instrument used is not specified by the manufacturer, it is a conventional product that can be obtained from the market.
[0038] Embodiment 1
[0039] The present embodiment proposes a biomass nanofiber, which is prepared by the following steps:
[0040] The kenaf fibers are stripped from the kenaf stems, washed with tap water, and then dried at 45°C. The dried sample is cut to 1-2 cm to obtain a kenaf raw sample;
[0041] The kenaf raw sample is treated with a sodium chlorite-glacial acetic acid solution at 70°C for 12h (3wt% sodium chlorite and 2wt% glacial acetic acid are added every 4h, a total of three times). The mass concentration of sodium chlorite in the sodium chlorite-glacial acetic acid solution is 3wt%, and the mass concentration of glacial acetic acid is 2wt%. The lignin component in the kenaf raw sample is removed to obtain a kenaf fiber containing pectin and hemicellulose.
[0042] Embodiment 2
[0043] The present embodiment proposes a biomass nanofiber, which is prepared by the following steps:
[0044] The kenaf fibers are stripped from the kenaf stems, washed with tap water, and then dried at 45°C. The dried sample is cut to 1-2 cm to obtain a kenaf raw sample;
[0045] The kenaf fiber containing hemicellulose is obtained by removing the pectin and lignin components in the kenaf fiber of the kenaf raw sample through the following steps: treating the kenaf raw sample with a 65℃ sodium chlorite-glacial acetic acid solution for 12h (adding 4wt% sodium chlorite and 3wt% glacial acetic acid every 4h for a total of three times), wherein the mass concentration of sodium chlorite in the sodium chlorite-glacial acetic acid solution is 4wt%, and the mass concentration of glacial acetic acid is 3wt%.
[0046] Example 3
[0047] The present example proposes a biomass nanofiber, which is prepared by the following steps:
[0048] The kenaf fiber is stripped from the kenaf stem, washed with tap water, and then dried at 40℃. The dried sample is cut to 1-2cm to obtain a kenaf raw sample.
[0049] The kenaf raw sample is treated with 100℃ boiling water for 4h, then soaked in 50mmol / L ammonium oxalate solution at room temperature for 24h, and then soaked in 50mmol / L sodium carbonate solution at room temperature for 24h. Then, the kenaf raw sample is treated with a 70℃ sodium chlorite-glacial acetic acid solution for 12h (adding 3wt% sodium chlorite and 2wt% glacial acetic acid every 4h for a total of three times), wherein the mass concentration of sodium chlorite in the sodium chlorite-glacial acetic acid solution is 3wt%, and the mass concentration of glacial acetic acid is 2wt%. The kenaf fiber containing hemicellulose is obtained by removing the pectin and lignin components in the kenaf fiber of the kenaf raw sample.
[0050] Comparative Example 1
[0051] The present example proposes a biomass nanofiber, which is prepared by the following steps:
[0052] The kenaf fiber is stripped from the kenaf stem, washed with tap water, and then dried at 45℃. The dried sample is cut to 1-2cm to obtain a kenaf raw sample.
[0053] The kenaf raw sample is treated with 100℃ boiling water for 4h, 50mmol / L ammonium oxalate solution at room temperature for 24h, and 50mmol / L sodium carbonate solution at room temperature for 24h. The kenaf fiber containing lignin and hemicellulose is obtained by removing the pectin component in the kenaf raw sample.
[0054] Comparative Example 2
[0055] The present example proposes a biomass nanofiber, which is prepared by the following steps:
[0056] Comparative Example 3
[0057] The comparative example uses Kenaf as raw material for comparison.
[0058] Comparative Example 4
[0059] The comparative example uses Whatman No. 1 filter paper as pure cellulose fiber for comparison.
[0060] The different Kenaf fibers of the examples and comparative examples, Kenaf as raw material and pure cellulose fiber were dispersed in purified water (0.5% by mass) respectively, and then the suspension was ball milled (ball-to-material ratio 2.5:1) at a speed of 1100 r / min for 1.5 h using a ball mill. The mixture obtained by ball milling was diluted to 0.2% by mass with purified water, and then homogenized 15 times at a pressure of 70 MPa using a high-pressure homogenizer to obtain a nanofiber suspension.
[0061] The polysaccharide components in the samples were analyzed by high-performance liquid chromatography and the lignin components in the samples were determined by ultraviolet-visible spectrophotometry according to the standard method of the U.S. National Renewable Energy Laboratory (NREL / TP-510-42618). The chemical compositions of the different nanofibers obtained are shown in Table 1 below.
[0062] Table 1 Composition of nanofibers obtained in each example and comparative example
[0063] Sample Cellulose Hemicellulose Pectin Lignin Example 1 74.57％ 17.42％ 5.80％ 2.21％ Example 2 75.71％ 16.12％ 5.3％ 2.87％ Example 3 78.93％ 19.57％ 0.61％ 0.89％ Comparative Example 1 67.27％ 18.10％ 2.33％ 12.30％ Comparative Example 2 74.57％ 17.42％ 5.80％ 2.21％ Comparative Example 3 63.04％ 17.27％ 6.47％ 13.22％ Comparative Example 4 99.07％ 0.93％ 0 0
[0064] From Figure 2 It can be seen that the nanofibers obtained in Example 1, Example 3 and each comparative example exhibit different distribution states; the sizes of the different nanofibers are shown in Table 2 below. The Kenaf nanofibers containing pectin and / or hemicellulose obtained in Example 1 and Example 3 have the largest aspect ratio (241-265), the aspect ratio of the pure cellulose nanofibers of Comparative Example 4 is second (122), and the aspect ratios of the Kenaf nanofibers containing lignin of Comparative Example 1, the mixed nanofibers of Comparative Example 2 and the Kenaf nanofibers as raw material of Comparative Example 3 are lower (22-50).
[0065] Table 2 Size of nanofibers obtained in each example and comparative example
[0066] Sample Average particle size Average length Aspect ratio Example 1 5.39 nm 1.30 μm 241 Example 3 5.40 nm 1.43 μm 265 Comparative Example 1 6.22 nm 0.31 μm 50 Comparative Example 2 6.35 nm 0.25 μm 39 Comparative Example 3 6.41 nm 0.14 μm 22 Comparative Example 4 10.53 nm 1.28 μm 122
[0067] The nanofiber suspensions obtained in Example 1, Example 3 and Comparative Examples 1-4 were centrifuged at a speed of 10,000 rpm for 5 minutes, and then the supernatant was carefully removed. The concentrated nanofiber suspension was poured into a glass culture dish and vacuum dried at 60°C to a constant weight. After drying, the nanofibers were immersed in purified water for 24 hours, and then stirred using a high-speed blender at 26,000 revolutions per minute for 1 minute to obtain a redispersed nanofiber suspension.
[0068] From Figure 3 and4 It can be seen that the red hemp nanofiber containing pectin and hemicellulose prepared in Example 1 has the best redispersion effect, the red hemp nanofiber containing hemicellulose prepared in Example 3 has the second best redispersion effect, the red hemp nanofiber containing lignin in Comparative Example 1, the mixed nanofiber in Comparative Example 2, the red hemp nanofiber as original sample in Comparative Example 3 and the pure cellulose nanofiber in Comparative Example 4 all have poor redispersion.
[0069] In combination with the data in Tables 1 and 2 and the results of Figures 2-4 It can be seen that only when both the conditions of containing sufficient pectin component and having sufficient aspect ratio are met, the biomass nanofiber with good redispersion can be obtained. In addition, the biomass nanofiber with good redispersion cannot be obtained by simply mixing pectin and hemicellulose components in nanocellulose, and the original pectin and hemicellulose components need to be retained in the process of preparing nanocellulose.
[0070] The specific embodiments of the present application described above do not constitute a limitation on the protection scope of the present application. Any various other corresponding changes and modifications made according to the technical concept of the present application shall be included in the protection scope of the claims of the present application.
Claims
1. A method for preparing biomass nanofibers, characterized by, The method comprises the following steps: treating the fiber in a sodium chlorite-glacial acetic acid solution at 60-70 DEG C, and then mechanically defibrating the fiber to obtain the biomass nanofiber.
2. The method for preparing biomass nanofibers according to claim 1, characterized in that, The mass concentration of sodium chlorite in the sodium chlorite-glacial acetic acid solution is 3-4 wt%, and the mass concentration of glacial acetic acid is 2-3 wt%; and / or, the treatment time is 12-15 hours.
3. The method for preparing biomass nanofibers according to claim 1, characterized in that, During the treatment, sodium chlorite and glacial acetic acid are added every 4-5 hours.
4. The method for preparing biomass nanofibers according to claim 3, characterized in that, The amount of sodium chlorite added each time is 3-4 wt% of the mass of the sodium chlorite-glacial acetic acid solution, and the amount of glacial acetic acid added each time is 2-3 wt% of the mass of the sodium chlorite-glacial acetic acid solution.
5. The method for preparing biomass nanofibers according to claim 1, characterized in that, The fiber is obtained by the following steps: stripping the fiber from a fiber crop, rinsing the fiber with water, drying the fiber, cutting the dried fiber to 1-2 cm, and obtaining the fiber sample.
6. The method for preparing biomass nanofibers according to claim 5, characterized in that, The fiber crop is one or more of ramie, flax, kenaf, jute, industrial hemp, and Russian hemp.
7. The method for preparing biomass nanofibers according to claim 1, characterized in that, The mechanical defibrating includes one or more of high-pressure homogenization, grinding, extrusion, high-speed shearing, ultrasonic treatment, steam explosion, and ball milling.
8. The method for preparing biomass nanofibers according to claim 1, characterized in that, Before the fiber sample is treated in the sodium chlorite-glacial acetic acid solution at 60-70 DEG C, the fiber sample is also treated in the following steps: treating the fiber sample in boiling water, then treating the fiber sample in an ammonium oxalate solution, and then treating the fiber sample in a sodium carbonate solution.
9. The method for preparing biomass nanofibers according to claim 8, characterized in that, The fiber sample is treated in boiling water for 4-5 hours; and / or, the fiber sample is treated in the ammonium oxalate solution for 24-26 hours; and / or, the fiber sample is treated in the sodium carbonate solution for 24-26 hours; and / or, the concentration of the ammonium oxalate solution is 50-55 mmol / L; and / or, the concentration of the sodium carbonate solution is 50-55 mmol / L.
10. A biomass nanofiber, characterized by, The biomass nanofiber is prepared by the method of any one of claims 1-9.