Bamboo carbon fiber and preparation method thereof

Abstract

The invention provides a bamboo carbon fiber and a preparation method thereof. The preparation method comprises the following steps: raw material pretreatment: processing mature phyllostachys pubescens into the diameter of 1t; the length is gt; the bamboo filaments with the thickness of 500 mm are aired, so that the water content of the bamboo filaments is reduced to 10% or below; chemical treatment: removing impurities and softening cell walls by sequentially using an acid solution and an alkali solution and cooking at the temperature of 100-200 DEG C; drying: controlling the moisture content to be 1t; 3%; pre-oxidation: breaking cell walls at 150-200 DEG C, and removing organic matters and crystal water; atmosphere protection treatment: introducing inert gas and iodine vapor in sequence at the temperature of 200-300 DEG C to complete pre-oxidation; gradient heating carbonization: the room temperature is 150 DEG C, the temperature is 5 DEG C / min, and the temperature is maintained for 1-2 h The temperature is 2000-2400 DEG C, the speed is 10 DEG C / min, and the temperature is Keeping the temperature at 2400-3000 DEG C at 15 DEG C / min for 1-2 hours, and carrying out high-temperature carbonization treatment; and graphitizing: graphitizing at the temperature of between 3000 and 3200 DEG C for 0.5 to 2 hours. According to the method, low-cost and high-performance preparation of the bamboo carbon fiber is realized, and the method has economical efficiency, functionality and environmental friendliness and has a wide market application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon fiber, and specifically to a bamboo carbon fiber and a preparation method thereof. Background Art

[0002] Traditional carbon fibers are made from petroleum-based materials such as polyacrylonitrile and pitch, which have problems such as high consumption of non-renewable resources and high costs. Although biomass fibers (such as bamboo pulp fibers) have received attention as alternative materials, the large-scale application of bamboo charcoal fibers is still limited due to complex preparation processes and low market recognition. Moso bamboo has advantages such as a short growth cycle and strong carbon sequestration ability, but the technology for its efficient conversion into carbon fiber is not yet mature. The present invention aims to achieve the efficient preparation of moso bamboo-based bamboo charcoal fibers and improve their mechanical properties by optimizing process parameters to replace traditional carbon fibers. Summary of the Invention

[0003] In view of the above problems, the present invention provides a preparation method of highly environmentally friendly bamboo carbon fiber using moso bamboo as the raw material. By optimizing process parameters, the efficient conversion of bamboo components is achieved, and high-performance and low-cost bamboo carbon fibers are obtained to replace traditional petroleum-based carbon fibers and meet the requirements of industrial production.

[0004] The technical solution of the present invention:

[0005] The present invention provides a preparation method of bamboo carbon fiber, including the following steps: Raw material pretreatment: Process mature moso bamboo into bamboo filaments with a diameter <1 mm and a length >500 mm, and then air-dry to reduce the moisture content of the bamboo filaments to less than 10%; Chemical treatment: Sequentially use acid solution, alkali solution, and cook at 100-200°C to remove impurities and soften the cell wall; Drying: Control the moisture content <3%; Pre-oxidation: Break the cell wall at 150°C-200°C to remove organic matter and crystal water; Atmosphere protection treatment: Successively introduce inert gas and iodine vapor at 200°C-300°C to complete pre-oxidation; Gradient heating carbonization: Room temperature-150°C, 5°C / min, hold for 1-2 h; 2000-2400°C, 10°C / min, hold for 1-2 h; 2400°C-3000°C, 15°C / min, hold for 1-2 h for high-temperature carbonization treatment; Graphitization: Graphitize at 3000°C-3200°C for 0.5-2 h to obtain bamboo carbon fiber.

[0006] According to an embodiment of the present invention, the preparation process of the bamboo filaments is as follows: Take mature moso bamboo, cut the bamboo with a bamboo splitting machine, then cut the bamboo into thin slices with a slicing machine, then cut the bamboo into pieces with a length greater than 500 mm with a bamboo sawing machine, and then draw the bamboo into bamboo filaments with a diameter less than 1 mm with a bamboo strip wire drawing machine.

[0007] According to an embodiment of the present invention, the acid solution is a hydrochloric acid solution with a concentration of 1-2 mol / L.

[0008] According to an embodiment of the present invention, the alkali solution is a sodium carbonate solution with a concentration of 1 to 2 mol / L.

[0009] According to an embodiment of the present invention, the drying process is drying in a dryer at 80 °C for 1 to 3 h.

[0010] According to an embodiment of the present invention, in the pre-oxidation process, the cell walls are first broken in a vertical furnace in air to remove organic substances and crystal water, and then an inert gas and iodine vapor are respectively applied in the vertical furnace for pre-oxidation for 1.5 to 2.5 h.

[0011] According to an embodiment of the present invention, the gradient heating carbonization is carried out in a vertical furnace.

[0012] According to an embodiment of the present invention, the graphitization is carried out in a vertical furnace.

[0013] The present invention also provides a bamboo carbon fiber, which is made by using the bamboo carbon fiber preparation method of the above embodiment.

[0014] According to an embodiment of the present invention, the tensile strength ≥ 300 MPa.

[0015] The bamboo carbon fiber preparation method described in the present invention has the following remarkable beneficial effects:

[0016] I. Raw material advantages and efficient conversion

[0017] Renewable resource utilization: Using mature bamboo as raw material, bamboo, as a fast-growing renewable biomass resource, has the characteristics of large quantity and extremely low cost. It solves the resource limitation of traditional polyacrylonitrile-based carbon fibers relying on petrochemical raw materials from the source, and conforms to the concept of green environmental protection and sustainable development.

[0018] Component purification and high carbon yield: Through raw material pretreatment (bamboo filament specification control, drying in the sun), chemical treatment (removing impurities with acid and alkali solutions, softening cell walls by high-temperature cooking), and multi-stage heat treatment (pre-oxidation, gradient carbonization, graphitization), the cellulose, hemicellulose, and lignin rich in bamboo can be efficiently converted into carbon fibers, and the carbon yield exceeds 80%, which is equivalent to the carbon content of petroleum-based polyacrylonitrile carbon fibers, realizing the deep utilization of biomass resources.

[0019] II. Simple process and low-cost production

[0020] Process optimization and equipment compatibility: The entire preparation process only includes drying, oxidation, high-temperature carbonization, and graphitization treatments, without the need for complex equipment or special reagents (only using conventional chemical raw materials such as hydrochloric acid and sodium carbonate), with low requirements for production equipment, a simple and controllable process route, significantly reducing equipment investment and energy consumption costs, and being suitable for large-scale industrial production.

[0021] Outstanding cost advantage: The economy of raw materials and treatment reagents combined with a simple process makes the cost of synthetic bamboo carbon fiber much lower than that of traditional carbon fiber, laying a cost foundation for its large-scale application in fields such as aerospace, automotive manufacturing, and sports equipment.

[0022] III. Excellent performance and structural improvement

[0023] Excellent mechanical properties: The prepared bamboo carbon fiber exhibits excellent mechanical properties, with a tensile strength exceeding 300 MPa, and both impact toughness and hardness being more than 10 times higher than those of natural wood, meeting the application requirements of high-strength materials.

[0024] Improved thermal and electrical conductivity: Graphitization treatment increases the fiber strength and modulus by more than 20%, significantly improves the crystallinity, and densifies the layered structure, not only enhancing the electrical conductivity but also indirectly improving the heat resistance due to the formation of a large number of aromatic rings in the crystal structure, broadening the application scope of the material in high-temperature and conductive scenarios.

[0025] Ordered regulation of carbon structure: Raman tests show that with the increase in temperature, the carbon structure of bamboo carbon fiber gradually transforms from disordered to short-range ordered and long-range ordered, achieving a controllable transformation from biomass carbon to high-order carbon fiber, providing a process path for precisely regulating the material properties.

[0026] IV. Environmental protection and sustainability

[0027] No harmful pollutant emissions during the entire preparation process, the chemical treatment reagents can be recycled, and renewable biomass is used as the raw material, reducing the dependence on fossil resources from the source, conforming to the trend of green manufacturing, and having significant environmental and social benefits.

[0028] V. Step-by-step synergy

[0029] By pre-treating the raw materials, the water content of the bamboo filaments is reduced to less than 10%, ensuring the effectiveness of subsequent chemical treatments; the acid solution and alkali solution in the chemical treatment step remove impurities and soften the cell walls, while the cooking process further removes impurities and softens the tissue structure. The subsequent drying step controls the moisture content to less than 3%, ensuring the stable progress of subsequent treatments. The pre-oxidation process breaks the cell walls under high-temperature conditions, removes organic matter and crystal water, and enhances the conversion efficiency of cellulose. The inert gas and iodine vapor in the atmosphere protection treatment protect the fibers at high temperature and promote their full oxidation. The gradient heating carbonization and graphitization treatments gradually increase the temperature by means of gentle heating and maintaining a certain time to ensure the complete conversion of bamboo filaments into carbon fibers, and graphitization treatment is carried out at 3000 °C - 3200 °C to improve the crystallinity and make the layered structure more compact. Through these process treatments, the bamboo carbon fiber obtains a tensile strength, impact toughness and hardness far higher than those of natural wood, while the strength, modulus and electrical conductivity are significantly improved, and the heat resistance is also enhanced. In terms of the working principle, the entire treatment process works synergistically to jointly improve the mechanical properties, thermal stability and electrical properties of the bamboo carbon fiber, realizing the efficient conversion of cellulose, hemicellulose and lignin in Moso bamboo.

[0030] In summary, through raw material innovation, process optimization and structure regulation, the present invention realizes the low-cost and high-performance preparation of bamboo carbon fiber, which has economy, functionality and environmental protection, and has broad market application prospects. Description of the Drawings

[0031] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but should not constitute a limitation to the present invention. In the drawings:

[0032] Figure 1 It is the first SEM image of the bamboo carbon fiber in Example 1;

[0033] Figure 2 It is the second SEM image of the bamboo carbon fiber in Example 1;

[0034] Figure 3 It is the third SEM image of the bamboo carbon fiber in Example 1;

[0035] Figure 4 It is the fourth SEM image of the bamboo carbon fiber in Example 1;

[0036] Figure 5 It is the fifth SEM image of the bamboo carbon fiber in Example 1;

[0037] Figure 6 It is the sixth SEM image of the bamboo carbon fiber in Example 1;

[0038] Figure 7The seventh SEM image of the bamboo carbon fiber in Example 1;

[0039] Figure 8 The eighth SEM image of the bamboo carbon fiber in Example 1. Specific Embodiments

[0040] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0041] Example 1

[0042] The method for preparing the bamboo carbon fiber of the present invention includes the following steps:

[0043] Step 1: Pretreatment of biomass bamboo. First, wash the bamboo repeatedly with clean water to remove the sediment and impurities on the surface. Then, perform trimming treatment to adjust its length and diameter. Process the mature bamboo into bamboo filaments with a diameter < 1 mm and a length > 500 mm, and then perform drying treatment to reduce the moisture content of the bamboo filaments to less than 10%.

[0044] Step 2: Subject the bamboo filaments obtained in Step 1 to acid, alkali, and high-temperature cooking treatments successively and then perform drying, controlling the moisture content < 3%. The length of the dried bamboo fiber is between 1 mm and 10 mm.

[0045] Step 3: Place the precursor obtained in Step 2 in a vertical furnace. Break the cell wall at 150 °C to remove organic matter and crystal water; at 200 °C, first introduce an inert gas argon atmosphere for protection and then add iodine to improve the catalytic performance, and then pre-oxidize for 2 h. Subsequently, raise the temperature in the vertical furnace and heat in gradients: room temperature - 150 °C, 5 °C / min, hold for 1 h; 2000 - 2400 °C, 10 °C / min, hold for 1 h; 2400 °C - 3000 °C, 15 °C / min, hold for 1 h, and perform high-temperature carbonization treatment. Then heat up to 3000 °C at 40 °C / min and hold for 1 h for graphitization treatment. Obtain carbon fibers with an average diameter of 16 microns, thick and long.

[0046] Through testing and calculation by a universal testing machine, the tensile strength of the bamboo carbon fiber is 300 MPa; the impact toughness is 11.19 ± 0.5 J / cm -3 More than 10 times higher than natural wood; the hardness is 8454 ± 263.5 pounds per inch, more than 10 times higher than natural wood.

[0047] Example 2

[0048] The method for preparing the bamboo carbon fiber of the present invention includes the following steps:

[0049] Steps 1 and 2 are the same as those in Example 1.

[0050] Step 3: Place the precursor obtained in Step 2 in a vertical furnace. Break the cell wall at 160 °C to remove organic substances and crystal water. First, introduce inert gas argon for atmosphere protection at 220 °C, then add iodine to improve the catalytic performance, and subsequently pre-oxidize for 1.5 h. Then, heat up in the vertical furnace with gradient heating: room temperature - 150 °C, at a rate of 5 °C / min, hold for 1.5 h; 2000 - 2400 °C, at a rate of 10 °C / min, hold for 1.5 h; 2400 °C - 3000 °C, at a rate of 15 °C / min, hold for 1.5 h for high-temperature carbonization treatment. Then, heat up to 3100 °C at a rate of 40 °C / min and hold for 0.5 h for graphitization treatment. Carbon fibers with an average diameter of 17 microns, thick and long, are obtained.

[0051] Through testing and calculation with a universal testing machine, the tensile strength of the bamboo carbon fiber is 301 MPa; the impact toughness is 11.15 ± 0.5 J / cm -3 More than 10 times higher than natural wood; the hardness is 8322 ± 263.5 pounds per inch, more than 10 times higher than natural wood.

[0052] Example 3

[0053] The preparation method of the bamboo carbon fiber of the present invention includes the following steps:

[0054] Both Step 1 and Step 2 are the same as those in Example 1.

[0055] Step 3: Place the precursor obtained in Step 2 in a vertical furnace. Break the cell wall at 170 °C to remove organic substances and crystal water. First, introduce inert gas argon for atmosphere protection at 240 °C, then add iodine to improve the catalytic performance, and subsequently pre-oxidize for 2.5 h. Then, heat up in the vertical furnace with gradient heating: room temperature - 150 °C, at a rate of 5 °C / min, hold for 2 h; 2000 - 2400 °C, at a rate of 10 °C / min, hold for 2 h; 2400 °C - 3000 °C, at a rate of 15 °C / min, hold for 2 h for high-temperature carbonization treatment. Then, heat up to 3200 °C at a rate of 40 °C / min and hold for 1.5 h for graphitization treatment. Carbon fibers with an average diameter of 19 microns, thick and long, are obtained.

[0056] Through testing and calculation with a universal testing machine, the tensile strength of the bamboo carbon fiber is 305 MPa; the impact toughness is 10.11 ± 0.5 J / cm -3 More than 10 times higher than natural wood; the hardness is 8213 ± 263.5 pounds per inch, more than 10 times higher than natural wood.

[0057] Example 4

[0058] The preparation method of the bamboo carbon fiber of the present invention includes the following steps:

[0059] Both Step 1 and Step 2 are the same as those in Example 1.

[0060] Step 3: Place the precursor obtained in Step 2 in a vertical furnace. Break the cell wall at 180 °C to remove organic substances and crystal water; at 260 °C, first introduce an inert gas argon atmosphere for protection and then add iodine to improve the catalytic performance, and then pre-oxidize for 2 h. Subsequently, heat up in the vertical furnace and perform gradient heating: room temperature - 150 °C, 5 °C / min, hold for 1 h; 2000 - 2400 °C, 10 °C / min, hold for 1 h; 2400 °C - 3000 °C, 15 °C / min, hold for 1 h for high-temperature carbonization treatment. Then heat up to 3000 °C at 40 °C / min and hold for 2 h for graphitization treatment. Carbon fibers with an average diameter of 18 μm, thick and long, are obtained.

[0061] Through the test and calculation by a universal testing machine, the tensile strength of the bamboo carbon fiber is 309 MPa; the impact toughness is 10.08 ± 0.5 J / cm -3 More than 10 times higher than natural wood; the hardness is 8119 ± 263.5 pounds per inch, more than 10 times higher than natural wood.

[0062] Example 5

[0063] The preparation method of the bamboo carbon fiber of the present invention includes the following steps:

[0064] Steps 1 and 2 are the same as those in Example 1.

[0065] Step 3: Place the precursor obtained in Step 2 in a vertical furnace. Break the cell wall at 190 °C to remove organic substances and crystal water; at 280 °C, first introduce an inert gas argon atmosphere for protection and then add iodine to improve the catalytic performance, and then pre-oxidize for 2 h. Subsequently, heat up in the vertical furnace and perform gradient heating: room temperature - 150 °C, 5 °C / min, hold for 1 h; 2000 - 2400 °C, 10 °C / min, hold for 1 h; 2400 °C - 3000 °C, 15 °C / min, hold for 1 h for high-temperature carbonization treatment. Then heat up to 3100 °C at 40 °C / min and hold for 2 h for graphitization treatment. Carbon fibers with an average diameter of 17 μm, thick and long, are obtained.

[0066] Through the test and calculation by a universal testing machine, the tensile strength of the bamboo carbon fiber is 311 MPa; the impact toughness is 10.21 ± 0.5 J / cm -3 More than 10 times higher than natural wood; the hardness is 8345 ± 263.5 pounds per inch, more than 10 times higher than natural wood.

[0067] Example 6

[0068] The preparation method of the bamboo carbon fiber of the present invention includes the following steps:

[0069] Steps 1 and 2 are the same as those in Example 1.

[0070] Step 3: Place the precursor obtained in Step 2 in a vertical furnace. Break the cell wall at 200 °C to remove organic matter and crystal water; at 300 °C, first introduce inert gas argon for atmosphere protection and then add iodine to improve the catalytic performance, and then pre-oxidize for 2 h. Subsequently, heat up in the vertical furnace with gradient heating: room temperature - 150 °C, 5 °C / min, hold for 1 h; 2000 - 2400 °C, 10 °C / min, hold for 1 h; 2400 °C - 3000 °C, 15 °C / min, hold for 1 h for high-temperature carbonization treatment. Then heat up to 3200 °C at 40 °C / min and hold for 2 h for graphitization treatment. Carbon fibers with an average diameter of 17 microns, thick and long, are obtained.

[0071] Through testing and calculation by a universal testing machine, the tensile strength of the bamboo carbon fiber is 312 MPa; the impact toughness is 11.09 ± 0.5 J / cm³, which is more than 10 times higher than that of natural wood; the hardness is 8377 ± 263.5 pounds per inch, which is more than 10 times higher than that of natural wood.

[0072] Comparative Example

[0073] The preparation method of the bamboo carbon fiber in this comparative example includes the following steps:

[0074] Steps 1 and 2 are the same as those in Example 1, and Step 3 is not graphitized.

[0075] Step 3: Place the precursor obtained in Step 2 in a vertical furnace. First introduce inert gas argon for atmosphere protection and then add iodine to improve the catalytic performance, and then pre-oxidize for 2 h. Subsequently, heat up in the vertical furnace with gradient heating: room temperature - 150 °C, 5 °C / min, hold for 1 h; 2000 - 2400 °C, 10 °C / min, hold for 1 h; 2400 °C - 3000 °C, 15 °C / min, hold for 1 h for high-temperature carbonization treatment.

[0076] Through testing and calculation by a universal testing machine, the tensile strength of the bamboo carbon fiber is 241 MPa; the impact toughness is 7.12 ± 0.5 J / cm -3 ; the hardness is 6357 ± 263.5 pounds per inch. This shows that the tensile strength, stiffness, and hardness of the bamboo carbon fiber obtained without graphitization treatment are poor.

[0077] During the graphitization treatment at 3000 °C for 1 h to 2 h, the strength and modulus of the carbon fiber increase by more than 20%, the crystallinity of the carbon fiber increases, and the layered structure is compact, making the electrical conductivity of the carbon fiber enhanced. At the same time, it is also found that after graphitization treatment, the crystal structure contains a large number of aromatic ring structures, and the existence of this structure indirectly improves the heat resistance of the carbon fiber.

[0078] Figure 1The first SEM image of the bamboo carbon fiber in Example 1, showing the structure after carbonization, is helpful for analyzing the microstructure of the carbon fiber.

[0079] Figure 2 The second SEM image of the bamboo carbon fiber in Example 1, showing the surface morphology of the carbon fiber, is helpful for analyzing the changes in surface topography.

[0080] Figure 3 The third SEM image of the bamboo carbon fiber in Example 1, showing the hollow structure after carbonization of the carbon fiber.

[0081] Figure 4 The fourth SEM image of the bamboo carbon fiber in Example 1, showing that the hollow structure of the carbon fiber maintains its integrity after carbonization.

[0082] Figure 5 The fifth SEM image of the bamboo carbon fiber in Example 1, with a field of view of 4.27×3.20 mm, showing the fracture morphology of the carbon fiber, which can analyze the fracture position.

[0083] Figure 6 The sixth SEM image of the bamboo carbon fiber in Example 1, with a field of view of 12.8×9.6 mm, the field of view becomes larger, showing the fracture morphology of the carbon fiber, which can better analyze the fracture position.

[0084] Figure 7 The seventh SEM image of the bamboo carbon fiber in Example 1, with the working distance of the objective lens being 9.3 mm, can analyze the diameter of the carbon fiber.

[0085] Figure 8 The eighth SEM image of the bamboo carbon fiber in Example 1, with the working distance of the objective lens being 8.3 mm, showing the phase structure of the carbon fiber.

[0086] Testing methods and performance analysis

[0087] The bamboo carbon fiber samples obtained from the comparative example and Examples 1-6 were respectively subjected to scanning electron microscope tests. It can be found that the bamboo carbon fiber has a high degree of graphitization, a smooth surface, and a regular structure, and the performance of the biomass carbon fiber obtained without graphitization treatment is poor in all aspects.

[0088] The bamboo carbon fiber samples obtained from the comparative example and Examples 1-6 were respectively subjected to Raman tests. It can be found that the carbon structure of the bamboo carbon fiber in Examples 1-6 gradually changes from disordered to short-range ordered. When the temperature continues to rise, the short-range ordered carbon structure gradually changes to long-range ordered; while the carbon structure of the bamboo carbon fiber in the comparative example is still relatively disordered. Generally, the degree of graphitization of the bamboo carbon fiber increases with the increase of the carbonization temperature.

[0089] It should be noted that the above embodiments are only used to illustrate the present invention, but the present invention is not limited to the above embodiments. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing bamboo carbon fiber, characterized in that, It includes the following steps: Raw material pretreatment: Process mature Phyllostachys edulis into bamboo filaments with a diameter < 1 mm and a length > 500 mm, and then air-dry them to reduce the water content of the bamboo filaments to less than 10%; Chemical treatment: Sequentially use an acid solution, an alkali solution, and cook at 100 - 200 °C to remove impurities and soften the cell wall; Drying: Control the moisture content < 3%; Pre-oxidation: Break the cell wall at 150 °C - 200 °C to remove organic substances and crystal water; Atmosphere protection treatment: Sequentially introduce an inert gas and iodine vapor at 200 °C - 300 °C to complete pre-oxidation; Gradient heating carbonization: From room temperature to 150 °C, at a rate of 5 °C / min, hold for 1 - 2 h; from 2000 °C to 2400 °C, at a rate of 10 °C / min, hold for 1 - 2 h; from 2400 °C to 3000 °C, at a rate of 15 °C / min, hold for 1 - 2 h for high-temperature carbonization treatment; Graphitization: Graphitize at 3000 °C - 3200 °C for 0.5 - 2 h to obtain bamboo carbon fiber.

2. The preparation method of bamboo carbon fiber according to claim 1, characterized in that, The preparation process of the bamboo filaments is as follows: Take mature Phyllostachys edulis, break the bamboo with a bamboo breaker, then cut the bamboo into thin slices with a slicing machine, then use a bamboo sawing machine to cut the bamboo into pieces with a length greater than 500 mm, and then use a bamboo strip wire drawing machine to draw the bamboo into bamboo filaments with a diameter less than 1 mm.

3. The method for preparing bamboo carbon fiber according to claim 1, wherein, The acid solution is a hydrochloric acid solution with a concentration of 1 - 2 mol / L.

4. The preparation method of bamboo carbon fiber according to claim 1, characterized in that, The alkali solution is a sodium carbonate solution with a concentration of 1 - 2 mol / L.

5. The method for preparing bamboo carbon fiber according to claim 1, wherein The drying process is to dry in a dryer at 80 °C for 1 - 3 h.

6. The method for preparing bamboo carbon fiber according to claim 1, characterized in that, The pre-oxidation process is as follows: First, break the cell wall in a vertical furnace in the air to remove organic substances and crystal water, and then apply an inert gas and iodine vapor in the vertical furnace for pre-oxidation for 1.5 - 2.5 h.

7. The method for preparing bamboo carbon fiber according to claim 1, wherein, The gradient heating carbonization is carried out in a vertical furnace.

8. The method for preparing bamboo carbon fiber according to claim 1, characterized in that, The graphitization is carried out in a vertical furnace.

9. A bamboo carbon fiber, characterized in that, It is made by using the bamboo carbon fiber preparation method described in any one of claims 1 - 8.

10. The bamboo carbon fiber according to claim 9, wherein, The tensile strength ≥ 300 MPa.

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