Method for green and cyclic preparation of high-yield bagasse dissolving pulp

Abstract

The invention belongs to the field of pulping and papermaking and functional material preparation, and discloses a method for preparing high-yield bagasse dissolving pulp in a green and circulating mode. According to the method, bagasse is used as a raw material, and a low-temperature oxygen-alkali cooking-biological enzyme enhanced hydrogen peroxide bleaching cleaning process system with sodium carbonate as an alkali source is constructed. The method is characterized in that bagasse is adopted as a raw material, dependence of traditional dissolving pulp preparation on wood fibers is broken through, and the raw material source is widened; a low-temperature oxygen-alkali cooking system is constructed, a green liquor self-circulation system is matched, efficient recycling of alkali components is achieved through evaporation concentration and high-temperature firing, the problems of silicon interference and white mud pollution in traditional alkali recovery are solved, and the closed-loop circulation rate of cooking waste liquor is 100%; a biological enzyme and hydrogen peroxide synergistic chlorine-free bleaching process is developed, so that the use amount of a bleaching agent and wastewater discharge are reduced, and the dissolving pulp with the yield of 35.2-37.8% is prepared. Through systematic innovation, a resource-saving and environment-friendly preparation system is constructed, the resource utilization efficiency and the clean production level are improved, and the method has great significance in industry green transformation.

Description

Technical Field

[0001] The invention belongs to the field of pulping, papermaking and functional material preparation, and relates to a method for preparing high-yield bagasse dissolving pulp through green circulation. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Dissolving pulp, as a key raw material in many fields such as papermaking, textiles, and chemical fibers, is highly favored for its high purity, high α-cellulose content, and good solubility. As a major by-product of the sugar industry, bagasse has significant potential as a dissolving pulp raw material due to its unique fiber structure and chemical composition. Oxygen-alkali pulping technology is suitable for loosely structured agricultural straw fiber raw materials such as bagasse. However, when the traditional oxygen-alkali system uses sodium hydroxide as the sole alkali source, its strong alkaline environment will trigger the peeling reaction of cellulose, resulting in the cleavage of 1,4-β-glycosidic bonds. At the same time, the dissolved silica forms a colloidal silicon complex in the black liquor, causing evaporator scaling and alkali recovery furnace fly ash adhesion problems, resulting in reduced alkali recovery efficiency and increased white mud pollution.

[0004] One study added alkali to wheat straw after enzyme pretreatment, introduced oxygen, and steamed it to produce an oxygen-alkali wheat straw pulp. Another study used enzymes to pretreat mechanically treated reeds, then subjected the enzyme-treated reeds to an oxygen-alkali steaming treatment in the presence of alkali to produce reed pulp. These methods, which incorporate a composite system of lipase, xylanase, and cellulase during the pretreatment phase, primarily aim to remove surface impurities and initially weaken the hemicellulose-lignin bonds; however, they struggle to meet the requirements for producing high-whiteness, high-yield bagasse dissolving pulp. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a method for preparing high-yield bagasse dissolving pulp in a green cycle. Different from the addition of a bio-enzyme complex system in the pretreatment stage, the present invention innovatively implements a post-cooking enzyme treatment process, and specifically selects enzyme preparations such as laccase and peroxidase to target the degradation of residual lignin-carbohydrate complexes (LCC) and stubborn lignin structures in the pulp, and reduces the consumption of chemicals in the bleaching stage through deep delignification. Secondly, at the process goal-oriented level, traditional bio-enzyme-assisted systems serve conventional pulp preparation, while the present invention constructs a highly selective delignification system suitable for dissolving pulp production through the synergistic optimization of enzyme treatment and low-temperature oxygen-alkali cooking, so that the purity and yield of α-cellulose are maintained at a high level. Furthermore, in order to improve the formula of the cooking system, the present invention innovatively introduces a magnesium sulfate chelating agent into the sodium carbonate / sodium hydroxide composite alkali solution, and effectively inhibits the peeling reaction and alkaline hydrolysis of cellulose under high-temperature alkaline conditions through the coordination effect of magnesium ions and transition metal ions. Finally, in terms of process temperature control, the present invention uses a breakthrough low-temperature cooking technology of 100-110°C, which is 50-60°C lower than the traditional method. Through thermodynamic control, selective dissolution of lignin is achieved, creating a more favorable reaction interface for the subsequent enzymatic bleaching stage.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A first aspect of the present invention provides a method for preparing high-yield bagasse dissolving pulp in a green recycling manner, comprising:

[0008] Taking sugarcane bagasse and performing hydrothermal pretreatment to obtain pretreated sugarcane bagasse;

[0009] The pretreated bagasse is subjected to a low-temperature oxygen-alkali cooking method to obtain a bagasse slurry, wherein the amount of alkali solution used is 15%-25%, the mass ratio of sodium carbonate to sodium hydroxide is 5 / 1-9 / 1, and the amount of magnesium sulfate used is 0.5%-1.0%;

[0010] The bagasse pulp is subjected to biological enzyme treatment and hydrogen peroxide bleaching to obtain bagasse dissolving pulp.

[0011] This invention establishes a comprehensive process system consisting of hydrothermal pretreatment, novel oxygen-alkali cooking, and enzymatic, fully chlorine-free bleaching, enabling the green and efficient production of bagasse dissolving pulp. This overcomes the challenges of traditional pulping processes, such as high energy consumption, severe environmental pollution, and raw material shortages, and provides new technical approaches and raw material options for the sustainable development of the dissolving pulp industry. This invention not only has important theoretical significance but also offers new ideas and practical examples for the green development of the pulp and paper industry.

[0012] The second aspect of the present invention provides bagasse dissolving pulp prepared by the above method.

[0013] The present invention uses sugarcane bagasse as raw material, and sequentially processes it through three stages: hydrothermal pretreatment, novel low-temperature oxygen-alkali pulping, and enzymatic-hydrogen peroxide synergistic bleaching, to ultimately produce high-yield sugarcane bagasse dissolving pulp; the process system achieves closed-loop circulation of pulping chemicals through a green circulation mode.

[0014] The third aspect of the present invention provides the application of the above-mentioned bagasse dissolving pulp in the fields of papermaking, textiles, and chemical fibers.

[0015] Beneficial effects of the present invention

[0016] (1) The use of sugarcane bagasse, a non-traditional wood fiber raw material, not only broadens the scope of raw materials for dissolving pulp preparation, but also effectively addresses the increasingly tight global fiber raw material resources situation.

[0017] (2) The new oxygen-alkali cooking process uses sodium carbonate as the main alkali source and develops a green circulation system to simplify the alkali recovery process. It also solves the technical bottleneck of silicon interference and the problem of white mud solid waste pollution in the traditional alkali recovery process, achieving "near-zero" emissions in the production process.

[0018] (3) A new chlorine-free bleaching mode using bio-enzymes in conjunction with hydrogen peroxide was adopted to improve bleaching efficiency and effect, reduce chemical usage and pollution, and lower production costs, ultimately producing a high-yield bagasse dissolving pulp with a yield of 35.2-37.8%.

[0019] (4) The preparation method of the present invention is simple, practical, and easy to promote. DETAILED DESCRIPTION

[0020] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0021] The present invention provides a method for preparing high-yield bagasse dissolving pulp in a green and circular manner, comprising:

[0022] Taking sugarcane bagasse and performing hydrothermal pretreatment to obtain pretreated sugarcane bagasse;

[0023] The pretreated bagasse is subjected to a low-temperature oxygen-alkali cooking method to obtain a bagasse slurry, wherein the amount of alkali solution used is 15%-25%, the mass ratio of sodium carbonate to sodium hydroxide is 5 / 1-9 / 1, and the amount of magnesium sulfate used is 0.5%-1.0%;

[0024] The bagasse pulp is subjected to biological enzyme treatment and hydrogen peroxide bleaching to obtain bagasse dissolving pulp.

[0025] Sodium carbonate is one of the best choices to replace alkali sources in oxygen-alkali pulping technology. Appropriate amount of Na2CO3 maintains the pH value of cooking liquor through buffering effect, delays O2 - The protonation process causes the generation pathway of active oxygen free radicals to change, making O2 - · / HO· ratio increases. In addition, CO3 2- The quenching effect of HO further reduces the HO· concentration, inhibits the cellulose peeling reaction, and enables the selective removal of lignin.

[0026] Hydrothermal pretreatment can remove hemicellulose and lignin from the raw material, improve enzymatic hydrolysis efficiency, and facilitate the preparation of dissolving pulp. Therefore, the present invention studies the solid-to-liquid ratio, temperature, and time of hydrothermal pretreatment. In some embodiments, the hydrothermal pretreatment solid-to-liquid ratio is 1:9-1:5, the holding temperature is 160-170°C, and the holding time is 30-150 minutes to achieve better pretreatment results.

[0027] The low-temperature oxygen-alkali pulping process of the present invention adopts a composite alkali system, with sodium carbonate as the main alkali source, sodium hydroxide as an auxiliary agent, and 0.5-1.0wt% of magnesium sulfate added as a stabilizer; the cooking black liquor is evaporated and concentrated, and high-temperature burning is converted into active sodium oxide, which is reused in the pulping system as a sodium carbonate supplement source.

[0028] The conditions of low-temperature oxygen-alkali cooking have a great influence on the yield, kappa number and viscosity of the slurry. Therefore, the present invention studies the solid-liquid ratio, oxygen pressure, temperature and time of low-temperature oxygen-alkali cooking. In some embodiments, the solid-liquid ratio of the low-temperature oxygen-alkali cooking is 1 / 6-1 / 4, the oxygen pressure is 0.5-0.8Mpa, the cooking temperature is 100-110°C, and the insulation time is 120-240min to improve the slurry yield and quality.

[0029] The enzymatic-hydrogen peroxide synergistic bleaching process of the present invention comprises two consecutive stages: (1) a biological enzyme pretreatment stage, in which a lignin-degrading enzyme system is used to directionally destroy the lignin-carbohydrate complex structure on the fiber surface; and (2) a chlorine-free bleaching stage, in which hydrogen peroxide is used to complete the final bleaching under alkaline conditions.

[0030] Traditional H2O2 bleaching relies on high alkalinity to generate hydrogen peroxide ions (HO2 - ), which can easily cause oxidative damage to cellulose. Enzyme-assisted bleaching technology can significantly reduce the amount of subsequent bleaching chemicals through enzymatic pretreatment. It can specifically attack lignin, LCC, or chromophores, providing a favorable foundation for subsequent bleaching. In some embodiments, the enzyme treatment conditions include a pH of 4.0-5.5, an enzyme dosage of 15U / g-30U / g, and a temperature of 45-55°C.

[0031] It is different from the traditional enzyme pretreatment method for hydrogen peroxide bleaching. The present invention has achieved three key technical breakthroughs in the construction of biological enzyme treatment and bleaching process system: First, in terms of research positioning, the above research focuses on the influence mechanism of enzyme pretreatment on hydrogen peroxide bleaching waste liquid, while the present invention is based on establishing the correlation between enzymatic bleaching and the improvement of dissolving pulp performance, achieving efficient dissolution of lignin, and simultaneously achieving an increase in α-cellulose content; secondly, in the enzyme treatment technology path, not only the traditional single enzyme application mode is used, but also a composite enzyme synergistic system is developed, which catalyzes the breaking of the β-ether bond between the phenylpropane structural units of lignin through laccase, and cooperates with xylanase to directional stripping of the hemicellulose wrapping layer, so that the exposed area of ​​lignin is increased, which significantly enhances The chemical accessibility of the subsequent bleaching stage is enhanced. Finally, in terms of formula optimization for the bleaching stage, a "H2O2-NaOH-MgSO4" ternary synergistic system was constructed. 0.3% sodium hydroxide regulates the reaction pH to the optimal range of 10.5-11.0, promoting the heterolytic decomposition of hydrogen peroxide to generate highly nucleophilic HO- radicals, achieving selective oxidative cleavage of carbonyl groups, double bonds, and quinone structures in lignin side chains. The introduction of 0.3% magnesium sulfate reduces the alkaline degradation rate of cellulose through a strong chelation effect between magnesium ions and the pulp. Combined with the low-temperature bleaching process, this reduces the loss of fiber polymerization degree, ultimately resulting in a high-whiteness, high-yield dissolving pulp product. Therefore, in some embodiments, the bioenzyme is selected from one or more of laccase, horseradish peroxidase, manganese peroxidase, and xylanase to achieve better bleaching results.

[0032] In the bleaching process, hydrogen peroxide, as a key oxidant in completely chlorine-free bleaching systems, has the potential to replace traditional chlorine-containing bleaching agents due to its environmentally friendly nature, producing no adsorbable organic halides (AOX), becoming a mainstream technology for achieving clean production in the modern pulping industry. Therefore, in some embodiments, the hydrogen peroxide bleaching conditions include a hydrogen peroxide dosage of 2.0-4.0%, a sodium hydroxide dosage of 0.2-0.5%, a magnesium sulfate dosage of 0.1-0.3%, a temperature of 80-90°C, and a bleaching time of 60-120 minutes.

[0033] Adding water to adjust the pulp concentration before bleaching can improve pulp fluidity, evenly distribute fibers, reduce energy consumption, and improve the quality of dissolving pulp. Therefore, the present invention studies pulp concentration. In some embodiments, water is added before bleaching to adjust the pulp concentration to 10%-15% to obtain a better bleaching effect.

[0034] The present invention also provides bagasse dissolving pulp prepared by the above method.

[0035] In some embodiments, the α-cellulose content is 91.9%-93.1%.

[0036] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0037] Example 1:

[0038] The novel method for preparing high-yield bagasse dissolving pulp by low-temperature oxygen-alkali-enzymatic hydrogen peroxide bleaching described in this embodiment specifically comprises the following steps:

[0039] (1) Hydrothermal pretreatment: 50 g of absolutely dry bagasse was thoroughly mixed with 300 ml of deionized water and placed in a homogeneous reactor. The cooking temperature was set to 170 °C and the holding time was 30 min.

[0040] (2) Novel low-temperature oxygen-alkali cooking: Prepare an alkali solution containing 25% alkali, 6 / 1 (w / w) sodium carbonate / sodium hydroxide, and 0.5% magnesium sulfate. The pretreated bagasse obtained in step (1) and the alkali solution are mixed at a liquid ratio of 1 / 6. The bagasse slurry is cooked at an oxygen pressure of 0.6 MPa, a cooking temperature of 105°C, and a holding time of 240 minutes.

[0041] (3) Enzyme treatment: 20 U / g xylanase and 20 U / g laccase were added to an acetic acid-sodium acetate buffer solution at pH 5.5, and the mixture was thoroughly mixed with the bagasse slurry obtained in step (2). The mixture was then placed in a water bath heated at 50°C. The slurry was kneaded every 30 minutes. The enzyme treatment lasted for 6 hours.

[0042] (4) Hydrogen peroxide bleaching: Take the slurry obtained in step (3), add water to adjust the slurry concentration to 10%, and add 3% hydrogen peroxide, 0.4% sodium hydroxide, and 0.3% magnesium sulfate respectively. Set the temperature to 90°C and the reaction time to 90 minutes. After the reaction is completed, the slurry is washed until neutral to obtain bagasse dissolving pulp.

[0043] The quality of the bagasse dissolving pulp prepared in this example is as follows: fine pulp yield 36.2%, viscosity 274 ml / g, brightness 82.4% ISO, α-cellulose 91.0%, and ash content 0.42%.

[0044] Example 2:

[0045] The novel method for preparing high-yield bagasse dissolving pulp by low-temperature oxygen-alkali-enzymatic hydrogen peroxide bleaching described in this embodiment specifically comprises the following steps:

[0046] (1) Hydrothermal pretreatment: 50 g of absolutely dry bagasse was thoroughly mixed with 400 ml of deionized water and placed in a homogeneous reactor. The cooking temperature was set to 170 °C and the holding time was 60 min.

[0047] (2) Novel low-temperature oxygen-alkali cooking: Prepare an alkali solution containing 22% alkali, 7 / 1 (w / w) sodium carbonate / sodium hydroxide, and 0.5% magnesium sulfate. The pretreated bagasse obtained in step (1) and the alkali solution are mixed at a liquid ratio of 1 / 4. The bagasse slurry is cooked at an oxygen pressure of 0.8 MPa, a cooking temperature of 100°C, and a holding time of 240 minutes.

[0048] (3) Enzyme treatment: 30 U / g xylanase and 30 U / g laccase were added to an acetic acid-sodium acetate buffer solution at pH 5.5, and the mixture was thoroughly mixed with the bagasse slurry obtained in step (2). The mixture was then placed in a water bath heated at 45°C. The slurry was kneaded every 30 minutes. The enzyme treatment lasted for 6 hours.

[0049] (4) Hydrogen peroxide bleaching: Take the slurry obtained in step (3), add water to adjust the slurry concentration to 10%, and add 2% hydrogen peroxide, 0.3% sodium hydroxide, and 0.3% magnesium sulfate respectively. Set the temperature to 80°C and the reaction time to 60 minutes. After the reaction is completed, the slurry is washed to neutrality to obtain bagasse dissolving pulp.

[0050] The quality of the bagasse dissolving pulp prepared in this example is as follows: fine pulp yield 37.4%, viscosity 293 ml / g, brightness 80.4% ISO, α-cellulose 93.1%, and ash content 0.38%.

[0051] Example 3:

[0052] The method for preparing high-yield bagasse dissolving pulp by low-temperature oxygen-alkali-enzymatic hydrogen peroxide bleaching based on a green circulation system described in this embodiment specifically includes the following steps:

[0053] (1) The black liquor from Example 2 was concentrated, incinerated, dissolved, filtered, and reused. The total alkali content of the solution was determined, and deionized water was added to ensure that the sodium carbonate concentration was the same as that described in Example 2. At the same time, sodium hydroxide and magnesium sulfate were added to the solution until the concentration was the same as that described in Example 2. This solution is called alkali liquor.

[0054] (2) Hydrothermal pretreatment: 50 g of absolutely dry bagasse was thoroughly mixed with 400 ml of deionized water and placed in a homogeneous reactor. The cooking temperature was set to 170 °C and the holding time was 60 min.

[0055] (3) Novel low-temperature oxygen-alkali cooking: The alkali solution described in step (1) is fully mixed with the pretreated sugarcane bagasse obtained in step (2), and the oxygen pressure is set to 0.8 MPa, the cooking temperature is set to 100° C., and the holding time is set to 240 min to cook the sugarcane bagasse slurry.

[0056] (4) Enzyme treatment: 30 U / g xylanase and 30 U / g laccase were added to an acetic acid-sodium acetate buffer solution at pH 5.5, and the mixture was thoroughly mixed with the bagasse slurry obtained in step (3). The mixture was then placed in a water bath heated at 45°C. The slurry was kneaded every 30 minutes. The enzyme treatment lasted for 6 hours.

[0057] (5) Hydrogen peroxide bleaching: Take the pulp obtained in step (4), add water to adjust the pulp concentration to 10%, and add 2% hydrogen peroxide, 0.3% sodium hydroxide, and 0.3% magnesium sulfate respectively. Set the temperature to 80°C and the reaction time to 60 minutes. After the reaction is completed, wash the pulp until it is neutral to obtain bagasse dissolving pulp.

[0058] The quality of the bagasse dissolving pulp prepared in this example is as follows: fine pulp yield 37.8%, viscosity 302 ml / g, brightness 80.1% ISO, α-cellulose 92.4%, and ash 0.45%.

[0059] Example 4:

[0060] The method for preparing high-yield bagasse dissolving pulp by low-temperature oxygen-alkali-enzymatic hydrogen peroxide bleaching based on a green circulation system described in this embodiment specifically includes the following steps:

[0061] (1) The black liquor from Example 3 was concentrated, incinerated, dissolved, filtered, and reused. The total alkali content of the solution was determined, and deionized water was added to ensure that the sodium carbonate concentration was the same as that described in Example 3. At the same time, sodium hydroxide and magnesium sulfate were added to the solution until the concentration was the same as that described in Example 3. This solution is called alkali liquor.

[0062] (2) Hydrothermal pretreatment: 50 g of absolutely dry bagasse was thoroughly mixed with 400 ml of deionized water and placed in a homogeneous reactor. The cooking temperature was set to 170 °C and the holding time was 60 min.

[0063] (3) Novel low-temperature oxygen-alkali cooking: The alkali solution described in step (1) is fully mixed with the pretreated sugarcane bagasse obtained in step (2), and the oxygen pressure is set to 0.8 MPa, the cooking temperature is set to 100° C., and the holding time is set to 240 min to cook the sugarcane bagasse slurry.

[0064] (4) Enzyme treatment: 30 U / g xylanase and 30 U / g laccase were added to an acetic acid-sodium acetate buffer solution at pH 5.5, and the mixture was thoroughly mixed with the bagasse slurry obtained in step (3). The mixture was then placed in a water bath heated at 45°C. The slurry was kneaded every 30 minutes. The enzyme treatment lasted for 6 hours.

[0065] (5) Hydrogen peroxide bleaching: Take the pulp obtained in step (4), add water to adjust the pulp concentration to 10%, and add 2% hydrogen peroxide, 0.3% sodium hydroxide, and 0.3% magnesium sulfate respectively. Set the temperature to 80°C and the reaction time to 60 minutes. After the reaction is completed, wash the pulp until it is neutral to obtain bagasse dissolving pulp.

[0066] The quality of the bagasse dissolving pulp prepared in this example is as follows: fine pulp yield 37.4%, viscosity 295 ml / g, brightness 81.6% ISO, α-cellulose 91.9%, and ash content 0.53%.

[0067] Compared with the traditional oxygen-alkali method and the existing sugarcane bagasse dissolving pulp preparation process, the technical system described in the present invention has achieved multi-dimensional performance breakthroughs. The traditional oxygen-alkali method relies on a single NaOH cooking system, which has technical bottlenecks such as low lignin removal efficiency resulting in insufficient α-cellulose purity (<90%), excessive cellulose degradation causing viscosity loss, and difficulty in alkali recovery due to the high silicon content of sugarcane bagasse. While the conventional sulfate method can produce sugarcane bagasse dissolving pulp, it requires high temperature and strong alkaline conditions that exacerbate fiber damage, and uses a chlorine-containing bleaching process, which not only results in high chemical consumption but also produces chlorine-containing organic pollutants. The innovative "hydrothermal pretreatment-novel low-temperature oxygen-alkali cooking-enzymatic bleaching" system constructed in this invention achieves 91.9%-93.1% high-purity α-cellulose enrichment through cooking with sodium carbonate as the main alkaline source, while simultaneously completing efficient desiliconization (ash content 0.38%-0.53%) and targeted lignin removal. The combination of a bio-enzyme catalytic system significantly reduces the amount of H2O2 used while achieving a pulp brightness of 80.1-81.6% ISO after bleaching. More importantly, the yield of sugarcane bagasse dissolving pulp obtained by this invention has been significantly increased to 37.4%-37.8%. Therefore, this process breaks through the contradictions of traditional technologies and, while ensuring pulp strength (viscosity 293-302 ml / g), achieves a significant reduction in chemical costs, an increase in black liquor alkali recycling rate to 100%, and the complete elimination of chlorine-containing pollutant emissions, establishing a closed-loop system for the green utilization of all components of sugarcane bagasse resources.

[0068] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing high-yield bagasse dissolving pulp by green recycling, characterized in that: include: Taking sugarcane bagasse and performing hydrothermal pretreatment to obtain pretreated sugarcane bagasse; The pretreated bagasse is subjected to a low-temperature oxygen-alkali cooking method to obtain a bagasse slurry, wherein the amount of alkali solution used is 15%-25%, the mass ratio of sodium carbonate to sodium hydroxide is 5 / 1-9 / 1, and the amount of magnesium sulfate used is 0.5%-1.0%; The bagasse pulp is subjected to biological enzyme treatment and hydrogen peroxide bleaching to obtain bagasse dissolving pulp.

2. The method for preparing high-yield bagasse dissolving pulp by green recycling according to claim 1, characterized in that: The solid-liquid ratio of the hydrothermal pretreatment is 1 / 9-1 / 5, the holding temperature is 160-170° C., and the holding time is 30-150 minutes.

3. The green recycling method for preparing high-yield bagasse dissolving pulp according to claim 1, characterized in that: The low-temperature oxygen-alkali cooking method has a solid-liquid ratio of 1 / 6-1 / 4, an oxygen pressure of 0.5-0.8 MPa, a cooking temperature of 100-110° C., and a heat preservation time of 120-240 minutes.

4. The method for preparing high-yield bagasse dissolving pulp by green recycling according to claim 1, characterized in that: The conditions for the bio-enzyme treatment are as follows: pH 4.0-5.5, bio-enzyme dosage 15U / g-30U / g, and temperature 45-55°C.

5. The method for preparing high-yield bagasse dissolving pulp by green recycling according to claim 1, characterized in that: The biological enzyme is selected from one or more of laccase, horseradish peroxidase, manganese peroxidase and xylanase.

6. The method for preparing high-yield bagasse dissolving pulp by green recycling according to claim 1, characterized in that: The conditions for hydrogen peroxide bleaching are as follows: 2.0-4.0% hydrogen peroxide, 0.2-0.5% sodium hydroxide, 0.1-0.3% magnesium sulfate, 80-90° C. temperature, and 60-120 min.

7. The green recycling method for preparing high-yield bagasse dissolving pulp according to claim 1, characterized in that: Before bleaching, water is added to adjust the pulp concentration to 10%-15%.

8. Bagasse dissolving pulp prepared by the method according to any one of claims 1 to 7.

9. The bagasse dissolving pulp according to claim 8, wherein The α-cellulose content is 91.9%-93.1%.

10. Use of the bagasse dissolving pulp according to claim 8 or 9 in the fields of papermaking, textile and chemical fiber.