A method for producing refined cotton coupling fermentation

Abstract

The present application relates to the technical field of refined cotton processing, and particularly relates to a refined cotton coupling fermentation production method, and the fermentation production step is as follows: S1, selecting microbial strains, the strains are active lignin enzymes, white cyst Hirsutella and Fomes fomentarius, lignin is used as an inducer to promote white cyst Hirsutella and Fomes fomentarius to form high-yield lignin enzymes, and the main components of the culture medium are selected, the microbial strains are proportionally prepared into fermentation liquor, filtration treatment is performed, solid residues in the fermentation liquor are removed through filtration, and the fermentation liquor is placed in a container for natural storage. The present application overturns the traditional chemical cooking and bleaching process, adopts a microbial coupling fermentation technology, improves fiber reaction uniformity, realizes a technical index of a polydispersity fluctuation range <80 of the same specification product, efficiently removes impurities and refines, improves impurity removal efficiency, reduces impurity content, ash content and metal ion content, and meets the quality requirements of the market of special paper and cellulose acetate.

Description

Technical Field

[0001] This invention belongs to the field of refined cotton processing technology, specifically a refined cotton coupled fermentation production method. Background Technology

[0002] Refined cotton is a specially processed cotton fiber product with characteristics such as uniform looseness and no impurities. Refined cotton is a white, fluffy fiber material, free of impurities such as wood chips, mud, oil, and mineral ions. Due to its wide application in food processing, papermaking, petrochemical, metallurgical, and aerospace industries, it is known as "industrial MSG". With people's increasing emphasis on green, healthy, and environmentally friendly consumption, and the gradual entry of the cellulose market into its traditional peak season, the market demand for refined cotton continues to grow. At present, the overall operation of domestic refined cotton manufacturers is still acceptable, the supply of raw cotton linters in the market is tight, and the price may still have room to rise. At the same time, the good cellulose market has also boosted the demand for refined cotton, which is beneficial to the spot market of refined cotton. Therefore, it is expected that the upward momentum of the refined cotton market will remain strong in the future.

[0003] Existing technologies use an alkaline pulping process to process refined cotton. This process involves preparing materials, preparing the cooking liquor, cooking the materials, washing and screening them after cooking, followed by bleaching, drying, and finishing. This completes the traditional refined cotton processing. However, the traditional chemical cooking and bleaching process suffers from low degree of polymerization control, a wide range of polymerization degrees, inconsistent fiber reactions, and cumbersome steps. To address this, we propose a coupled fermentation production method for refined cotton. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a refined cotton coupled fermentation production method to solve the above-mentioned technical problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for producing refined cotton through coupled fermentation, wherein the fermentation production steps are as follows:

[0006] S1. Select microbial strains, namely active ligninase, *Bacillus thunbergii* and *Inonotus obliquus*. Use lignin as an inducer to promote the formation of high-yield ligninase by *Bacillus thunbergii* and *Inonotus obliquus*. Select the main components of the culture medium, prepare the microbial strains into fermentation broth according to the proportion, filter the broth to remove solid residues, and place the fermentation broth in a container for natural storage.

[0007] S2. Prepare cotton linters, steam and bleach the cotton linters, and dehydrate and loosen the cotton linters.

[0008] S3. Add organic acids and surfactants to the fermentation broth, stir, let stand, and optimize the fermentation efficiency;

[0009] S4. Sample the fermentation broth and verify the degree of polymerization of the prepared fermentation broth;

[0010] S5. Fermentation is carried out in an environment with an ambient temperature above 15℃ and a humidity above 75%. The prepared fermentation liquid is mixed with cotton linters, and the microorganisms begin to degrade and decompose the impurities in the cotton linters. The fermentation time is 72 hours, allowing the microorganisms to fully process the cotton linters.

[0011] S6. Bleaching the fermented cotton with sodium hypochlorite bleach, then washing and drying it, and finally packaging it.

[0012] S7. The residue from the fermentation liquid is processed into solid organic fertilizer.

[0013] In this application, the entire process uses biodegradation technology to remove impurities from cotton linters, improving product quality and solving the waste disposal problem, thus achieving a win-win situation for both environmental protection and economic benefits.

[0014] Preferably, in step S1, enzyme production is induced by mixing sawdust, cottonseed hulls, hemicellulose, and lignin materials in *Pterygium buergerianum* and *Inonotus obliquus* to form high-yield ligninase. Lignin acts as an inducer to stimulate the fungi to produce ligninase. Sawdust, cottonseed hulls, hemicellulose, and lignin materials are added to the culture medium, and the proportions of carbon source, nitrogen source, and inorganic salt nutrients in the culture medium are adjusted. The medium is then prepared in an environment with a temperature above 22°C.

[0015] Lignin, as an inducer, can promote the production of ligninase. As an important inducer in the growth process of fungi, lignin can stimulate fungi such as *Pterygomycetes* and *Inonotus obliquus* to produce ligninase. These enzymes play an important role in the degradation of lignin and can improve the utilization rate of lignin materials by fungi.

[0016] Fungi such as *Pterygomycetes* and *Inonotus obliquus* grow faster at higher temperatures. Cultivating the culture medium at temperatures above 22°C can accelerate fungal growth and shorten the fermentation cycle.

[0017] Preferably, in step S2, the cotton linter cooking and bleaching involves preparing cotton linters as raw material, mixing the cotton linters with the cooking liquid, placing them in a cooking device for cooking, removing the pulp after cooking, washing to remove residues from the cotton linters, using a bleaching agent to bleach the cotton linters, and then removing them for dehydration after bleaching.

[0018] During the cooking process, impurities such as oils, fats, pectin, cotton bolls, and lignin in the cotton linters are effectively removed by chemical methods in an alkaline environment, which improves the purity of the cotton pulp. The dehydrated cotton pulp is more compact, which facilitates subsequent processing and improves overall production efficiency.

[0019] Preferably, in step S2, dewatering is used to remove excess water from the cotton linters. The dewatering step involves placing the cotton linter raw material on a mesh belt dewatering machine for initial dewatering. The mesh belt dewatering machine uses a mesh conveyor belt to filter out excess water from the slurry, reducing the moisture content of the cotton linters. Then, the linters enter the multi-roller pressing dewatering zone, where the cotton linters undergo progressive pressurization dewatering through sequentially arranged pressing roller groups to further remove moisture from the cotton linters. The cotton linter loosening treatment involves placing the cotton linters on a loosening device to loosen and open the fibers.

[0020] The mesh belt dewatering machine, as a preliminary dewatering tool, effectively filters out excess water from the slurry using a mesh conveyor belt, initially reducing the moisture content of the cotton linters. The multi-roller pressing dewatering zone further removes moisture from the cotton linters through progressive pressure dewatering, achieving an even lower moisture content. This helps reduce energy consumption and time in subsequent drying processes, improving production efficiency. The loosening equipment breaks up the cotton linters, loosening the originally tightly wrapped fibers, which helps ensure uniform fiber distribution and mixing during subsequent processing, improving product uniformity and consistency.

[0021] Preferably, in step S3, organic acid is added to the fermentation broth beforehand and stirred. After stirring for 3 minutes, surfactant is added to the fermentation broth and stirring is continued. After stirring for another 5 minutes, the broth is placed on the table and left to stand to optimize the efficiency of fermentation.

[0022] Organic acids can adjust the pH of the fermentation broth, providing a suitable growth environment for fermenting microorganisms. A suitable pH is beneficial to the metabolic activities of microorganisms, thereby improving fermentation efficiency. Adjusting the pH of the fermentation broth to the optimal growth range of the target microorganisms makes it easier for them to absorb and utilize these nutrients, thus accelerating the fermentation process, inhibiting the growth of miscellaneous bacteria in the fermentation broth, reducing the production of harmful substances, improving the purity and quality of fermented products, and increasing the activity of key enzymes during fermentation, thereby accelerating the fermentation reaction.

[0023] Surfactants have the ability to reduce the surface tension of a solution, which helps improve the fluidity of the fermentation broth, making it easier for nutrients and oxygen to be evenly distributed in the fermentation system. They also increase the stability and adaptability of enzymes, prevent enzyme inactivation or passivation due to temperature fluctuations or stirring shear forces, enhance the dispersibility, permeability, and action rate of organic acids, allowing them to better exert their effects, improve their performance and fully release their function, and increase their viscosity and stability. This, in turn, facilitates the control of the fermentation process and the separation and purification of the product.

[0024] Preferably, in step S4, the degree of polymerization verification is performed by using an Ubbelohde viscometer to measure the viscosity of the fermentation broth at 25°C, and the measured result is compared with the degree of polymerization of the standard sample to determine the degree of polymerization of the fermentation broth.

[0025] Degree of polymerization is one of the important indicators reflecting the characteristics of the product during fermentation. By monitoring changes in the degree of polymerization, the stability and efficiency of the fermentation process can be evaluated, providing data support for process optimization.

[0026] Preferably, the mixing time in step S5 is 1 hour. After the mixing is completed, the mixture is left to stand and wait for the microorganisms to ferment and degrade it in order to treat the cotton linters.

[0027] When the prepared fermentation broth and pretreated cotton linters are fed into a dedicated mixing device, the device will start mixing for one hour. This is sufficient to ensure that the microorganisms in the fermentation broth are evenly distributed in every fiber gap of the cotton linters, and also helps the nutrients and enzymes in the fermentation broth to fully penetrate into the cotton linters. After mixing is complete, the device will automatically stop operating, and the mixture will enter a static state. The microorganisms will then degrade the lignin and hemicellulose components in the cotton linters using the fermentation broth. The ambient temperature must be maintained above 15°C, and the humidity must be above 75% to facilitate the growth and reproduction of microorganisms. By observing the changes in the color, odor, and texture of the mixture, the progress of the fermentation process and the activity state of the microorganisms can be preliminarily judged. Subsequently, the bleaching, washing, drying, and packaging processes can be carried out to finally obtain cotton linters products that meet the requirements.

[0028] Preferably, in step S6, bleaching is performed by preparing auxiliary tools, including a stirrer, thermometer, and pH meter, weighing sodium hypochlorite solution, and maintaining a well-ventilated environment. The fermented cotton is pretreated, including impurity removal, washing, and pH adjustment. The pH of the fermented cotton is adjusted to 9.5-10.5 by adding hydrochloric acid or sodium carbonate. The pretreated fermented cotton is then placed in a bleaching tank, and the prepared sodium hypochlorite solution is added. The mixture is stirred evenly with a stirrer to ensure the sodium hypochlorite solution fully penetrates the fermented cotton for bleaching. After bleaching, the fermented cotton is thoroughly rinsed with clean water to remove residual sodium hypochlorite and other impurities. The water is changed multiple times during rinsing until the rinsing solution is clear.

[0029] Preferably, in step S6, the drying process involves placing the cleaned fermented cotton in front of a dryer for drying at a temperature of 50°C, followed by packaging the refined cotton after drying.

[0030] In this application, the drying temperature is set at 50℃. Based on a comprehensive consideration of the material characteristics of fermented cotton and drying efficiency, this temperature can effectively remove moisture without damaging the fiber structure of the fermented cotton, maintaining its original softness and toughness. At the same time, it also helps to kill residual microorganisms and improve the hygiene standards of the product.

[0031] Preferably, in step S6, the filtered residue is collected, and the moisture content of the residue is adjusted to between 45% and 50%. Straw and sawdust are added to the residue to adjust the carbon-nitrogen ratio. The residue is then added to a fermenter, evenly sprinkled on the residue, stirred and mixed, and placed in a fermentation tank for pile fermentation. The fermentation time is 30 days, and the fermentation tank is turned over every day to complete the fermentation. After drying, solid organic fertilizer is obtained.

[0032] The reuse of fermentation liquid residue effectively reduces waste generated in agricultural and industrial processes, lowering the risk of environmental pollution from these wastes. By converting waste into organic fertilizer, resource recycling is achieved, which aligns with the concepts of environmental protection and sustainable development.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] This application revolutionizes traditional chemical cooking and bleaching processes by employing microbial coupled fermentation technology. It precisely controls fermentation time and detects the degree of enzymatic hydrolysis of lignin and the uniformity of directional polymerization of cellulose. This surpasses the effects of traditional steam cooking and bleaching processes for reducing polymerization and controlling the degree of polymerization. It narrows the range of polymerization degree, improves the uniformity of fiber reaction, and achieves the technical indicator that the degree of polymerization fluctuation range of products of the same specification is <80%. It also efficiently removes impurities and refines the product, improving the efficiency of impurity removal and reducing the content of impurities, ash, and metal ions, thus meeting the quality requirements of the specialty paper and cellulose acetate markets. Attached Figure Description

[0035] Figure 1 This is a flowchart of the fermentation production steps of the present invention. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] A method for producing refined cotton through coupled fermentation, comprising the following fermentation steps:

[0039] S1. Select microbial strains, namely active ligninase, *Bacillus thunbergii* and *Inonotus obliquus*. Use lignin as an inducer to promote the formation of high-yield ligninase by *Bacillus thunbergii* and *Inonotus obliquus*. Select the main components of the culture medium and prepare the fermentation broth by mixing the microbial strains in a certain ratio, with the ratio of *Bacillus thunbergii* to *Inonotus obliquus* being 4:3. Filter the broth to remove solid residues and place it in a container for natural storage.

[0040] S2. Prepare cotton linters, steam and bleach the cotton linters, and dehydrate and loosen the cotton linters.

[0041] S3. Add organic acids and surfactants to the fermentation broth, stir, let stand, and optimize the fermentation efficiency;

[0042] S4. Sample the fermentation broth and verify the degree of polymerization of the prepared fermentation broth;

[0043] S5. Fermentation is carried out in an environment with an ambient temperature above 15℃ and a humidity above 75%. The prepared fermentation liquid is mixed with cotton linters, and the microorganisms begin to degrade and decompose the impurities in the cotton linters. The fermentation time is 72 hours, allowing the microorganisms to fully process the cotton linters.

[0044] S6. Bleaching the fermented cotton with sodium hypochlorite bleach, then washing and drying it, and finally packaging it.

[0045] S7. The residue from the fermentation liquid is processed into solid organic fertilizer.

[0046] Comparative Example 1

[0047] The steps in the alkaline pulping process for refining cotton are as follows:

[0048] A1. Raw material selection: High-quality cotton linters without impurities are selected as raw materials;

[0049] A2. Preparation of alkaline solution: The main component of the cooking liquor is sodium hydroxide. A certain concentration of sodium hydroxide solution is used to spray the loosened, cleaned and opened cotton linters, and the sodium hydroxide solution is fully and evenly penetrated into the cotton linters to form alkaline fibers through extrusion treatment.

[0050] A3. Under the action of the additives, the alkali-impregnated fibers are repeatedly sprayed and rolled to achieve full and uniform penetration of the alkali solution into the fibers. The alkali solution generated during the rolling process is recycled and reused.

[0051] A4. The pretreated alkali fiber is put into a sealed steaming ball, and the temperature inside the steaming ball is gradually increased to the set value by heating in stages, while maintaining a certain pressure and time for steaming.

[0052] A5. The cooked cotton pulp is washed multiple times to remove impurities and adjust the pH value. Bleaching agent is added for bleaching. After bleaching, dechlorination is required to remove residual chlorine. The pH value is then adjusted by washing.

[0053] A6. Remove excess water from the cotton pulp by pressing or other methods, and then dry the water-removed cotton pulp to obtain finished refined cotton. The dried refined cotton is then packaged for storage and transportation.

[0054] Table 1 below shows the properties of the refined cotton prepared in the examples and comparative examples.

[0055] Degree of aggregation (DP) 14000 10000 Appearance Complete and undamaged Complete and undamaged Impurity content (%) 2.5 8.5

[0056] Table 1

[0057] Degree of polymerization detection:

[0058] Prepare the refined cotton samples for the examples and comparative examples, ensuring they are clean and free of impurities. Cut the samples into appropriately sized pieces for subsequent dissolution and measurement.

[0059] Under standard temperature and humidity, a certain amount of refined cotton scraps is accurately weighed, 2.4 mg of which is calculated based on the cotton fiber moisture content being 8% under standard temperature and humidity, and placed in a brown bottle;

[0060] Add copper wire and distilled water, then add copper ethylenediamine solution, purge the air from the bottle with nitrogen or hydrogen, seal the bottle opening, and shake in a shaker for 2 hours to fully dissolve the cotton fibers.

[0061] Transfer the dissolved solution to a viscometer and equilibrate it in a constant temperature water bath for 5 minutes to ensure that the solution temperature remains constant.

[0062] The time it takes for a solution to flow from one scale to another in a viscometer is measured and recorded as the outflow time of the test liquid.

[0063] The effluent time of the blank solution was measured using the same method as a reference.

[0064] Based on the measured outflow time and the outflow time of the blank solution, the specific viscosity (ηsp) and intrinsic viscosity (η) of the solution are calculated, and the degree of polymerization (DP) of refined cotton is calculated using the Schutz-Blasschk formula.

[0065] Appearance inspection

[0066] Obtain refined cotton samples from the comparative and examples to ensure that the samples can reflect the quality of the entire batch of products.

[0067] Visually inspect the refined cotton to see if the color is uniform and consistent, and whether there are any discolored fibers or spots. Check its luster to determine if it meets the product standards. Observe the morphological characteristics of the refined cotton, such as fiber length, thickness, and crimp. Check whether its structure is compact and whether there are any loose or broken phenomena. Carefully check whether the sample contains impurities such as dust, oil stains, and metal shavings.

[0068] Identify and record defects such as broken seeds, cotton-like knots, and infertile seeds, as these defects may affect the quality and performance of the product.

[0069] The observed appearance features and test results are recorded and scored according to product standards.

[0070] Impurity content detection

[0071] Obtain a sample and separate the impurities from the fibers. Common impurity separation methods include manual picking and mechanical separation. During the separation process, it is important to ensure that no impurities are missed or mixed with other impurities.

[0072] Observation and classification: Carefully observe and classify the separated impurities to identify their types and sources. Based on the nature of the impurities, they can be divided into organic impurities and inorganic impurities.

[0073] Count and weigh all types of impurities, and record their quantity and weight. When counting and weighing, relevant standards or customer requirements should be followed to ensure the accuracy and reliability of the data.

[0074] Impurity content is calculated based on the weight of the impurities and the original mass of the sample. The impurity content is usually expressed as a percentage, and the calculation formula is: Impurity content = (Impurity weight / Original mass of sample) × 100%.

[0075] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0076] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for producing refined cotton through coupled fermentation, characterized in that, The fermentation production steps are as follows: S1. Select microbial strains, namely active ligninase, *Bacillus thunbergii* and *Inonotus obliquus*. Use lignin as an inducer to promote the formation of high-yield ligninase by *Bacillus thunbergii* and *Inonotus obliquus*. Select the main components of the culture medium, prepare the microbial strains into fermentation broth according to the proportion, filter the broth to remove solid residues, and place the fermentation broth in a container for natural storage. S2. Prepare cotton linters, steam and bleach the cotton linters, and dehydrate and loosen the cotton linters. S3. Add organic acids and surfactants to the fermentation broth, stir, let stand, and optimize the fermentation efficiency; S4. Sample the fermentation broth and verify the degree of polymerization of the prepared fermentation broth; S5. Fermentation is carried out in an environment with an ambient temperature above 15℃ and a humidity above 75%. The prepared fermentation liquid is mixed with cotton linters, and the microorganisms begin to degrade and decompose the impurities in the cotton linters. The fermentation time is 72 hours, allowing the microorganisms to fully process the cotton linters. S6. Bleaching the fermented cotton with sodium hypochlorite bleach, then washing and drying it, and finally packaging it. S7. The residue from the fermentation liquid is processed into solid organic fertilizer; In step S1, enzyme production is induced by mixing sawdust, cottonseed hulls, hemicellulose, and lignin in *Pterygomycetes var. albopictus* and *Pterygomycetes biloba* to form high-yield ligninase. Lignin acts as an inducer to stimulate the fungi to produce ligninase. Sawdust, cottonseed hulls, hemicellulose, and lignin are added to the culture medium, and the ratio of carbon source, nitrogen source, and inorganic salt nutrients in the culture medium is adjusted. The medium is then prepared in an environment with a temperature above 22°C.

2. The refined cotton coupled fermentation production method according to claim 1, characterized in that: In step S2, the cotton linter cooking and bleaching process involves preparing cotton linters as raw material, mixing them with cooking liquor, and cooking them in a cooking device. After cooking, the pulp is removed and washed to remove any residue from the cotton linters. The cotton linters are then bleached using a bleaching agent. After bleaching, the linters are removed and dehydrated.

3. The refined cotton coupled fermentation production method according to claim 1, characterized in that: In step S2, dewatering is used to remove excess water from the cotton linters. This step involves placing the cotton linter raw material on a mesh belt dewatering machine for initial dewatering. The mesh belt dewatering machine uses a mesh conveyor belt to filter out excess water from the slurry, reducing the moisture content of the cotton linters. Then, the linters enter the multi-roller pressing dewatering zone, where sequentially arranged pressing rollers progressively increase pressure to further remove moisture from the cotton linters. The cotton linter loosening treatment involves placing the cotton linters on a loosening device to loosen and open the fibers.

4. The refined cotton coupled fermentation production method according to claim 1, characterized in that: In step S3, organic acid is added to the fermentation broth beforehand and stirred. After stirring for 3 minutes, surfactant is added to the fermentation broth and stirring is continued. After stirring for another 5 minutes, the broth is placed on the table and left to stand to optimize the efficiency of fermentation.

5. The refined cotton coupled fermentation production method according to claim 1, characterized in that: In step S4, the degree of polymerization is verified by measuring the viscosity of the fermentation broth at 25°C using an Ubbelohde viscometer. The measured result is then compared with the degree of polymerization of a standard sample to determine the degree of polymerization of the fermentation broth.

6. The refined cotton coupled fermentation production method according to claim 1, characterized in that: In step S5, the mixing time is 1 hour. After mixing is completed, the mixture is left to stand and wait for microbial fermentation and degradation to process the cotton linters.

7. The refined cotton coupled fermentation production method according to claim 1, characterized in that: In step S6, bleaching is performed by preparing auxiliary tools, including a stirrer, thermometer, and pH meter. Sodium hypochlorite solution is weighed, and the operation is carried out in a well-ventilated environment. The fermentation cotton is pretreated, including impurity removal, washing, and pH adjustment. The pH of the fermentation cotton is adjusted to 9.5-10.5 by adding hydrochloric acid or sodium carbonate. The pretreated fermentation cotton is then placed in a bleaching tank, and the prepared sodium hypochlorite solution is added. The mixture is stirred evenly with a stirrer to ensure the sodium hypochlorite solution fully penetrates the fermentation cotton for bleaching. After bleaching, the fermentation cotton is thoroughly rinsed with clean water to remove residual sodium hypochlorite and other impurities. The water is changed several times during rinsing until the rinsing solution is clear.

8. The refined cotton coupled fermentation production method according to claim 1, characterized in that: In step S6, drying is performed by placing the cleaned fermented cotton in front of a dryer for drying at a temperature of 50°C. After drying, the refined cotton is packaged.

9. The refined cotton coupled fermentation production method according to claim 1, characterized in that: In step S6, the filtered residue is collected, and its moisture content is adjusted to between 45% and 50%. Straw and sawdust are added to the residue to adjust the carbon-nitrogen ratio. The residue is then added to a fermentation machine, evenly sprinkled on it, and stirred and mixed. The mixture is then placed in a fermentation tank for fermentation for 30 days. The fermentation tank is turned over daily until fermentation is complete. After drying, solid organic fertilizer is obtained.

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