Preparation method of bacterial cellulose powder, and product and application thereof
By combining pulping, alkali soaking, and modification treatment with conventional pulverization, the problem of difficult bacterial cellulose pulverization has been solved, realizing the preparation of environmentally friendly and efficient bacterial cellulose powder, which is suitable for multiple application fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HAINAN UNIV
- Filing Date
- 2024-12-30
- Publication Date
- 2026-06-30
AI Technical Summary
Bacterial cellulose nanofibers have high crystallinity and high mechanical strength, making them difficult to pulverize and prepare into powder. Existing methods are time-consuming, require sophisticated equipment, and are not environmentally friendly.
By combining pulping, alkali soaking, and modification with conventional pulverizers, the molecular chain stacking structure of bacterial cellulose is altered using chemical methods, reducing the intermolecular hydrogen bond energy. The pulverizing effect can then be achieved using ordinary pulverizing equipment.
The process is simple and environmentally friendly, reducing energy consumption and production costs in crushing. The resulting bacterial cellulose powder has high purity and good dispersibility, making it suitable for multiple fields.
Smart Images
Figure CN122302326A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing bacterial cellulose powder, the resulting product, and its applications, belonging to the field of biomaterial processing and application technology. Background Technology
[0002] Cellulose powder can be produced through chemical, mechanical, and biological methods. Chemical methods offer advantages such as uniform particle size, high purity, and low energy consumption; however, they may introduce toxic substances and require large amounts of chemical reagents, causing serious environmental impact. Mechanical methods, while avoiding the introduction of toxic substances, suffer from high energy consumption and low yield. Biological methods require chemical extraction of cellulose, followed by biological treatment, and finally mechanical processing to obtain the powder. While this method reduces the use of chemical reagents, it is time-consuming and complex, thus limiting its application. Researchers have found that first treating cellulose chemically and then using mechanical methods to produce cellulose powder significantly reduces preparation time and effectively increases yield. Therefore, industrially, a combination of chemical and mechanical methods is preferred for cellulose powder production.
[0003] Bacterial cellulose is a chain of cellulose synthesized and secreted by microorganisms within their cells. These protofibrils, with a diameter of less than 1.5 nm, are the finest natural fibers discovered to date. These protofibrils align extracellularly to form microfibrils of 3-6 nm in diameter. Adjacent microfibrils are connected by hydrogen bonds, further self-assembling to form ribbon-like fibers with a width of 40-100 nm and a length of several micrometers. These ribbon-like fibers form an interconnected porous network structure with high porosity, strong mechanical properties, and high crystallinity. The numerous intramolecular and intermolecular hydrogen bonds in bacterial cellulose endow it with excellent mechanical properties; however, this property also makes it difficult to pulverize and process. Using ordinary pulverizers, it is difficult to pulverize it to the specified particle size, which limits the processing and application of bacterial cellulose. Summary of the Invention
[0004] To address the technical problem of bacterial cellulose nanofibers having high crystallinity and high mechanical strength, making them difficult to pulverize into powder, this invention provides a method for preparing bacterial cellulose powder and the resulting product. This method is simple, all reagents used are recyclable and reusable, making it environmentally friendly. Furthermore, by combining operations such as pulping, alkali soaking, and modification, the difficulty of pulverizing the final bacterial cellulose is greatly reduced. Satisfactory pulverization results can be achieved using conventional pulverizers, without the need for special equipment, resulting in low production costs.
[0005] The specific technical solution of this invention is as follows: A method for preparing bacterial cellulose powder, wherein the bacterial cellulose gel is subjected to rinsing, pulping, impurity removal, alkali soaking, modification, filtration, washing, drying, pulverizing and sieving to obtain bacterial cellulose powder product.
[0006] Furthermore, the bacterial cellulose gel used in this invention is obtained by the bio-fermentation of Acetic Acid Bacillus. It is in gel form and can be commercially available or prepared by methods disclosed in the prior art.
[0007] Furthermore, the rinsing refers to washing the bacterial cellulose gel with water to remove surface impurities and dirt.
[0008] Furthermore, the pulping process refers to breaking down the rinsed bacterial cellulose gel into a paste using a pulping machine. Pulping can initially pulverize the bacterial cellulose gel, making its particles smaller, allowing the bacterial cellulose to better contact with the treatment reagents in subsequent processing steps, thereby improving treatment efficiency and effectiveness.
[0009] Furthermore, the impurity removal refers to treating the bacterial cellulose slurry obtained from pulping with an oxidizing agent, followed by washing and filtration. Specifically, an oxidizing agent is added to the bacterial cellulose slurry to treat the bacterial cellulose. After treatment, filtration is performed to remove impurities such as proteins and bacterial cells entrained in the bacterial cellulose. Then, washing and filtration are carried out to completely remove the impurities. Concentration is simultaneously achieved during the impurity removal process. The filtered bacterial cellulose is redispersed in water for further processing.
[0010] Furthermore, the oxidant used in the impurity removal process can be hypochlorous acid solution, hydrogen peroxide, or ozone.
[0011] Furthermore, during the impurity removal process, the bacterial cellulose content in the bacterial cellulose slurry obtained by pulping is 0.5-3 wt%. When the oxidant is hypochlorous acid, the concentration of hypochlorous acid in the bacterial cellulose slurry obtained by pulping is 10-20 g / L. When the oxidant is hydrogen peroxide, the concentration of hydrogen peroxide in the bacterial cellulose slurry obtained by pulping is 10-30 g / L. When the oxidant is ozone, the ratio of ozone to bacterial cellulose slurry obtained by pulping is 10-50 mg: 1 L.
[0012] Furthermore, during the impurity removal process, the temperature for treatment with hypochlorous acid solution and hydrogen peroxide is 20-60℃, and the treatment time is 20-60min; the temperature for treatment with ozone is 20-30℃, and the treatment time is 30-60min.
[0013] Furthermore, alkali soaking refers to adding an alkaline solution to the purified bacterial cellulose until the alkali content of the system reaches 1-3 wt%, boiling for 30-50 minutes, and then adding another alkaline solution until the alkali content of the system reaches 5-10 wt%, boiling for 10-20 minutes. The alkaline solution used is sodium hydroxide solution, potassium hydroxide solution, or a mixture thereof. This invention uses two stages of alkali treatment with different concentrations during the alkali soaking process, which is more conducive to reducing the intermolecular and chain-related forces of bacterial cellulose.
[0014] Furthermore, the modification refers to mixing the alkali-treated bacterial cellulose with an alkaline solution and a poor solvent of the alkali, and then treating it under stirring or ultrasound. The stirring time is 30-180 min, and the ultrasound time is 15-60 min.
[0015] Furthermore, the unsuitable solvent for the alkali is a solvent in which the alkali is insoluble, sparingly soluble, or slightly soluble, but miscible with water, such as at least one of dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide. Experiments have shown that when the unsuitable solvent for the alkali is a mixture of dimethyl sulfoxide and N,N-dimethylformamide, the resulting powder is easier to pulverize and has a smaller particle size. Preferably, the mass ratio of dimethyl sulfoxide to N,N-dimethylformamide is 3-5:3.
[0016] Furthermore, the mass of the unsuitable solvent for the alkali is approximately 3-7 times the mass of the mixture of bacterial cellulose and alkali solution, for example, 3, 4, 5, 6, or 7 times. If the amount of unsuitable solvent used is too low, the modification time is too long; if the amount used is too high, the cost of recycling and reusing the alkali and its unsuitable solvent is too high.
[0017] Furthermore, filtration refers to filtering the modified mixture containing bacterial cellulose; both conventional filtration and pressure filtration are acceptable, with pressure filtration being preferred. The filtrate is then separated by distillation to separate water, the undesirable solvent of alkali, and the alkali itself, allowing for their recovery and reuse.
[0018] Furthermore, washing refers to washing the filtered modified bacterial cellulose sample with dilute acid solution and pure water until neutral, and then further filtering the washed sample to obtain a neutral alkaline bacterial cellulose sample.
[0019] Further drying involves drying the neutral alkali-condensed bacterial cellulose sample at a temperature of 80-105℃ until the moisture content is less than 5%.
[0020] Furthermore, pulverization refers to physically crushing the dried bacterial cellulose to obtain bacterial cellulose powder. This can be done using conventional mechanical methods such as pulverizers, or by grinding. Any ordinary industrial pulverizer will suffice.
[0021] Sieving refers to the process of separating pulverized bacterial cellulose powder into smaller particles to select those that meet the particle size requirements.
[0022] The bacterial cellulose powder product obtained by this invention is white or off-white, odorless and tasteless. This product is a mixture of rod-shaped bacterial cellulose and cellulose crystals, with a particle size of less than 100 μm. The bacterial cellulose powder of this invention is a green and biodegradable material that can replace microplastics, microcrystalline cellulose, and ordinary cellulose powder in the fields of medicine, food, cosmetics, composite materials, and textile finishing.
[0023] This invention employs a chemical method to alter the packing structure of highly dispersed bacterial cellulose molecular chains, regulating the hydrogen bonds within and between cellulose molecular chains. This reduces the hydrogen bond energy between bacterial cellulose molecules, weakens the intermolecular forces, and thus reduces the mechanical properties of bacterial cellulose. Therefore, conventional mechanical crushing or grinding is sufficient to achieve the desired crushing effect. Compared with existing technologies, this invention has the following advantages: 1. The process of this invention is simple, and all reagents used can be recycled and reused, reducing the amount of chemical reagents used. It is green and environmentally friendly. The pulverization can be carried out by ordinary means without the need for special pulverization equipment, which reduces the investment in equipment and greatly reduces the energy consumption of pulverizing to prepare cellulose powder. It has significant economic benefits and huge ecological and environmental benefits.
[0024] 2. This invention utilizes the principle of alkali condensation to alter the molecular chain stacking structure of bacterial cellulose. The resulting bacterial cellulose powder is pure cellulose, a mixture of rod-shaped bacterial cellulose and cellulose crystals, with high purity. It is white or off-white in appearance, odorless, tasteless, non-adhesive, and has good dispersibility. It can be applied in fields such as medicine, food, cosmetics, composite materials, medical treatment, and catering. Attached Figure Description
[0025] Figure 1 This invention provides a process flow for preparing bacterial cellulose powder.
[0026] Figure 2 This is a photograph of the bacterial cellulose dispersion obtained in Example 1.
[0027] Figure 3 The image shows the IR spectrum of the bacterial cellulose powder obtained in Example 1.
[0028] Figure 4 This is a SEM image of the bacterial cellulose powder obtained in Example 1.
[0029] Figure 5 The image shows a SEM image of the bacterial cellulose powder obtained in Comparative Example 2. Detailed Implementation
[0030] The present invention will be further explained and illustrated below through specific embodiments. The following descriptions are merely exemplary and do not limit its content. In the following embodiments, unless otherwise specified, all concentrations are mass concentrations.
[0031] Example 1 1. Take bacterial cellulose (BC) gel, rinse it with tap water to remove dirt from the surface of the fine cellulose gel, and then use a pulper to break it into a thin paste.
[0032] 2. Add hypochlorous acid solution to a thin, paste-like dispersion with a BC content of 0.5% until the hypochlorous acid concentration reaches 10 g / L. Then, let it stand at 60°C for 30 minutes. Filter the solution through a screen to remove excess hypochlorous acid and impurities. Wash the filter cake with pure water until neutral, then redisperse it in water to obtain a bacterial cellulose dispersion (BC content 0.5%). Figure 2 As shown.
[0033] 3. Mix the above-mentioned purified bacterial cellulose dispersion with sodium hydroxide solution and stir to obtain a sodium hydroxide / bacterial cellulose system with a sodium hydroxide content of 3%. Boil for 40 minutes, and then add sodium hydroxide solution until the sodium hydroxide content in the system is 9 wt%. Boil for 15 minutes.
[0034] 4. Mix the above sodium hydroxide / bacterial cellulose system with a mixture of dimethyl sulfoxide and N,N-dimethylformamide in a 1:1 mass ratio (3 times by weight) and sonicate for 30 min. Then compress and filter to separate the filter cake and filtrate.
[0035] 5. Take the above filter cake, wash it with dilute hydrochloric acid until neutral, wash it twice with pure water, and further filter it to obtain neutral modified bacterial cellulose. Take the above filtrate and distill it to obtain a mixture of sodium hydroxide and dimethyl sulfoxide / N,N-dimethylformamide. The sodium hydroxide is recycled in the alkali leaching process, and the dimethyl sulfoxide / N,N-dimethylformamide mixture is recycled in the modification process.
[0036] 6. The above-mentioned neutral modified bacterial cellulose was dried at 80℃ for 8 hours. 100g of the dried modified bacterial cellulose was placed in a common pulverizer and pulverized at a pulverizing speed of 3000r / min for 10 minutes. The resulting powder was passed through a 160-mesh sieve with a 100% pass rate. After passing through a 200-mesh sieve, 92g of bacterial cellulose powder product was obtained with a 92% pass rate. The powder is white, odorless, tasteless, well-dispersible, and non-adhesive.
[0037] Figure 3 The image shows the IR spectrum of the obtained bacterial cellulose powder. Its characteristic peaks are consistent with those of cellulose, indicating that the obtained product is cellulose. Figure 4 The SEM image shows that the product contains granular material with a particle size of less than 10 μm.
[0038] Example 2 1. Take the bacterial cellulose gel, rinse it with tap water to remove dirt from the surface of the fine cellulose gel, and then use a pulper to break it into a thin paste.
[0039] 2. Add hydrogen peroxide to a thin paste-like dispersion with a BC content of 1.6% until the hydrogen peroxide concentration is 20 g / L, stir evenly, let stand at 50℃ for 40 min, filter with a filter screen to remove excess hydrogen peroxide and impurities, wash the filter cake with pure water until neutral, and then redisperse it in water to obtain a bacterial cellulose dispersion (BC content of 1.6%).
[0040] 3. Mix the above-mentioned purified bacterial cellulose dispersion with potassium hydroxide solution and stir to obtain a potassium hydroxide / bacterial cellulose system with a potassium hydroxide content of 2%. Boil for 50 minutes, and then add potassium hydroxide solution until the potassium hydroxide content in the system is 10 wt%. Boil for 10 minutes.
[0041] 4. Mix the above potassium hydroxide / bacterial cellulose system with a mixture of dimethyl sulfoxide and N,N-dimethylacetamide in a 1:1 mass ratio (4 times by weight) and sonicate for 45 min. Then compress and filter to separate the filter cake and filtrate.
[0042] 5. Take the above filter cake, wash it with dilute sulfuric acid until neutral, wash it twice with pure water, and further filter by pressure to obtain neutral modified bacterial cellulose. Take the above filtrate for distillation and dehydration to obtain a mixture of potassium hydroxide and dimethyl sulfoxide / N,N-dimethylacetamide. The potassium hydroxide is recycled in the alkali leaching process, and the dimethyl sulfoxide / N,N-dimethylacetamide mixture is recycled in the modification process.
[0043] 6. The above-mentioned neutral modified bacterial cellulose was dried at 90℃ for 7 hours. 100g of the dried modified bacterial cellulose was placed in a common pulverizer and pulverized at a pulverizing speed of 3000r / min for 10 minutes. The resulting powder was passed through a 160-mesh sieve with a 100% pass rate. After passing through a 200-mesh sieve, 87g of bacterial cellulose powder product was obtained with a 87% pass rate. The powder is white, odorless, tasteless, well-dispersible, and non-adhesive.
[0044] Example 3 1. Take the bacterial cellulose gel, rinse it with tap water to remove dirt from the surface of the fine cellulose gel, and then use a pulper to break it into a thin paste.
[0045] 2. While stirring, ozone was introduced into a thin paste-like dispersion with a BC content of 1%, with 35 mg of ozone introduced per liter of dispersion. The mixture was kept at room temperature for 50 min, filtered through a filter screen, and the filter cake was washed with pure water until neutral. Then it was redispersed in water to obtain a bacterial cellulose dispersion (BC content of 1%).
[0046] 3. Mix the above-mentioned purified bacterial cellulose dispersion with a sodium hydroxide and potassium hydroxide solution in a mass ratio of 1:1 and stir to obtain a mixed alkali / bacterial cellulose system with a total sodium hydroxide and potassium hydroxide content of 1%. Boil for 30 minutes, and then add a sodium hydroxide and potassium hydroxide solution in a mass ratio of 1:1 until the total sodium hydroxide and potassium hydroxide content in the system is 8 wt%. Boil for 20 minutes.
[0047] 4. Mix the above-mentioned mixed alkali / bacterial cellulose system with a mixture of N,N-dimethylformamide and N,N-dimethylacetamide at a mass ratio of 5:3 (5 by weight) and sonicate for 50 min. Then compress and filter to separate the filter cake and filtrate.
[0048] 5. Take the above filter cake, wash it with dilute hydrochloric acid until neutral, wash it twice with pure water, and further filter by pressure to obtain neutral modified bacterial cellulose. Take the above filtrate for distillation and dehydration to obtain a mixed alkali of sodium hydroxide and potassium hydroxide and a mixed solution of N,N-dimethylformamide and N,N-dimethylacetamide. The mixed alkali of sodium hydroxide and potassium hydroxide is recycled in the alkali leaching process, and the mixed solution of N,N-dimethylformamide and N,N-dimethylacetamide is recycled in the modification process.
[0049] 6. The above-mentioned neutral modified bacterial cellulose was dried at 100℃ for 6 hours. 100g of the dried modified bacterial cellulose was placed in a common pulverizer and pulverized at a pulverizing speed of 3000r / min for 10 minutes. The resulting powder was passed through a 160-mesh sieve with a 100% pass rate. After passing through a 200-mesh sieve, 82g of bacterial cellulose powder product was obtained with a 82% pass rate. The powder is white, odorless, tasteless, well-dispersible, and non-adhesive.
[0050] Example 4 1. Take the bacterial cellulose gel, rinse it with tap water to remove dirt from the surface of the fine cellulose gel, and then use a pulper to break it into a thin paste.
[0051] 2. Add hydrogen peroxide to a thin paste-like dispersion with a BC content of 3% until the hydrogen peroxide concentration is 30 g / L, stir evenly, let stand at 60℃ for 40 min, filter with a filter screen to remove excess hydrogen peroxide and impurities, wash the filter cake with pure water until neutral, and then redisperse it in water to obtain a bacterial cellulose dispersion (BC content of 3%).
[0052] 3. Mix the above-mentioned purified bacterial cellulose dispersion with sodium hydroxide solution and stir to obtain a sodium hydroxide / bacterial cellulose system with a sodium hydroxide content of 2%. Boil for 40 minutes, and then add sodium hydroxide solution until the sodium hydroxide content in the system is 6 wt%. Boil for 15 minutes.
[0053] 4. Mix the above sodium hydroxide / bacterial cellulose system with 7 times its mass of anhydrous dimethyl sulfoxide and stir for 180 min. Then compress and filter to separate the filter cake and filtrate.
[0054] 5. Take the above filter cake, wash it with dilute sulfuric acid until neutral, wash it twice with pure water, and further filter by pressure to obtain neutral modified bacterial cellulose. Take the above filtrate for distillation and dehydration to obtain sodium hydroxide and dimethyl sulfoxide. Sodium hydroxide is recycled in the alkali leaching process, and dimethyl sulfoxide is recycled in the modification process.
[0055] 6. The above-mentioned neutral modified bacterial cellulose was dried at 105℃ for 5 hours. 100g of the dried modified bacterial cellulose was placed in a common pulverizer and pulverized at a pulverizing speed of 3000r / min for 10 minutes. The powder obtained was passed through a 160-mesh sieve with a 100% sieve pass rate. After passing through a 200-mesh sieve, 75g of bacterial cellulose powder product was obtained with a 75% sieve pass rate. The powder was off-white, odorless, tasteless, well dispersible, and non-adhesive.
[0056] Example 5 1. Take the bacterial cellulose gel, rinse it with tap water to remove dirt from the surface of the fine cellulose gel, and then use a pulper to break it into a thin paste.
[0057] 2. Add hypochlorous acid solution to the dilute BC dispersion with a BC content of 2.5% to adjust the hypochlorous acid concentration to 20 g / L, let it stand at 60℃ for 50 min, filter with a filter screen to remove excess hypochlorous acid and impurities, wash the filter cake with pure water until neutral, and then redisperse it in water to obtain bacterial cellulose dispersion (BC content of 2.5%).
[0058] 3. Mix the above-mentioned purified bacterial cellulose dispersion with sodium hydroxide solution and stir to obtain a sodium hydroxide / bacterial cellulose system with a sodium hydroxide content of 2%. Boil for 40 minutes, and then add sodium hydroxide solution until the sodium hydroxide content in the system is 5 wt%. Boil for 15 minutes.
[0059] 4. Mix the above sodium hydroxide / bacterial cellulose system with 7 times its mass of dimethyl sulfoxide and stir for 60 min. Then compress and filter to separate the filter cake and filtrate.
[0060] 5. Take the above filter cake, wash it with dilute hydrochloric acid until neutral, wash it twice with pure water, and filter it by pressure to obtain neutral modified bacterial cellulose. Take the above filtrate and dehydrate it by distillation to obtain sodium hydroxide and dimethyl sulfoxide. Sodium hydroxide is recycled in the alkali leaching process, and dimethyl sulfoxide is recycled in the modification process.
[0061] 6. The above-mentioned neutral modified bacterial cellulose was dried at 105℃ for 5 hours. 100g of the dried modified bacterial cellulose was placed in a common pulverizer and pulverized at a pulverizing speed of 3000r / min for 10 minutes. The powder obtained was passed through a 160-mesh sieve with a 100% sieve pass rate. After passing through a 200-mesh sieve, 66g of bacterial cellulose powder product was obtained with a sieve pass rate of 66%. The powder was off-white, odorless, tasteless, well dispersible, and non-adhesive.
[0062] Comparative Example 1 1. Take compressed bacterial cellulose gel and rinse the surface of the fine cellulose gel with tap water to remove dirt; soak it several times to fully rehydrate it, with a size of 35cm * 25cm * 1cm, and wash until neutral to obtain a bacterial cellulose gel with a bacterial cellulose content of approximately 0.8%.
[0063] 2. Immerse the pretreated bacterial cellulose gel in sodium hydroxide solution, adjust the concentration, and soak for 10 hours to obtain a bacterial cellulose gel system with a sodium hydroxide content of 1.2%. Then heat to 100℃ and maintain for 40 minutes.
[0064] 3. Wash with pure water to remove the brown color from the bacterial cellulose gel until it is neutral and the bacterial cellulose gel is colorless or slightly white.
[0065] 4. Immerse the purified bacterial cellulose gel in sodium hydroxide solution, adjust the concentration, and soak for 10 hours to obtain a sodium hydroxide / bacterial cellulose gel system with an alkali content of 3%.
[0066] 5. Take the above-mentioned alkaline bacterial cellulose gel, filter the water, and immerse it in 4 times its weight of a mixed dehydrating agent (dimethyl sulfoxide and N,N-dimethylacetamide in a mass ratio of 1:1) for dehydration. Turn the gel over every 10-20 minutes until the bacterial cellulose gel no longer shrinks. The dehydration rate of the bacterial cellulose gel is 92%. Recover the mixed alkali and the mixed dehydrating agent.
[0067] 6. Take the bacterial cellulose gel dehydrated product by alkali shrinkage, squeeze it multiple times to remove the mixed alkali and mixed dehydrating agent, further recover the mixed alkali and mixed dehydrating agent, and wash it with pure water until neutral.
[0068] 7. Take the above sample and repeatedly flatten it with a flattener until no water droplets are produced. Let it air dry at room temperature to obtain a pure bacterial cellulose structural material product. Commonly used pulverizers cannot pulverize it and cannot obtain bacterial cellulose powder.
[0069] Comparison Column 2 Bacterial cellulose powder was prepared according to the method in Example 1, with the following differences: In step 3, the purified bacterial cellulose dispersion was mixed with sodium hydroxide solution and stirred to obtain a sodium hydroxide / bacterial cellulose system with an alkali content of 2%, and boiled for 60 min; in step 4, the above sodium hydroxide / bacterial cellulose system was mixed with acetonitrile in a ratio of 3 by mass and ultrasonicated for 30 min. Then, it was compressed and filtered to separate the filter cake and filtrate. The pulverized bacterial cellulose exhibited obvious fibrous and irregular granular structures, with a sieve pass rate of less than 10% through a 200-mesh sieve. Figure 5 As shown.
[0070] Comparison Column 3 Bacterial cellulose powder was prepared according to the method in Example 1, with the following differences: In step 3, the above bacterial cellulose dispersion was mixed with sodium hydroxide solution and stirred to obtain a sodium hydroxide / bacterial cellulose system with an alkali content of 12%, and boiled for 60 min; in step 4, the above sodium hydroxide / bacterial cellulose system was mixed with a mixture of dimethyl sulfoxide and acetone in a mass ratio of 1:1 (2 times by mass), and sonicated for 30 min. Then, the mixture was compressed and filtered to separate the filter cake and filtrate. After pulverization, the bacterial cellulose appeared as large, irregular particles, with a sieve pass rate of less than 10% through a 200-mesh sieve.
[0071] Comparative Example 4 1. Take the bacterial cellulose gel and rinse it with tap water to remove dirt from the surface of the fine cellulose gel.
[0072] 2. Add hypochlorous acid solution to the above BC gel soaking solution to adjust the hypochlorous acid concentration to 10 g / L, let stand for 24 h, wash with pure water until neutral, and obtain bacterial cellulose gel.
[0073] 3. Take the above BC gel (2cm thick) and dry it. Due to the high water content, the drying time is about 24 hours to obtain paper-like bacterial cellulose.
[0074] 4. Due to the strong toughness and strength of paper-like bacterial cellulose, it is difficult to crush with ordinary pulverizers. In addition, high-speed pulverizers operate for a long time, resulting in severe blade wear. The resulting product is pale yellow, has a high water absorption rate, and is difficult to disperse.
[0075] Comparison Column 5 1. Take the bacterial cellulose gel, rinse it with tap water to remove dirt from the surface of the fine cellulose gel, and then use a pulper to break it into a thin paste.
[0076] 2. Add hypochlorous acid solution to the dilute BC dispersion to adjust the hypochlorous acid concentration to 10 g / L, let stand for 24 h, wash with pure water until neutral, and obtain bacterial cellulose dispersion.
[0077] 3. The above bacterial cellulose dispersion is dried. Due to the strong water absorption of bacterial cellulose, the drying time is relatively long, resulting in paper-like and granular bacterial cellulose solids with strong hardness.
[0078] 4. Due to the strong toughness and rigidity of bacterial cellulose solids, they are difficult to crush with ordinary pulverizers, and high-speed pulverizers suffer severe wear. The resulting product is gray, with large and uneven particle size, high water absorption, and is difficult to disperse.
Claims
1. A method for preparing bacterial cellulose powder, characterized in that: The bacterial cellulose gel is subjected to rinsing, pulping, impurity removal, alkali soaking, modification, filtration, washing, drying, pulverizing and sieving to obtain bacterial cellulose powder.
2. The preparation method according to claim 1, characterized in that: The pulping process involves using a pulping machine to pulverize the rinsed bacterial cellulose gel into a paste.
3. The preparation method according to claim 1, characterized in that: The impurity removal process involves treating the bacterial cellulose slurry obtained from pulping with an oxidant, followed by washing and filtration.
4. The preparation method according to claim 3, characterized in that: The oxidant is hypochlorous acid solution, hydrogen peroxide, or ozone; preferably, the bacterial cellulose content in the bacterial cellulose slurry obtained by pulping is 0.5-3 wt%, the concentration of hypochlorous acid in the bacterial cellulose slurry obtained by pulping is 10-20 g / L, the concentration of hydrogen peroxide in the bacterial cellulose slurry obtained by pulping is 10-30 g / L, and the ratio of ozone to the bacterial cellulose slurry obtained by pulping is 10-50 mg:1 L; preferably, the temperature for treatment with hypochlorous acid solution and hydrogen peroxide is 20-60℃, and the treatment time is 20-60 min; the temperature for treatment with ozone is 20-30℃, and the treatment time is 30-60 min.
5. The preparation method according to claim 1, characterized in that: The alkali soaking process involves adding alkali solution to the purified bacterial cellulose until the alkali content in the system is 1-3 wt%, boiling for 30-50 minutes, and then adding alkali solution until the alkali content in the system is 5-10 wt%, and boiling for 10-20 minutes.
6. The preparation method according to claim 1, characterized in that: The modification involves mixing the alkali-treated bacterial cellulose with an alkaline solution and a poor solvent for alkali, and then treating it under stirring or ultrasound.
7. The preparation method according to claim 6, characterized in that: The unsuitable solvent for the alkali is at least one of dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide, preferably dimethyl sulfoxide and N,N-dimethylformamide; the mass ratio of the mixture of bacterial cellulose after alkali treatment and the unsuitable solvent for the alkali is 1:3-7; the stirring time is 30-180 min, and the sonication time is 15-60 min.
8. The preparation method according to claim 1, characterized in that: The crushing process employs mechanical crushing or grinding.
9. Bacterial cellulose powder prepared according to the method for preparing bacterial cellulose powder according to any one of claims 1-8; preferably, the particle size of the powder is less than 100 μm; preferably, the powder is a mixture of rod-shaped bacterial cellulose and cellulose crystals.
10. The application of the bacterial cellulose powder according to claim 9 in the fields of medicine, food, cosmetics, composite materials, and textile post-processing.