Method for producing regenerated cellulose fibers

Abstract

A method for producing regenerated bacterial cellulose fibers, the method comprising either contacting bacterial cellulose powder with an aqueous solution containing a quaternary ammonium hydroxide and optionally urea under conditions that result in at least partial dissolution of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose, or contacting bacterial cellulose powder with an aqueous solution containing a metal complex under conditions that result in at least partial dissolution of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose, and extruding the cellulose dope into a coagulation bath, thereby forming regenerated bacterial cellulose fibers.

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 485,028, filed February 15, 2023, the contents of which are incorporated herein by reference in their entirety.

[0002] The present disclosure generally relates to a method for producing regenerated cellulose fibers from bacterial cellulose powder produced during kombucha fermentation. [Background technology]

[0003] Cellulosic materials obtained from wood, cotton, and bamboo have been widely used for thousands of years as materials for paper, construction, energy, textiles, and furniture. Cotton fibers and wood-based regenerated cellulose fibers are the most common types of cellulosic fibers in the textile industry. However, cellulosic fibers exhibit certain disadvantages.

[0004] Cotton is a natural plant fiber that grows around the seeds of the cotton plant. Cotton fiber is obtained from the cotton plant and spun into yarn, which is then woven or knitted into fabric. According to the World Wildlife Fund, cotton's most significant environmental impacts are due to its use of pesticides, its high water consumption, and the amount of land space it requires.

[0005] Regenerated cellulosic fibers can be produced by extracting cellulose from wood pulp, which is then chemically dissolved and extruded as continuous filaments.

[0006] Conventional processes for making regenerated cellulose fibers typically involve toxic chemicals and / or by-products.

[0007] For example, the Kraft process commonly used to make regenerated cellulosic fibers can be highly polluting because it uses H2S to break the bonds between lignin, hemicellulose, and cellulose, as shown in Figure 1.

[0008] In another example, as shown in Figure 2, viscose is produced by reacting cellulose with sodium hydroxide to form alkali cellulose, which is then reacted with highly toxic carbon disulfide to form cellulose xanthate, which is subsequently dissolved in dilute sodium hydroxide and extruded as regenerated cellulose fibers.

[0009] Therefore, there is a need for new methods of making regenerated cellulosic fibers that avoid the use of polluting chemicals used in conventional methods.

[0010] Kombucha is a fermented tea that has grown in popularity in recent years, due in part to the belief that its consumption can flush out toxins, boost energy, strengthen the immune system, and aid in weight loss. In 2021, the global kombucha market was valued at US$2.64 billion, and is expected to expand at a compound annual growth rate of 15.6% from 2022 to 2030.

[0011] As shown in Figure 3, the symbiotic colony of bacteria and yeast (SCOBY) pellicle is a gelatinous biofilm formed during the kombucha production process and contains bacterial cellulose. Kombucha bacterial cellulose does not contain other biopolymers such as lignin, hemicellulose, and pectin. SCOBY pellicle is an attractive alternative source for cellulosic fiber production due to its high purity, high degree of polymerization (DP), and high crystallinity.

[0012] There remains a need for improved methods for producing and isolating bacterial cellulose fibers from kombucha SCOBY pellicles. Summary of the Invention

[0013] In this disclosure, bacterial cellulose using SCOBY pellicles, produced as a sidestream of kombucha fermentation, is developed as a sustainable source for the production of regenerated cellulose fibers. The method described herein addresses several challenges, including (1) developing a solvent system for efficient dissolution of bacterial cellulose and (2) optimizing the conditions for wet-spinning of regenerated bacterial cellulose fibers, as shown in Figure 5. High-purity, high-degree-of-polymerization, and high-crystalline bacterial cellulose can be utilized as an alternative source for cellulosic fiber production. Advantages of the method described herein include, but are not limited to, the rapid growth rate of the SCOBY pellicles and the bacterial cellulose fibers contained therein, the absence of pesticides and toxic chemicals, and low water requirements.

[0014] In a first aspect, provided herein is a method for making regenerated bacterial cellulose fibers, the method comprising either contacting bacterial cellulose powder with an aqueous solution containing a quaternary ammonium hydroxide and optionally urea under conditions that result in at least partial dissolution of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose, or contacting bacterial cellulose powder with an aqueous solution containing a metal complex under conditions that result in at least partial dissolution of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose, and extruding the cellulose dope in a coagulation bath, thereby forming regenerated bacterial cellulose fibers.

[0015] In certain embodiments, the bacterial cellulose powder is kombucha bacterial cellulose powder.

[0016] In certain embodiments, the quaternary ammonium hydroxide is NROH, where R is independently at each occurrence alkyl, cycloalkyl, or phenyl, and the metal complex comprises a metal selected from the group consisting of aluminum, calcium, copper, iron, nickel, and zinc.

[0017] In certain embodiments, the quaternary ammonium hydroxide is tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide, and the metal complex is bis(ethylenediamine)copper(II) hydroxide.

[0018] In certain embodiments, the quaternary ammonium hydroxide is present in the aqueous solution at a concentration of 20% (w / w) to 60% (w / w) and the metal complex is present in the aqueous solution at a concentration of 0.5M to 2M.

[0019] In certain embodiments, urea is present in an aqueous solution at a concentration of 0.1% (w / w) to 0.5% (w / w).

[0020] In certain embodiments, the coagulation bath comprises a primary drawing bath and further comprises a secondary drawing bath.

[0021] In certain embodiments, the first and second draw baths each independently have a pH between 0 and 1.

[0022] In certain embodiments, the primary and secondary drawing baths each comprise an aqueous solution of H2SO4 and optionally Na2SO4.

[0023] In certain embodiments, the concentration of H2SO4 in each of the first and second drawing baths is independently between 0.25M and 1M.

[0024] In certain embodiments, the cellulose dope contains bacterial cellulose at a concentration of 2% (w / w) to 10% (w / w).

[0025] In certain embodiments, the method further includes providing a symbiotic colony of bacteria and yeast (SCOBY) pellicle, contacting the SCOBY pellicle with an alkaline aqueous solution, thereby forming a treated SCOBY pellicle, optionally washing and drying the treated SCOBY pellicle, and powdering the treated SCOBY pellicle, thereby forming bacterial cellulose powder.

[0026] In certain embodiments, the method further comprises washing the regenerated bacterial cellulose fibers with water and drying the washed regenerated bacterial cellulose fibers.

[0027] In certain embodiments, the conditions that result in at least partial dissolution of the bacterial cellulose powder include maintaining an aqueous solution containing a quaternary ammonium hydroxide and optionally urea at 25°C to 50°C for 8 to 24 hours, or maintaining an aqueous solution containing a metal complex at 75°C to 90°C for 1 to 2 hours.

[0028] In certain embodiments, the method includes contacting the bacterial cellulose powder with an aqueous solution containing 20% ​​(w / w) to 60% (w / w) of N(C1-C5)4OH and optionally 0.1% (w / w) to 0.5% (w / w) of urea at 25°C to 40°C for 8 hours to 24 hours to dissolve at least a portion of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose at a concentration of 4% (w / w) to 10% (w / w); or contacting the bacterial cellulose powder with an aqueous solution containing 0.5M to 2M of urea at 25°C to 40°C for 8 hours to 24 hours to dissolve at least a portion of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose at a concentration of 4% (w / w) to 10% (w / w). the method comprises either dissolving at least a portion of the bacterial cellulose powder by contacting the bacterial cellulose dope with an aqueous solution containing bis(ethylenediamine)copper(II) oxide at 75°C to 90°C for 1 to 2 hours, thereby forming a cellulose dope containing bacterial cellulose at a concentration of 2% (w / w) to 6% (w / w); or extruding the cellulose dope in a coagulation bath containing a first drawing bath and a second drawing bath, the first drawing bath and the second drawing bath independently having a pH of 0 to 0.5, thereby forming regenerated bacterial cellulose fibers.

[0029] In certain embodiments, the cellulose dope contains bacterial cellulose at a concentration of 3.5% (w / w) to 5.5% (w / w).

[0030] In certain embodiments, the method further includes providing a symbiotic colony of bacteria and yeast (SCOBY) pellicle, contacting the SCOBY pellicle with an alkaline aqueous solution, thereby forming a treated SCOBY pellicle, optionally washing and drying the treated SCOBY pellicle, and powdering the treated SCOBY pellicle, thereby forming bacterial cellulose powder.

[0031] In certain embodiments, the alkaline aqueous solution has a pH of 13-14.

[0032] In certain embodiments, the alkaline aqueous solution comprises NaOH.

[0033] In certain embodiments, the method includes providing a symbiotic colony of bacteria and yeast (SCOBY) pellicle; contacting the SCOBY pellicle with an alkaline aqueous solution having a pH of 13 to 13.5, thereby forming a treated SCOBY pellicle; optionally washing and drying the treated SCOBY pellicle; powdering the treated SCOBY pellicle, thereby forming a bacterial cellulose powder; and contacting the bacterial cellulose powder with an aqueous solution comprising 20% ​​(w / w) to 60% (w / w) N(C1-C5)4OH and optionally 0.1% (w / w) to 0.5% (w / w) urea at 25°C to 40°C for 8 hours to 24 hours to dissolve at least a portion of the bacterial cellulose powder, thereby forming a bacterial cellulose powder. The method includes either forming a cellulose dope containing bacterial cellulose at a concentration of 3.5% (w / w) to 5.5% (w / w) by contacting bacterial cellulose powder with an aqueous solution containing 0.5 M to 2 M bis(ethylenediamine)copper(II) hydroxide at 75°C to 90°C for 1 to 2 hours to dissolve at least a portion of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose at a concentration of 3.5% (w / w) to 5.5% (w / w); and extruding the cellulose dope in a coagulation bath containing a first drawing bath and a second drawing bath, each containing an aqueous solution of H2SO4 and Na2SO4 with a pH of 0 to 0.5, thereby forming regenerated bacterial cellulose fibers.

[0034] The methods disclosed herein can include one of three different bacterial cellulose powder dissolution methods:

[0035] 1. Quaternary ammonium hydroxide (QAH) aqueous solvent system A QAH solution containing tetramethylammonium hydroxide (TMAH, 25% aqueous solution), tetraethylammonium hydroxide (TEAH, 30% aqueous solution), tetrapropylammonium hydroxide (TPAH, 35% aqueous solution), or tetrabutylammonium hydroxide (TBAH, 55% aqueous solution) can be used as a solvent system to dissolve bacterial cellulose powder.

[0036] Without wishing to be bound by theory, it is believed that anions and cations may play an important role in the dissolution of bacterial cellulose powder. The anions can participate in interactions with the hydroxyl protons on the cellulose, and the hydrophobic substituents present on QAH can interact with the hydrophobic moieties of cellulose through van der Waals forces, thereby dissolving the QAH. + -Cellulose intermediates are produced, which can promote the dissolution of bacterial cellulose powder. These effects may lead to the destruction of inter- and intramolecular hydrogen bonds, resulting in the effective dissolution of bacterial cellulose powder.

[0037] 2. QAH / urea aqueous solvent system Without wishing to be bound by theory, it is believed that urea may improve the solubility and stability of cellulose in solution by accumulating near hydrophobic regions due to van der Waals forces. The addition of urea to aqueous QAH solutions may not only reduce the amount of QAH solution required, but also facilitate dissolution at room temperature.

[0038] 3. Metal complex-based solvent systems The advantage of using a metal complex as a solvent system is that it can form stronger metal-ligand bonds with the substituents present on cellulose. Decomplexation of the metal complex can release the cellulose. Unlike hydrogen-bonding solvents, the proposed metal complex solvent system can effectively increase the solubility of bacterial cellulose powder.

[0039] The optimization of the medium concentration, culture environment and temperature of the culture medium was determined by applying the Box-Behnken design.

[0040] The objective of the present disclosure is to provide a method for producing regenerated cellulose fibers from bacterial cellulose. The cellulose pellicle formed during fermentation is purified under alkaline treatment, followed by a washing and drying process. After grinding the dried bacterial cellulose, the bacterial cellulose powder can be used to prepare a spinning dope, which can then be used to spin fibers.

[0041] In this disclosure, we investigate dope fabrication by direct dissolution of bacterial cellulose powder in three dissolution systems. In certain embodiments, the bacterial cellulose powder dissolution methods include: 1) tetrabutylammonium hydroxide solution (TBAH, 40%-55% aqueous solution), 2) a tetrabutylammonium hydroxide (TBAH) / urea aqueous solvent system, and 3) a metal complex-based solvent system. Advantageously, these solvent systems eliminate the need for high spinning temperatures and the use of contaminating chemicals and synthetic polymers in both the solvent and raw materials. The properties of the cellulose dopes are analyzed at different dissolution concentrations. Furthermore, wet spinning of the different dopes is demonstrated, and fiber characterization is performed.

[0042] These and other objects and features of the present disclosure will become apparent from the following description of the disclosure when considered in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0043] [Figure 1] FIG. 1 illustrates the craft process. [Figure 2] FIG. 1 shows viscose production. [Figure 3] 1 is a photograph showing an exemplary SCOBY pellicle. [Figure 4] This is a graph showing the solubility of bacterial cellulose in common solvents such as N-methylmorpholine N-oxide (NMMO), the ionic liquid zinc chloride trihydrate, 1-ethyl-3-methylimidazolium acetate (EMIMAc), and N,N-dimethylacetamide / lithium chloride (LiCl / DMAc), and the time required for complete dissolution. [Figure 5]1 is a flow chart illustrating an exemplary process for making regenerated bacterial cellulose fibers in accordance with certain embodiments described herein. [Figure 6] FIG. 1 shows a theoretical reaction sequence illustrating the complexation and dissolution of bacterial cellulose with a metal complex and the decomplexation of the metal complex to regenerate cellulose. [Figure 7] 1 is a photograph showing the product of Example 3 after cutting and grinding. DETAILED DESCRIPTION OF THE INVENTION

[0044] definition Throughout this disclosure, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising" will be understood to mean the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers. Also, in this disclosure, and particularly in the claims and / or paragraphs, terms such as "comprises," "comprised," "comprising," and the like may have the meaning ascribed to them in U.S. patent law, e.g., they may mean "includes," "included," "including," etc. It should also be noted that terms such as "consisting essentially of" and "consists essentially of" have the meaning ascribed to them in U.S. patent law, e.g., allowing for elements not expressly recited, but excluding elements found in the prior art or that affect a basic or novel characteristic of the invention.

[0045] Furthermore, throughout this disclosure and claims, unless the context requires otherwise, the word "include" or variations such as "includes" or "including" will be understood to mean the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

[0046] The use of the singular herein includes the plural (and vice versa) unless specifically stated otherwise. Additionally, when the term "about" is used before a quantitative value, the present teachings also include the specific quantitative value itself, unless specifically stated otherwise.

[0047] As used herein, the term "about" refers to a variation of ±10%, ±7%, ±5%, ±3%, ±1%, or ±0% from the nominal value, unless otherwise indicated or estimated.

[0048] The present disclosure provides methods for making a cellulose dope, methods for making regenerated cellulose fibers from the cellulose dope, and the products thereof. The regenerated cellulose fibers can optionally contain functional materials that affect the physical, chemical, mechanical, and / or optical properties of the regenerated cellulose fibers.

[0049] In a first aspect, provided herein is a method for making regenerated bacterial cellulose fibers, the method comprising either contacting bacterial cellulose powder with an aqueous solution containing a quaternary ammonium hydroxide and optionally urea under conditions that result in at least partial dissolution of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose, or contacting bacterial cellulose powder with an aqueous solution containing a metal complex under conditions that result in at least partial dissolution of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose, and extruding the cellulose dope in a coagulation bath, thereby forming regenerated bacterial cellulose fibers.

[0050] Regenerated bacterial cellulose fibers made according to the methods described herein can be used in many potential applications, including, but not limited to, paper and packaging, biopharmaceuticals and pharmaceuticals, food and cosmetics, biosensors and energy storage, and / or textiles and materials.

[0051] In certain embodiments, the bacterial cellulose powder is kombucha bacterial cellulose powder derived from the SCOBY pellicle that forms during fermentation of a kombucha culture.

[0052] The kombucha culture may include a carbon source and a nitrogen source.

[0053] The carbon source is not particularly limited as long as it can support the growth of the SCOBY. In certain embodiments, the carbon source is selected from the group consisting of ethanol, glucose, sucrose, fructose, galactose, inositol, glycerol, xylose, dextrose, lactose, dextrin, ribitol, mannitol, mannose, maltose, raffinose, coconut palm sugar, sugarcane, jaggery, honey, malt extract, molasses, etc.

[0054] In certain embodiments, the nitrogen source comprises at least one organic nitrogen source selected from the group consisting of yeast extract, peptone, soy, casamino acids, tryptone, and malt extract, NH4Cl, NH4NO3, NaNO3, (NH4)2SO4, tea (such as green tea or black tea), coffee, red wine, white wine, malt, beer, juice, fruit, peel, vegetables, coconut milk, or other nitrogen-containing organic matter.

[0055] In certain embodiments, the kombucha culture comprises tea and sucrose.

[0056] A SCOBY can include one or more bacteria and one or more yeasts. In certain embodiments, the SCOBY includes acetic acid bacteria, lactic acid bacteria, and osmophilic yeasts.

[0057] The bacteria are not particularly limited as long as they are capable of producing bacterial cellulose. In certain embodiments, the one or more bacteria are selected from the group consisting of Gluconobacter, Komagataeibacter, Pseudomonas, Agrobacterium, Rhizobium, Lactobacillus, Acetobacter, Azotobacter, Gluconacetobacter, Aerobacter, Sarcina, and Alcaligenes. Specific examples of bacteria useful in the methods described herein include, but are not limited to, Komagataeibacter xylinus, Komagataeibacter intermedius, Komagataeibacter rhaeticus, Komagataeibacter saccharivorans, Komagataeibacter kombuchae, Acetobacter pasteurianus, Acetobacter aceti, Acetobacter xylinum, Acetobacter ransens, and Enterobacter species.

[0058] The one or more yeasts can be selected from the group consisting of Zygosaccharomyces, Candida, Torulaspora, Pichia, Koleckera, Brettanomyces, Schizosaccharomyces, Saccharomyces, Saccharomycodes, and Cyberlindnera jadini. Specific examples of yeasts useful in the methods described herein include, but are not limited to, Candida stellata, Saccharomycodes ludwigii, Saccharomycodes apiculatus, Schizosaccharomyces pombe, Brettanomyces bruxellensis, Zygosaccharomyces bailii, and Saccharomyces cerevisiae.

[0059] Bacterial cellulose powder can be produced from SCOBY pellicles, which typically form on the surface of the culture medium during fermentation. The SCOBY pellicle can optionally be purified before dissolution, which involves liquid-solid extraction with an alkaline aqueous solution to remove any undesired contaminants. In certain exemplary embodiments, the alkaline solution is produced by dissolving a metal hydroxide, such as LiOH, NaOH, KOH, or Ca(OH)2, in water. In an exemplary embodiment, approximately 6 g to 12 g of sodium hydroxide is dissolved in 1 L of water. Purification can be aided by completely immersing the SCOBY pellicle in the alkaline aqueous solution, followed by heating, for example, at 70°C to 90°C for 0.5 to 1 hour. Contaminants diffuse from the SCOBY pellicle, resulting in a purified SCOBY pellicle. The alkaline aqueous solution is then replaced with water and the SCOBY pellicle is washed, for example, by heating at 60°C to 80°C for 0.5 to 1 hour. The washing process can be optionally repeated two, three, four or more times until the pH value of the water washes is between 6 and 8.

[0060] The SCOBY pellicle can optionally be dried, for example, by heating in a vacuum oven at, for example, 40°C to 70°C for 0.5 to 1 hour, or by freeze-drying for, for example, 24 to 48 hours. The SCOBY pellicle can then be shredded or pulverized to smaller particles, for example, less than 1.0 mm in diameter, and finally ground to a fine powder, for example, less than 0.2 mm in diameter. In certain embodiments, the drying process can be omitted, and the bacterial cellulose can be dissolved in a wet state.

[0061] The solubility of cellulose powder in common solvents is extremely low. However, by appropriately selecting the solvent system and dissolution conditions, it is possible to improve not only the solubility but also the dissolution rate of cellulose powder in the solvent system. Figure 4 shows four common solvent systems for dissolving cellulose powder. Some solvent systems can achieve high solubility and good dissolution rates, but the need to use organic solvents or ionic liquid solvents can be prohibitively expensive on a large scale and may pose potential health and environmental risks. Furthermore, some solvent systems require high temperatures and very slow dissolution rates (up to 70 hours for dissolution), which hinders their widespread use.

[0062] The cellulose powder dissolution system described herein utilizes readily available reagents to rapidly dissolve bacterial cellulose powder, yielding cellulose dopes containing cellulose at concentrations up to 10% (w / w).

[0063] A quaternary ammonium hydroxide can have the chemical structure NROH, where each occurrence of R is independently alkyl, cycloalkyl, or phenyl, or two instances of R, taken together with the nitrogen to which they are attached, form a 3- to 6-membered heterocycloalkyl. In certain embodiments, each R is independently C1-C4 alkyl. Specific examples of quaternary ammonium hydroxides useful in the methods described herein include, but are not limited to, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

[0064] In certain embodiments, the metal complex comprises a metal selected from the group consisting of aluminum, calcium, copper, iron, nickel, manganese, indium, tungsten, and zinc, and at least one anion selected from the group consisting of bromide, chloride, sulfate, bisulfate, carbonate, bicarbonate, nitrate, acetate, valerate, oleate, palmitate, stearate, laurate, benzoate, lactate, phosphate, tosylate, citrate, maleate, fumarate, succinate, tartrate, naphthylate, mesylate, glucoheptonate, lactobionate, laurylsulfonate, etc., and optionally a ligand. The metal can exist in the +1, +2, +3, or +4 oxidation state.

[0065] The type of ligand used is not particularly limited as long as it can coordinate to at least a portion of the selected metal. In certain embodiments, the ligand is a monodentate, bidentate, tridentate, or tetradentate ligand. Exemplary ligands include, but are not limited to, bipyridine, phenanthroline, 2-phenylpyridine bipyrimidine, bipyrazyl, glycinate, acetylacetonate, 2,6-bis(1-methylbenzimidazol-2-yl)pyridine, ethylenediamine, diaminocyclohexane, 1,3-propanediamine, 1,3-diamino-2-hydroxypropane, 1,6-hexanediamine, acetylacetonate (acac), ethylenediaminetetraacetic acid, diethylenetriaminopentaacetic acid, propylenediaminetetraacetic acid, amino acids, and the like.

[0066] The metal complex must be charge balanced. The ratio of the metal to at least one anion is determined by the formula (A t+ ) U (B u- ) T where A represents a metal, B represents at least one anion, t represents the charge of the metal, u represents the charge of the at least one anion, U is equal to the absolute value of the charge of the at least one anion, and T is equal to the absolute value of the charge. For example, in the case of SO4, where the metal has a charge of 1+ and the anion has a charge of -2, 2-If so, the charge balance equation is (A 1+ )2(SO4 2- )

[0067] In certain embodiments, the metal complex is bis(ethylenediamine)copper(II) hydroxide.

[0068] The cellulose powder and the aqueous solution can be contacted at a mass ratio of 1-10:90-99, 1-9:91-99, 1-8:92-99, 1-7:93-99, 1-6:94-99, 2-6:90-98, 3-6:90-97, 3-5:95-97, or 3.5-4.5:95.5-96.5, respectively.

[0069] The cellulose dope contains bacterial cellulose at 1%(w / w)~10%(w / w), 2%(w / w)~10%(w / w), 3%(w / w)~10%(w / w), 4%(w / w)~10%(w / w), 5%(w / w)~10%(w / w), 6%(w / w)~10%(w / w), 7%(w / w)~10%(w / w), The cellulose dope may contain bacterial cellulose at a concentration of 1% (w / w) to 9% (w / w), 1% (w / w) to 8% (w / w), 1% (w / w) to 7% (w / w), 1% (w / w) to 6% (w / w), 2% (w / w) to 6% (w / w), 3% (w / w) to 6% (w / w), 3% (w / w) to 5% (w / w), or 3.5% (w / w) to 4.5% (w / w). In certain embodiments, the cellulose dope contains bacterial cellulose at a concentration of about 4% (w / w).

[0070] Quaternary ammonium hydroxide is present in aqueous solutions at concentrations of 1% (w / w) to 60% (w / w), 5% (w / w) to 60% (w / w), 10% (w / w) to 60% (w / w), 15% (w / w) to 60% (w / w), 20% (w / w) to 60% (w / w), 25% (w / w) to 60% (w / w), 30% (w / w) to 60% (w / w), 30% (w / w) to 55% (w / w), and 30% (w / w) to 50% (w In certain embodiments, the quaternary ammonium hydroxide is present in the aqueous solution at a concentration of about 40% (w / w) or about 55% (w / w).

[0071] Urea may optionally be present in the aqueous solution at a concentration of 0.1% (w / w) to 1% (w / w), 0.1% (w / w) to 0.9% (w / w), 0.1% (w / w) to 0.8% (w / w), 0.1% (w / w) to 0.7% (w / w), 0.1% (w / w) to 0.6% (w / w), 0.1% (w / w) to 0.5% (w / w), 0.1% (w / w) to 0.4% (w / w), 0.1% (w / w) to 0.3% (w / w), or 0.15% (w / w) to 0.25% (w / w). In certain embodiments, urea is present in the aqueous solution at a concentration of about 0.2% (w / w).

[0072] The metal complex may be present in the aqueous solution at a concentration of 0.1 M to 2 M, 0.5 M to 2 M, 0.5 M to 1.5 M, 0.6 M to 1.4 M, 0.7 M to 1.3 M, 0.8 M to 1.2 M, or 0.9 M to 1.1 M. In certain embodiments, the metal complex is present in the aqueous solution at a concentration of about 1 M.

[0073] Conditions that result in at least partial dissolution of the bacterial cellulose powder can be readily determined by one skilled in the art. Methods such as stirring, sonication, and / or heating can be used to aid in the dissolution of the bacterial cellulose powder.

[0074] In certain embodiments, the conditions that result in at least partial dissolution of the bacterial cellulose powder include maintaining an aqueous solution containing quaternary ammonium hydroxide and optionally urea at 25°C to 60°C, 25°C to 55°C, 30°C to 55°C, 30°C to 50°C, or 35°C to 45°C.

[0075] The aqueous solution containing the quaternary ammonium hydroxide and optionally urea can be maintained at a temperature or temperature range desired for dissolution until substantially all of the bacterial cellulose powder is dissolved in the aqueous solution or until the aqueous solution is saturated with the bacterial cellulose powder. Once the aqueous solution is saturated with the bacterial cellulose, additional portions of the quaternary ammonium hydroxide and / or water can be added. In certain embodiments, the aqueous solution containing the quaternary ammonium hydroxide and optionally urea is maintained at the temperature or temperature range desired for dissolution for 5 minutes to 24 hours, 30 minutes to 24 hours, 1 hour to 24 hours, 2 hours to 24 hours, 3 hours to 24 hours, 4 hours to 24 hours, 5 hours to 24 hours, 6 hours to 24 hours, 7 hours to 24 hours, 8 hours to 24 hours, 9 hours to 24 hours, 10 hours to 24 hours, 12 hours to 24 hours, 14 hours to 24 hours, 16 hours to 24 hours, 18 hours to 24 hours, 20 hours to 24 hours, 22 hours to 24 hours, 6 hours to 18 hours, 8 hours to 16 hours, or 10 hours to 14 hours. In certain embodiments, the aqueous solution containing the quaternary ammonium hydroxide and optionally urea is maintained at the temperature or temperature range desired for dissolution for about 12 hours.

[0076] In certain embodiments, the conditions that result in at least partial dissolution of the bacterial cellulose powder include maintaining the aqueous solution containing the metal complex at 50°C to 100°C, 60°C to 100°C, 70°C to 100°C, 70°C to 90°C, 75°C to 90°C, or 80°C to 90°C.

[0077] The aqueous solution containing the metal complex can be maintained at a temperature or temperature range desired for dissolution until substantially all of the bacterial cellulose powder is dissolved in the aqueous solution or until the aqueous solution is saturated with bacterial cellulose powder. Once the aqueous solution is saturated with bacterial cellulose, additional portions of the metal complex and / or water can be added. In certain embodiments, the aqueous solution containing the metal complex can be maintained at a temperature or temperature range desired for dissolution for 5 minutes to 5 hours, 30 minutes to 5 hours, 1 hour to 5 hours, 1 hour to 4 hours, 1 hour to 3 hours, or 1 hour to 2 hours. In certain embodiments, the aqueous solution containing the metal complex can be maintained at a temperature or temperature range desired for dissolution for approximately 90 minutes.

[0078] In certain embodiments, dissolution of bacterial cellulose powder can be achieved using the methods described herein, for example, after a dissolution time of 8 to 24 hours in a 40% to 55% aqueous solution of TBAH or a TBAH / urea aqueous solvent system at room temperature to 40°C with gentle stirring, or after a dissolution time of 1 to 2 hours at 75°C to 90°C in an aqueous solution containing a metal complex.

[0079] In certain embodiments, substantially all of the bacterial cellulose powder is dissolved in the aqueous solution when at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 99%, or all of the bacterial cellulose powder contacted with the aqueous solution is dissolved. Any undissolved bacterial cellulose powder can be removed from the aqueous solution, optionally using any means, such as filtration, centrifugation, and decanting.

[0080] Any undissolved cellulose powder can be removed from the cellulose dope using at least one optional filter. In certain embodiments, the cellulose dope is filtered using one or more filters having pore sizes between 5 μm and 500 μm. Filtration of the cellulose dope can be improved by sequentially filtering the cellulose dope through increasingly finer filters. This reduces the likelihood of the filter being clogged with particles and / or aggregates larger than the pore size of the filter. Thus, in certain embodiments, the cellulose dope is filtered through one, two, three, four, five, six, or more filters having pore sizes between 5 μm and 500 μm. The cellulose dope is filtered through one, two, three, four, five, six, or more filters having pore sizes between 5 μm and 20 μm, 50 μm and 100 μm, 100 μm and 300 μm, and 300 μm and 500 μm. In one particular embodiment, the cellulose dope is filtered through six filters having pore sizes of 500 μm, 300 μm, 100 μm, 50 μm, 20 μm, and 5 μm to obtain a solution containing particles having at least one dimension less than 5 μm.

[0081] The optionally filtered cellulose dope can then be degassed using a centrifuge. In certain embodiments, the optionally filtered cellulose dope is centrifuged at 3,000 rpm to 8,000 rpm for 5 minutes to 30 minutes. Degassing is continued until substantially all gas is removed from the optionally filtered cellulose dope or until no further gas is removed.

[0082] The prepared cellulose dope is fed into an extruder while maintaining the temperature of the dope throughout the spinning process. The extrusion rate of the dope from the spinneret can be controlled by a gear pump. The spinneret can be positioned horizontally and submerged in a coagulation bath. Cellulose fiber formation was carried out at room temperature in the primary drawing bath (coagulation) and secondary drawing bath (drawing). 0.25M to 1.0M sulfuric acid and sodium sulfate in a molar ratio of 1:1 or 1:1.1 were used as coagulants in both the primary and secondary drawing baths. The regenerated fibers were then washed with water at 60°C to 80°C in a washing bath. The fibers were recovered and dried at 40°C to 70°C for 4 to 8 hours.

[0083] The structure and properties of the fiber can be adjusted by the residence time of the fiber in the coagulation bath. Therefore, the rotation speed of the gear pump, the take-up speed of the primary drawing bath and the secondary drawing bath can be expressed as follows: ω=(v0×n×π×r 2 ) / C v1=v0×σ1 v2=v1×σ2 where: ω: Gear pump rotation speed n: number of holes in the spinneret r: radius of the spinneret hole C: Flow rate per revolution v1: Winding speed of the first drawing bath v2: Winding speed of the secondary drawing bath σ1: Primary drawing ratio (drawing ratio) σ2: Secondary stretching ratio

[0084] The step of extruding the cellulose dope in a coagulation bath can include passing the cellulose dope through a spinneret into the coagulation bath. In certain embodiments, the coagulation bath includes a primary drawing bath (coagulation) and optionally wet drawing in a secondary drawing bath (drawing) of the coagulation bath.

[0085] The spinneret can be a monofilament spinneret or a multifilament spinneret.

[0086] The cellulose dope can be passed through the spinneret at a flow rate of 3 meters / minute to 12 meters / minute, 4 meters / minute to 11 meters / minute, 4 meters / minute to 10 meters / minute, 5 meters / minute to 10 meters / minute, 6 meters / minute to 10 meters / minute, or 7 meters / minute to 9 meters / minute. In certain embodiments, the cellulose dope is passed through the spinneret at a rate of about 8 meters / minute.

[0087] The first and second drawing baths can each independently comprise any solvent in which the cellulose dope has low solubility. In certain embodiments, the first and second drawing baths each comprise an aqueous solvent containing an acid, a metal salt, or a combination thereof. In certain embodiments, the metal salt is Li + , Na + , Ca 2+ and Mg 2+ and one or more anions selected from the group consisting of halides, nitrates, phosphates, carbonates, sulfates, acetates, etc. Exemplary metal salts include, but are not limited to, NaCl, LiCl, CaCl2, NaBr, LiBr, CaBr2, Li2SO4, Na2SO4, CaSO4, Na3PO4, Li3PO4, and NaOAc. Exemplary acids include HCl, H2SO4, and HSO4 - In certain embodiments, the first and second drawing baths include, but are not limited to, H2SO4. In certain embodiments, the first and second drawing baths further include Na2SO4.

[0088] The concentration of the metal salt or acid in the primary and secondary drawing baths may be in the range of 0.1M to 3M, 0.1M to 2.5M, 0.1M to 2M, 0.1M to 1.5M, 0.1M to 1M, 0.1M to 0.5M, 0.5M to 3M, 1M to 3M, 1.5M to 3M, 2M to 3M, 0.5M to 2.5M, 0.5M to 2M, 0.5M to 1.5M, 0.5M to 1M, 0.25M to 0.75M, 0.375M to 0.75M, 1M to 2M, or 1.5M to 2M. In certain embodiments, the primary draw bath comprises an acid concentration of about 0.75M and a metal salt concentration of about 0.75M to about 0.825M, and the secondary draw bath comprises an acid concentration of about 0.375M and a metal salt concentration of about 0.375M to about 0.412M.

[0089] When the first and / or second drawing baths contain both an acid and a metal salt, the molar ratio of the acid to the metal salt can be in the range of 0.01:1 to 1:0.01, 1:0.1 to 1:5, 1:0.1 to 1:4, 1:0.1 to 1:3, 1:0.1 to 1:2, 1:0.5 to 1:2, 1:0.5 to 1:1.5, 1:0.75 to 1:1.5, 1:0.75 to 1:1.4, 1:0.75 to 1:1.3, 1:0.9 to 1:1.3, 1:0.9 to 1:1.2, or 1:1.1 to 1:1.2, respectively. In certain embodiments, the molar ratio of the acid to the metal salt in the first and / or second drawing baths is in the range of about 1 to about 1.1, respectively.

[0090] When the first stretching bath and the second stretching bath contain an acid, the pH of the first stretching bath and the second stretching bath can independently be 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.5 or less, or 0 or less. In certain embodiments, the pH of each of the first stretching bath and the second stretching bath is independently -1 to 6, -1 to 5, -1 to 4, -1 to 3, -1 to 2, -1 to 1, -1 to 0, 0 to 6, 0 to 5, 0 to 4, 0 to 3, 0 to 2, 0 to 1, or 0 to 0.5. In certain embodiments, the pH of the first stretching bath is about 0.12, and the pH of the second stretching bath is about 0.43.

[0091] The regenerated bacterial cellulose fibers can be optionally stretched in the first and second stretching baths by adjusting the stretch ratio. The regenerated bacterial cellulose fibers can be stretched in the coagulation bath at a stretch ratio of 1% to 2%.

[0092] The step of wet-drawing the regenerated bacterial cellulose fibers in the secondary drawing bath can include drawing the regenerated bacterial cellulose fibers at a temperature of 40° C. to 60° C., 40° C. to 55° C., 40° C. to 50° C., or 40° C. to 45° C. In certain embodiments, the wet-drawing step, which can include drawing the filaments, can be carried out at about 45° C.

[0093] Varying the conditions used to produce regenerated bacterial cellulose fibers according to the methods described herein can alter the properties of the regenerated cellulose fibers so produced. In certain embodiments, the regenerated cellulose fibers can have a linear density of 2 dtex to 9 dtex, 3 dtex to 9 dtex, 3 dtex to 8 dtex, 3 dtex to 7 dtex, 3 dtex to 6 dtex, 3 dtex to 5 dtex, 3 dtex to 9 dtex, 4 dtex to 9 dtex, 5 dtex to 9 dtex, 6 dtex to 9 dtex, or 6 dtex to 8 dtex. In certain embodiments, the regenerated cellulose fibers may have a tenacity at maximum load of 0.8 cN / dtex to 2.0 cN / dtex, 0.9 cN / dtex to 2.0 cN / dtex, 1.0 cN / dtex to 2.0 cN / dtex, 1.1 cN / dtex to 2.0 cN / dtex, 1.2 cN / dtex to 2.0 cN / dtex, 1.3 cN / dtex to 2.0 cN / dtex, 1.4 cN / dtex to 2.0 cN / dtex, 1.5 cN / dtex to 2.0 cN / dtex, 1.3 cN / dtex to 1.6 cN / dtex, 1.5 cN / dtex to 1.6 cN / dtex, or 1.6 cN / dtex to 2.0 cN / dtex. [Example]

[0094] Example 1 - Cultivation of bacterial cellulose by kombucha fermentation Three liters of water was brought to a boil and 12% (w / w) sucrose was added while boiling. 0.6% (w / w) black tea leaves in a tea bag were added, and the solution was boiled for 15 minutes to 1 hour. After cooling to room temperature, the tea bag was removed, and the sweet tea was inoculated with a 33% (w / w) SCOBY culture and poured into a pre-sterilized container. The mixture was incubated at 31°C for 14 days. The newly formed daughter cultures were floating and formed a cellulose pellicle over the entire available surface.

[0095] Example 2 - Preparation of bacterial cellulose by alkali treatment The floating bacterial cellulose pellicle was removed from the surface of the culture medium and placed in a container. 12 g of sodium hydroxide dissolved in 1 L of water was poured into the container. The cellulose pellicle was completely immersed in the solution and then heated to 60 °C for 1 hour. The BC pellicle was then washed with water at 60 °C for 1 hour. The washing process was repeated two or three times until the pH value reached 6-8. White BC pellicle was obtained after the alkali treatment.

[0096] Example 3 - Preparation of bacterial cellulose powder The treated BC pellicle was removed from the solution. The liquid on the surface was absorbed with a dry towel, and then the BC pellicle was placed in a vacuum oven. The BC pellicle was spread evenly on a tray and uniformly dispersed. The pellicle was dried in a vacuum oven at 60°C for 12 hours. The dried cellulose was then cut into small pieces and further shredded into fine particles by two mechanical grinding passes. The first grinding pass produced particles less than 1.0 mm in diameter, and the second grinding pass produced a powder less than 0.2 mm in diameter.

[0097] Example 4 - Preparation of spin dope with TBAH aqueous solvent system 4.5 g of BC powder was placed in 95.5 g of 55% TBAH aqueous solution in a reaction vessel to achieve a cellulose weight content of 4.5 wt%. The mixture was mechanically stirred at 25°C for 12 hours to dissolve the BC powder. After complete dissolution, the solution was degassed by centrifugation at 4,000 rpm for 15 minutes. The rheological viscosity of the cellulose solution was measured to be around 50 Pa·s to 120 Pa·s. The experimental results are shown in "Table 1. Results of Example 4." According to the above experiment, the BC powder was completely dissolved in the solvent system, forming a yellow solution.

[0098] [Table 1]

[0099] Example 5 - Preparation of spin dope with TBAH / urea aqueous solvent system To promote cellulose dissolution, 0.1 g / g urea was introduced into a 55% TBAH aqueous solution. The mixture was stirred at room temperature for 30 minutes until the urea dissolved. 4.5 g of BC powder was added to 95.5 g of TBAH / urea aqueous solution in a reaction vessel to achieve a cellulose weight content of 4.5 wt%. The mixture was mechanically stirred at 25°C for 12 hours to dissolve the BC powder. After complete dissolution, the solution was degassed by centrifugation at 4,000 rpm for 15 minutes. The rheological viscosity of the cellulose solution was measured to be around 50 Pa·s to 120 Pa·s. The experimental results are shown in "Table 2. Results of Example 5." According to the above experiment, the BC powder was completely dissolved in the solvent system, forming a yellow solution.

[0100] [Table 2]

[0101] Example 6 - Preparation of spin dopes with metal complex-based solvent systems Four grams of BC powder was placed in 96 grams of 1 M Cu(en)2(OH)2 solution in a reaction vessel to achieve a cellulose weight content of 4 wt%. The mixture was mechanically stirred at 80 °C for 1 to 2 hours to dissolve the BC powder. After complete dissolution, the solution was degassed by centrifugation at 4,000 rpm for 15 minutes. The rheological viscosity of the cellulose solution was measured to be around 50 to 120 Pa·s.

[0102] According to Example 6, the BC powder was completely dissolved in the solvent system to form a viscous, deep blue solution.

[0103] Example 7 - Fiber regeneration by wet spinning Fibers were regenerated by wet spinning using a FET-200 LAB wet spinning machine.

[0104] 1,000 mL of the cellulose solutions prepared in Examples 4 to 6 were extruded at room temperature through a multi-hole spinneret (100 holes, capillary diameter 60 μm or 100 μm) using a gear pump. Cellulose fibers were formed in a first drawing bath (coagulation) and a second drawing bath (drawing) at room temperature. 0.75 M sulfuric acid and sodium sulfate (0.75 M to 0.825 M) were used as the coagulant drawing bath, and 0.375 M sulfuric acid and sodium sulfate (0.375 M to 0.412 M) were used as the coagulant in the second drawing bath. The regenerated bacterial cellulose fibers could be drawn in the first drawing bath and the second drawing bath by adjusting the draw ratio as desired. The regenerated bacterial cellulose fibers could be drawn in the coagulation bath at a draw ratio of 1.7%. The regenerated fibers were then washed with water at 60°C in a washing bath. The fibers were recovered and dried at 40°C to 70°C for 4 to 8 hours. [Industrial Applicability]

[0105] From an environmental perspective, bacterial cellulose fibers are more advantageous than conventional regenerated cellulose fibers in terms of the purity of the cellulose source, the small amount of land space required for production, the short production cycle, the low water consumption, and the absence of pesticides. In this invention, food or beverage waste is used to produce bacterial cellulose. In this invention, SCOBY waste from kombucha production is an excellent choice for our demonstration. In 2021, the global kombucha market was valued at US$2.64 billion. This is expected to grow at a compound annual growth rate (CAGR) of 15.6% from 2022 to 2030 due to consumers' shift toward healthier and more well-being choices.

[0106] In this study, bacterial cellulose (BC) is developed as a sustainable source for the production of regenerated cellulose fibers. The key elements of this study are (1) developing a solvent system for efficiently dissolving bacterial cellulose and (2) finding optimal conditions for wet-spinning the regenerated bacterial cellulose fibers.

[0107] Abbreviation BC: Bacterial cellulose Cu(en)2(OH)2: bis(ethylenediamine)copper(II) hydroxide DP: Degree of polymerization KBC: Kombucha Bacterial Cellulose QAH: Quaternary ammonium hydroxide SCOBY: Symbiotic Colony of Bacteria and Yeast TBAH: tetrabutylammonium hydroxide

Claims

1. 1. A method for making regenerated bacterial cellulose fibers, comprising: contacting bacterial cellulose powder with an aqueous solution containing quaternary ammonium hydroxide and optionally urea under conditions that result in at least partial dissolution of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose; or contacting a bacterial cellulose powder with an aqueous solution containing a metal complex under conditions that result in at least partial dissolution of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose; extruding the cellulose dope in a coagulation bath, thereby forming the regenerated bacterial cellulose fibers; A method comprising:

2. 2. The method of claim 1, wherein the bacterial cellulose powder is kombucha bacterial cellulose powder.

3. The quaternary ammonium hydroxide is NR ４ OH, where R is independently at each occurrence alkyl, cycloalkyl, or phenyl, and the metal complex comprises a metal selected from the group consisting of aluminum, calcium, copper, iron, nickel, and zinc.

4. 2. The method of claim 1, wherein the quaternary ammonium hydroxide is tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide, and the metal complex is bis(ethylenediamine)copper(II) hydroxide.

5. 2. The method of claim 1, wherein the quaternary ammonium hydroxide is present in the aqueous solution at a concentration of 20% (w / w) to 60% (w / w) and the metal complex is present in the aqueous solution at a concentration of 0.5 M to 2 M.

6. 2. The method of claim 1, wherein the urea is present in the aqueous solution at a concentration of 0.1% (w / w) to 0.5% (w / w).

7. The method of claim 1 , wherein the coagulation bath comprises a primary draw bath and further comprises a secondary draw bath.

8. The method of claim 7, wherein the primary draw bath and the secondary draw bath each independently have a pH of 0 to 1.

9. The first stretching bath and the second stretching bath are each H ２ SO ４ and optionally Na ２ SO ４ 8. The method of claim 7, comprising an aqueous solution of

10. H in each of the first and second drawing baths ２ SO ４ 10. The method of claim 9, wherein the concentrations of are independently 0.25 M to 1 M.

11. 2. The method of claim 1, wherein the cellulose dope contains the bacterial cellulose at a concentration of 2% (w / w) to 10% (w / w).

12. providing a symbiotic colony of bacteria and yeast (SCOBY) pellicle; contacting the SCOBY pellicle with an alkaline aqueous solution, thereby forming a treated SCOBY pellicle; Optionally, washing and drying the treated SCOBY pellicle; powdering the treated SCOBY pellicle, thereby forming the bacterial cellulose powder; The method of claim 1 further comprising:

13. 10. The method of claim 1, further comprising washing the regenerated bacterial cellulose fibers with water and drying the washed regenerated bacterial cellulose fibers.

14. 2. The method of claim 1, wherein the conditions that result in at least partial dissolution of the bacterial cellulose powder include maintaining the aqueous solution containing the quaternary ammonium hydroxide and optionally urea at 25°C to 50°C for 8 hours to 24 hours, or maintaining the aqueous solution containing the metal complex at 75°C to 90°C for 1 hour to 2 hours.

15. Bacterial cellulose powder and 20% (w / w) to 60% (w / w) of N(C １ ~C ５ ) ４ or contacting the bacterial cellulose powder with an aqueous solution containing OH and optionally 0.1% (w / w) to 0.5% (w / w) urea at 25°C to 40°C for 8 hours to 24 hours to dissolve at least a portion of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose at a concentration of 4% (w / w) to 10% (w / w); or contacting a bacterial cellulose powder with an aqueous solution containing 0.5M to 2M bis(ethylenediamine)copper(II) hydroxide at 75°C to 90°C for 1 hour to 2 hours to dissolve at least a portion of the bacterial cellulose powder, thereby forming a cellulose dope containing the bacterial cellulose at a concentration of 2% (w / w) to 6% (w / w); extruding the cellulose dope in a coagulation bath including a first drawing bath and a second drawing bath, the first drawing bath and the second drawing bath independently having a pH of 0 to 0.5, thereby forming regenerated bacterial cellulose fibers; The method of claim 1 , comprising:

16. 16. The method of claim 15, wherein the cellulose dope comprises bacterial cellulose at a concentration of 3.5% (w / w) to 5.5% (w / w).

17. providing a symbiotic colony of bacteria and yeast (SCOBY) pellicle; contacting the SCOBY pellicle with an alkaline aqueous solution, thereby forming a treated SCOBY pellicle; Optionally, washing and drying the treated SCOBY pellicle; powdering the treated SCOBY pellicle, thereby forming the bacterial cellulose powder; 16. The method of claim 15, further comprising:

18. 18. The method of claim 17, wherein the alkaline aqueous solution has a pH of 13 to 14.

19. 18. The method of claim 17, wherein the alkaline aqueous solution comprises NaOH.

20. providing a symbiotic colony of bacteria and yeast (SCOBY) pellicle; contacting the SCOBY pellicle with an alkaline aqueous solution having a pH of 13 to 13.5, thereby forming a treated SCOBY pellicle; Optionally, washing and drying the treated SCOBY pellicle; powdering the treated SCOBY pellicle, thereby forming the bacterial cellulose powder; Bacterial cellulose powder and 20% (w / w) to 60% (w / w) of N(C １ ~C ５ ) ４ or contacting the bacterial cellulose powder with an aqueous solution containing OH and optionally 0.1% (w / w) to 0.5% (w / w) urea at 25°C to 40°C for 8 hours to 24 hours to dissolve at least a portion of the bacterial cellulose powder, thereby forming a cellulose dope containing bacterial cellulose at a concentration of 3.5% (w / w) to 5.5% (w / w); or contacting a bacterial cellulose powder with an aqueous solution containing 0.5M to 2M bis(ethylenediamine)copper(II) hydroxide at 75°C to 90°C for 1 hour to 2 hours to dissolve at least a portion of the bacterial cellulose powder, thereby forming a cellulose dope containing the bacterial cellulose at a concentration of 3.5% (w / w) to 5.5% (w / w); The cellulose dope is extruded in a coagulation bath including a first stretching bath and a second stretching bath, and each of the first stretching bath and the second stretching bath is H O ... ２ SO ４ and Na ２ SO ４ thereby forming regenerated bacterial cellulose fibers; The method of claim 1 , comprising:

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