A simple method for rapid and batch decomposition of cellulose

Abstract

The present invention discloses a simple method for rapid and batch decomposition of cellulose, which relates to the fields of applied chemistry and physical technology. The chemical decomposition of cellulose is extremely difficult and is a global problem. The method of the present invention solves the problem of fast decomposition speed with low dosage of medicine. It comprises: spraying 22% (W / V) NaOH evenly on pure cotton fiber, using an amount of W g Cotton fiber: 22% NaOH V mL The method comprises the following steps: uniformly spraying the cotton fibers with NaOH in a 15°C refrigerator for more than 12 hours for preliminary digestion and decomposition; placing the preliminarily digested cotton fibers in a muffle furnace at (200±5)°C for another 0.5 hour for digestion and decomposition. This temperature prevents carbonization of the cellulose, at which point the cellulose is completely decomposed into short-chain polysaccharides; neutralizing the NaOH in the decomposed cellulose with 5.5 mol / L HCl; and removing salts and small molecular decomposition products with a dialysis bag having a molecular weight cutoff of 3500D to obtain purified short-chain β-1,4-glycosidic bond molecules.

Description

Technical Field

[0001] This invention belongs to the field of applied chemistry technology, specifically relating to a simple, low-cost, and pollution-free method for decomposing cellulose. More specifically, this invention relates to a simple method for rapidly and in batches decomposing cellulose. Background Technology

[0002] The decomposition and polymerization of cellulose have applications in many areas of daily life and production. Cellulose products are easily decomposed in nature, do not cause environmental pollution, and have a wide range of uses. However, the complex and costly preparation process of cellulose limits its application.

[0003] Currently, cellulose is decomposed using methods such as enzymatic hydrolysis, microbial degradation, and low-temperature alkaline dissolution, but these methods suffer from drawbacks such as slow decomposition rates and low decomposition rates.

[0004] Chemical methods for dissolving cellulose include the copper ammonia solution degradation method, which requires 10 mL of 10% CuSO4, 5 mL of 10% NaOH, and 12.8 mL of 28% NH3·H2O to dissolve 0.1 g of cotton fiber. A second commonly used method is to dissolve cellulose using N-methylmorpholine-N-oxide (NMMO), but the amount dissolved is below 0.5% (v / w), and the reagent is expensive. Academician Zhang Lina used 7% NaOH and 12% NH3·H2O pre-cooled to -12℃, which also resulted in cellulose dissolution, but the amount dissolved was limited, only below 0.5% (w / v). All of these chemical methods have limited capacity to degrade or dissolve cellulose, and the chemicals can easily cause environmental pollution and are difficult to recycle.

[0005] Cellulose enzymatic hydrolysis and microbial degradation methods have technical problems such as high technical requirements, expensive cellulase, and slow microbial degradation of cellulose, which limit the large-scale application of cellulose degradation.

[0006] Alkalis can degrade cellulose at low temperatures, and strong alkalis such as NaOH, KOH, and LiOH all have the ability to degrade cellulose at low temperatures. However, after numerous experiments, weak alkalis or other strong alkalis such as Na₂CO₃, Al(OH)₃, and Ca(OH)₃ have limited ability to degrade cellulose, whether at room temperature or under special conditions.

[0007] Lower temperatures favor the reaction between alkali and cellulose glycosidic bonds, but NaOH liquid is prone to crystallization at low temperatures above freezing, which limits the reaction process between -OH ions and β-1,4-glycosidic bonds.

[0008] Table 1 Freezing points of NaOH at different concentrations

[0009]

[0010]

[0011] The high-temperature decomposition temperature of cellulose is mainly concentrated between 250℃ and 360℃, with cellulose essentially carbonized above 250℃. Between 250℃ and 300℃, cellulose primarily undergoes dehydration. With increasing temperature and time, intramolecular hydrogen bonds break and hydroxyl groups dehydrate, resulting in the formation of numerous carbonyl groups, olefin double bonds, and cyclic ether structures. At 300℃, the pyran ring of cellulose opens and glycosidic bonds break, leading to rearrangement, condensation, and aromatic cyclization of double bonds and carbonyl groups into benzene rings, aryl alkyl ethers, and other structures. Carbonization between 300℃ and 460℃ is primarily a deoxygenation reaction, increasing the aromatic ring content. Carbonization above 460℃ is primarily a dehydrogenation reaction, resulting in carbonized structures with a high degree of condensation in aromatic hydrocarbons. Currently, various cellulose decomposition processes suffer from problems such as incomplete decomposition, complex processes, high costs, environmental pollution, and the inability to perform large-scale decomposition and production.

[0012] Based on the above reasons, this application is hereby submitted. Summary of the Invention

[0013] Based on the above reasons, and addressing the problems or deficiencies in existing technologies, the purpose of this invention is to provide a simple method for the rapid and large-scale decomposition of cellulose, solving or at least partially solving the aforementioned technical deficiencies in existing technologies. Through experimentation and design regarding alkali content, different low-temperature decomposition temperatures, low-temperature decomposition times, high-temperature decomposition temperatures, high-temperature decomposition times, and desalination processes, this invention has found the optimal cellulose decomposition pathway. This method solves the technical problems of cellulose's inability to be decomposed in large quantities and produced on a large scale, as well as the high decomposition costs.

[0014] To achieve the above-mentioned objectives of the present invention, the technical solution adopted by the present invention is as follows:

[0015] A simple method for rapid and batch decomposition of cellulose, the method specifically includes the following steps:

[0016] Step 1: Soak the cellulose in an inorganic strong alkaline solution according to the formula to obtain fully soaked cellulose;

[0017] Step 2: Place the fully soaked cellulose in a low-temperature environment for low-temperature preliminary digestion and decomposition to obtain preliminary decomposition products;

[0018] Step 3: Transfer the preliminary decomposition product to a high-temperature environment and carry out high-temperature complete digestion and decomposition under sealed conditions to obtain high-temperature digestion and decomposition product;

[0019] Step 4: Cool the high-temperature digestion and decomposition products to room temperature, and then adjust them to neutral using dilute acid to obtain neutral decomposition products;

[0020] Step 5: Dialyze the neutral decomposition product multiple times to remove NaCl from the product and obtain purified cellulose decomposition product, namely short-chain β-1,4-glycosidic bond molecules.

[0021] Furthermore, in the above technical solution, the inorganic strong alkali solution is a NaOH solution or a KOH solution. In a preferred embodiment of the present invention, the inorganic strong alkali solution is preferably a NaOH solution, as NaOH is inexpensive, and the recovered solution forms a salt after neutralization with HCl, which will not affect the environment.

[0022] Furthermore, in the above technical solution, the concentration of the inorganic strong alkali solution in step 1 is 22% (W / V).

[0023] Furthermore, in the above technical solution, the ratio of cellulose to inorganic strong alkali solution in step 1 is 1 part by mass: 6 parts by volume; wherein: the part by mass and the part by volume are based on g:mL.

[0024] Furthermore, in the above technical solution, the low temperature used for the preliminary digestion and decomposition in step 2 is -15℃.

[0025] Furthermore, in the above technical solution, the preliminary digestion and decomposition time in step 2 should be more than 12 hours, for example, overnight. At low temperatures, the H on the surface of cellulose... + As the electronic energy level decreases, the electron cloud shifts towards the C atom, the H atom has a bare nucleus, and the cellulose is covered by -OH, resulting in a colloidal property.

[0026] Furthermore, in the above technical solution, the high-temperature thorough digestion and decomposition in step 3 adopts a gradient temperature, which is specifically set as follows: from room temperature to 100℃ and hold for 10 minutes, then continue to heat to 200℃ and hold for 30 minutes.

[0027] Preferably, in the above technical solution, the time to heat from room temperature to 100°C is 10 minutes. The purpose of this step is to completely evaporate the moisture in the initially degraded fiber products.

[0028] Preferably, in the above technical solution, the time to heat from 100°C to 200°C is 10 minutes. The purpose of this step is to... - OH ions combine with β-1,4-glycosidic bonds at low temperatures and completely degrade β-1,4-glycosidic bonds at high temperatures.

[0029] Specifically, in the above technical solution, the ambient temperature refers to the natural room temperature conditions in all four seasons, without additional cooling or heating treatment. The ambient temperature is generally controlled between 10℃ and 30℃, and preferably between 15℃ and 25℃.

[0030] Furthermore, in the above technical solution, the dilute acid in step 4 can be dilute HCl, dilute H2SO4, or dilute HNO3, etc. However, considering the recovery and reuse of the alkali in the product and the degree of environmental impact, dilute HCl is selected as the optimal neutralizing acid. The concentration of the dilute acid is 1 mol / L to 10 mol / L. In a preferred embodiment of the present invention, the dilute acid is dilute HCl, and the concentration of the dilute HCl is 5.5 mol / L.

[0031] Furthermore, in a preferred embodiment of the present invention, the molecular weight cutoff of the dialysis bag in step 5 is 3500D.

[0032] Compared with existing technologies, the simple method for rapid and batch decomposition of cellulose disclosed in this invention has the following beneficial effects:

[0033] (1) The advantages of this invention are: ① Significantly reduced alkali usage: Zhang Lina's technology uses 7% NaOH and 12% urea as low-temperature solvents, reducing the weight of cotton fibers (W) g The volume (V) of the NaOH aqueous solution mL The ratio is approximately 1:200. The weight (W) of cotton fibers in the copper ammonia solution... g The volume (V) of the NaOH aqueous solution mL The ratio is approximately 1:280. The weight (W) of the cotton fibers in this invention... g The volume (V) of the NaOH aqueous solution mL The ratio is 1:6. ② The chemical reagents and degradation products do not produce environmentally polluting compounds. The experiment used NaOH as the chemical reagent, and the salt formed by the product is NaCl. However, the copper ammonia solution produces a large amount of Cu. 2+ This invention can easily cause environmental pollution. ③ The equipment required for this invention is simple; only low-temperature and high-temperature control equipment is needed for the large-scale degradation and production of cellulose. ④ The production cost is low. From initial sample degradation to completion, only NaOH and HCl are needed, reducing the amount of chemical reagents used and saving a significant amount of production costs. ⑤ The production process is short. A batch of samples only needs 2 days from initial degradation to completion, which can greatly shorten the cellulose degradation production time.

[0034] (2) Considering the cost of chemical reagents for cellulose degradation, the convenience of large-scale production, the recovery of reaction products, and environmental pollution, this invention selects NaOH as the ideal strong alkali for cellulose degradation. In addition to its low market price, NaOH also has the advantage that the recovered liquid after cellulose degradation can be neutralized and recovered with HCl, thus avoiding environmental pollution. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a graph showing the relationship between the concentration and freezing point of NaOH solution.

[0037] Figure 2 The image shows the effect of dissolving cotton fibers in a 22% (w / v) NaOH solution at -15°C for 12 hours in Example 7.

[0038] Figure 3 This is a photograph of the sample of cellulose with a small amount of carbonization after high-temperature degradation, corresponding to test group 5 in Table 3 of Example 6.

[0039] Figure 4 This is a photograph of the product after the completely decomposed cellulose in step 4 of Example 8 is neutralized with 5.5 mol / L HCl to remove excess alkali.

[0040] Figure 5 Microstructure of the completely decomposed cellulose obtained in step 4 of Example 8 (100×);

[0041] Figure 6 This is a schematic diagram of the desalting process of the dialysis bag (molecular weight cutoff of 3500D) in step 5 of Example 8;

[0042] Figure 7 This is a photograph of the degraded cotton cellulose obtained by drying at 60°C after desalination in step 5 of Example 8. Detailed Implementation

[0043] This invention provides a simple method for the rapid and large-scale decomposition of cellulose, relating to the fields of applied chemistry and physics. The chemical decomposition of cellulose is extremely difficult and a global challenge. This invention solves the problem of using small amounts of chemical reagents while achieving rapid decomposition. The method includes: uniformly spraying 22% (w / v) NaOH onto pure cotton fibers, using an amount of W... g Cotton fiber: 22% NaOH V mLThe ratio of NaOH to cellulose was 1:6. Cotton fibers uniformly sprayed with NaOH were placed in a -15℃ refrigerator for 12 hours for preliminary digestion and decomposition. The preliminarily digested cotton fibers were then placed in a muffle furnace at (200±5)℃ for further digestion and decomposition for 0.5 hours. This temperature ensured that the cellulose would not carbonize. At this point, the cellulose was completely decomposed into short-chain polysaccharides. The NaOH in the cellulose was neutralized with 5.5 mol / L HCl. Then, the salt and small molecule decomposition products were removed using a dialysis bag with a molecular weight cutoff of 3500D to obtain purified short-chain β-1,4-glycosidic bonds.

[0044] The present invention will be further described in detail below through implementation examples. These implementation examples are carried out based on the technology of the present invention. Detailed implementation methods and specific operating procedures are provided to illustrate the inventiveness of the present invention, but the scope of protection of the present invention is not limited to the following implementation examples.

[0045] The equipment and raw materials used in this invention are all commercially available or commonly used in the field. Unless otherwise specified, the methods in the following embodiments are conventional methods in the field.

[0046] Example 1

[0047] The purpose of this embodiment is to preliminarily determine the suitable concentration of NaOH solution used for rapid and batch decomposition of cellulose.

[0048] The key factor determining cellulose degradation is the concentration of the NaOH solution. Both low and high concentrations of NaOH aqueous solutions have relatively high freezing points. While low-concentration NaOH solutions can partially degrade cellulose over a long period, the decomposition is incomplete, which is detrimental to large-scale production. Excessively high concentrations of NaOH aqueous solutions, in addition to raising the freezing point, also increase production costs during the cellulose degradation process. Based on the freezing points of NaOH aqueous solutions, concentrations of 10% (w / v)–25% (w / v) and 10% (w / v)–30% (w / v) have freezing points between -26℃ and -10.2℃ and between -26℃ and 0℃, respectively. Therefore, the experimental design of this invention initially determines the selection range of NaOH solution concentration to be between 10% (w / v)–25% (w / v) and 10% (w / v)–30% (w / v).

[0049] Example 2

[0050] The purpose of this embodiment is to determine the mixing ratio of NaOH solution and cotton fiber.

[0051] To reduce the amount of alkali used, lower costs, and facilitate subsequent desalination, the principle for adding alkali is to ensure that the NaOH solution completely saturates the cotton fibers without causing any liquid sedimentation. The ratio of cotton weight (W) to NaOH solution volume (V) is determined by visual inspection.

[0052] The mixing ratio of the NaOH solution to the cotton fibers was obtained by screening according to the following steps:

[0053] Accurately weigh 5g of cotton fiber and place it in a petri dish. Slowly add a 22% (w / v) NaOH aqueous solution to the cotton fiber, pressing with a glass rod as you add. The principle for adding alkali is to completely saturate the cotton fiber with the NaOH aqueous solution, but without any liquid sedimentation. Use 30mL of alkali. Using visual observation, determine that the ratio of cotton fiber weight (W) to NaOH aqueous solution volume (V) is 1:6 (W / V). g :V mL When the cotton fibers are fully soaked, the cotton fibers are completely saturated.

[0054] Example 3

[0055] The purpose of this embodiment is to preliminarily determine the low-temperature digestion temperature used for rapid and batch decomposition of cellulose.

[0056] At room temperature, the decomposition of cellulose by alkali is slow, making it unsuitable for large-scale production. At low temperatures, the NaOH aqueous solution must not form ice crystals. This requires lowering the outer electron energy levels of the cotton fibers while maximizing the contact between -OH ions and the β-1,4-glycosidic bonds in the cellulose. The concentration of the NaOH aqueous solution has a non-linear relationship with the freezing point (e.g., ...). Figure 1 As shown: NaOH aqueous solutions with concentrations of 10% (w / v) to 25% (w / v) and 10% (w / v) to 30% (w / v) have freezing points between -26℃ and -10.2℃ and between -26℃ and 0℃, respectively. The preliminary design of this invention sets the low-temperature range between -10℃ and -25℃. Due to limitations in the temperature control accuracy of the cryogenic equipment, the horizontal gradient is defined as a 5℃ increment.

[0057] Table 1. Comparison of Low Temperatures Required for Treating Cotton Fibers with Different Concentrations of NaOH Solution

[0058] NaOH solution concentration (%, W / V) 5 10 15 20 25 Freezing point temperature (°C) -4.71 -10.2 -10.8 -26 -16.4 Test temperature (°C) -4 -8 -8 -25 -15

[0059] Example 4

[0060] The purpose of this embodiment is to preliminarily determine the time for low-temperature preliminary decomposition used for rapid and batch decomposition of cellulose.

[0061] according to Figure 1The relationship between different NaOH solution concentrations and freezing points was investigated. The ratio of cotton fiber weight (W) to NaOH aqueous solution volume (V) was 1:200. 0.1g of cotton fiber was weighed and placed in a test tube, with 20mL of NaOH aqueous solutions of different concentrations added. The tubes were then placed at temperatures above the freezing point of the NaOH solutions for dissolution testing. Observations were taken every 2 hours. For the NaOH concentrations of 5%, 10%, and 15%, no cellulose dissolution was observed after 7 days at temperatures above the corresponding freezing points. For NaOH solution concentrations of 20%, 22%, and 25%, cellulose dissolution occurred after 2 hours at temperatures above the corresponding freezing points. After 12 hours, especially overnight, all the cotton cellulose dissolved into a gel-like state.

[0062] Example 5

[0063] The purpose of this embodiment is to preliminarily determine the temperature and time for high-temperature decomposition used for rapid and batch decomposition of cellulose.

[0064] Selection of temperature and time during the high-temperature decomposition of cotton fibers. Cellulose is unstable at around 120℃ and undergoes drastic degradation above 300℃. In the experimental design of this invention, the temperature must be below the fiber carbonization temperature, and the lower the temperature, the better; the shorter the time, the better. This requirement is beneficial to improving the yield of cellulose decomposition products. Therefore, the temperature in the high-temperature environment is selected between 100℃ and 250℃. Due to the limitations of the temperature control accuracy of the high-temperature instrument, the gradient of large-scale horizontal changes is set at 50℃ increments, and further experiments use 10℃ increments. Heating the fiber at 120℃ for a long time will decrease the degree of polymerization and reduce the yield of cellulose degradation products. Therefore, the initial design of the cellulose degradation time in the high-temperature environment is between 10 min and 60 min, with 10 min increments.

[0065] Example 6

[0066] Based on the value ranges of the main influencing factors in Examples 1-5, the number of levels and the magnitude of each main factor were determined. Appropriate value ranges were selected, and conditions were used to determine the range of cellulose decomposition capacity for the four factors: NaOH solution concentration, low-temperature digestion temperature, high-temperature digestion temperature, and time. The specific design is as follows:

[0067] Table 2. Range of values ​​for a 4-factor, 4-level experimental design

[0068] Label A B C D factor NaOH solution concentration Low temperature High temperature High temperature time unit % (W / V) ℃ ℃ min 1 10 -10 100 10 2 15 -15 150 30 3 20 -20 200 40 4 25 -25 250 60

[0069] With the goal of maximizing the degree of cellulose decomposition, an orthogonal array L64(4) with 4 factors and 4 levels was selected based on the number and level of each major factor. 4 Arrange test combinations.

[0070] Experiments were conducted under different conditions for the factors listed in Table 3 below. L64(4) 4 Orthogonal design was used, and different experimental results were tested to select the best combination.

[0071] Table 3 L64(4) 4 Orthogonal design table

[0072]

[0073]

[0074]

[0075] According to the experimental results in Table 3, No. 10 and No. 53 have the best effect on decomposing cellulose. However, No. 10 requires a high amount of alkali, so No. 53 is selected. The optimal result is that the NaOH solution concentration is roughly in the range of 20% (W / V), and the initial decomposition is carried out at -15℃ for 12 hours and the decomposition is carried out at a high temperature of 200℃ for 30 minutes.

[0076] In summary, based on the experimental results in Table 3, the optimal experimental combination is determined to be approximately 20% (W / V) of NaOH solution concentration, -15℃ for initial low-temperature decomposition, 200℃ for high-temperature decomposition, and 30 min for high-temperature degradation.

[0077] Example 7

[0078] Example 1 preliminarily determined that the concentration range of the NaOH solution used for rapid and batch decomposition of cellulose was between 10% (W / V) and 25% (W / V) and between 10% (W / V) and 30% (W / V). Example 2 determined that the ratio of cotton weight (W) to NaOH aqueous solution volume (V) used for rapid and batch decomposition of cellulose was 1:6 (W / V). g :V mL Example 4 determined that the initial low-temperature decomposition time for rapid and batch cellulose degradation was more than 12 hours or overnight. Example 6 determined that the optimal experimental combination for rapid and batch cellulose degradation was a NaOH solution concentration of approximately 20% (w / v), a low-temperature initial decomposition temperature of -15°C, a high-temperature decomposition temperature of 200°C, and a high-temperature degradation time of 30 minutes.

[0079] The purpose of this embodiment is to preliminarily determine the optimal concentration of NaOH solution used for rapid and batch decomposition of cellulose. The inventors further designed experiments to refine the precise concentration of NaOH and the high-temperature decomposition time. The optimal concentration of the NaOH solution was obtained through screening using the following steps, specifically as follows:

[0080] Table 4. Range of values ​​for a 2-factor, 8-level experimental design

[0081]

[0082] With the goal of maximizing the degree of cellulose decomposition, an orthogonal array L48(2) with 2 factors and 8 levels was selected based on the number and level of each major factor. 8 Arrange test combinations.

[0083] Experiments were conducted under different conditions for the factors listed in Table 5 below. L48(2) 8 Orthogonal design was used, and different experimental results were tested to select the best combination.

[0084] Table 5 L48(2) 8 Orthogonal design table

[0085]

[0086]

[0087] Table 5 shows that the decomposition of each component is incomplete below 30 minutes at high temperature, and carbonization occurs above 30 minutes. The best decomposition effect is achieved at 200℃ and 30 minutes when the NaOH solution concentration is above 22% (w / v). To save on alkali usage, this invention selects a minimum alkali concentration of 22% (w / v) to achieve the same effect.

[0088] In the above experiments, when the alkali concentration was below 22% (W / V), carbonization occurred at 150℃ before complete decomposition. When the alkali concentration was above 22%, carbonization also occurred with increasing temperature, resulting in waste of alkali.

[0089] During the high-temperature decomposition process, open flames should be avoided to prevent spontaneous combustion or explosion caused by the decomposition of cellulose and the volatilization of small molecules.

[0090] After the experiment completed the low-temperature and high-temperature decomposition of cellulose, the cellulose had formed short-chain β-1,4-glycosidic bonds. It could be lightly ground in a mortar and pestle, completely decomposing the long-chain cellulose molecules into short-chain cellulose. The product was then adjusted to neutral pH with 5.5 mol / L HCl.

[0091] The decomposed short-chain cellulose molecules are placed into a dialysis bag with a molecular weight cutoff of 3500D to remove salts and small molecule decomposition products, thereby obtaining purified cellulose decomposition products.

[0092] Example 8

[0093] This embodiment provides a simple method for rapid and large-scale decomposition of cellulose, using the optimal ratio of cotton cellulose weight (W) to NaOH aqueous solution volume (V) selected in Example 2 as 1:6 (W).g :V mL Example 4: The optimal low-temperature decomposition time exceeds 12 hours or overnight; Example 6: The optimal low-temperature initial decomposition temperature is determined to be -15°C, the optimal high-temperature decomposition temperature is 200°C, and the optimal high-temperature maintenance time is 30 minutes; Example 7: The optimal concentration of NaOH solution is determined to be 22% (W / V).

[0094] This embodiment presents a simple method for rapid and batch decomposition of cellulose, comprising the following steps:

[0095] Step 1: Accurately weigh 2g of cotton cellulose and soak the cotton fiber in 12mL of 22% (w / v) NaOH aqueous solution.

[0096] Step 2: Place the fibers that were fully soaked in Step 1 in a low-temperature refrigerator, adjusting the temperature to -15°C. Allow to stand overnight or for more than 12 hours for digestion and decomposition.

[0097] Step 3: The cellulose product from the preliminary alkaline digestion in Step 2 does not need to be dried. It is directly transferred to a muffle furnace for high-temperature complete digestion. Before placing it in the muffle furnace, the preliminarily decomposed product is placed in a crucible and covered for protection to prevent spontaneous combustion or explosion due to reaction between open flame and small molecules of cellulose decomposition during the heating process.

[0098] The muffle furnace temperature rise procedure is as follows: reaching 100℃ takes 10 minutes, and is maintained for 10 minutes; the temperature rise from 100℃ to 200℃ takes 10 minutes; maintaining 200℃ for 30 minutes is optimal. The temperature error at 200℃ is 5℃, i.e., (200±5)℃.

[0099] Step 4: Place the cotton cellulose products decomposed at low and high temperatures at room temperature and neutralize the excess alkali in the reaction with a 5.5 mol / L dilute HCl solution.

[0100] Step 5: The cellulose decomposition product obtained after the neutralization reaction in Step 4 is placed into a dialysis bag with a molecular weight cutoff of 3500D. The bag is then suspended in a beaker of distilled water to remove salt and small molecule decomposition products. The distilled water is changed several times until all salt is removed through dialysis purification. Finally, the purified cellulose molecules are dried in a 60°C drying oven to obtain the β-1,4-glycosidic bond small molecule product used in production. The yield of the β-1,4-glycosidic bond small molecule product described in this example is 93% (1.86 g).

[0101] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0102] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A simple method for rapid and batch decomposition of cellulose, characterized in that: The method specifically includes the following steps: Step 1: Soak cellulose in an inorganic strong alkali solution according to the specified ratio to obtain fully soaked cellulose; the inorganic strong alkali solution is NaOH solution or KOH solution; the concentration of the inorganic strong alkali solution is 20% to 25% (W / V); the ratio of cellulose to inorganic strong alkali solution is 1 part by mass: 6 parts by volume; wherein: the parts by mass and parts by volume are based on g:mL. Step 2: The fully soaked cellulose is placed in a low-temperature environment for preliminary digestion and decomposition to obtain preliminary decomposition products; the low temperature used for the preliminary digestion and decomposition is -15℃. Step 3: Transfer the preliminary decomposition product to a high-temperature environment and perform high-temperature complete digestion and decomposition under sealed conditions to obtain high-temperature digestion and decomposition product; the high temperature used for the high-temperature complete digestion and decomposition is 200°C; the high-temperature time used for the high-temperature complete digestion and decomposition is 30 minutes. Step 4: Cool the high-temperature digestion and decomposition products to room temperature, and then adjust them to neutral using dilute acid to obtain neutral decomposition products; Step 5: Dialyze the neutral decomposition product multiple times to remove NaCl from the product and obtain purified cellulose decomposition product, namely short-chain β-1,4-glycosidic bond molecules.

2. The method according to claim 1, characterized in that: The concentration of the inorganic strong base solution mentioned in step 1 is 22% (w / v).

3. The method according to claim 1, characterized in that: The initial low-temperature digestion and decomposition process described in step 2 should take more than 12 hours.

4. The method according to claim 1, characterized in that: The high-temperature thorough digestion and decomposition in step 3 uses a gradient temperature, which is specifically set as follows: heat from room temperature to 100℃ and hold for 10 minutes, then continue to heat to 200℃ and hold for 30 minutes.

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