Preparation method of enzyme-assisted low-conversion high-yield bamboo pulp

Abstract

The invention discloses a preparation method of enzyme-assisted low-yield bamboo pulp, and belongs to the technical field of pulping and papermaking pretreatment, the key point of the technical scheme comprises the following steps: 1) taking one-year-old fresh bamboo wood, cleaning and slicing; (2) the fresh bamboo chips are soaked in a NaHCO3 solution for 5 h, drained and taken out; (3) the bamboo chips are placed in a 100 DEG C steam furnace to be steamed for 4 h and then cleaned to be neutral; 4) putting the steamed bamboo chips into a compound enzyme solution with the temperature of 40-60 DEG C and the pH value of 4-7, and treating for 8-12 hours, wherein the compound enzyme solution comprises pectinase, cutinase and xylanase; and 5) continuously stirring by using a cantilever stirrer in the enzyme treatment process. According to the method, the high-yield bamboo pulp is prepared with assistance of a low-temperature enzyme method, consumption of chemicals in the traditional pulp boiling process can be reduced, and damage of excessive chemicals to fibers can also be reduced and prevented; and meanwhile, the pulping performance of the fiber can be improved, the discharge and treatment capacity of wastewater are reduced through auxiliary treatment of the enzyme, and the pollution to the environment is reduced.

Description

Technical Field

[0001] The invention relates to a method for preparing bamboo pulp, and more specifically to a method for pulping bamboo raw materials. Background Art

[0002] As a natural plant fiber with abundant reserves in my country, the rational, efficient and green use of bamboo will effectively alleviate the current shortage of pulp and paper raw materials in my country. Bamboo has a high cellulose content, slender fiber shape, good mechanical properties and plasticity. As a good alternative material for wood papermaking raw materials, bamboo can meet the pulp requirements for making medium and high-end paper. Studies have shown that bamboo has good pulping properties due to its chemical composition and fiber properties. The performance of bamboo pulp is second only to coniferous wood pulp, and is better than broad-leaved wood pulp and grass pulp. Vigorously developing the bamboo pulping and papermaking industry is of great significance to alleviating the current shortage of wood pulp raw materials. However, due to the compactness of the bamboo structure itself, additional chemicals are usually consumed in the pulping process, and the bamboo fiber will also be damaged, resulting in a reduced yield. Patent CN 115637600A discloses a method for preparing bamboo pulp using a composite bacterial agent, in which chemicals such as hydrogen peroxide, sodium silicate, caustic soda and DTPA are also added. Patent CN 114775317A discloses a method for preparing pulp by pretreating wood chips using Pleurotus eryngii. The patent uses a 6% sodium hydroxide lye solution, which is cooked for 30 minutes at a temperature of 130°C and a material-liquid ratio of 1:4. However, there are still problems of large alkali dosage and high pulping energy consumption. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an enzyme-assisted degraded bamboo pulp preparation method with low alkali usage, high bamboo pulp yield and reduced wastewater pollution in view of the above-mentioned deficiencies in the prior art.

[0004] The technical solution of the present invention is as follows:

[0005] An enzyme-assisted method for preparing low-chemical high-yield bamboo pulp comprises the following steps:

[0006] 1) Collect 1-2 year old fresh bamboo, remove the skin with a scraper and slice it;

[0007] 2) Soak fresh bamboo slices in NaHCO3 solution for 5 hours, drain and take out;

[0008] 3) Steam the bamboo strips in a 100°C steam oven for 4 hours and then clean them until they are neutral;

[0009] 4) Then, the steamed bamboo slices are placed in a compound enzyme solution at a temperature of 40-60°C and a pH of 4-7 for 8-12 hours.

[0010] 5) Continuous stirring during enzyme treatment by cantilever stirrer

[0011] In the above-mentioned enzyme-assisted low-chemical high-yield bamboo pulp preparation method, the peeling in step 1) is to remove the outer skin on the surface of one-year-old bamboo by a scraper, and then the bamboo is sliced ​​by a mechanical cutting method.

[0012] In the above-mentioned enzyme-assisted low-chemical high-yield bamboo pulp preparation method, the concentration of the NaHCO3 solution used in step 2) is 5wt%, and the soaking temperature is room temperature.

[0013] In the above-mentioned enzyme-assisted method for preparing low-chemical high-yield bamboo pulp, the pH of the reaction between the bamboo slices and the compound enzyme in step 4) is 4-7, wherein the optimal pH is 6.8.

[0014] In the above-mentioned enzyme-assisted low-chemical high-yield bamboo pulp preparation method, the optimal compound enzyme in step 4) contains 100u / mL pectinase, 200u / mL xylanase, and 100u / mL cutinase, and is treated at pH 6.8 and temperature 50°C for 12 hours.

[0015] The present invention provides a method for treating bamboo materials by the above-mentioned treatment method to obtain raw pulp suitable for pulping and papermaking.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) The method adopted by the present invention is a biological enzyme-assisted treatment method. Compared with the pure chemical treatment method, it reduces the damage to bamboo fiber during the chemical cooking process and retains the original properties of the fiber. At the same time, the pollution caused by the enzyme solution is lower than that of chemicals, which reduces the pollution to the environment.

[0018] (2) The present invention adopts the method of alkali soaking and steaming, and the alkali solution can be reused, while the amount of alkali used is reduced.

[0019] (3) The present invention adopts a combined treatment method, which greatly protects the original fibers of the bamboo material, thereby increasing the yield of bamboo pulp. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The bamboo pulp is obtained after combined treatment. DETAILED DESCRIPTION

[0021] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. If the manufacturer of the reagents or instruments used is not indicated, they are deemed to be conventional products that can be purchased commercially.

[0022] Example 1

[0023] (1) Peeling and splitting: Take freshly cut bamboo, remove the outer skin of the bamboo with a scraper and cut it into 5cm*1cm*0.2cm size with an electric saw.

[0024] (2) Low-alkali soaking treatment: The bamboo pieces were soaked in a 5 wt% NaHCO3 solution for 5 h, then the water was drained and taken out. NaHCO3 was analytical grade and purchased from MacLean Reagent Co., Ltd.

[0025] (3) Steaming: Place the bamboo strips in a steamer in a proper manner, staggered to allow air passages to rise.

[0026] (4) Compound enzyme solution treatment: The bamboo material after steaming was placed in a neutral enzyme solution at a temperature of 50°C and pH 6.8 at a bath ratio of 1:30 for 12 hours. The pectinase and xylanase used in this example were purchased from Shanghai MacLean Co., Ltd., and the cutinase used was from Ruichenxing Biotechnology (Guangzhou) Co., Ltd., wherein the concentrations of pectinase, cutinase, and xylanase were 100u / mL, 100u / mL, and 200u / mL, respectively.

[0027] (5) During the enzyme solution treatment process, continuous stirring is performed at a rotation speed of 200-500 rpm using a cantilever stirrer to promote the contact reaction between the enzyme solution and the bamboo material.

[0028] After the reaction is completed, the bamboo pulp is filtered, cleaned, and processed, and then screened on a flat plate to form pulp for papermaking.

[0029] Example 2

[0030] (1) Peeling and splitting: Take freshly cut bamboo, remove the outer skin of the bamboo with a scraper and cut it into 5cm*1cm*0.2cm size with an electric saw.

[0031] (2) Soaking treatment: Soak the bamboo strips in aqueous solution for 5 hours and then drain and take them out.

[0032] (3) Steaming: Place the bamboo strips in a steamer in a proper manner, staggered to allow air passages to rise.

[0033] (4) Compound enzyme solution treatment: The bamboo material after steaming was placed in a neutral enzyme solution at a temperature of 50°C and pH 6.8 at a bath ratio of 1:30 for 12 hours. The pectinase and xylanase used in this example were purchased from Shanghai MacLean Co., Ltd., and the cutinase used was from Ruichenxing Biotechnology (Guangzhou) Co., Ltd., wherein the concentrations of pectinase, cutinase, and xylanase were 100u / mL, 100u / mL, and 200u / mL, respectively.

[0034] (5) During the enzyme solution treatment process, continuous stirring is performed at a rotation speed of 200-500 rpm using a cantilever stirrer to promote the contact reaction between the enzyme solution and the bamboo material.

[0035] After the reaction is completed, the bamboo pulp is filtered, cleaned, and processed, and then screened on a flat plate to form pulp for papermaking.

[0036] Example 3

[0037] (1) Peeling and splitting Peeling and splitting: Take freshly cut bamboo, remove the outer skin of the bamboo with a scraper and cut it into 5cm*1cm*0.2cm sizes using an electric saw.

[0038] (2) Low-alkali soaking treatment: The bamboo pieces were soaked in a 5 wt% NaHCO3 solution for 5 h, then the water was drained and taken out. NaHCO3 was analytical grade and purchased from MacLean Reagent Co., Ltd.

[0039] (3) Steaming: Place the bamboo strips in a steamer in a proper manner, staggered to allow air passages to rise.

[0040] (4) Water treatment: The steamed bamboo is placed in a neutral aqueous solution at a temperature of 50°C and a pH of 6.8 for 12 hours.

[0041] (5) During the water treatment process, the cantilever stirrer is used to continuously stir at a speed of 200-500 rpm to promote the contact reaction between the liquid and the bamboo.

[0042] After the reaction is completed, the bamboo pulp is filtered, cleaned, and processed, and then screened on a flat plate to form pulp for papermaking.

[0043] Comparative Example 1

[0044] (1) Peeling and splitting: Take freshly cut bamboo, remove the outer skin of the bamboo with a scraper and cut it into 5cm*1cm*0.2cm size with an electric saw.

[0045] (2) Alkali cooking treatment: Place the bamboo slices in a cooking pot, add 2.5% potassium hydroxide, 2% sodium sulfite and 1.5% sodium tripolyphosphate, and cook at 140°C for 120 minutes.

[0046] (3) Extrusion and tearing: The cooked pulp is sent to a twin-screw refiner for grinding and filament separation to obtain a coarse pulp.

[0047] After the reaction is completed, the bamboo pulp is filtered, cleaned, and processed, and then screened on a flat plate to form pulp for papermaking.

[0048] The slurry obtained above was dried by freeze drying and weighed, and the yield was calculated by comparing with the original bamboo chips. The results are shown in Table 1. The fiber length and degree of polymerization were analyzed by a fiber quality analyzer and a pulp viscosity meter. The results are shown in Table 2:

[0049] Table 1: Good pulp yield in different treatment cases

[0050] Example 1 Example 2 Example 3 Comparative Example 1 Good pulp yield (%) 67.36％ 2.32％ 28.51％ 53.26％

[0051] Table 2: Analysis of fiber quality and degree of polymerization after different treatments

[0052] Example 1 Example 2 Example 3 Comparative Example 1 Average fiber length (mm) 0.55 0.21 0.51 0.49 Degree of Polymerization 761 — 634 652

[0053] As can be seen from Table 1, the yield of good pulp by biological enzyme treatment in Example 1 is as high as 67.36%, which is significantly higher than that of the chemical method in Comparative Example 1. This may be due to the relatively mild enzyme treatment conditions, which greatly reduces the loss of fiber by high temperature and strong alkali. At the same time, Example 2 cannot be pulped because it cannot achieve the dissociation of z bamboo by enzyme treatment alone. In Example 3, due to the high temperature alkaline steaming treatment, the bamboo chips are partially dissociated, but the yield is still low. At the same time, the results of Table 2 show that the bamboo pulp obtained after the combined treatment has a higher fiber length and degree of polymerization, which indicates that the bamboo pulp prepared by this method can be used as an excellent source of bamboo pulp for papermaking.

[0054] The above embodiments are only preferred implementation modes of the present invention and are only used to explain the present invention rather than to limit the present invention. Any changes, substitutions, modifications, etc. made by those skilled in the art without departing from the spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. An enzyme-assisted method for preparing low-chemical high-yield bamboo pulp, characterized in that The steps include: 1) Collect 1-2 year old fresh bamboo, remove the skin with a scraper and slice it; 2) Soak fresh bamboo slices in NaHCO3 solution for 5 hours, drain and take out; 3) Steam the bamboo strips in a 100°C steam oven for 4 hours and then clean them until they are neutral; 4) Then, the steamed bamboo slices are placed in a compound enzyme solution at a temperature of 40-60°C and a pH of 4-7 for 8-12 hours. 5) Continuous stirring is performed by a cantilever stirrer during the enzyme treatment.

2. The method for removing bast rubber by using a composite enzyme according to claim 1, characterized in that: The bark used in step (1) is one of paper mulberry, mulberry, celtis sinensis and smilax china.

3. The method for preparing an enzyme-assisted low-chemical high-yield bamboo pulp according to claim 1, characterized in that: After cutting in step (1), the size of the bamboo pieces is 5 cm*1 cm*0.2 cm.

4. The method for preparing an enzyme-assisted low-chemical high-yield bamboo pulp according to claim 1, characterized in that: In step (2), the concentration of the NaHCO3 solution is 5 wt % and the soaking temperature is room temperature.

5. The method for preparing an enzyme-assisted low-chemical high-yield bamboo pulp according to claim 1, characterized in that: In step (4), the pH of the reaction between the bamboo chips and the complex enzyme is 4-7, wherein the optimal pH is 6.

8.

6. The method for preparing an enzyme-assisted low-chemical high-yield bamboo pulp according to claim 1, characterized in that: In step (4), the enzyme solution comprises cutinase, pectinase and xylanase, and the concentrations of the cutinase, pectinase and xylanase are 100-200 U / mL, 100-200 U / mL and 100-200 U / mL respectively.

7. The method for preparing an enzyme-assisted low-chemical high-yield bamboo pulp according to claim 1, characterized in that: In step (4), the reaction time of the complex enzyme and the bamboo chips is 8-12 hours, and the optimal reaction time is 12 hours.

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