Energy-saving enhanced enzymatic pretreatment process for unbleached bamboo pulp
By treating unbleached bamboo pulp with a complex enzyme system of cleaving polysaccharide monooxygenase and cellulase, the problems of high pulping energy consumption and insufficient fiber strength are solved, achieving an energy-saving and enhanced pretreatment effect, improving fiber flexibility and paper strength, and meeting the requirements of green papermaking.
Patent Information
- Application Number
- CN202511951596.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-02-10
AI Technical Summary
Existing technologies are insufficient in reducing energy consumption in beating unbleached bamboo pulp and preserving fiber strength. Traditional methods are energy-intensive and cause severe fiber damage, while bio-enzymatic methods are inefficient and pose a risk of excessive hydrolysis.
A complex enzyme system consisting of cleaving polysaccharide monooxygenase and cellulase, combined with acetate/sodium acetate buffer solution and ascorbic acid, was used to synergistically treat unbleached bamboo pulp. This mild enzymatic pretreatment softened the fiber structure and improved the enzymatic hydrolysis efficiency.
It significantly reduces pulping energy consumption, maintains or improves the tensile strength and bursting strength of the finished paper, is environmentally friendly and in line with the trend of green papermaking, reduces chemical consumption and equipment corrosion, and enhances fiber flexibility and swelling capacity.
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Figure CN121496773A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of pulp manufacturing, and particularly relates to an energy-saving and enhanced enzyme pretreatment process for unbleached bamboo pulp. BACKGROUND
[0002] As a green and renewable resource, bamboo fiber is showing great application potential in the context of the global paper industry pattern transforming into a circular, low-carbon and green economy.
[0003] Beating is a crucial section in the pulp and papermaking process, and its purpose is to make the fibers swell, separate and floss through mechanical action, so as to increase the bonding area between fibers and improve the physical strength of the paper. However, traditional mechanical beating separates and flosses the fibers through high-intensity physical friction, which inevitably leads to serious damage to the fiber length and consumes a large amount of energy while improving the fiber bonding force (which is beneficial to the tensile strength). For unbleached bamboo pulp, which has thick cell walls and strong rigidity, more energy is often consumed to achieve the desired beating degree. Therefore, developing a pretreatment technology that can essentially "soften" the fibers to reduce beating energy consumption at the source while also considering the strength performance of the paper has been a long-term pursuit but has not been fully realized in the field, and it has great practical significance for promoting energy saving and emission reduction and reducing costs in the paper industry.
[0004] Currently, the pretreatment methods used to reduce beating energy consumption mainly include physical methods, chemical methods and biological enzyme methods.
[0005] Although the physical method (such as disc mill pretreatment) can cut the fibers to some extent, it has high energy consumption and limited improvement in the internal flexibility of the fibers. Although the chemical method (such as using acid, alkali or oxidizing agent treatment) can effectively soften the fibers, it often accompanies the degradation and loss of cellulose, leading to a decrease in pulp yield and strength performance, and also has problems such as chemical consumption, equipment corrosion and environmental pollution.
[0006] Bio-enzymatic method, especially using cellulase for pretreatment, is considered as a more promising green alternative. Cellulase can loosen the fiber structure by hydrolyzing the amorphous region on the surface of the fiber, thus reducing the energy consumption of beating to some extent. However, this technology also faces significant bottlenecks in practical application: first, there is a complex lignin-carbohydrate complex (LCC) in the cell wall of bamboo fiber, with lignin content as high as 20-25% and hemicellulose content about 18-22%, this stubborn "anti-degradation barrier" seriously hinders the limited accessibility between enzymes and cellulose, thus greatly reducing the efficiency of enzymatic hydrolysis. In order to improve the efficiency of enzymatic hydrolysis, pretreatment of biomass must be carried out before enzymatic hydrolysis to decompose its complex structure and change its chemical composition. Secondly, excessive action of cellulase or improper control of treatment conditions can easily lead to excessive hydrolysis of cellulose, causing permanent damage to fiber length and strength performance, i.e. the risk of "over-degradation", which limits the increase of its dosage and the full play of its effect in practice.
[0007] Some studies use lytic polysaccharide monooxygenases (such as LPMO) for biomass pretreatment, but their application scenarios and targets are completely different. The combination of monooxygenase and cellulase aims to maximize and completely degrade cellulose into fermentable sugar, and the process target and parameter design are completely service for the ultimate index of "saccharification yield". It is essentially a "complete deconstruction" of the fiber structure, which is different from the goal of the paper industry to "controllably optimize" the fiber structure to retain its function as a reinforcing material. It has not been found that this known mechanism is applied to solve the specific industrial problem of the inherent contradiction between energy consumption and strength in the papermaking beating process and can produce significant synergistic effect.
[0008] In summary, there is an urgent need in the art for a pretreatment method that can soften the fiber structure more efficiently, more gently and more targeted, thereby improving the efficiency of enzymatic hydrolysis, and thus significantly reducing the energy consumption of beating, while maximizing the retention of fiber strength. Lytic polysaccharide monooxygenase (LPMO) is a highly efficient oxidoreductase catalyst that catalyzes the degradation of polysaccharide molecules. It can cut the glycosidic bond in polysaccharide by oxidation, thus depolymerizing the crystalline region of cellulose that is difficult to degrade and exposing more binding sites for cellulase, thereby accelerating the hydrolysis of cellulose. SUMMARY
[0009] The present application aims at the above-mentioned deficiencies of the prior art, and provides an energy-saving and enhanced enzyme method pretreatment process for unbleached bamboo pulp, which can significantly reduce the beating energy consumption of the unbleached bamboo pulp while maintaining or even improving the tensile strength and burst strength of the paper made therefrom.
[0010] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:
[0011] The first object of the present application is to provide an energy-saving and enhanced enzyme method pretreatment process for unbleached bamboo pulp, comprising the following steps:
[0012] 1) soaking, defibrating, spinning and beating the unbleached bamboo pulp board with deionized water to obtain pulp;
[0013] 2) mixing the acetic acid / sodium acetate buffer solution with the unbleached bamboo pulp and preheating in a low-temperature water bath shaker oscillator, and the reaction temperature is 30-50℃;
[0014] 3) dissolving and diluting the mixed solution of the lytic polysaccharide monooxygenase liquid and the cellulase liquid with the acetic acid / sodium acetate buffer solution, and then adding them into the preheated unbleached bamboo pulp in sequence until the final concentration is 4%-10%, inactivating and washing after a certain reaction time, and then vacuum filtering to obtain unbleached pulp;
[0015] or dissolving and diluting the lytic polysaccharide monooxygenase liquid and the ascorbic acid with the acetic acid / sodium acetate buffer solution, and then adding them into the preheated unbleached bamboo pulp in sequence until the final concentration is 4%-10%, shaking and oscillating, inactivating, repeatedly washing the pulp with deionized water, and then vacuum filtering to obtain the pulp, then mixing the acetic acid / sodium acetate buffer solution with the pulp, dissolving the cellulase with the acetic acid / sodium acetate buffer solution and adding it into the pulp until the final concentration is 4%-10%, shaking and oscillating for a certain time, inactivating, repeatedly washing the pulp with deionized water, and then vacuum filtering to obtain the pulp;
[0016] 4) taking 10-30g of the absolutely dry pulp after reaction, adjusting the pulp concentration to 3-10% with deionized water, and then performing beating in a PFI beater.
[0017] Further, the unbleached bamboo pulp board is a sulfite unbleached bamboo pulp board.
[0018] Further, the unbleached bamboo pulp board is soaked with deionized water for 3-5h.
[0019] Further, the pH value of the acetic acid / sodium acetate buffer solution is 4.8-5.0.
[0020] Furthermore, the mass ratio of the cleavable polysaccharide monooxygenase to unbleached bamboo pulp is 1.25 mg / g to 10 mg / g.
[0021] Furthermore, the mass ratio of the cellulase to unbleached bamboo pulp is 1.25 mg / g to 10 mg / g.
[0022] Furthermore, the mass ratio of the cleavage polysaccharide monooxygenase solution to the cellulase solution is 1:1-2.
[0023] Furthermore, the concentration of the ascorbic acid diluent is 1–10 mM.
[0024] Furthermore, the low-temperature water bath shaker has an oscillation time of 2–6 hours and a frequency of 200–300 rpm.
[0025] Furthermore, the PFI refining speed is 8000–15000 r; the refining gap is 0.1–0.3 mm; and the refining consistency is 3–10%.
[0026] Compared with the prior art, the present invention has the following advantages:
[0027] (1) Significantly reduced energy consumption: After this pretreatment, the flexibility and swelling capacity of bamboo pulp fiber are fundamentally improved, and the energy consumption of subsequent mechanical beating can be expected to be reduced by about 52.38%. The cleaving polysaccharide monooxygenase opens up the dense structure of the fiber, creating more accessible action sites for subsequent cellulase, achieving deep and precise softening of the fiber structure. The combined effect of the two achieves a softening effect far exceeding that of single enzyme treatment. Compared with traditional methods, a higher degree of beating can be obtained at the same beating intensity.
[0028] (2) Protecting fiber strength: Compared with harsh chemical or mechanical pretreatment, this method has mild reaction conditions, which can effectively avoid excessive degradation of fibers and better maintain the inherent length and strength of fibers, thus contributing to the improvement of the physical strength of paper.
[0029] (3) Green and environmentally friendly: The whole process is catalyzed by biological enzymes, without the need for high temperature, high pressure or strong acid and strong alkali. Compared with chemical methods, this invention reduces the consumption of chemicals, reduces the corrosion of equipment and the pollution to the environment, which is in line with the development trend of green papermaking.
[0030] (4) The enzyme treatment disclosed in the prior art is applied in biomass refining or bioconversion, and its ultimate goal is to maximize the destruction of the fiber structure and convert it into sugar or ethanol. This is a destructive application. However, the papermaking field to which this invention pertains is a field of structural and functional applications. Our goal is to precisely and controllably soften and optimize the fiber structure in order to manufacture high-performance paper.
[0031] (5) The pretreatment method of the present invention provides an efficient, environmentally friendly and economical solution for the pulp and paper industry, which helps the industry achieve new breakthroughs in energy conservation and emission reduction, cost reduction and product quality improvement.
[0032] This invention provides a novel biotechnology solution for the high-value, low-energy processing of unbleached bamboo pulp. Attached Figure Description
[0033] Figure 1 This is a graph showing the pulping effect of adding different amounts of polysaccharide monooxygenase in Example 3 of the present invention;
[0034] Figure 2 This is a scanning electron microscope image of bamboo pulp fiber without enzyme treatment in Comparative Example 1 of the present invention;
[0035] Figure 3 This is a scanning electron microscope image of bamboo pulp fiber treated with cellulase, which is Comparative Example 3 of the present invention.
[0036] Figure 4 This is a scanning electron microscope image of bamboo pulp fiber treated with cleaving polysaccharide monooxygenase and cellulase in Example 2 of the present invention;
[0037] Figure 5 These are XRD patterns of bamboo pulp fibers after treatment according to Comparative Examples 1, 2, 3 and 2 of the present invention. Detailed Implementation
[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, embodiments of the present invention are described in detail below. However, the present invention is not limited to these embodiments.
[0039] Comparative Example 1
[0040] This comparative example provides a pulping process without any enzyme treatment.
[0041] (1) Select 200g of unbleached bamboo pulp chemical pulp board with no cut edges and tear it into samples of about 5mm×5mm. Soak the samples in deionized water for 4 hours. Use a Wali pulping machine to loosen the soaked small pieces of pulp until the fibers in the pulp are evenly dispersed. Take out the pulp, dry it, disperse it, and put it into a sealed bag to balance the moisture for later use.
[0042] (2) Pour the unbleached bamboo pulp into an Erlenmeyer flask, prepare a pulp concentration of 6% with an acetic acid / sodium acetate buffer solution of pH=5, and preheat it in a low-temperature water bath shaker. The reaction temperature is 30-50℃, the reaction time is 3h, and the amplitude is 200rpm.
[0043] (3) After the hydrothermal pretreatment, take 24g of oven-dry slurry and mix it with a slurry concentration of 10%. Then, grind the slurry in a PFI grinder. Grinding conditions: slurry concentration 10%, grinding gap 0.2mm, rotation speed 8000r. Measure the freeness and energy consumption.
[0044] (4) Testing of the physical properties of handmade sheets; PFI pulp was formed into 60g / m³ sheets using a high-speed paper forming machine. 2 Each group of hand-copied sheets consists of 5 to 8 sheets. After equilibration in a constant temperature and humidity laboratory at (23±1)℃ and (50±2)% for 4 hours, the paper strength is measured.
[0045] (5) The degree of freeness was measured to be 19°SR, and the specific energy consumption for pulping was 0.126 (kWh / °SR·kg).
[0046] Comparative Example 2
[0047] This comparative example provides a pulping process using only a cleaving polysaccharide monooxygenase.
[0048] (1) Select 200g of unbleached bamboo pulp chemical pulp board with no cut edges and tear it into samples of about 5mm×5mm. Soak the samples in deionized water for 4 hours. Use a Wali pulping machine to loosen the soaked small pieces of pulp until the fibers in the pulp are evenly dispersed. Take out the pulp, dry it, disperse it, and put it into a sealed bag to balance the moisture for later use.
[0049] (2) Pour the unbleached bamboo pulp into an Erlenmeyer flask, add a pH=5 acetic acid / sodium acetate buffer solution and mix it evenly with the pulp. Take an appropriate amount of pH=5 acetic acid / sodium acetate buffer solution to dissolve the cleaving polysaccharide monooxygenase (2.5 mg / g cleaving polysaccharide monooxygenase) and ascorbic acid respectively. Then add the enzyme solution to the pulp and mix evenly. Add 1 mM ascorbic acid solution until the pulp concentration is 6%. Place it in a low-temperature water bath shaker for preheating. Seal the Erlenmeyer flask with a breathable membrane to provide oxygen. The reaction temperature is 30-50℃, the reaction time is 3h, and the amplitude is 200 rpm.
[0050] (3) After the reaction is complete, inactivate with boiling water for 10 minutes, and wash repeatedly with deionized water to remove residual enzyme solution and decomposition products.
[0051] (4) Take 24g of oven-dry pulp and mix it with a pulp consistency of 10%. Then, grind the pulp in a PFI refiner. Refining conditions: pulp consistency 10%, refining gap 0.2mm, speed 8000r. Measure the freeness and energy consumption.
[0052] (5) Testing of physical properties of handmade sheets: PFI pulp was processed into 60g / m2 handmade sheets using a rapid paper forming machine. Each group produced 5 to 8 sheets. After equilibration in a constant temperature and humidity laboratory at (23±1)℃ and (50±2)% for 4 hours, the paper strength was measured.
[0053] (5) The degree of freeness was measured to be 26°SR, and the specific energy consumption for pulping was 0.092 (kWh / °SR·kg).
[0054] Comparative Example 3
[0055] This comparative example provides a pulping process using cellulase treatment alone.
[0056] (1) Select 200g of unbleached bamboo pulp chemical pulp board with no cut edges and tear it into samples of about 5mm×5mm. Soak the samples in deionized water for 4 hours. Use a Wali pulping machine to loosen the soaked small pieces of pulp until the fibers in the pulp are evenly dispersed. Take out the pulp, dry it, disperse it, and put it into a sealed bag to balance the moisture for later use.
[0057] (2) Pour the unbleached bamboo pulp into an Erlenmeyer flask, add a pH=5 acetic acid / sodium acetate buffer solution and mix it evenly with the pulp. Take an appropriate amount of pH=5 acetic acid / sodium acetate buffer solution to dissolve cellulase (2.5 mg / g cellulase), and then add the enzyme solution to the pulp and mix until the pulp concentration is 6%. Place it in a low-temperature water bath shaker for preheating. The reaction temperature is 30-50℃, the reaction time is 3h, and the amplitude is 200 rpm.
[0058] (3) After the reaction is complete, inactivate with boiling water for 10 minutes, and wash repeatedly with deionized water to remove residual enzyme solution and decomposition products.
[0059] (4) Take 24g of oven-dry pulp and mix it with a pulp consistency of 10%. Then, grind the pulp in a PFI refiner. Refining conditions: pulp consistency 10%, refining gap 0.2mm, speed 8000r. Measure the freeness and energy consumption.
[0060] (5) Testing of physical properties of handmade sheets: PFI pulp was processed into 60g / m2 handmade sheets using a rapid paper forming machine. Each group produced 5 to 8 sheets. After equilibration in a constant temperature and humidity laboratory at (23±1)℃ and (50±2)% for 4 hours, the paper strength was measured.
[0061] (6) The degree of freeness was measured to be 32°SR, and the specific energy consumption for freeness was 0.075 (kWh / °SR·kg).
[0062] Example 1
[0063] This embodiment provides an energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp, the specific steps of which are as follows:
[0064] (1) Select 200g of unbleached bamboo pulp chemical pulp board with no cut edges and tear it into samples of about 5mm×5mm. Soak the samples in deionized water for 4 hours. Use a Wali pulping machine to loosen the soaked small pieces of pulp until the fibers in the pulp are evenly dispersed. Take out the pulp, dry it, disperse it, and put it into a sealed bag to balance the moisture for later use.
[0065] (2) Pour the unbleached bamboo pulp into an Erlenmeyer flask, add a pH=5 acetic acid / sodium acetate buffer solution and mix it evenly with the pulp. Take an appropriate amount of pH=5 acetic acid / sodium acetate buffer solution to dissolve the mixed enzyme solution of cleaving polysaccharide monooxygenase (2.5 mg / g cleaving polysaccharide monooxygenase) and cellulase and ascorbic acid respectively. Then add the mixed enzyme solution to the pulp and mix evenly. Then add 1 mM ascorbic acid solution until the pulp concentration is 6%. Place it in a low-temperature water bath shaker for preheating. Seal the Erlenmeyer flask with a breathable membrane to provide oxygen. The reaction temperature is 30-50℃, the reaction time is 3h, and the amplitude is 200rpm.
[0066] (3) After the reaction is complete, inactivate with boiling water for 10 minutes, and wash repeatedly with deionized water to remove residual enzyme solution and decomposition products.
[0067] (4) Take 24g of oven-dry pulp and mix it with a pulp consistency of 10%. Then, grind the pulp in a PFI refiner. Refining conditions: pulp consistency 10%, refining gap 0.2mm, speed 8000r. Measure the freeness and energy consumption.
[0068] (5) The degree of freeness was measured to be 36.75°SR, and the specific energy consumption for freeness was 0.065 (kWh / °SR·kg).
[0069] Example 2
[0070] This embodiment provides an energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp, the specific steps of which are as follows:
[0071] (1) Select 200g of unbleached bamboo pulp chemical pulp board with no cut edges and tear it into samples of about 5mm×5mm. Soak the samples in deionized water for 4 hours. Use a Wali pulping machine to loosen the soaked small pieces of pulp until the fibers in the pulp are evenly dispersed. Take out the pulp, dry it, disperse it, and put it into a sealed bag to balance the moisture for later use.
[0072] (2) Pour the unbleached bamboo pulp into an Erlenmeyer flask, add an acetic acid / sodium acetate buffer solution of pH=5 and mix it evenly with the pulp. Take an appropriate amount of acetic acid / sodium acetate buffer solution of pH=5 to dissolve the cleaving polysaccharide monooxygenase (2.5 mg / g cleaving polysaccharide monooxygenase) and ascorbic acid respectively. Then add the enzyme solution to the pulp and mix evenly. Then add 1 mM ascorbic acid solution until the pulp concentration is 6%. Place it in a low temperature water bath shaker for preheating. The reaction temperature is 30-50℃, the reaction time is 3h, and the amplitude is 200 rpm.
[0073] (3) After the reaction is complete, inactivate with boiling water for 10 minutes, and wash the slurry repeatedly with deionized water to remove residual enzyme solution and decomposition products.
[0074] (4) Add pH=5 acetic acid / sodium acetate buffer solution and mix evenly with the slurry. Take an appropriate amount of pH=5 acetic acid / sodium acetate buffer solution to dissolve cellulase (2.5 mg / g cellulase). Then add the enzyme solution to the slurry and mix until the slurry concentration is 6%. Place it in a low-temperature water bath shaker for preheating. Seal the conical flask with a breathable membrane to provide oxygen. The reaction temperature is 30-50℃, the reaction time is 3h, and the amplitude is 200rpm.
[0075] (5) After the reaction is complete, inactivate with boiling water for 10 minutes, and wash repeatedly with deionized water to remove residual enzyme solution and decomposition products.
[0076] (6) Take 24g of oven-dry pulp and mix it with a pulp consistency of 10%. Then, grind the pulp in a PFI refiner. Refining conditions: pulp consistency 10%, refining gap 0.2mm, speed 8000r. Measure the freeness and energy consumption.
[0077] (7) The degree of freeness was measured to be 39°SR, and the specific energy consumption for pulping was 0.060 (kWh / °SR·kg).
[0078] Example 3
[0079] This embodiment provides an energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp, which is basically the same as in Embodiment 2, except that the addition amounts of different polysaccharide-cleaving monooxygenases (5 mg / g, 10 mg / g, 20 mg / g, and 40 mg / g) were investigated, and the results are as follows. Figure 1 .
[0080] refer to Figure 1 The figure shows the pulping effect of adding different amounts of cleaving polysaccharide monooxygenase in Example 3. As can be seen from the figure, the enzyme dosage and pulping effect are not a simple linear relationship, but rather there is a range of enzyme ratios. Within this range, the pulping effect can be improved. When the ratio of cleaving polysaccharide monooxygenase to cellulase exceeds 4:1, the pulping effect of the combined treatment is the same as or lower than that of the single cellulase treatment in Comparative Example 3.
[0081] The microstructure of the pretreated fibers was characterized using scanning electron microscopy, taking Comparative Example 1, Comparative Example 2 and Example 2 as examples.
[0082] refer to Figure 2 The image shows a scanning electron microscope (SEM) image of bamboo pulp fibers from Comparative Example 1 that have not undergone enzyme treatment. It is clearly visible from the image that the bamboo pulp fibers have a smooth surface and distinct fiber morphology. In contrast, [the image shows a different image]. Figure 3 The image shown is a scanning electron microscope image of bamboo pulp fiber treated with cellulase in Comparative Example 3. From the image, it can be observed that some wrinkles and grooves appear on the fiber surface, there is slight brooming, some small pores appear on the fiber surface, and the number of fine fibers increases. Figure 4 The image shown is a scanning electron microscope image of bamboo pulp fibers treated with cleaving polysaccharide monooxygenase and cellulase in Example 2. It can be seen from the image that more microfibrils appear inside the fibers, the surface is rough and porous, with a large number of large-sized grooves and pores, and more fine fibers, which greatly improves the pulp beating degree and reduces the pulp beating energy consumption.
[0083] The structural changes of the pretreated fibers were characterized using X-ray diffraction, and the changes in relative crystallinity were calculated by peak fitting, taking Comparative Example 1, Comparative Example 2 and Example 2 as examples.
[0084] refer to Figure 5 The figures show the XRD patterns of bamboo pulp fibers after treatment with Comparative Examples 1, 2, 3, and 2. As can be seen, the pretreatment methods did not alter the crystal structure of cellulose. Compared to Comparative Example 1, the relative crystallinity of bamboo pulp fibers treated with Comparative Example 2 decreased significantly to 64.86%, demonstrating the oxidative effect of the polysaccharide monooxygenase, which mainly acts on the crystalline cellulose region. The relative crystallinity of bamboo pulp fibers treated with Comparative Example 3 was slightly higher than that of Comparative Example 1. Cellulase mainly acts on the amorphous region, leading to an increase in the proportion of the crystalline region and thus an increase in relative crystallinity. The relative crystallinity of bamboo pulp fibers treated with Example 2 was higher than that of Comparative Examples 1 and 3, but lower than that of Comparative Example 2. The combined treatment involved two steps: first, the polysaccharide monooxygenase (LPMO) destroyed the fibers, causing the crystallinity to decrease towards the direction of LPMO treatment alone; then, the cellulase further hydrolyzed the fibers, removing the destroyed parts and causing the crystallinity to recover towards the direction of cellulase treatment. The final result was a balance between the two effects, with the crystallinity falling precisely between the two.
[0085] The results of beating degree and specific beating energy consumption of Comparative Examples 1, 2, and 3 and Examples 1 and 2 are shown in Table 1.
[0086] The formula for calculating the specific energy consumption of pulping in the table is as follows:
[0087] In the formula, SEC (specific energy consumption) is the specific beating energy consumption, kWh / (°SR·kg); W1 is the actual energy consumption corresponding to the beating revolutions during PFI beating, kWh; W0 is the idle energy consumption corresponding to the beating revolutions, kWh; m is the oven-dry mass of the fiber, kg; and S is the degree of freeness of the pulp after beating, °SR.
[0088] Table 1. Pulping effect of bamboo pulp fibers after different pretreatment methods
[0089] Sample Shopper (°SR) Specific energy consumption for beating (kWh / °SR·kg) Comparative Example 1 19 0.126 Comparative Example 2 20 0.092 Comparative Example 3 32 0.075 Example 1 36.75 0.065 Example 2 39 0.060
[0090] As shown in Table 1, unbleached bamboo pulp treated with the combined action of cleaving polysaccharide monooxygenase and cellulase achieves higher freeness and lower specific beating energy consumption under the same beating strength. Compared with Comparative Example 1, Example 1 shows a 93.42% increase in freeness and a 48.4% decrease in specific beating energy consumption, while Example 2 shows a 105.26% increase in freeness and a 52.38% decrease in specific beating energy consumption. The treatment effect of Example 2 is superior to that of Example 1, demonstrating the significant energy-saving effect of this invention. A synergistic effect between cleaving polysaccharide monooxygenase and cellulase is clearly demonstrated: cleaving polysaccharide monooxygenase opens up the dense structure of the fiber, creating more accessible action sites for cellulase, while cellulase effectively hydrolyzes the exposed amorphous regions. The combined effect of both achieves a softening effect far exceeding that of single enzyme treatment, resulting in better beating, enhanced fiber bonding, and to some extent, an increase in paper strength, as shown in Table 2.
[0091] Table 2. Changes in paper properties after treating bamboo pulp fibers with different pretreatment methods
[0092] Sample Tensile index (N·m / g) Resistance to break index (kPa-m / g) 2 / g) Tear index (mN-m / g) 2 / g) Comparative Example 1 46.114 3.137 4.346 Comparative Example 2 48.151 3.151 4.254 Comparative Example 3 47.635 2.716 2.577 Example 2 53.667 3.218 3.050
[0093] As shown in Table 2, the tensile index, bursting index, and tear index of the paper in Example 2 are 53.667 N·m / g, 3.218 kPa·m, and 3.218 kPa·m, respectively. 2 / g, 3.050mN·m 2The tensile strength and bursting strength of Example 2 were improved compared to Comparative Examples 1, 2, and 3, while the tear index was lower than that of Comparative Examples 1 and 2. Compared to Comparative Example 1, the tensile strength increased by 16.38% and the bursting strength increased by 2.58%. Comparative Example 3 showed some improvement in tensile strength and bursting strength, but fiber properties were damaged, and the tear index of the paper was the lowest among them. The tear index of Example 2 was lower than that of Comparative Examples 1 and 2, but better than that of Comparative Example 3, because the pretreatment with cleaving polysaccharide monooxygenase increased the cellulose content. Enzymatic hydrolysis is very effective in promoting fiber splitting and swelling (improving binding strength), but at the same time, it also causes a certain degree of moderate cutting or microfibrillation of the fibers, resulting in a slight decrease in average fiber length and a decrease in tear index. Example 2 replaced some of the violent mechanical action with a mild biochemical action, and achieved a significant increase in binding strength and a significant reduction in energy consumption with a small loss of fiber length. This shows that the present invention has achieved an excellent balance between reducing energy consumption, improving fiber binding strength and maintaining fiber length and strength, which meets the performance requirements of high-grade paper.
[0094] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art can make modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the direction of the present invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.
Claims
1. An energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp, characterized in that, Includes the following steps: 1) Soak, loosen, spin dry, and break up the unbleached bamboo pulp board with deionized water to obtain pulp; 2) Mix the acetic acid / sodium acetate buffer solution and the unbleached bamboo pulp in a low-temperature water bath shaker and preheat the mixture to a reaction temperature of 30-60℃; 3) The mixture of cleavage polysaccharide monooxygenase solution and cellulase solution and ascorbic acid were dissolved and diluted with acetic acid / sodium acetate buffer solution and then added to the preheated unbleached bamboo pulp until the final concentration was 4% to 10%. After reacting for a certain period of time, the pulp was inactivated, washed and filtered to obtain unbleached pulp. Alternatively, the cleavage polysaccharide monooxygenase solution and ascorbic acid can be dissolved and diluted separately with acetate / sodium acetate buffer solution, and then added sequentially to the preheated unbleached bamboo pulp to a final concentration of 4%–10%. The mixture is shaken on a shaker for a certain period of time, and after inactivation, the pulp is repeatedly washed with deionized water and vacuum filtered to obtain the pulp. Then, the acetate / sodium acetate buffer solution is mixed with the pulp, the cellulase is dissolved in the acetate / sodium acetate buffer solution and added to the pulp to a final concentration of 4%–10%. The mixture is shaken on a shaker for a certain period of time, and after inactivation, the pulp is repeatedly washed with deionized water and vacuum filtered to obtain the pulp. 4) Take 10-30g of the oven-dry pulp after the reaction, adjust the pulp consistency to 3-10% with deionized water, and then grind it in a PFI refiner.
2. The energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp as described in claim 1, characterized in that, The unbleached bamboo pulp board is sulfate-free unbleached bamboo pulp board.
3. The energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp as described in claim 1, characterized in that, The unbleached bamboo pulp board was soaked in deionized water for 3-5 hours.
4. The energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp as described in claim 1, characterized in that, The acetic acid / sodium acetate buffer solution has a pH value of 4.5 to 5.
0.
5. The energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp as described in claim 1, characterized in that, The mass ratio of the cleavable polysaccharide monooxygenase to unbleached bamboo pulp is 1.25 mg / g to 10 mg / g.
6. The energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp as described in claim 1, characterized in that, The cellulase has an enzyme activity of 10,000 to 100,000 U / g and is added at a rate of 10 to 40 U / g.
7. The energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp as described in claim 1, characterized in that, The mass ratio of the cleavage polysaccharide monooxygenase solution to the cellulase solution is 1:1 to 4:
1.
8. The energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp as described in claim 1, characterized in that, The concentration of the ascorbic acid diluent is 1–10 mM.
9. The energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp as described in claim 1, characterized in that, The low-temperature water bath shaker oscillates for 2 to 6 hours at a frequency of 200 to 400 rpm.
10. The energy-saving and enhanced enzymatic pretreatment process for unbleached bamboo pulp as described in claim 1, characterized in that, The PFI refining speed is 8000–16000 r; the refining gap is 0–0.3 mm; and the refining consistency is 3–10%.