Pulping method based on enzyme treatment of phyllostachys edulis bamboo shoot shells
By treating bamboo shoot shells with pectinase and cellulase, the pulping effect of cellulase was improved, the aspect ratio of cellulase and the tear resistance index of paper were increased, the problem of pectin affecting the pulping process was solved, and the efficient utilization of bamboo shoot shells was achieved.
Patent Information
- Application Number
- CN202511248495.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-03
- Publication Date
- 2025-10-17
AI Technical Summary
In the prior art, pectin in bamboo shoot shells affects the pulping process, resulting in unclear cellulase treatment effects and affecting paper performance.
The bamboo shoot shells were pretreated with pectinase and/or cellulase, and pulping was carried out by combining mechanical and chemical methods, including pretreatment, soaking and beating steps. The enzyme addition amount and conditions were optimized to improve the fiber properties.
Through enzyme treatment, cellulase treatment has the best effect, the fiber length increases, the width decreases, the aspect ratio increases, and the fiber kink index decreases after pectinase treatment. The paper performance is significantly improved, and the tear resistance index increases by 36.5%.
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Figure CN120797450A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of pulp preparation, and particularly relates to a method for preparing pulp based on enzyme treatment of bamboo shoot shell. BACKGROUND
[0002] The outer protective structure produced during the growth of bamboo shoots is called bamboo shoot shell, which can protect the bamboo joints. The shoot shell will gradually fall off and eventually scatter in the bamboo forest during the natural growth of the bamboo. The bamboo shoot shell is usually not utilized. China has abundant bamboo resources, with bamboo forest area exceeding 6 million hm 2 , annual bamboo shoot production of about 3.2 million tons, and shoot product production of about 800,000 tons. About 60% of the bamboo shoots are used to process into primary processed products such as water bamboo shoots and dried bamboo shoots every year. About 70% of the bamboo shoot heads or shells and other waste materials are regarded as waste during the processing, which are often used as feed, fuel or directly discarded, causing great impact on the environment and health. Utilizing the bamboo shoot shell waste and exploring suitable processing methods for the bamboo shoot shell to realize efficient and green conversion of waste can effectively improve the added value of bamboo raw materials and promote the high-quality development of circular economy.
[0003] Bamboo shoot shell is a widely available, renewable and productive resource, which is attracting more and more attention. The processing methods of bamboo shoot shell mainly include physical method, chemical method and biological method. The effects of the bamboo shoot shell processed by different methods are different, and the extracted substances and application directions are also different. At present, the research on bamboo shoot shell fibers mainly focuses on food, wastewater treatment and medicine, and the application in the field of pulp is still in the primary stage. The demand for raw materials in the papermaking industry is extremely high, and the current pulp raw materials are mainly wood pulp and waste paper. In recent years, bamboo has shown a significant increase in bamboo pulp production due to its special fiber properties, and the production capacity has reached more than 2 million tons per year. The bamboo shoot shell is also rich in natural cellulose and has good mechanical properties. Utilizing the bamboo shoot shell fibers through environmentally friendly pulping technology can not only effectively fill the gap of domestic pulp raw materials, but also realize large-scale utilization of bamboo shoot shell, turning waste into treasure, which is of great significance to guarantee resource security and promote ecological civilization construction.
[0004] The method for preparing pulp by pretreating raw materials with microorganisms or enzymes produced by the microorganisms and then combining mechanical, chemical and organic solvent methods is a biological method for preparing pulp, which can effectively alleviate the environmental problems of traditional pulp preparation and papermaking and is an important driving force for the green development of the paper industry. Some studies have shown that enzyme treatment can improve fiber performance, reduce the amount of chemicals used, and reduce energy consumption and wastewater pollution. Among them, cellulase is often used to promote fibrillation and improve paper physical properties in the pulp and papermaking process. However, the effect of enzyme pretreatment on the pulping performance of bamboo shoot shell is not clear. Bamboo shoot shell is mainly composed of cellulose, hemicellulose, lignin and pectin, of which pectin accounts for 7.14%, which can affect the pulping process. Therefore, it is of great significance to study a method for preparing bamboo shoot shell based on enzyme treatment of bamboo shoot shell. SUMMARY
[0005] The present application aims to provide a method for preparing bamboo shoot shell based on enzyme treatment of bamboo shoot shell, to solve the problem of pectin in bamboo shoot shell affecting the pulping process in the prior art.
[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:
[0007] The present application provides a method for preparing bamboo shoot shell based on enzyme treatment of bamboo shoot shell, comprising the following steps:
[0008] (1) Disperse bamboo shoot shell in water, add enzymes for pretreatment, and obtain enzyme-pretreated bamboo shoot shell;
[0009] The enzyme is pectinase and / or cellulase;
[0010] (2) Soak the pretreated bamboo shoot shell in water, take out the pre-soaked fiber slurry for free dispersion and pressure beating, and obtain bamboo shoot shell fiber slurry.
[0011] As a preferred, the ratio of bamboo shoot shell to water is 1g:6-12mL.
[0012] As a preferred, the addition amount of the enzyme is 40-80IU / g.
[0013] As a preferred, the initial pH value during the pretreatment is 8-10; the pretreatment temperature is 50-60℃, and the pretreatment time is 40-80min.
[0014] As a preferred, in step (2), the soaking time is 3-5h.
[0015] As a preferred, in step (2), the pre-soaked fiber slurry is subjected to free dispersion in a tank beater.
[0016] As a preferred, in step (2), the free dispersion time is 5-15min.
[0017] As preferred, in the step (2), the Canadian Standard Freeness of the bamboo shoot shell fiber pulp is >600 mL or the Schopper Riegler beating degree is <20°SR.
[0018] Advantages of the present application:
[0019] In the present application, the bamboo shoot shell is pretreated by cellulase, pectinase or a mixture of the two enzymes. After enzyme pretreatment, the fiber length of the bamboo shoot shell increases slightly, the width decreases slightly, the aspect ratio increases, and the performance of short fiber pulping and papermaking is improved compared with the untreated pulp. The treatment effect of cellulase is the best. After pectinase treatment, the kink index of the fiber decreases, and the fiber is more flat, which plays a positive role in improving the performance of the paper. In the microscopic morphology, it can also be found that the fiber surface changes to different degrees after enzyme treatment, and the fiber disperses.
[0020] The burst index of the paper after enzyme treatment increases from 0.63 kPa·m 2 / g to 0.8 kPa·m 2 / g or more. The treatment effect of cellulase is the best. This is related to the length and separation degree of the fiber after enzyme treatment. A certain enzyme treatment has a positive effect on the preparation of bamboo shoot shell fibers, and the bamboo shoot shell waste has potential papermaking capacity. BRIEF DESCRIPTION OF DRAWINGS
[0021] Figure 1 The figure is a microscope image of untreated bamboo shoot shell fiber and bamboo shoot shell fiber treated by cellulase, pectinase and mixed enzyme;
[0022] Figure 2 The figure is an XRD image of untreated bamboo shoot shell fiber and bamboo shoot shell fiber treated by cellulase, pectinase and mixed enzyme;
[0023] Figure 3 The figure is an FTIR spectrum of untreated bamboo shoot shell fiber and bamboo shoot shell fiber treated by cellulase, pectinase and mixed enzyme;
[0024] Figure 4 The figure is a comparison of the burst index of paper made from untreated bamboo shoot shell fiber and bamboo shoot shell fiber treated by cellulase, pectinase and mixed enzyme. DETAILED DESCRIPTION
[0025] The present application provides a pulping method based on enzyme treatment of bamboo shoot shell, comprising the following steps:
[0026] (1) dispersing the bamboo shoot shell in water, adding enzyme for pretreatment to obtain enzyme pretreated bamboo shoot shell;
[0027] The enzyme is pectinase and / or cellulase;
[0028] (2) soaking the pretreated bamboo shoot shell in water, taking out the fiber slurry after pre-soaking to perform free dispersion and pressure beating, and obtaining the bamboo shoot shell fiber slurry.
[0029] In the present application, the bamboo shoot shell is preferably washed with clean water, dried for the first time, broken, and dried for the second time.
[0030] In the present application, the specific process of the first drying is as follows: drying at 60℃ for 4h, then drying at 80℃ for 4h, and finally drying at 103℃ for 16h.
[0031] In the present application, the temperature of the second drying is 105℃ until constant weight.
[0032] In the present application, the ratio of the bamboo shoot shell to water is 1g:6-12mL, preferably 1g:8-11mL, and further preferably 1g:9-10mL.
[0033] In the present application, the enzyme is added in an amount of 40-80IU / g, preferably 50-70IU / g, and further preferably 60IU / g.
[0034] In the present application, during the pretreatment, the initial pH value is 8-10, preferably 9; the temperature is 50-60℃, preferably 52-58℃, and further preferably 55℃; and the time is 40-80min, preferably 50-70min, and further preferably 60min.
[0035] In the present application, in the step (2), the mass-volume ratio of the pretreated bamboo shoot shell to water is 200-400g:5L, preferably 220-380g:5L, and further preferably 260-360g:5L.
[0036] In the present application, in the step (2), the soaking time is 3-5h, preferably 3.5-4.5h, and further preferably 4h.
[0037] In the present application, in the step (2), the fiber slurry after pre-soaking is subjected to free dispersion in a tank beater.
[0038] In the present application, water is added to the tank beater, and the mass-volume ratio of the pretreated bamboo shoot shell to water in the tank beater is 200-400g:18L, preferably 220-380g:18L, and further preferably 260-360g:18L.
[0039] In the present application, in the step (2), the free dispersion time is 5-15min, preferably 8-12min, and further preferably 10min.
[0040] In the present application, in the step (2), the Canadian Standard Freeness of the bamboo shoot shell fiber slurry is >600 mL or the Schopper Riegler beating degree is <20°SR.
[0041] The technical solutions provided by the present application are described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.
[0042] The bamboo shoot shell used in the embodiments of the present application is taken from a bamboo sample plot of a bamboo planting resource gene library of Jiangxi Forestry Academy, and the shoot shell is washed clean with clean water and then dried: dried at 60℃ for 4h, then dried at 80℃ for 4h, and finally dried at 103℃ for 16h. After drying, the shoot shell is crushed into particles in a crusher, and the shoot shell particles are dried to constant weight in an oven at 105℃ and then stored in a desiccator for standby use.
[0043] Pectinase, M6346, biotechnology grade, 30000 U / g, purchased from Macklin Reagent;
[0044] Cellulase, C6339, biotechnology grade, 50 U / mg, purchased from Macklin Reagent.
[0045] Example 1
[0046] The absolutely dry bamboo shoot shell is dispersed in distilled water, the solid-liquid ratio is 1g:9mL, cellulase is added (the addition amount is 60IU / g of absolutely dry bamboo shoot shell), the pH value is adjusted to 9.0, and the pretreatment is carried out in a water bath at 55℃, the constant temperature water bath is 60min, after the pretreatment is completed, the filtration, distilled water washing and drying in an oven at 105℃ are carried out for standby use, and the enzyme pretreated bamboo shoot shell is obtained.
[0047] The 360g absolutely dry enzyme pretreated bamboo shoot shell is soaked in 5L deionized water for 4h, the pre-soaked fiber slurry is slowly poured into the beating tank of the tank beater with 18L water in 5min, and the free dispersion is carried out for 10min without applying pressure, and then the pressure (tantalum) beating is carried out, the beating degree is detected at 5min, 15min, 30min, 60min and 90min respectively, the Schopper Riegler beating degree is <20°SR, and the beating is stopped, and the bamboo shoot shell fiber slurry is prepared.
[0048] Example 2
[0049] The difference from example 1 is that pectinase is added, and other conditions are the same.
[0050] Example 3
[0051] The difference from Example 1 is that a mixed enzyme of pectinase and cellulase is added, wherein the added amount of pectinase is 30 IU / g of absolute dry bamboo shoot shell, the added amount of cellulase is 30 IU / g of absolute dry bamboo shoot shell, and other conditions are the same.
[0052] Comparative Example 1
[0053] Take 360 g of absolute dry bamboo shoot shell without enzyme pretreatment and soak in 5 L of deionized water for 4 h. Take out the pre-soaked fiber slurry and slowly pour it into the beating tank of a tank beater with 18 L of water within 5 min. Disperse freely for 10 min without applying pressure, and then add pressure (tantalum) beating. Sample and test the beating degree at 5 min, 15 min, 30 min, 60 min, and 90 min, respectively. Stop beating when the Shore beating degree is < 20°SR, and prepare the untreated bamboo shoot shell fiber slurry.
[0054] The two-dimensional image testing technology is used to measure the fiber length and width and kink index of the pulp before and after enzyme treatment on the L&W fiber analyzer (LORENTZEN & WETTRE GMBH, Sweden). The shell fiber is dispersed by alcohol washing and placed under an optical microscope (Olympus, BK6000) to observe its micro-morphology, and the results are shown in Figure 1
[0055] Table 1 Mass test results of enzyme-treated shell pulp fibers of Examples 1-3 and untreated shell pulp fibers of Comparative Example 1
[0056]
[0057]
[0058] Table 2 Fiber quality of other pulp raw materials
[0059] type Length / mm Width / μm Aspect ratio Kink Index Sweet Bamboo 2.18 2.18 18.15 120.11 Eucalyptus 0.725 0.725 17.6 41.19 wheat straw 0.855 0.855 35.2 24.29 corn stalks 0.811 0.811 23.5 34.51
[0060] Generally speaking, the length of the fiber is one of the important indicators for evaluating the papermaking performance of the pulp. The longer the fiber, the better the strength, and the higher the length-width ratio, the more fine and dense the fiber distribution. As can be seen from Table 1, the length of the untreated shell pulp fiber is 0.543 mm, the width is 40.1 μm, and the length-width ratio is 13.54. Compared with other common pulp raw materials in Table 2, the fiber length is shorter, and the length-width ratio is low due to the excessive width, and the dispersion between the fibers is poor.
[0061] It can be seen from Table 2 that the fiber morphology of the pulp after enzyme treatment changes slightly, the fiber length increases slightly, the width decreases slightly, and the length-width ratio increases, so the cellulase treatment is better. The beating process will cause the fiber to twist, and the kink index is mainly used to evaluate the degree of twisting and deformation of single fiber. In general, the higher the average kink index, the worse the paper performance. The kink index of the fiber after pectinase treatment decreases, and the fiber is more flat, close to eucalyptus wood.
[0062] It can be seen from Figure 1 that the bamboo shoot shell fiber is a bundle fiber formed by the connection and combination of multiple single fibers, and there are unevenness, grooves, cracks and other characteristics on the surface. Before enzyme treatment, the single fibers are tightly combined, mostly mechanically twisted and broken. After enzyme treatment, some fibers are dispersed, and cellulase treatment causes the fibers to tear and damage. After pectinase treatment, the fiber surface is smoother, and after mixed enzyme treatment, the fiber surface also appears eroded.
[0063] X-ray diffraction analysis of bamboo shoot shell pulp before and after enzyme treatment was determined on a copper target X-ray diffractometer (XRD, Japan Rigaku SmartLab SE) by powder method, the scanning angle was 5°-90°, and the scanning speed was 2° / min, and the results are shown in Figure 2
[0064] It can be seen from Figure 2 that the untreated bamboo shoot shell pulp fiber has a diffraction characteristic peak of SiO2 near 20.8°, which indicates that there are many impurities in the bamboo shoot shell raw material, which will have adverse effects on pulping process, equipment, product quality and black liquor recovery, etc. Consistent with the higher ash content in the previous experiment, the bamboo shoot shell raw material still needs to be pretreated. The diffraction peaks of 101 plane and 002 plane of cellulose near 16.7° and 22.8° represent the crystalline and non-crystalline regions of cellulose. After cellulase treatment, the non-crystalline region and crystalline region of the fiber are reduced, which indicates that cellulase treatment has hydrolyzed the non-crystalline part and the imperfect crystalline part of cellulose, resulting in a decrease in the crystallinity of the product. After pectinase treatment, the crystalline region of the fiber changes slightly, and the non-crystalline region decreases slightly, because pectinase degrades pectin (polygalacturonic acid), hemicellulose, lignin and other amorphous structure non-cellulose components, reducing the proportion of amorphous region. The increase of the crystallinity of the pulp will increase the physical strength of the pulp to a certain extent. After mixed enzyme treatment, the non-crystalline region of the fiber increases, which indicates that under the joint action of cellulase and pectinase, the hydrolysis of hemicellulose and sugar is more sufficient, and the crystalline region is converted to non-crystalline region.
[0065] Fourier transform infrared spectrometer (FTIR, USA Thermo Fisher Scientific Nicolet iS20) analysis, scanning wavelength range 400-4000 cm-1 .
[0066] In order to better compare the changes of bamboo shoot shell before and after enzyme treatment, the FTIR spectra of bamboo shoot shell fibers before and after enzyme treatment were normalized, and the untreated was offset by 2 times on the Y axis, as shown in Figure 2 The absorption peak at about 3420 cm -1 is caused by the vibration stretching of -OH in the bamboo shoot shell, and the absorption peak at about 2924 cm -1 is caused by the vibration stretching of -CH of cellulose. It can be found from the local magnification that the absorption peak at 1040 cm -1 formed by the vibration stretching of hemicellulose xylan and glycosidic bond is shifted to high wave number after enzyme treatment, indicating that the hemicellulose is removed after treatment. The same shift also occurs in the C-O of hemicellulose xylan at 1249 cm -1 , and the CH2 functional group of cellulose at 1317 cm -1 . The absorption peak at 1433 cm -1 is caused by the C-OH bending vibration of the cellulose CH2-OH group, and after enzyme treatment, it is shifted to low wave number 1427 cm -1 , indicating that enzyme treatment hydrolyzes the cellulose, making the CH2 symmetric bending vibration peak of the xylan xylose ring at 1454 cm -1 more obvious. The absorption peak at 1625 cm -1 corresponds to the characteristic peak of the aromatic ring of lignin, and after enzyme treatment, the absorption peak at 1625 cm -1 is shifted to low wave number, which may be related to the stronger adsorption of lignin to the enzyme, and the wave peak is more obvious after mixed enzyme treatment.
[0067] The four uniformly dispersed bamboo shoot shell fiber slurries of Examples 1-3 and Comparative Example 1 were papered using an RK-3A paper former (PTI, Austria), and the basis weight was controlled at 125 g / m 2 .
[0068] According to the requirements of GB / T 454-2020 "Determination of Paper Bursting Strength", the test results are shown in Figure 4 .
[0069] Fiber bonding is the main reason affecting the bursting strength of paper, and the increase of fiber length can increase the contact space between fibers. The better the combination between fibers, the greater the bursting index. The bursting index of paper before and after enzyme treatment is shown in Figure 4 , and the bursting index of paper after enzyme treatment is obviously improved, among which the effect of cellulase treatment is the best, which is increased by about 36.5%, which is consistent with the result that the fiber length is the longest after cellulase treatment.
[0070] After enzyme treatment, the fibers were hydrolyzed to different degrees, the crystalline and non-crystalline regions of the fibers were reduced after cellulase treatment, indicating that cellulase had an effect on the crystalline and non-crystalline regions of the fibers, and the cellulose characteristic peaks in the infrared spectrum changed more obviously at 1433 cm -1 , 1454 cm -1 , and 1040 cm -1 ; the non-crystalline region slightly decreased after pectinase treatment, indicating that pectinase mainly acted on the non-crystalline region; the non-crystalline region of the fibers increased in intensity after mixed enzyme treatment, indicating that under the superimposed effect, the crystalline region was hydrolyzed more, and the group changes in the infrared spectrum were the most obvious; however, there were many impurities in the bamboo shoot shell before enzyme treatment, which would have a great influence on pulping and component analysis, so alkali, sulfuration and other treatments need to be combined before the preparation of the subsequent bamboo shoot shell pulp to obtain pulp with better performance.
[0071] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, several improvements and refinements can be made, and these improvements and refinements should also be considered within the scope of protection of the present application.
Claims
1. A pulping method based on enzyme treatment of bamboo shoot shells, characterized in that: The steps include: (1) dispersing bamboo shoot shells in water, adding enzyme for pretreatment, and obtaining enzyme-pretreated bamboo shoot shells; The enzyme is pectinase and / or cellulase; (2) The pretreated bamboo shoot shells are soaked in water, and the pre-soaked fiber slurry is taken out for free dispersion and pressurized beating to obtain bamboo shoot shell fiber slurry.
2. The pulping method based on enzyme treatment of bamboo shoot shells according to claim 1, characterized in that The material-liquid ratio of the bamboo shoot shell and water is 1g:6-12mL.
3. The pulping method based on enzyme treatment of bamboo shoot shells according to claim 1 or 2, characterized in that, The added amount of the enzyme is 40 to 80 IU / g.
4. The pulping method based on enzyme treatment of bamboo shoot shells according to claim 3, characterized in that During the pretreatment, the initial pH value is 8-10; the pretreatment temperature is 50-60° C., and the pretreatment time is 40-80 minutes.
5. The pulping method based on enzyme treatment of bamboo shoot shells according to claim 1, 2 or 4, characterized in that, In the step (2), the soaking time is 3 to 5 hours.
6. The pulping method based on enzyme treatment of bamboo shoot shells according to claim 5, characterized in that In the step (2), the pre-impregnated fiber slurry is freely dispersed in a trough-type beater.
7. The pulping method based on enzyme treatment of bamboo shoot shells according to claim 4 or 6, characterized in that In the step (2), the free dispersion time is 5 to 15 minutes.
8. The pulping method based on enzyme treatment of bamboo shoot shells according to claim 7, characterized in that In the step (2), the Canadian standard freeness of the bamboo shoot shell fiber pulp is greater than 600 mL or the Shore beating degree is less than 20°SR.