Method for removing black bark shells by using biological enzyme

Abstract

The invention discloses a method for removing black bark shells by biological enzyme, which belongs to the technical field of pulping and papermaking pretreatment, and is characterized by comprising the following steps of: 1) peeling off bark from a trunk or a branch; 2) soaking the peeled bark in deionized water with the temperature of 25 DEG C and the pH value of 6.8 for 24 hours; 3) putting the soaked bark into a compound enzyme solution with the temperature of 40-60 DEG C and the pH value of 4-7, and treating for 2-6 hours, wherein the compound enzyme solution comprises pectinase, cutinase and xylanase; and 4) rubbing the barks at set intervals in the enzyme treatment process so as to ensure that the enzyme liquid treatment is more effective. According to the method, the black shells in the barks are removed by adopting a biological enzyme method, so that the damage to fibers in a chemical degumming process can be reduced; meanwhile, the pulping performance of the fiber can be improved, the treated enzyme liquid can be repeatedly used, the discharge and treatment capacity of wastewater are reduced, and the pollution to the environment is reduced.

Description

Technical Field

[0001] The invention relates to a method for removing black shells from biomass, and more specifically to a method for pretreating bark papermaking raw materials with biological enzymes. Background Art

[0002] As the largest natural plant fiber, wood provides abundant raw materials for the pulp and paper industry. Despite the extensive research on the development of wood, there are still shortcomings in using bark as raw material for pulp and paper. Compared with the core of the tree, bark has more impurities (pectin, pigments, lipids, etc.), which will affect the quality of paper products during the papermaking process. In recent years, the development and utilization of bast fiber has gradually attracted people's attention, but the raw materials used are relatively single and not universal. For example, Chinese patent application CN200510104676.6 (publication number CN1793489A, publication date June 28, 2006) discloses a "mulberry bark pulp production process for producing viscose fiber", which is to use mulberry bark to produce viscose fiber pulp raw material; and another Chinese patent application CN200610044256.8 (publication number CN1858343A, publication date November 8, 2006) discloses a "paper pulp preparation method for producing viscose fiber", which is to use paper bast to produce viscose fiber pulp raw material. In addition, some existing biological methods also take a long time and have relatively low efficiency. For example, the "biological enzyme degumming method for tree bast fiber" disclosed in Chinese patent CN200810025684.5 (publication number CN101215718, publication date 2008.07.09) is to first treat the fiber with an acidic enzyme solution, or with an alkaline enzyme solution to achieve the purpose of tree bast degumming, which basically takes about 10 hours. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for removing black shells from tree bast fibers by biological enzymes, which is fast and simple, can improve fiber quality and reduce 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] A method for removing black shells from bast fibers by using a biological enzyme comprises the following steps:

[0006] 1) Peeling bark off a tree trunk or branch;

[0007] 2) Soak the peeled bark in deionized water at 25°C and pH 6.8 for 24 hours;

[0008] 3) Then, the mixture is placed in a compound enzyme solution at a temperature of 40 to 60°C and a pH of 4 to 7 for treatment for 2 to 6 hours;

[0009] 4) During the treatment, the bark was rubbed every 15 minutes to promote the enzyme reaction.

[0010] In the above-mentioned method of removing the black shell of bast fiber by using a biological enzyme, in step 1), the old bark on the bark surface of three-year-old trees is removed mechanically, and then the phloem layer is separated from the tree trunk manually or by a barking machine; while for branches or shrubs grown within one year, the bark can be directly peeled off manually or by a barking machine for later use.

[0011] In the above-mentioned method for removing the black shell of bast fiber by a biological enzyme, the deionized water used in step 2) is homemade in the laboratory and is used to completely immerse the bark.

[0012] In the above-mentioned method for removing black shell of bast fiber by using biological enzymes, the solid-liquid ratio of bark to enzyme solution in step 3) is 1g:30-50mL, wherein the bark is calculated based on the absolute dry weight, and the optimal condition is 1g:30mL.

[0013] In the above-mentioned method for removing black shell of bast fiber by using biological enzymes, the optimal compound enzyme in step 3) contains 1g / L pectinase, 1g / L cellulase, and 2g / L cutinase, and is treated at pH 6.8 and temperature 50°C for 4 hours.

[0014] In the above-mentioned method for removing black shell of bast fiber by biological enzyme, in step 4), the soaked bark is rubbed manually every 15 minutes in a small-scale reaction.

[0015] The present invention provides a method for removing black shells from bark by the above-mentioned treatment method to obtain a raw material 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 treatment method. Compared with the chemical treatment method, it reduces the damage to the bast fiber during the chemical treatment process and improves the papermaking performance of the fiber. At the same time, the enzyme solution can be reused, reducing pollution to the environment.

[0018] (2) The present invention is applicable to a wide range of raw materials and has strong universality.

[0019] (3) The present invention adopts a one-stage complex enzyme treatment, which takes a short time and is simple to operate, and is suitable for industrial rapid production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The results of degumming of the bark of the tung tree after biological enzyme degumming are shown in Figure 1, where 1 is the control group without enzyme treatment; 2 is the single pectinase treatment; and 3 is the compound enzyme 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) Removing the bark: Take freshly cut twigs of the twig and manually separate the bark from the stem. Try to avoid bringing in the hard wood fiber layer inside the branch.

[0024] (2) Cold water immersion treatment: Soak the bark of the tree branch in neutral deionized water at a temperature of 25° C. and a pH of 6.8 for 24 hours. The neutral deionized water used in this example was homemade in the laboratory.

[0025] (3) Compound enzyme solution treatment: The bark treated with cold water 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 4 hours. The pectinase and cellulase used in this example were purchased from Shanghai MacLean Co., Ltd., and the cutinase used was from Ruichenxing Biotechnology (Guangzhou) Co., Ltd., where the concentrations of pectinase, cutinase, and cellulase were 1 g / L, 2 g / L, and 1 g / L, respectively.

[0026] (4) During the enzyme treatment process, rub the bark every 15 minutes to promote the reaction of the enzyme and accelerate the shedding of the black shell.

[0027] After the reaction is completed, the bark is filtered, high-pressure cleaned, tanned, dried and other processes to form pulp for papermaking. The filtrate after treatment is collected and inactivated at high temperature and then the aldehyde acid content is determined.

[0028] Example 2

[0029] (1) Removing the bark: Take freshly cut twigs of the twig and manually separate the bark from the stem. Try to avoid bringing in the hard wood fiber layer inside the branch.

[0030] (2) Cold water immersion treatment: Soak the bark of the tree branch in neutral deionized water at a temperature of 25° C. and a pH of 6.8 for 24 hours. The neutral deionized water used in this example was homemade in the laboratory.

[0031] (3) Compound enzyme solution treatment: The bark treated with cold water 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 4 hours. The pectinase and cellulase used in this example were purchased from Shanghai MacLean Co., Ltd., and the cutinase used was from Ruichenxing Biotechnology (Guangzhou) Co., Ltd., where the concentrations of pectinase, cutinase, and cellulase were all 1g / L.

[0032] (4) During the enzyme treatment process, rub the bark every 15 minutes to promote the reaction of the enzyme and accelerate the shedding of the black shell.

[0033] After the reaction is completed, the bark is filtered, high-pressure cleaned, tanned, dried and other processes to form pulp for papermaking. The filtrate after treatment is collected and inactivated at high temperature and then the aldehyde acid content is determined.

[0034] Example 3

[0035] (1) Removing the bark: Take freshly cut twigs of the twig and manually separate the bark from the stem. Try to avoid bringing in the hard wood fiber layer inside the branch.

[0036] (2) Cold water immersion treatment: Soak the bark of the tree branch in neutral deionized water at a temperature of 25° C. and a pH of 6.8 for 24 hours. The neutral deionized water used in this example was homemade in the laboratory.

[0037] (3) Compound enzyme solution treatment: the bark treated with cold water 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 4 hours. The pectinase used in this example was purchased from Shanghai MacLean Co., Ltd., where the concentration of pectinase was 1 g / L.

[0038] (4) During the enzyme treatment process, rub the bark every 15 minutes to promote the reaction of the enzyme and accelerate the shedding of the black shell.

[0039] After the reaction is completed, the bark is filtered, high-pressure cleaned, tanned, dried and other processes to form pulp for papermaking. The filtrate after treatment is collected and inactivated at high temperature and then the aldehyde acid content is determined.

[0040] Comparative Example 1

[0041] (1) Removing the bark: Take freshly cut twigs of the twig and manually separate the bark from the stem. Try to avoid bringing in the hard wood fiber layer inside the branch.

[0042] (2) Cold water immersion treatment: Soak the bark of the tree branch in neutral deionized water at a temperature of 25° C. and a pH of 6.8 for 24 hours. The neutral deionized water used in this example was homemade in the laboratory.

[0043] (3) Heating treatment: The bark that had been soaked in cold water was placed in deionized water at 50°C and pH 6.8 at a bath ratio of 1:30 for 4 hours.

[0044] (4) During the enzyme treatment process, rub the bark every 15 minutes to promote the reaction of the enzyme and accelerate the shedding of the black shell.

[0045] After the reaction is completed, the bark is filtered, high-pressure cleaned, tanned, dried and other processes to form pulp for papermaking. The filtrate after treatment is collected and inactivated at high temperature and then the aldehyde acid content is determined.

[0046] The aldehyde content in the solution after enzymatic hydrolysis was determined by ion chromatography (calculated based on 1g of original bark). The results are shown in Table 1:

[0047] Example 1 Example 2 Example 3 Comparative Example 1 Aldehydic acid content (%) 6.36 5.82 3.21 1.68

[0048] Table 1

[0049] As can be seen from Table 1, compared with comparative case 1, the addition of biological enzymes allows more aldehyde acid to be released from the bark. Under the optimal conditions, the amount of aldehyde acid released reaches 6.36%, which indicates that the treatment with the compound enzymes has greatly reduced the pectin in the bark, and pectin is conducive to the separation of black shell and phloem fiber. It can be seen that the use of compound enzyme treatment can well achieve the removal of black shell from bark, providing a basis for the use of bast fibers such as bark in the field of pulping and papermaking.

[0050] 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. A method for removing black bark by biological enzymes, characterized in that The steps include: 1) Peeling bark off a tree trunk or branch; 2) Soak the peeled bark in deionized water at 25°C and pH 6.8 for 24 hours; 3) Then, the soaked bark is placed in a compound enzyme solution at a temperature of 40 to 60°C and a pH of 4 to 7 for 2 to 6 hours; 4) During the treatment, the bark was rubbed every 15 minutes to promote the enzyme reaction.

2. The method for removing black bark by biological 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 removing black bark by biological enzyme according to claim 1, characterized in that: In step (3), the solid-liquid ratio of bark to enzyme solution is 1 g:30-50 mL, wherein the bark is calculated based on the absolute dry weight.

4. The method for removing black bark by using a biological enzyme according to claim 1, characterized in that: In step (3), the reaction temperature of the bark and the complex enzyme is 40-60°C, wherein the optimum temperature is 50°C.

5. The method for removing black bark by biological enzyme according to claim 1, characterized in that: In step (3), the pH of the reaction between the bark and the complex enzyme is 4-7, wherein the optimal pH is 6.

8.

6. The method for removing black bark by biological enzyme according to claim 1, characterized in that: In step (3), the enzyme solution comprises cutinase, pectinase and xylanase, and the concentrations of the cutinase, pectinase and xylanase are 1-2 g / L, 1-2 g / L and 1 g / L respectively.

7. The method for removing black bark by biological enzyme according to claim 1, characterized in that: In step (3), the reaction time of the complex enzyme and the bark is 2 to 6 hours, and the optimal reaction time is 4 hours.

8. The method for removing black bark by biological enzyme according to claim 1, characterized in that: In step (4), the small-scale reaction of the compound enzyme with the bark is carried out by kneading, and large-scale preparation can be achieved by using a stirrer.

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