CN112301779A

CN112301779A - Method for improving softness of bamboo pulp fibers through laccase-assisted cellulase treatment

Info

Publication number: CN112301779A
Application number: CN202011185713.1A
Authority: CN
Inventors: 刘洪斌; 张润青; 安兴业; 刘利琴; 杨健; 张伟; 李晨曦; 杨伟松
Original assignee: Tianjin University of Science and Technology
Current assignee: Tianjin University of Science and Technology
Priority date: 2020-10-28
Filing date: 2020-10-28
Publication date: 2021-02-02

Abstract

The invention discloses a method for improving the softness of bamboo pulp fibers by laccase-assisted cellulase treatment, and belongs to the field of pulping and papermaking. The method is characterized by mainly comprising the following steps: 1) defibering the fiber raw material until the fiber raw material is completely dispersed; 2) adjusting the pH value to 3-6, and adjusting the concentration of the slurry to 0.05% -6%; 3) heating the slurry obtained in the step (2) to 30-60 ℃, introducing oxygen, adding laccase and a mediator, wherein the dosage of the laccase is 5-70U/g, the dosage of the mediator is 1-2%, and reacting for 1-15 h; 4) cleaning the slurry; 5) adjusting the pH of the obtained slurry to 3-7, adjusting the slurry concentration to 0.5% -2%, heating to 30-60 ℃, adding cellulase with the enzyme dosage of 0.1-3 EGU/g, and reacting for 30-60 min; 6) the softness of the resulting fibers was measured. The invention adopts laccase-cellulase to treat the fiber, utilizes the laccase to degrade lignin, increases the fibrillation degree of the fiber, provides more adsorption sites for the cellulase, improves the treatment efficiency and simultaneously improves the softness of single fiber.

Description

Method for improving softness of bamboo pulp fibers through laccase-assisted cellulase treatment

Technical Field

The invention belongs to the field of pulping and papermaking, and particularly relates to a method for improving the softness of bamboo pulp fibers by laccase-assisted cellulase treatment.

Background

Bamboo pulp is a long-standing paper-making raw material. In recent years, bamboo pulp has also gained more development space due to its own advantages. Compared with wood pulp, bamboo pulp has many advantages, and as for raw materials, bamboo has rich resources, wide sources, high growth speed and short period, so the bamboo pulp fiber has great advantages in price and obviously saves the cost of raw materials. The bamboo pulp fiber is applied to the papermaking industry, has good water absorption performance, long and thin fiber and excellent paper forming performance, and has high cellulose content in the internal components. However, the bamboo pulp fiber has some problems which cannot be ignored in the using process. For example, bamboo pulp fiber is very stiff because the inner cavity is circular and small, the fiber structure is relatively compact and the fiber contains more lignin, so the bamboo pulp fiber has poor flexibility and the poor flexibility hinders the application of the bamboo pulp fiber in many aspects.

The cellulase can remove the outermost layer of the fiber cell wall, reduce the thickness of the cell wall, and degrade the amorphous area of the fiber by cellulase treatment, so that the rigidity of the fiber is reduced, and the softness of the fiber is improved. But the bamboo pulp fiber has high lignin content, few adsorption sites of cellulase and low reaction efficiency. Therefore, the method finds an auxiliary means for degrading the fibers by the cellulase, improves the reaction efficiency of the cellulase, makes up the defects of the cellulase, and has important significance.

Laccases (EC 1.10.3.2) are copper-containing one-electron oxidoreductases that can directly oxidize compounds such as phenols, dyes, aromatic amines, etc. Laccase Mediator System (LMS) refers to a process in which Laccase biocatalysis occurs in the presence of small molecule oxidation mediators and oxygen. The mediator may act as a bridge, first being oxidized by the laccase and then mediating the oxidation of the substrate. Laccases are the second generation of bio-bleaching and are the most promising enzymes in the pulp bleaching industry. Compared with other peroxidases, laccase has the advantages of selectively catalyzing and degrading lignin, not damaging cellulose and hemicellulose, not generating toxic substances and having great value in practical application. In the research, laccase can react with lignin in the bamboo pulp fiber to remove the lignin in the fiber and promote devillicate fibrillation of the fiber, so that more adsorption sites can be provided for the cellulase, the treatment efficiency of the cellulase is improved, and the softness of the bamboo pulp fiber is improved. Compared with the traditional method for improving the softness of the fibers, the method has the advantages of environmental friendliness, mild reaction and the like.

Disclosure of Invention

The invention provides a method capable of obviously improving the softness of fibers, which utilizes the characteristic that laccase reacts with lignin in the fibers and the devillicate fibrillation degree of the fibers is increased, opens the structure of bamboo pulp fibers while improving the softness of the fibers, and provides larger contact area and more adsorption sites for later cellulase treatment.

The invention provides a method for treating fibers by combining laccase with cellulase, which can improve the accessibility of the cellulase to the fibers through laccase pretreatment, thereby improving the efficiency of improving the softness performance of the fibers through cellulase treatment.

The technical method of the invention is summarized as follows:

a method for improving the softness of bamboo pulp comprises the following steps;

step 1: defibering the fiber raw material until the fiber raw material is completely dispersed to obtain fiber slurry;

step 2: adjusting the pH value of the diluted slurry to 3-6, adding water to adjust the mass concentration of the fiber slurry to 0.05% -6%, heating the obtained slurry to 30-60 ℃, maintaining the temperature with a water bath kettle, introducing oxygen, and then adding laccase and a mediator, wherein the dosage of the laccase is 5-70U/g, the dosage of the mediator is 1% -2%, and the action time is 1-15 h; and cleaning the slurry after laccase reaction, and obtaining the single fiber softness of the fiber by using a glass-metal wire method.

And step 3: adjusting the pH value of the slurry obtained in the step (2) to 3-7, adjusting the concentration of the slurry to 0.5% -2%, heating to 30-60 ℃, adding cellulase, and reacting for 30-60 min, wherein the dosage of the cellulase is 0.1-3 EGU/g;

and 4, step 4: and (4) squeezing out moisture from the slurry obtained in the step (3), and measuring the bending degree of the fibers by using a glass-metal wire method to quantitatively analyze the softness of the single fibers.

The invention adopts laccase to treat the pulp, removes part of lignin in the fiber, exposes more cellulose, destroys the surface structure of the fiber, and improves the devillicate brooming degree of the fiber, thereby improving the softness of the fiber, and simultaneously increasing the contact area of the cellulose and the bamboo pulp fiber. The method combining laccase treatment and cellulase treatment is mild in reaction, green, safe and small in environmental pollution; compared with the simple cellulase treatment, the method improves the cellulase treatment efficiency and has important significance for improving the softness of the bamboo pulp fibers.

Drawings

Fig. 1 is an SEM picture of raw high yield bamboo pulp fiber. FIG. 2 is SEM picture of high yield bamboo pulp fiber treated with laccase (40U/g, 10 h). FIG. 3 is SEM picture of high yield bamboo pulp fiber pretreated with laccase (40U/g, 10h) and then treated with cellulase (0.9 EGU/g). Fig. 4 is an SEM picture of cellulase-treated high-yield bamboo pulp fiber without laccase pretreatment.

Detailed Description

The invention will be more fully and more readily understood by reference to the following examples, which are given to illustrate the invention more clearly, and are not intended to limit the invention in any way.

The laccase activity of each embodiment was 120U/g; the cellulase activity was 700 EGU/g. And are not intended to limit the invention.

Example 1

A method for improving the softness of bamboo pulp fibers by laccase treatment comprises the following steps:

step 1: defibering the high-yield bamboo pulp until the fibers are completely dispersed; obtaining fiber slurry;

step 2: taking five parts of fiber pulp with the same absolute dry mass, respectively adjusting the pH value to 6.5, adding water to adjust the mass concentration of the fiber pulp to 2%, respectively putting the five parts of pulp into laccase and a mediator, wherein the dosage of the laccase is respectively 10U/g, 20U/g, 30U/g, 50U/g and 60U/g, the dosage of the mediator is 1.5%, and the water bath is used for maintaining the temperature during the laccase action.

And step 3: and (3) squeezing the material obtained in the step (2) to remove water, and measuring the softness of the single fiber by a method for quantitatively analyzing the softness of the fiber by measuring the bending degree of the fiber by a glass-metal wire method. See tables 1 and 2.

TABLE 1 influence of laccase treatment time on softness of high-yield bamboo pulp fibers at 10U/g laccase dosage

Table 2 influence of laccase dosage on softness of high-yield bamboo pulp fiber at 10h laccase treatment time

Example 2

The method for improving the softness of bamboo pulp fibers by combining the laccase effect with the cellulase treatment comprises the following steps:

step 1: defibering the high-yield bamboo pulp until the fibers are completely dispersed to obtain fiber pulp;

step 2: taking six equal mass fiber pulp, respectively adjusting the pH value to 6.5, adding water to adjust the mass concentration of the fiber pulp to 2%, respectively putting the five pulp into laccase and a mediator, wherein the dosage of the laccase is 0U/g, 10U/g, 20U/g, 30U/g, 40U/g and 50U/g, the dosage of the mediator is 1.5%, and the temperature is kept by using a water bath kettle during the laccase action.

And step 3: and (3) adjusting the pH value of the material obtained in the step (2) to 6.5, adjusting the mass concentration of the fiber slurry to 1%, heating to 50 ℃, adding cellulase till the dosage of the cellulase is respectively 0EGU/g, 0.2EGU/g, 0.6EGU/g, 0.9EGU/g, 2EGU/g and 3EGU/g, and acting for 50 min.

And 4, step 4: and (3) squeezing out moisture from the material obtained in the step (3), and measuring the softness of the single fiber by a method for quantitatively analyzing the softness of the fiber by measuring the bending degree of the fiber by a glass-metal wire method. See tables 3 and 4.

And 5: taking six parts of equal mass of fiber pulp, adjusting the pH value to 6.5, respectively adding water to adjust the mass concentration of the fiber pulp to 1%, adjusting the six parts to be added with different amounts of cellulase, respectively enabling the dosages of the cellulase to be 0EGU/g, 0.2EGU/g, 0.6EGU/g, 0.9EGU/g, 2EGU/g and 3EGU/g, and acting for 50min at 50 ℃;

step 6: and (5) squeezing the water out of the material obtained in the step (5), and measuring the softness of the single fiber by measuring the bending degree of the fiber by a glass-metal wire method to quantitatively analyze the softness of the fiber for comparison. See table 5.

TABLE 3 influence of cellulase dosage on softness of high yield bamboo pulp fiber at laccase dosage of 40U/g

TABLE 4 influence of laccase dosage on softness of high yield bamboo pulp fiber at cellulase dosage of 0.9EGU/g

TABLE 5 influence of cellulase dosage on softness of high yield bamboo pulp fiber

Claims

1. A method for improving the softness of bamboo pulp fibers by laccase-assisted cellulase treatment is characterized by comprising the following steps:

step 1: defibering the fiber raw material until the fiber raw material is completely dispersed and has no fiber agglomeration to obtain slurry fiber;

step 2: adjusting the pH value of the diluted slurry to 3-6, adding water to adjust the mass concentration of the fiber slurry to 0.05% -6%, heating the obtained slurry to 30-60 ℃, maintaining the temperature with a water bath kettle, introducing oxygen, and then adding laccase and a mediator, wherein the dosage of the laccase is 5% -70%, the dosage of the mediator is 1% -2%, and the action time is 1-15 h; and cleaning the slurry after laccase reaction, and obtaining the single fiber softness of the fiber by using a glass-metal wire method.

And step 3: adjusting the pH value of the slurry obtained in the step (2) to 3-7, adjusting the concentration of the slurry to 0.5% -2%, heating to 30-60 ℃, adding cellulase, and reacting for 30-60 min, wherein the dosage of the cellulase is 1-3 EGU/g;

2. The method of claim 1, wherein: the pH value of the laccase is 3-6.

3. The method of claim 1, wherein: the concentration of the laccase acting pulp is 0.05-6%.

4. The method of claim 1, wherein: the laccase action temperature is 30-60 ℃.

5. The method of claim 1, wherein: the laccase is used in an amount of 5-70%.

6. The method of claim 1, wherein: the dosage of the laccase mediator is 1% -2%.

7. The method of claim 1, wherein: the acting time of the laccase is 1-15 h.

8. The method of claim 1, wherein: the pH value of the cellulase treatment slurry is 3-7.

9. The method of claim 1, wherein: the concentration of the cellulase treated pulp is 0.5-2%.

10. The method of claim 1, wherein: the cellulase treatment temperature is 30-60%.

11. The method of claim 1, wherein: the dosage of the cellulase is 1 EGU/g-3 EGU/g.

12. The method of claim 1, wherein: the reaction time of the cellulase is 30 min-60 min.

13. The method of claim 1, wherein: the softness of the fibers was measured using the glass-wire method.