Modified bio-enzyme preparation and application of modified bio-enzyme preparation in synergistic microorganism pretreatment production of sticky paper pulp

Abstract

The invention discloses a modified bio-enzyme preparation and application thereof in synergistic microbial pretreatment production of sticky paper pulp, and belongs to the technical field of paper pulp manufacturing. The modified biological enzyme preparation is prepared from cellulase, hemicellulase, lignin degrading enzyme, hydrophobic amino acid and a surfactant. The modified bio-enzyme preparation cooperates with microorganisms to pre-treat wood pulp fibers, and pulping treatment of a double-screw pulping machine is combined, so that the pulping efficiency can be greatly improved, the pulping energy consumption can be reduced, the prepared sticky paper pulp is high in strength and good in performance, and the tensile index and burst index of paper are improved. The method has the characteristics of energy conservation, environmental protection and high efficiency, responds to a new concept of high-valued sustainable development of biomass, and has high popularization value.

Description

Technical Field

[0001] The invention relates to the technical field of pulp manufacturing, in particular to a modified bioenzyme preparation and application thereof in producing viscous pulp through coordinated microbial pretreatment. Background Art

[0002] With the rapid development of the papermaking industry, traditional chemical pulping methods are facing problems such as environmental pollution and high energy consumption. In particular, the production of high-strength viscous pulp usually requires high-energy mechanical pulping and chemical treatment, which not only increases production costs but also puts great pressure on the environment. In recent years, the application of biotechnology in the field of pulping and papermaking has gradually attracted attention, especially bio-enzyme pretreatment technology, which has become one of the effective ways to reduce energy consumption and improve pulp quality due to its environmental protection and high efficiency. Bio-enzymes can selectively degrade lignin and hemicellulose, improve the accessibility of fibers, thereby reducing pulping energy consumption and improving the strength properties of pulp. However, the effect of single bio-enzyme treatment is limited, the treatment time is long, and the enzyme catalytic efficiency is subject to the influence of reaction conditions and substrate structure, which is difficult to meet the needs of industrial production.

[0003] In order to further improve the catalytic efficiency of bio-enzymes, researchers began to explore the synergistic effect of microorganisms and bio-enzymes. Microbial agents can produce a variety of enzymes through metabolism, which can act in synergistic manner with bio-enzymes on wood fibers and enhance the pretreatment effect. In addition, the introduction of surfactants can improve the contact efficiency between enzymes and fibers, further enhancing the enzymatic hydrolysis effect. However, there are currently few studies on the synergistic pretreatment of wood pulp by microorganisms, bio-enzymes and surfactants, especially their application in the production of high-strength viscous pulp has not been fully developed. Therefore, the development of an efficient modified bio-enzyme coupled microbial pretreatment technology can not only significantly improve the catalytic efficiency of bio-enzymes and shorten the processing time, but also reduce pulping energy consumption, improve pulp performance and paper strength, and has important industrial application value and environmental significance. Summary of the Invention

[0004] The purpose of the present invention is to provide a modified bio-enzyme preparation and its application in the production of viscous pulp by synergistic microbial pretreatment, so as to solve the problems existing in the above-mentioned prior art. The present invention utilizes cellulase, hemicellulase, lignin-degrading enzyme, hydrophobic amino acid and surfactant to prepare a modified bio-enzyme preparation. The modified bio-enzyme preparation cooperates with microorganisms to pretreat wood pulp fibers, and combined with the refining treatment of a twin-screw refiner, it can greatly improve the refining efficiency, reduce the refining energy consumption, and make the prepared viscous pulp have high strength and good performance, and improve the tensile index and bursting resistance index of paper. It has the characteristics of energy saving, environmental protection and high efficiency, responds to the new concept of high-value sustainable development of biomass, and has high promotion value.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a method for preparing a modified bioenzyme preparation for producing viscous pulp, comprising the following steps:

[0007] (1) mixing a cellulase solution, a hemicellulase solution, and a lignin degradation enzyme solution to obtain a composite biological enzyme solution;

[0008] (2) mixing the composite bio-enzyme solution with activated hydrophobic amino acids, reacting them to obtain a surface-hydrophobized bio-enzyme solution;

[0009] (3) mixing the surface-hydrophobized bioenzyme solution with a surfactant and reacting them to obtain the modified bioenzyme preparation.

[0010] Optionally, in step (1), the enzyme activities of the cellulase solution, hemicellulase solution and lignin degrading enzyme solution are all 90,000-110,000 U / mL; and the volume ratio of the cellulase solution, hemicellulase solution and lignin degrading enzyme solution when mixed is (15-25):(45-55):(25-35).

[0011] Optionally, the cellulase solution includes endoglucanase solution; the hemicellulase solution includes xylanase solution; and the lignin-degrading enzyme solution includes laccase solution.

[0012] Optionally, in step (2), the activated hydrophobic amino acid is obtained by activating the hydrophobic amino acid using EDC and NHS;

[0013] During the mixing, the activated hydrophobic amino acid is prepared into a solution having the same concentration as the composite bio-enzyme solution, and the two are mixed at a mass ratio of 1:400-600;

[0014] The reaction temperature is 4° C. and the reaction time is 4-6 h.

[0015] Optionally, the hydrophobic amino acid includes leucine.

[0016] Optionally, in step (3), the final concentration of the mixed surfactant is 2 wt%-4 wt%, the reaction temperature is 20-25° C., and the reaction time is 1-2 h.

[0017] Optionally, the surfactant includes fatty alcohol polyoxyethylene ether.

[0018] The present invention also provides a modified bioenzyme preparation prepared by the above preparation method.

[0019] The present invention also provides application of the modified bioenzyme preparation in producing viscous pulp.

[0020] The present invention also provides a method for producing viscous pulp by using a modified bio-enzyme preparation in conjunction with microbial pretreatment, comprising the following steps:

[0021] S1. preparing a wood pulp culture medium, diluting it with water, and inoculating it with a white rot fungus agent for pretreatment to obtain wood pulp pretreated with the microbial agent;

[0022] S2, adjusting the concentration of the wood pulp pretreated with the microbial agent, adding the modified bio-enzyme preparation, and performing preliminary refining and enzymatic hydrolysis;

[0023] S3, finely refining the enzymatically hydrolyzed wood pulp to obtain the viscous pulp.

[0024] Furthermore, the composition of the wood pulp culture medium is: 75wt%-85wt% of absolute dry wood pulp, 0.4wt%-0.6wt% of glucose, 0.4wt%-0.6wt% of peptone, 0.1wt%-0.3wt% of phosphate buffer, and the balance is water; the pH value is 5.0-6.0;

[0025] The concentration of the diluted wood pulp culture medium is 30wt%-60wt%;

[0026] The inoculation amount of the white rot fungus agent is 3wt%-5wt% of the wood pulp culture medium; the temperature of the pretreatment is 20-25°C, and the time is 6-10 days.

[0027] Optionally, the wood pulp includes but is not limited to bleached softwood pulp, bleached hardwood pulp or mixed wood pulp.

[0028] Optionally, the white rot fungus agent has a bacterial concentration of 80-120 million per kg.

[0029] Optionally, the pulp concentration of the wood pulp pretreated with the microbial agent after adjustment is 20wt%-25wt%; the addition amount of the modified bioenzyme preparation is 0.01wt%-0.02wt% of the absolute dry pulp of the wood pulp pretreated with the microbial agent;

[0030] The pressure during the initial refining is 0.5 MPa, the number of extrusion and thread rolling is 5-10 times, and the time is 15-30 minutes;

[0031] The enzymatic hydrolysis temperature is 40-60° C., the pH value is 4-9, and the time is 60 min-180 min.

[0032] Furthermore, the method of fine refining is: adjusting the enzymatically hydrolyzed wood pulp to a pulp concentration of 4wt%-8wt%, using two-stage disc refining, with the first stage refining gap set to 0.9-1.1mm, and the second stage refining gap set to 0.04-0.06mm; stopping refining when the beating degree is 50±2°SR.

[0033] The present invention discloses the following technical effects:

[0034] The present invention combines cellulase, hemicellulase, and lignin-degrading enzyme into a composite bioenzyme. This is surface-modified with an activated hydrophobic amino acid (leucine) to render the bioenzyme molecules hydrophobic. A surfactant is then added to bond the enzymes through hydrophobic interactions, resulting in a highly efficient modified bioenzyme preparation. This modified bioenzyme preparation boasts high catalytic efficiency and requires minimal dosage, significantly improving the enzymatic hydrolysis and pretreatment efficiency of wood pulp fibers and laying the foundation for improved wood pulp refining performance.

[0035] The present invention further utilizes microorganisms (white rot fungi) to synergize modified bio-enzyme preparations to pretreat wood pulp fibers. Compared with the traditional bio-enzyme pretreatment refining method, this method achieves high-concentration mixing and refining by coupling microorganisms with modified bio-enzymes to assist twin-screw refining. This synergistic effect effectively decomposes the interior of the fibers, promotes the water absorption, stretching and fibrillation of the fibers during the refining process, reduces the amount of enzymes used, reduces production costs, reduces refining energy consumption by 30%, increases paper strength by 20%, and greatly improves production efficiency. It overcomes the defects of large single bio-enzyme dosage, low pretreatment efficiency, and low paper strength, and solves the problem of high refining energy consumption. The method of the present invention is energy-saving, environmentally friendly, and efficient, responds to the new concept of high-value sustainable development of biomass, and has high promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 This is the process flow chart of Example 2. DETAILED DESCRIPTION

[0038] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0039] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0040] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0041] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0042] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0043] The technical solution of the present invention is implemented based on the following principles:

[0044] 1. Modification improves enzyme stability and activity: The combination of surfactants can stabilize the specific conformation of the enzyme and prevent the enzyme from denaturing at high temperature, extreme pH or in organic solvents. The hydrophobic group of the surfactant binds to the hydrophobic group of the enzyme, and the hydrophilic group binds to cellulose, enhancing the interaction between the enzyme and the substrate, thereby improving the catalytic efficiency. The introduction of surfactant binding sites can prevent non-specific aggregation between enzyme molecules and improve the solubility and dispersibility of the enzyme. The use of modified enzymes can not only quickly penetrate into the internal structure of wood pulp fibers with the help of the good penetration and dispersion effect of surfactants, but also effectively remove some of the re-deposited xylan, increase the pores of the pulp matrix, release the trapped soluble lignin, make it easier for the enzyme to contact the fiber substrate, and further improve the catalytic efficiency of the enzyme.

[0045] 2. Synergistic Effect of Modified Bio-Enzymes Coupled with Microorganisms: Oxidase secreted by white-rot fungi degrades lignin and hemicellulose, first destroying the fiber structure of the wood pulp, increasing water permeability, promoting fiber swelling, and reducing fiber cohesion. The synergistic effect of modified bio-enzymes coupled with white-rot fungi not only improves the enzymatic hydrolysis efficiency of the pulp and reduces the amount of bio-enzyme preparations used, but also allows the bio-enzymes to quickly penetrate the pulp fibers and decompose them, promoting fiber fibrillation and brooming during the refining process, creating more bonding points between fibers, improving paper strength and forming uniformity, reducing the mechanical force of beating, making beating easier, and saving beating energy.

[0046] 3. Twin-screw refining achieves high efficiency and energy saving: through two intermeshing screws to shear, squeeze and rub the fiber raw materials, the pulp fibers are initially fibrillated and evenly dispersed, and the fibers and biological enzymes are fully mixed, and the physical properties of the pulp (such as strength, smoothness, etc.) are improved.

[0047] Compared to traditional enzyme pretreatment refining methods, this method achieves high-consistency mixing and refining through the coupling of microorganisms with modified enzymes to assist twin-screw refining. This synergistic effect effectively decomposes the fiber interior, promoting fiber water absorption, stretching, and fibrillation during the refining process. This reduces enzyme usage, lowers production costs, reduces refining energy consumption by 30%, and increases paper strength by 20%, significantly improving production efficiency and promising broad application prospects.

[0048] The experimental methods in the following examples, unless otherwise specified, are all conventional methods. The instruments and equipment used in the following examples, unless otherwise specified, are all conventional laboratory instruments and equipment; the experimental materials used in the following examples, unless otherwise specified, are all purchased from conventional biochemical reagent stores.

[0049] The white rot fungal agent used in the following examples was purchased from Beijing Beina Chuanglian Biotechnology Research Institute.

[0050] Example 1

[0051] This embodiment provides a modified bioenzyme preparation, the preparation process of which is as follows:

[0052] (1) Endoglucanase (cellulase), xylanase (hemicellulase), and laccase (lignin degrading enzyme) were prepared into solutions using PBS buffer (pH 7.4). The enzyme activity of each solution was 100,000 U / mL. The endoglucanase solution, xylanase solution, and laccase solution were mixed in a volume ratio of 20:50:30 to prepare a 1% composite enzyme solution.

[0053] (2) NHS ester reagent (EDC and NHS) and leucine were mixed in a mass ratio of 3:1 and activated at 25°C for 1.5 h to obtain NHS-leucine ester intermediate.

[0054] (3) NHS-leucine ester intermediate (concentration of 1%) and composite bio-enzyme solution were mixed in a mass ratio of 1:500 (NHS-leucine ester intermediate was 0.2wt% of the composite bio-enzyme), and the NHS-leucine ester intermediate was slowly added to the composite bio-enzyme solution during mixing. The mixture was reacted at 4°C for 5 hours to obtain a surface-hydrophobicized bio-enzyme solution. A surfactant JFC (fatty alcohol polyoxyethylene ether) solution was added to the surface-hydrophobicized bio-enzyme solution to a final concentration of JFC of 3wt%, and the mixture was incubated at 25°C for 2 hours to obtain a modified bio-enzyme preparation.

[0055] Example 2

[0056] This embodiment provides a method for producing viscous pulp by pre-treatment and refining with microorganisms coupled with modified bio-enzymes. The process flow is as follows: Figure 1 The specific process is as follows:

[0057] 1. Microbial agent pretreatment

[0058] Prepare a wood pulp culture medium: 80 wt% wood pulp (absolutely dry), 0.5 wt% glucose, 0.5 wt% peptone, 0.2 wt% phosphate buffer, and the balance water. Dilute the wood pulp culture medium with water to a concentration of 50 wt%, sterilize at high temperature, and then inoculate with a white rot fungus inoculum (at a concentration of 100 million fungi / kg, representing 4 wt% of the wood pulp culture medium). Treat at 25°C for 6-10 days to obtain wood pulp pretreated with the microbial inoculum.

[0059] 2. Modified bio-enzyme pretreatment

[0060] The wood pulp pretreated with the microbial agent was adjusted to a 20 wt% concentration, and the modified bioenzyme preparation prepared in Example 1 was added at a rate of 0.02 wt% based on the absolute dry pulp. Mixing and preliminary refining were performed using a twin-screw refiner, with a pressure of 0.5 MPa, 6 extrusions, and a mixing time of 20 minutes. The pulp was then transferred to an enzymatic hydrolysis reaction tank for enzymatic pretreatment under the following pretreatment conditions: temperature of 50°C, pH 7, and treatment time of 120 minutes, yielding a modified bioenzyme-pretreated wood pulp.

[0061] 3. Second stage disc grinding for fine pulping

[0062] The pulp, pretreated with the modified bio-enzyme, was adjusted to a 5wt% consistency and refined using a two-stage disc refiner. The first refining gap was set at 0.9-1.1 mm, and the second refining gap was set at 0.04-0.06 mm. The pulp discharge was controlled at 50 ± 2°SR. After refining, the pulp was drained and water was added to adjust the consistency to 3wt%. The pulp was then pumped to a pulp storage tank. After delatching for 30 minutes, it was directly used for sheeting. The paper's tensile index and burst strength were measured.

[0063] Example 3

[0064] The method is the same as Example 2; the only difference is that the amount of modified bioenzyme preparation used in step 2 is 0.01 wt% of the absolute dry pulp.

[0065] Comparative Example 1

[0066] The method is the same as that in Example 2; the only difference is that no bioenzyme preparation is added during the treatment of the wood pulp.

[0067] Comparative Example 2

[0068] The method is the same as that of Example 2; the only difference is that the bioenzyme preparation used in step 2 is a bioenzyme preparation without the addition of NHS-leucine ester intermediate (the other steps of the bioenzyme preparation preparation method are the same as those of Example 1).

[0069] Comparative Example 3

[0070] The method is the same as that of Example 2; the only difference is that the microbial agent pretreatment in step 1 is not performed.

[0071] Test Example 1

[0072] The beating degree, refining energy consumption, pulp viscosity and paper performance of Example 2, Example 3 and Comparative Example 1 were tested respectively. The results are shown in Table 1.

[0073] Table 1 Beating degree, refining energy consumption, pulp viscosity and paper properties of each group

[0074] Experimental parameters Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 2 Example 3 <![CDATA[Beating degree ( o SR)]]> 53±2 50±2 51±2 52±2 51±2 Refining energy consumption (Kw / h·t) 421.06 350.32 373.90 286.96 301.77 <![CDATA[Slurry viscosity (mm 2 / s)]]> 838 830 828 840 824 <![CDATA[Tensile index (N·m 2 ·g -1 )]]> 64 70 69 80 76 <![CDATA[Bursting strength index (kPa·m 2 ·g -1 )]]> 3.8 3.9 3.8 4.1 3.9

[0075] As can be seen from the data in Table 1, Example 2 of the present invention obtains the best papermaking pulp performance and significantly reduces the energy consumption for refining. When the beating degree reaches 50±2°SR, the energy consumption for refining after microbial coupled modified bio-enzyme pretreatment is only 286.96Kw / h·t, while the energy consumption for refining in Comparative Example 1 without modified bio-enzyme coupled microbial pretreatment is as high as 421.06Kw / h·t. Compared with Comparative Example 1, Example 2 of the present invention saves more than 30% of energy consumption, improves the paper tensile index by more than 20%, and improves the bursting index by about 7%; compared with Comparative Example 2, it saves more than 18% of energy consumption, improves the paper tensile index by more than 14%, and improves the bursting index by about 5%; compared with Comparative Example 3, it saves more than 23% of energy consumption, improves the paper tensile index by more than 15%, and improves the bursting index by about 7%. This shows that the modified bio-enzyme preparation of the present invention cooperates with microbial pretreatment of wood pulp slurry to significantly reduce refining energy consumption, improve the paper tensile index, and is conducive to more efficient production of viscous pulp.

[0076] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a modified bioenzyme preparation for producing viscous pulp, characterized in that: Includes the following steps (1) mixing a cellulase solution, a hemicellulase solution, and a lignin degradation enzyme solution to obtain a composite biological enzyme solution; (2) mixing the composite bio-enzyme solution with activated hydrophobic amino acids, reacting them to obtain a surface-hydrophobized bio-enzyme solution; (3) mixing the surface-hydrophobized bioenzyme solution with a surfactant and reacting them to obtain the modified bioenzyme preparation.

2. The preparation method according to claim 1, characterized in that In step (1), the enzyme activities of the cellulase solution, hemicellulase solution and lignin degradation enzyme solution are all 90,000-110,000 U / mL; the volume ratio of the cellulase solution, hemicellulase solution and lignin degradation enzyme solution when mixed is (15-25):(45-55):(25-35).

3. The preparation method according to claim 1, characterized in that In step (2), the activated hydrophobic amino acid is obtained by activating the hydrophobic amino acid using EDC and NHS; During the mixing, the activated hydrophobic amino acid is prepared into a solution having the same concentration as the composite bio-enzyme solution, and the two are mixed at a mass ratio of 1:400-600; The reaction temperature is 4° C. and the reaction time is 4-6 h.

4. The preparation method according to claim 1, characterized in that In step (3), the final concentration of the mixed surfactant is 2 wt%-4 wt%, the reaction temperature is 20-25° C., and the reaction time is 1-2 h.

5. The modified bioenzyme preparation prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the modified bioenzyme preparation according to claim 5 in producing viscous pulp.

7. A method for producing viscous pulp by using a modified bioenzyme preparation in conjunction with microbial pretreatment, characterized in that: The steps include: S1. preparing a wood pulp culture medium, diluting it with water, and inoculating it with a white rot fungus agent for pretreatment to obtain wood pulp pretreated with the microbial agent; S2, adjusting the concentration of the wood pulp pretreated with the microbial agent, adding the modified bioenzyme preparation according to claim 5, and performing preliminary refining and enzymatic hydrolysis; S3, finely refining the enzymatically hydrolyzed wood pulp to obtain the viscous pulp.

8. The method according to claim 7, characterized in that The wood pulp culture medium is composed of: 75wt%-85wt% of absolute dry wood pulp, 0.4wt%-0.6wt% of glucose, 0.4wt%-0.6wt% of peptone, 0.1wt%-0.3wt% of phosphate buffer, and the balance is water; the pH value is 5.0-6.0; The concentration of the diluted wood pulp culture medium is 30wt%-60wt%; The inoculation amount of the white rot fungus agent is 3wt%-5wt% of the wood pulp culture medium; the temperature of the pretreatment is 20-25°C, and the time is 6-10 days.

9. The method according to claim 7, characterized in that The pulp concentration of the wood pulp pretreated with the microbial agent after adjustment is 20wt%-25wt%; the addition amount of the modified bioenzyme preparation is 0.01wt%-0.02wt% of the absolute dry pulp of the wood pulp pretreated with the microbial agent; The pressure during the initial refining is 0.5 MPa, the number of extrusion and thread rolling is 5-10 times, and the time is 15-30 minutes; The enzymatic hydrolysis temperature is 40-60° C., the pH value is 4-9, and the time is 60 min-180 min.

10. The method according to claim 7, characterized in that The method for fine refining is as follows: adjusting the enzymatically hydrolyzed wood pulp to a pulp concentration of 4wt%-8wt%, using a two-stage disc refiner, with the first stage refining gap set to 0.9-1.1mm and the second stage refining gap set to 0.04-0.06mm; stopping refining when the beating degree is 50±2°SR.

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