A wheat straw pulping method based on cellulase treatment technology

Abstract

The invention discloses a wheat straw pulping method based on a cellulase treatment technology, comprising the following steps: squeezing and washing the wheat straw, placing the wheat straw in a sealed bag, adding alkali solution into the sealed bag, and then sealing the sealed bag; placing the sealed bag in a water bath, performing a first water bath heating treatment at 90-100°C, and the water bath heating time is 10-30min; washing the wheat straw subjected to water bath heating to neutrality, placing the wheat straw in a sealed bag, adding polydimethyldiallylammonium chloride and cellulase into the sealed bag, and after sealing, placing the sealed bag in a water bath at 50-60°C for a second water bath heating treatment, the water bath heating time is 1.5-2.5h, and the amount of PDADMAC is 0.2-1.4×10 ‑3 g / g wheat straw, the amount of cellulase used is 10-25U / g wheat straw; finally, the treated wheat straw is washed and pulped. The pulping method can improve the treatment efficiency of cellulase in the pulping process and improve the water filterability and papermaking performance of wheat straw pulp.

Description

Technical Field

[0001] The invention belongs to the technical field of wheat straw biochemical mechanical pulping, and specifically relates to a wheat straw pulping method based on cellulose enzyme treatment technology, which can effectively improve the cellulose enzyme treatment efficiency and improve the water filterability and paper-forming properties of the obtained pulp. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Wheat straw is abundant in northern my country, but is usually abandoned or burned and not fully utilized. Wheat straw has a high cellulose content. Using wheat straw as a pulping material can not only reduce environmental pollution caused by burning, but also increase the supply of raw materials for the pulp and paper industry. However, wheat straw has the following disadvantages as a raw material for pulp and papermaking: the traditional chemical pulping yield is low, and the high silicon content in wheat straw makes alkali recovery very difficult, increasing the pollution load; there are many fine components in the pulp, and the water filterability is poor.

[0004] In recent years, people have studied a variety of green pulping methods for wheat straw to reduce pollution loads, among which bio-enzyme treatment technology has shown great prospects in wheat straw pulping. Bio-enzyme treatment can not only reduce pollution but also effectively reduce pulping energy consumption, improve pulp filterability, and improve pulp performance. However, the problem of bio-enzyme treatment efficiency in the pulping process has always been a difficult problem to be solved. Summary of the invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a wheat straw pulping method based on cellulase treatment technology.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A wheat straw pulping method based on cellulase treatment technology comprises the following steps:

[0008] The wheat straw is squeezed and washed, and then placed in a sealed bag. Alkali solution is added to the sealed bag, which can remove part of the lignin and hemicellulose and increase the adsorption area of ​​cellulose enzymes, and then the sealed bag is sealed;

[0009] Place the sealed bag in a water bath and perform the first water bath heating treatment at 90-100°C. Place the wheat straw in the sealed bag to avoid loss of alkali solution during the water bath treatment. The water bath heating time is 10-30 minutes.

[0010] The wheat straw treated by water bath heating was washed to neutrality, put into a sealed bag, and polydimethyldiallyl ammonium chloride (PDADMAC) and cellulase were added into the sealed bag. PDAMAC can increase the adsorption amount of cellulase on the wheat straw. After sealing, the sealed bag was placed in a 50-60°C water bath for a second water bath heating treatment. The water bath heating time was 1.5-2.5h, and the amount of PDADMAC was 0.2-1.4×10 -3 g / g wheat straw. Too much or too little amount will affect the adsorption of cellulase on wheat straw. The amount of cellulase is 10-25U / g wheat straw.

[0011] Finally, the processed wheat straw is washed and pulped.

[0012] In some embodiments, the wheat straw is extruded using a screw extruder.

[0013] In some embodiments, the alkali solution is a sodium hydroxide solution or a potassium hydroxide solution, and the mass concentration of the alkali solution is 3%-6%.

[0014] Preferably, after adding the alkali solution into the sealed bag, knead it thoroughly and evenly.

[0015] Preferably, the mass ratio of the wheat straw to the alkali solution is 1:3-5.

[0016] Further preferably, the mass ratio of the alkali solution to wheat straw is 1:4.

[0017] In some embodiments, the temperature of the first water bath heating treatment is 90-100° C., and the water bath heating time is 10-30 min.

[0018] In some embodiments, the temperature of the second water bath heating treatment is 50-60°C.

[0019] In some embodiments, the pulping comprises the following steps: grinding the treated wheat straw into pulp using a high-consistency disc refiner;

[0020] The pulp is beaten using a refiner and defibrated using a defibrator.

[0021] Preferably, the method further comprises the step of using a Kaiser sheeter to sheet the deflaked pulp into paper.

[0022] Preferably, the method of grinding wheat straw into pulp using a high-consistency disc refiner adopts two-stage refining, with the first-stage refining gap being 0.4-0.6 mm and the second-stage refining gap being 0.1-0.3 mm.

[0023] The beneficial effects achieved by one or more embodiments of the present invention are as follows:

[0024] The pulping method can improve the processing efficiency of cellulase in the pulping process. It can be found from the results of the examples and comparative examples that the addition of PDADMAC improves the water filterability and paper-forming properties of wheat straw pulp. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0026] Figure 1 is a process flow chart of a wheat straw pulping method according to an embodiment of the present invention;

[0027] Figure 2 This is a diagram showing the effect of PDADMAC on cellulase adsorption improvement in Example 1 of the present invention;

[0028] Figure 3 The distribution diagram of cellulase on the surface of wheat straw when PDADMAC is added and not added in Example 1 of the present invention, wherein a is (sample without PDADMAC added and fluorescence combination diagram), b is (fluorescence diagram without PDADMAC added), c is (sample diagram without PDADMAC added), d is (sample with PDADMAC added and fluorescence diagram), e is (fluorescence diagram with PDADMAC added), and f is (sample diagram with PDADMAC added);

[0029] Figure 4 This is a comparison chart of the water filtration effects of the pulp prepared in Examples 2 and 3;

[0030] Figure 5 The physical strength index graph of the finished paper obtained with and without the addition of PDADMAC. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0032] The present invention will be further described below in conjunction with the embodiments.

[0033] Example 1

[0034] Put a certain amount of air-dried wheat straw into a sealed bag, add 100°C alkaline hot water (4% NaOH, liquid ratio of 1:4), knead it evenly, soak it in a 100°C water bath for 20 minutes, and then wash the wheat straw until it is neutral.

[0035] Take 8 portions of 80g of alkali-soaked wheat straw and put them into a sealed bag. Add PDADMAC and cellulase into the sealed bag in sequence. The cellulase dosage is 15U / g wheat straw. The PDADMAC dosage is adjusted to 0 and 0.2×10 -3 g / g wheat straw, 0.4×10 -3 g / g wheat straw, 0.6×10 -3 g / g wheat straw, 0.8×10 -3 g / g wheat straw, 1×10 -3 g / g wheat straw, 1.2×10 -3 g / g wheat straw, 1.4×10 -3 g / g wheat straw, rub evenly, and place in a 55℃ water bath for 2h.

[0036] The adsorption of cellulase on the surface of wheat straw was detected. The effect of PDADMAC on the adsorption of cellulase is shown in the figure. Figure 2 ,according to Figure 2 It can be seen that the addition of PDADMAC can effectively improve the adsorption of cellulase by wheat straw, which is beneficial to improving the treatment efficiency of cellulase.

[0037] The distribution of cellulase on the surface of wheat straw is shown in the figure Figure 3 As shown, from Figures a and d, it can be found that cellulase is mainly distributed in the pores and lines on the surface of wheat straw. Compared with Figure a, the fluorescence intensity in Figure d is higher and more uniform. The results of calculating the average fluorescence intensity of Figure b and Figure e using ImageJ software show that the average fluorescence intensity of Figure e is higher than that of Figure b, which indicates that PDADMAC-assisted treatment can make more cellulase adsorbed on the surface of wheat straw.

[0038] Example 2

[0039] Put a certain amount of air-dried wheat straw into a sealed bag, add 100°C alkaline hot water (4% NaOH, liquid ratio of 1:4), knead it evenly, soak it in a 100°C water bath for 20 minutes, and then wash the wheat straw until it is neutral.

[0040] Take 80g of alkali-soaked wheat straw and put it into a sealed bag. Then add PDADMAC and cellulase into the sealed bag in sequence. The amount of PDADMAC is 1×10 -3 g / g, the dosage of cellulase is 10U / g, rub evenly, and place in a 55℃ water bath for 2h.

[0041] After the treatment, the straw is washed and then ground into pulp using a high-consistency disc refiner, and the resulting pulp is beaten using a PFI refiner.

[0042] The mass of pulp filtered water within 30 seconds was measured to be 455 g.

[0043] The obtained pulp was defibrated using a fiber disintegrator, and then the pulp was made into paper. The ring crush index of the finished paper was 10.88N·m / g and the tear index was 1.79mN·m 2 / g, and the tensile index is 27.24N·m / g.

[0044] Except for not adding PDADMAC, other process conditions are the same.

[0045] The water-filtered mass of the pulp within 30 seconds was measured to be 336 g.

[0046] The obtained pulp was defibrated using a fiber disintegrator and then made into paper. The ring crush index of the finished paper was 8.81 N·m / g and the tear index was 1.67 mN·m 2 / g, and the tensile index is 26.23N·m / g.

[0047] Comparison between the two shows that the water filtration quality of pulp in 30 seconds increased by 35.4%; the paper strengths such as ring pressure, tearing and tensile strength all increased to varying degrees.

[0048] Example 3

[0049] Put a certain amount of air-dried wheat straw into a sealed bag, add 100°C alkaline hot water (4% NaOH, liquid ratio of 1:4), knead it evenly, soak it in a 100°C water bath for 20 minutes, and then wash the wheat straw until it is neutral.

[0050] Take 80g of alkali-soaked wheat straw and put it into a sealed bag. Then add PDADMAC and cellulase into the sealed bag in sequence. The amount of PDADMAC is 1×10 -3 g / g, the amount of cellulase used is 15U / g, rub evenly, and place in a 55℃ water bath for 2h.

[0051] After the treatment, the straw is washed and then ground into pulp using a high-consistency disc refiner, and the resulting pulp is beaten using a PFI refiner.

[0052] The water-filtered mass of the pulp within 30 seconds was measured to be 464 g.

[0053] The obtained pulp was defibrated using a fiber disintegrator, and then the pulp was made into paper. The ring crush index of the finished paper was 11.88N·m / g and the tear index was 1.73mN·m 2 / g, and the tensile index is 31.97N·m / g.

[0054] Except for not adding PDADMAC, other process conditions are the same.

[0055] The mass of pulp filtered water within 30 seconds was measured to be 399 g.

[0056] The obtained pulp was defibrated using a fiber disintegrator, and then the pulp was made into paper. The ring crush index of the paper was measured to be 11.54 N·m / g, and the tear index was 1.87 mN·m 2 / g, and the tensile index is 28.67N·m / g.

[0057] Comparison between the two shows that the water filtration quality of pulp increased by 16.3% in 30 seconds; the paper strengths such as ring pressure, tearing and tensile strength all increased to varying degrees.

[0058] The comparison of the water filtration effect of the pulp prepared in Examples 2-3 is shown in FIG. Figure 4 As shown, Figure 4 In the figure, the 30s drainage performance of pulp is compared when the cellulase dosage is 10U / g and 15U / g, with and without the addition of PDADMAC.

[0059] Example 4

[0060] Put a certain amount of air-dried wheat straw into a sealed bag, add 95°C alkaline hot water (4% NaOH, liquid ratio of 1:4), knead it evenly, soak it in a 100°C water bath for 25 minutes, and then wash the wheat straw until it is neutral.

[0061] 80 g of alkali-soaked wheat straw was placed in a sealed bag, and PDADMAC and cellulase were added to the sealed bag in sequence. The amount of PDADMAC was 1.4 × 10 -3 g / g, the amount of cellulase is 20U / g, rub evenly, and place in a 55℃ water bath for 2h.

[0062] After the treatment, the straw is washed and then ground into pulp using a high-consistency disc refiner, and the resulting pulp is beaten using a PFI refiner.

[0063] The mass of pulp filtered water within 30 seconds was measured to be 353 g.

[0064] The obtained pulp was defibrated using a fiber disintegrator, and then the pulp was made into paper. The ring crush index of the finished paper was 10.53N·m / g and the tear index was 3.64mN·m 2 / g, and the tensile index is 31.80N·m / g.

[0065] Except for not adding PDADMAC, other process conditions are the same.

[0066] The mass of pulp filtered water within 30 seconds was measured to be 306 g.

[0067] The obtained pulp was defibrated using a fiber disintegrator, and then the pulp was made into paper. The ring crush index of the paper was measured to be 10.17 N·m / g, and the tear index was 2.90 mN·m 2 / g, and the tensile index is 30.8N·m / g.

[0068] Comparison between the two shows that the water drainage quality of pulp increased by 15.36% after 30 seconds; the paper strengths such as ring pressure, tearing and tensile strength all increased to varying degrees.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A wheat straw pulping method based on cellulase treatment technology, characterized in that: The method comprises the following steps: squeezing and washing the wheat straw, and then putting the wheat straw in a sealed bag, adding alkali solution into the sealed bag, and then sealing the sealed bag, wherein the alkali solution is a sodium hydroxide or potassium hydroxide solution, and the mass concentration of the alkali solution is 3%-6%; the squeezing is to extrude the wheat straw using a screw extruder; Place the sealed bag in a water bath and perform the first water bath heating treatment at 90-100°C for 10-30 minutes; The wheat straw treated by water bath heating was washed to neutrality, put into a sealed bag, and polydimethyldiallyl ammonium chloride and cellulase were added to the sealed bag. After sealing, the sealed bag was placed in a 50-60°C water bath for a second water bath heating treatment. The water bath heating time was 1.5-2.5h, and the amount of PDADMAC was 0.2-1.4×10 -3 g / g wheat straw, the amount of cellulase is 10-25U / g wheat straw; Finally, the treated wheat straw is washed and pulped; The addition of the polydimethyldiallylammonium chloride can effectively improve the adsorption of cellulase by wheat straw, thereby helping to improve the treatment efficiency of cellulase; The addition of the polydimethyldiallylammonium chloride improves the drainage and paper-forming properties of the wheat straw pulp, wherein the paper-forming properties include ring crushing, tearing and tensile properties; The pulping comprises the following steps: grinding the treated wheat straw into pulp using a high-consistency disc grinder; The pulp is beaten using a pulp refiner and the pulp is defibrated using a fiber disintegrator; The method of grinding wheat straw into pulp using a high-consistency disc refiner adopts two-stage refining, wherein the first-stage refining gap is 0.4-0.6 mm, and the second-stage refining gap is 0.1-0.3 mm.

2. The method for making wheat straw pulp based on cellulase treatment technology according to claim 1, characterized in that: The temperature of the alkali solution is 90-100° C. After adding the alkali solution into the sealed bag, knead it thoroughly and evenly.

3. The method for making wheat straw pulp based on cellulase treatment technology according to claim 1, characterized in that: The mass ratio of the alkali solution to the wheat straw is 1:3-5.

4. The method for making wheat straw pulp based on cellulase treatment technology according to claim 1, characterized in that: The method also includes the step of using a Kaiser sheeter to make paper from the fluffed pulp.

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