A deinking and bleaching treatment process for recycling waste paper

Abstract

The present invention belongs to the technical field of recycled waste paper processing, and particularly relates to a deinking and bleaching treatment process for recycled waste paper. The deinking and bleaching treatment process for recycled waste paper of the present invention comprises the following steps: S1, cleaning and impurity removal, soaking, and pulping; S2, steam explosion; S3, enzymatic treatment; S4, bleaching, washing, and pulping. The deinking and bleaching treatment process for recycled waste paper provided by the present invention combines chemical, physical, and biological deinking technologies, comprehensively optimizes the quality and efficiency of recycled paper production, can more effectively remove ink particles attached to waste paper, significantly improves the whiteness of recycled paper, and protects the integrity of fibers, reduces fiber breakage and damage, thereby improving the physical properties of recycled paper, such as burst index, tensile index, and tear index, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of recycled waste paper processing, and particularly relates to a deinking and bleaching treatment process for recycled waste paper. Background Art

[0002] In recent years, the global pulp and paper industry has faced multiple challenges, with the core issues focusing on the vulnerability of the raw material supply chain and the increasing pressure of environmental protection regulations. With the decline of the global forest coverage rate and the strengthening of ecological conservation policies, exploring environmentally friendly raw material substitution options has become a key issue for the sustainable development of the paper industry. In this context, the recycling of waste paper fibers, as an important part of the circular economy, has become increasingly prominent in terms of its status and value. The recycling of waste paper fibers can not only effectively reduce the dependence of the paper industry on virgin wood fibers, but also significantly reduce the exploitation of forest resources, thereby alleviating the damage to the natural environment and conforming to the global vision of green, low-carbon, and sustainable development. By efficiently recycling and reusing waste paper, the paper industry can maintain production while significantly reducing its negative impact on the environment, promoting the industry's transformation towards a more environmentally friendly and resource-saving direction. The recycling and reuse of waste paper fibers can not only effectively alleviate the dependence of the paper industry on virgin fibers, but also significantly reduce deforestation and the pressure on the environment, which is in line with the general trend of green, low-carbon, and circular development.

[0003] However, some inherent defects have emerged during the reuse of waste paper, which restrict its wide application in the production of high-quality products: 1. Decreased swelling ability: During the recycling process of waste paper fibers, the fiber structure is damaged, resulting in a weakened ability to absorb water and expand. The decrease in swelling ability directly affects the dispersibility and binding property of the fibers in the pulp, and thus affects the uniformity and smoothness of the paper. 2. Reduced paper strength: As the number of reuse times increases, the length and strength of waste paper fibers gradually decrease, leading to a decrease in the mechanical strength (such as tensile strength and tear strength) of the produced paper, making it difficult to meet the requirements of some high-demand application scenarios, such as high-grade packaging materials and special paper products. 3. Poor drainage performance: The decline in the drainage performance of waste paper fibers means that during the papermaking process, the filtration speed of the fiber suspension becomes slower, increasing energy consumption, prolonging the production cycle, and may also affect the drying efficiency of the paper and the final flatness. And in the existing deinking process, especially in the mechanical disintegration and washing stages, the fibers may be damaged and shortened. This results in a decrease in the fiber length and strength of the recycled pulp, thereby affecting the quality and physical properties of the recycled paper.

[0004] Therefore, there is a need to provide a deinking and bleaching treatment for recycled waste paper, which can improve the drainage performance and bleaching performance of waste paper pulp and improve the deinking effect of waste paper, minimizing fiber damage to the greatest extent, thereby enhancing the recycling of waste paper fibers. Summary of the Invention

[0005] To solve the problems existing in the prior art, the object of the present invention is to provide a deinking and bleaching treatment process for recycled waste paper. The deinking and bleaching treatment process for recycled waste paper provided by the present invention combines chemical, physical and biological deinking technologies, comprehensively optimizes the quality and efficiency of the production of recycled paper, can more effectively remove the ink particles attached to the waste paper, significantly improve the whiteness of the recycled paper, and protects the integrity of the fibers, reduces fiber breakage and damage, thereby improving the physical properties of the recycled paper, such as burst index, tensile index and tear index, etc.

[0006] The technical solution of the present invention is as follows:

[0007] A deinking and bleaching treatment process for recycled waste paper, comprising the following steps:

[0008] S1. Cleaning and impurity removal, soaking, and pulping: The recycled waste paper is cleaned and impurities are removed, then soaked in a sodium hydroxide solution, and then a deinking agent is added for pulping treatment to obtain a pretreated pulp;

[0009] S2. Steam explosion: The pretreated pulp obtained in step S1 is subjected to steam explosion treatment;

[0010] S3. Enzymatic hydrolysis treatment: The pH of the pulp after steam explosion in step S2 is adjusted to 7, and then primary enzymatic hydrolysis is carried out; then the pH of the system is adjusted to 4.5 - 5.5, and then a composite auxiliary agent, laccase and α-amylase are added and stirred evenly, and then the temperature of the system is adjusted to 5 - 15 °C and left standing for a period of time for secondary enzymatic hydrolysis;

[0011] S4. Bleaching, washing, and pulping: A bleaching agent is added to the pulp after enzymatic hydrolysis in step S3 for bleaching treatment, and then filtration and washing are carried out to obtain deinked pulp.

[0012] Further, the addition amount of the deinking agent in step S1 is 0.9 - 1.5 wt% of the weight of the pulp soaked in the sodium hydroxide solution, and the deinking agent in step S1 is composed of isooctyl polyoxyethylene ether phosphate, sodium metasilicate and lauryl hydroxy sulfobetaine in a weight ratio of (1 - 3:2 - 5:1), preferably (2:3:1).

[0013] Furthermore, the isooctyl polyoxyethylene ether phosphate is isooctyl polyoxyethylene ether phosphate OEP-98, purchased from Jinan Baoliyuan Chemical Co., Ltd.; the CAS number of the sodium metasilicate is 6834-92-0; the CAS number of the lauryl hydroxy sulfobetaine is 13197-76-7.

[0014] Further, the amount of the sodium hydroxide solution used in step S1 is 5 - 7 times the dry weight of the waste paper, and the concentration of the sodium hydroxide solution is 0.3 - 0.5%; the soaking temperature is 50 - 60 °C, and the soaking time is 20 - 30 min.

[0015] Furthermore, the pulping process in step S1 is carried out in a hydro-pulper, and the rotational speed of the pulping process is 600 - 800 r / min, and the treatment time is 20 - 30 min.

[0016] Furthermore, the pressure during the steam explosion process in step S2 is 1.3 - 1.5 MPa, preferably 1.4 MPa, the temperature is 130 - 150 °C, and the treatment time is 5 - 10 min.

[0017] The deinking and bleaching treatment process for recycled waste paper provided by the present invention first removes impurities such as dust and sand on the surface of waste paper through cleaning and impurity removal to provide a clean substrate for subsequent chemical treatment. Then, it is soaked in an alkaline environment to fully swell the waste paper, and then a deinking agent is added for pulping treatment, and the pretreated pulp after pulping is subjected to steam explosion treatment. Steam explosion is a physical treatment method. By acting on the waste paper pulp with high-temperature and high-pressure steam, the fibers rapidly expand and the pressure is instantaneously released, resulting in strong vibration and rapid expansion of the fibers. And the present invention creatively adds a deinking agent composed of isooctyl polyoxyethylene ether phosphate, sodium metasilicate and lauryl hydroxysulfobetaine in a specific proportion during the process of using the steam explosion method. It can better break the tight binding between fibers, promote fiber separation, and at the same time accelerate the penetration of the deinking agent, so that the binding force between the fibers and the ink and other impurities is weakened, which helps the loosening and removal of the ink and other non-fiber impurities and improves the deinking effect. And in the above steps, the deinking agent and steam explosion method are adopted, and the reaction conditions in the steps are controlled to comprehensively treat the pulp, which can effectively dissolve and separate the ink and adhesives without over-damaging the fibers and without destroying the integrity of the fibers, and thus can effectively improve the physical properties of the prepared recycled paper products, such as tensile strength, burst index, tear index, etc.

[0018] Furthermore, the addition amount of cellulase in the first enzymatic hydrolysis in step S3 is 10 - 15 U / g, preferably 12 U / g based on the dry weight of the waste paper in step S1; the temperature during the first enzymatic hydrolysis process is 50 - 55 °C, and the enzymatic hydrolysis time is 12 - 18 h.

[0019] Furthermore, the addition amount of laccase in the second enzymatic hydrolysis process in step S3 is 6 - 10 U / g, preferably 8 U / g, and the addition amount of α-amylase is 5 - 8 U / g, preferably 6 U / g, based on the dry weight of the waste paper in step S1; the temperature during the second enzymatic hydrolysis process is 35 - 45 °C, and the enzymatic hydrolysis time is 12 - 24 h.

[0020] Furthermore, the cellulase, laccase, and α-amylase used in the present invention are all commonly used biological enzyme preparations in the prior art. The CAS number of the cellulase is 9012-54-8, the CAS number of the laccase is 80498-15-3, and the CAS number of the α-amylase is 9000-90-2.

[0021] Further, after the primary enzymatic hydrolysis in step S3, the pH of the system is adjusted to 4.5-5.5. Then, a composite auxiliary agent, laccase, and α-amylase are added and stirred evenly. After that, the temperature of the system is adjusted to 5-15°C and left standing for 3-5 hours.

[0022] Further, the addition amount of the composite auxiliary agent in step S3 is 1.2-2.0 wt% of the weight of the pulp after the primary enzymatic hydrolysis, preferably 1.8 wt%. The composite auxiliary agent is composed of polyethylene glycol monooleate and tyrosine in a weight ratio of (3-6:2), preferably (5:2).

[0023] Furthermore, the CAS number of the polyethylene glycol monooleate is 9004-96-0.

[0024] In the present invention, the pulp after steam explosion treatment is first enzymatically hydrolyzed with cellulase, and then a composite auxiliary agent composed of polyethylene glycol monooleate and tyrosine, laccase, and α-amylase are added. After standing at a low temperature for a period of time, secondary enzymatic hydrolysis is carried out. In the above steps, two enzymatic hydrolyses are carried out by selecting different types of enzymes in a specific environment. Before the secondary enzymatic hydrolysis, a composite auxiliary agent composed of polyethylene glycol monooleate and tyrosine, laccase, and α-amylase are added first, and then left standing at a low temperature for a period of time, which can promote the stabilization of the enzymatic hydrolysis products and the further separation of ink particles. On the one hand, it can improve the deinking efficiency and pulp whiteness, and on the other hand, it can reduce the damage of fibers, maintain the length and flexibility of fibers, promote the cross-linking between pulp fibers, and further improve the fluidity of the pulp and the physical properties of the paper.

[0025] Further, the bleaching agent in step S4 is composed of sodium salt of ethylenediaminetetraacetic acid and hydrogen peroxide. The addition amount of the sodium salt of ethylenediaminetetraacetic acid is 0.08-0.12 wt% of the weight of the pulp after enzymatic hydrolysis in step S3, and the addition amount of hydrogen peroxide in step S4 is 2.5-3.0 wt% of the weight of the pulp after enzymatic hydrolysis in step S3.

[0026] Furthermore, the sodium salt of ethylenediaminetetraacetic acid is disodium ethylenediaminetetraacetate (EDTA disodium).

[0027] Further, the temperature of the bleaching treatment in step S4 is 60-80°C, and the time is 30-60 minutes.

[0028] Further, the filtering process in step S4 is to pass the bleached pulp through a coarse sieve with an aperture of 1-3 mm and a fine sieve with an aperture of 0.2-0.4 mm in sequence, and then adjust the pulp concentration of the deinked pulp to 4-6%.

[0029] Compared with the prior art, a deinking and bleaching treatment process for recycling waste paper provided by the present invention has the following advantages:

[0030] (1) The deinking and bleaching treatment process for recycling waste paper provided by the present invention combines chemical, physical, and biological deinking technologies, comprehensively optimizes the quality and efficiency of recycled paper production, can more effectively remove ink particles attached to waste paper, and significantly improves the whiteness of recycled paper.

[0031] (2) The deinking and bleaching treatment process for recycling waste paper provided by the present invention also protects the integrity of fibers by precisely controlling the raw material reagents and process parameters of each step, reduces fiber breakage and damage, and thus improves the physical properties of recycled paper, such as burst index, tensile index, and tear index, etc.

[0032] (3) The deinking and bleaching treatment process for recycling waste paper provided by the present invention improves the fiber recovery rate, which not only saves natural resources, but also improves production efficiency and economic benefits, and reduces the use of harmful chemical reagents and the emission of harmful chemicals in traditional deinking processes, meeting the trend of green manufacturing. Specific embodiments

[0033] The present invention will be further described below through the description of specific embodiments, but this is not a limitation to the present invention. Those skilled in the art can make various modifications or improvements according to the basic idea of the present invention, but as long as they do not depart from the basic idea of the present invention, they are within the protection scope of the present invention.

[0034] In the following examples and comparative examples, reagents not specifically described are conventional reagents and can be purchased from conventional reagent production and sales companies. The methods used, unless otherwise specified, are all prior art.

[0035] Example 1

[0036] A deinking and bleaching treatment process for recycling waste paper includes the following steps:

[0037] S1. Cleaning, impurity removal, soaking, and pulping: Cut the recycled office waste paper into pieces of 3 cm, rinse it with flowing clear water to remove surface impurities, then soak it in a sodium hydroxide solution with a concentration of 0.3% and 5 times the dry weight of the waste paper for 20 min at a soaking temperature of 50 °C to fully swell the waste paper. Then add a deinking agent accounting for 0.9 wt% of the pulp weight to the sodium oxide solution, stir evenly, and perform pulping treatment in a hydraulic crusher for 20 min at a rotational speed of 800 r / min to obtain pretreated pulp; the deinking agent is composed of isooctyl polyoxyethylene ether phosphate OEP-98, sodium metasilicate, and lauryl hydroxy sulfobetaine in a weight ratio of (1:5:1).

[0038] S2. Steam explosion: Place the pretreated pulp obtained in step S1 in a steam exploder, carry out the treatment for 10 min under the conditions of a pressure of 1.3 MPa and a temperature of 130 °C, and then rapidly decompress to release the material.

[0039] S3. Enzymatic hydrolysis treatment: Cool the temperature of the pulp after steam explosion in step S2 to room temperature, adjust the pH to 7, then add cellulase, and the addition amount of the cellulase is 10 U / g based on the dry weight of the waste paper in step S1. Carry out enzymatic hydrolysis at a temperature of 50 °C for 18 h, then adjust the pH of the system to 4.5, then add a composite auxiliary agent, laccase, and α-amylase, stir evenly, adjust the system temperature to 5 °C, and let it stand for 3 h. The addition amount of the laccase is 6 U / g, and the addition amount of the α-amylase is 5 U / g based on the dry weight of the waste paper in step S1. Then carry out enzymatic hydrolysis at a temperature of 50 °C for 12 h; the addition amount of the composite auxiliary agent is 1.2 wt% of the pulp weight after the first enzymatic hydrolysis, and the composite auxiliary agent is composed of polyethylene glycol monooleate and tyrosine in a weight ratio of (3:2).

[0040] S4. Bleaching, washing, and pulping: Add 0.08 wt% of disodium ethylenediaminetetraacetate and 2.5 wt% of hydrogen peroxide to the pulp after enzymatic hydrolysis in step S3, and carry out bleaching treatment at 60 °C for 60 min, and then pass through a coarse sieve with a pore size of 1 - 3 mm and a fine sieve with a pore size of 0.2 - 0.4 mm in sequence; then wash the pulp with clear water until the pH value of the pulp is neutral, and then adjust the pulp concentration to 4% to obtain deinked pulp.

[0041] Example 2

[0042] A deinking and bleaching treatment process for recycled waste paper, comprising the following steps:

[0043] S1. Cleaning, impurity removal, soaking and pulping: Cut the recycled office waste paper into 3 cm pieces, rinse with running water to remove impurities on the surface, then add it into a sodium hydroxide solution with a concentration of 0.4% which is 6 times the dry weight of the waste paper and soak it for 25 minutes at a soaking temperature of 55°C to make the waste paper fully swell, then add a sodium oxide solution to soak a deinking agent which is 1.2wt% of the weight of the pulp, stir evenly and then carry out pulping treatment in a hydraulic crusher for 25 minutes at a speed of 700r / min to obtain pretreated pulp; the deinking agent is composed of isooctyl alcohol polyoxyethylene ether phosphate OEP-98, sodium metasilicate and lauryl hydroxysulfonobetaine in a weight ratio of (2:3:1);

[0044] S2, steam explosion: the pretreated pulp obtained in step S1 is placed in a steam explosion device, and is subjected to a steam explosion at a pressure of 1.4 MPa and a temperature of 145° C. for 8 minutes, followed by rapid decompression to release the material;

[0045] S3, enzymatic hydrolysis: the temperature of the pulp after steam explosion in step S2 is lowered to room temperature, the pH is adjusted to 7, and then cellulase is added, the amount of the cellulase added is 12U / g, based on the dry weight of the waste paper in step S1, the enzymatic hydrolysis is carried out at a temperature of 52°C for 16 hours, and then the pH of the system is adjusted to 5, and then the composite auxiliary agent, laccase, and α-amylase are added and stirred evenly, and the temperature of the system is adjusted to 10°C and allowed to stand for 4 hours, the amount of the laccase added is 8U / g, and the amount of the α-amylase added is 6U / g, based on the dry weight of the waste paper in step S1, and then the enzymatic hydrolysis is carried out at a temperature of 40°C for 18 hours; the amount of the composite auxiliary agent added is 1.8wt% of the weight of the pulp after one enzymatic hydrolysis, and the composite auxiliary agent is composed of polyethylene glycol monooleate and tyrosine in a weight ratio of (5:2);

[0046] S4, bleaching, washing, and pulping: add 0.1 wt% of disodium ethylenediaminetetraacetate and 2.7 wt% of hydrogen peroxide to the pulp after enzymatic hydrolysis in step S3, and bleach it at 70°C for 50 minutes, and then pass it through a coarse sieve with a pore size of 1 to 3 mm and a fine sieve with a pore size of 0.2 to 0.4 mm in sequence; then wash the pulp with clean water until the pH value of the pulp is neutral, and then adjust the pulp concentration to 5% to obtain deinked pulp.

[0047] Example 3

[0048] A deinking and bleaching process for recycling waste paper comprises the following steps:

[0049] S1. Cleaning, impurity removal, soaking, and pulping: Cut the recycled office waste paper into pieces of 3 cm, rinse it with flowing clean water to remove surface impurities, then soak it in a sodium hydroxide solution with a concentration of 0.5% and 7 times the dry weight of the waste paper for 30 min at a soaking temperature of 60 °C to fully swell the waste paper. Then add a deinking agent accounting for 1.5 wt% of the pulp weight to the sodium oxide solution, stir evenly, and perform pulping treatment in a hydraulic crusher for 30 min at a rotation speed of 800 r / min to obtain pretreated pulp; the deinking agent is composed of isooctyl polyoxyethylene ether phosphate OEP-98, sodium metasilicate, and lauryl hydroxy sulfobetaine in a weight ratio of (3:2:1).

[0050] S2. Steam explosion: Place the pretreated pulp obtained in step S1 in a steam exploder, carry out for 5 min under the conditions of a pressure of 1.5 MPa and a temperature of 150 °C, and then rapidly decompress to release the material.

[0051] S3. Enzymatic hydrolysis treatment: Cool the temperature of the pulp after steam explosion in step S2 to room temperature, adjust the pH to 7, then add cellulase, and the addition amount of the cellulase is 15 U / g based on the dry weight of the waste paper in step S1. Carry out enzymatic hydrolysis at a temperature of 55 °C for 12 h, then adjust the pH of the system to 5.5, then add a composite auxiliary agent, laccase, and α-amylase, stir evenly, adjust the system temperature to 15 °C, and let it stand for 5 h. The addition amount of the laccase is 10 U / g, and the addition amount of the α-amylase is 8 U / g based on the dry weight of the waste paper in step S1. Then carry out enzymatic hydrolysis at a temperature of 35 °C for 24 h; the addition amount of the composite auxiliary agent is 2.0 wt% of the pulp weight after the first enzymatic hydrolysis, and the composite auxiliary agent is composed of polyethylene glycol monooleate and tyrosine in a weight ratio of (6:2).

[0052] S4. Bleaching, washing, and pulping: Add 0.12 wt% of disodium ethylenediaminetetraacetate and 3.0 wt% of hydrogen peroxide to the pulp after enzymatic hydrolysis in step S3, carry out bleaching treatment at 80 °C for 30 min, and then pass through a coarse sieve with a pore size of 1 - 3 mm and a fine sieve with a pore size of 0.2 - 0.4 mm in sequence; then wash the pulp with clean water until the pH value of the pulp is neutral, and then adjust the pulp concentration to 6% to obtain deinked pulp.

[0053] Comparative Example 1

[0054] Compared with Example 2, the difference lies in that isooctyl polyoxyethylene ether phosphate OEP-98 in the deinking agent in step S1 is replaced with fatty alcohol polyoxyethylene ether AEO-9 (CAS No. 68213-23-0), and other raw material components and preparation methods are the same as those in Example 2.

[0055] Comparative Example 2

[0056] Compared with Example 2, the difference lies in that sodium metasilicate is not added to the deinking agent in step S1, and the dosage of octyl polyoxyethylene ether phosphate OEP-98 is correspondingly increased. That is, the deinking agent consists of isooctyl polyoxyethylene ether phosphate OEP-98 and lauryl hydroxy sulfobetaine in a weight ratio of (5:1). Other raw material components and preparation methods are the same as those in Example 2.

[0057] Comparative Example 3

[0058] Compared with Example 2, the difference lies in that the pressure during the steam explosion treatment in step S2 is 1.8 Mpa and the temperature is 160 °C. Other raw material components and preparation methods are the same as those in Example 2.

[0059] Comparative Example 4

[0060] Compared with Example 2, the difference lies in that after adding the composite auxiliary agent, laccase, and α-amylase and stirring evenly in step S3, the system temperature is not adjusted to 10 °C and left standing for 4 h, but directly enzymatically hydrolyzed at a temperature of 40 °C for 18 h (secondary enzymatic hydrolysis). Other raw material components and preparation methods are the same as those in Example 2.

[0061] Comparative Example 5

[0062] Compared with Example 2, the difference lies in that tyrosine is not added to the composite auxiliary agent in step S3, and it is only polyethylene glycol monooleate. That is, the addition amount of polyethylene glycol monooleate is 1.8 wt% of the weight of the pulp after primary enzymatic hydrolysis. Other raw material components and preparation methods are the same as those in Example 2.

[0063] Test Example 1. Performance detection of paper products made from the deinked pulp prepared by the present invention

[0064] Test method:

[0065] (1) Dilute the deinked pulp prepared in Examples 1-3 and Comparative Examples 1-5 of the present invention to a pulp concentration of 1.2%, and then use the rapid Kersey forming method to make paper with a basis weight of 60 g / m 2 of paper.

[0066] (2) The detection standards and detection data are shown in Tables 1 and 2.

[0067] Table 1

[0068] Group National Standard for Testing Example 1 Example 2 Example 3 Residual Ink Content (ppm) GB / T 20216-2016 219.6 204.9 213.1 Whiteness (% ISO) GB / T 7974-2013 86.3 88.6 87.6 Folding Endurance (times) GB / T 457-2008 39 43 41 <![CDATA[Bulk density (cm 3 ·g -1 )]]> GB / T 451.3-2002 2.1 2.2 2.1 Tensile Index (N·m / g) GB / T 453-2002 55.6 59.6 56.4 <![CDATA[Bursting strength index (KPa·m 2 ·g -1 )]]> GB / T 454--2002 3.71 3.85 3.74 <![CDATA[Tear Index (mN·m 2 ·g -1 )]]> GB / T 455-2002 5.13 5.26 4.96

[0069] Table 2

[0070]

[0071] As can be seen from Table 1, the whiteness of the recycled paper prepared in Examples 1 to 3 of the present invention can reach 88.6% ISO, the residual ink amount is low, and it has excellent physical properties. Compared with the examples of the present invention, the quality of the recycled paper prepared in Comparative Examples 1 to 5 is far lower than that of Examples 1 to 3 of the present invention. Thus, it can be seen that the preparation process provided by the present invention can effectively remove the ink particles attached to the waste paper, significantly improve the whiteness of the recycled paper, and protect the integrity of the fibers, reduce fiber breakage and damage, thereby improving the physical properties of the recycled paper, such as burst index, tensile index, and tear index, etc.

[0072] The above embodiments merely illustrate the principles and effects of the present invention, rather than limiting the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A deinking and bleaching treatment process for recycling waste paper, characterized in that, It includes the following steps: S1. Cleaning, impurity removal, soaking, and pulping: The recycled waste paper is cleaned and the impurities are removed, then soaked in a sodium hydroxide solution, and then a deinking agent is added for pulping treatment to obtain pretreated pulp; S2. Steam explosion: The pretreated pulp obtained in step S1 is subjected to steam explosion treatment; S3. Enzymatic hydrolysis treatment: The pH of the pulp after steam explosion in step S2 is adjusted to 7, and then cellulase is added for primary enzymatic hydrolysis; then the pH of the system is adjusted to 4.5 - 5.5, and then a composite auxiliary agent, laccase, and α - amylase are added and stirred evenly, and then the temperature of the system is adjusted to 5 - 15 °C and left standing for a period of time for secondary enzymatic hydrolysis; S4. Bleaching, washing, and pulping: A bleaching agent is added to the pulp after enzymatic hydrolysis in step S3 for bleaching treatment, and then filtration and washing are carried out to obtain deinked pulp; The deinking agent in step S1 is composed of isooctyl polyoxyethylene ether phosphate, sodium metasilicate, and lauryl hydroxy sulfobetaine in a weight ratio of 1 - 3:2 - 5:1; In the steam explosion process in step S2, the pressure is 1.3 - 1.5 MPa, the temperature is 130 - 150 °C, and the treatment time is 5 - 10 min; After the primary enzymatic hydrolysis in step S3, the pH of the system is adjusted to 4.5 - 5.5, and then a composite auxiliary agent, laccase, and α - amylase are added and stirred evenly, and then the temperature of the system is adjusted to 5 - 15 °C and left standing for 3 - 5 h; The composite auxiliary agent is composed of polyethylene glycol monooleate and tyrosine in a weight ratio of 3 - 6:

2.

2. The deinking and bleaching treatment process for recycling waste paper according to claim 1, characterized in that, The addition amount of the deinking agent in step S1 is 0.9 - 1.5 wt% of the weight of the pulp soaked in the sodium hydroxide solution; 3. The deinking and bleaching treatment process for recycling waste paper according to claim 1, characterized in that, The amount of the sodium hydroxide solution used in step S1 is 5 - 7 times the dry weight of the waste paper, the concentration of the sodium hydroxide solution is 0.3 - 0.5%, the soaking temperature is 50 - 60 °C, and the soaking time is 20 - 30 min; 4. The deinking and bleaching treatment process for recycling waste paper according to claim 1, characterized in that, The pulping treatment process in step S1 is carried out in a hydraulic pulper, the rotation speed of the pulping treatment is 600 - 800 r / min, and the treatment time is 20 - 30 min; 5. The deinking and bleaching treatment process for recycling waste paper according to claim 1, characterized in that, In the primary enzymatic hydrolysis in step S3, the addition amount of cellulase is 10 - 15 U / g based on the dry weight of the waste paper in step S1; the temperature in the primary enzymatic hydrolysis is 50 - 55 °C, and the enzymatic hydrolysis time is 12 - 18 h; In the secondary enzymatic hydrolysis process in step S3, the addition amount of laccase is 6 - 10 U / g, and the addition amount of α - amylase is 5 - 8 U / g based on the dry weight of the waste paper in step S1; the temperature in the secondary enzymatic hydrolysis process is 35 - 45 °C, and the enzymatic hydrolysis time is 12 - 24 h; 6. The deinking and bleaching treatment process for recycling waste paper according to claim 1, characterized in that, The addition amount of the composite auxiliary agent in step S3 is 1.2 - 2.0 wt% of the weight of the pulp after primary enzymatic hydrolysis; 7. The deinking and bleaching treatment process for recycling waste paper according to claim 1, characterized in that, The bleaching agent in step S4 is composed of sodium ethylenediaminetetraacetate and hydrogen peroxide. The addition amount of the sodium ethylenediaminetetraacetate is 0.08 - 0.12 wt% of the weight of the pulp after enzymatic hydrolysis in step S3, and the addition amount of hydrogen peroxide in step S4 is 2.5 - 3.0 wt% of the weight of the pulp after enzymatic hydrolysis in step S3.

8. The deinking and bleaching treatment process for recycling waste paper according to claim 1, characterized in that, The filtering process in the step S4 is as follows: the bleached pulp is successively passed through a coarse sieve with a pore size of 1 - 3 mm and a fine sieve with a pore size of 0.2 - 0.4 mm, and then the concentration of the deinked pulp is adjusted to 4 - 6%.

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