CN120139012A - A pulp bleaching method based on electric field gradient coupling oxygen nuclei - Google Patents
A pulp bleaching method based on electric field gradient coupling oxygen nuclei Download PDFInfo
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- CN120139012A CN120139012A CN202510339141.4A CN202510339141A CN120139012A CN 120139012 A CN120139012 A CN 120139012A CN 202510339141 A CN202510339141 A CN 202510339141A CN 120139012 A CN120139012 A CN 120139012A
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1021—Electrochemical processes
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
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Abstract
本发明公开了一种基于电场梯度耦合氧核的纸浆漂白方法。该方法包括以下步骤：向反应釜中加入纸浆，加入碱和保护剂，搅拌混匀，加热；当加热至90～100℃时，保持温度，高速搅拌下，向反应釜内施加直流电场并通入氧气，反应3～5 min；低速搅拌下反应30～120 min。该方法解决了现有氧脱木素工艺中反应效率低、氧气利用率低的问题。通过在反应釜外壁施加直流电场，借助电场力使氧气分子电荷分离，提升其与纸浆纤维表面的结合能力。该方法显著提高了木质素的去除效率，显著改善了纸浆白度和卡伯值。本发明适用于制浆造纸领域，特别是对环保要求较高的漂白工艺具有重要意义。
The invention discloses a pulp bleaching method based on electric field gradient coupling oxygen nuclei. The method comprises the following steps: adding pulp to a reactor, adding alkali and a protective agent, stirring and mixing, and heating; when heated to 90-100°C, maintaining the temperature, applying a direct current electric field to the reactor under high-speed stirring and introducing oxygen, reacting for 3-5 minutes; reacting for 30-120 minutes under low-speed stirring. The method solves the problems of low reaction efficiency and low oxygen utilization rate in the existing oxygen delignification process. By applying a direct current electric field to the outer wall of the reactor, the electric field force is used to separate the charge of oxygen molecules, thereby improving their ability to bind to the surface of pulp fibers. The method significantly improves the removal efficiency of lignin, and significantly improves the whiteness and kappa number of pulp. The invention is applicable to the field of pulping and papermaking, and is particularly important for bleaching processes with high environmental protection requirements.
Description
Technical Field
The invention relates to the technical field of pulping and papermaking processes, in particular to a pulp bleaching method based on electric field gradient coupling oxygen nuclei.
Background
In the field of pulping and papermaking, oxygen delignification is taken as a key process, and aims to remove lignin in paper pulp by using oxygen and improve the quality of the paper pulp. However, this process faces many challenges in practical applications.
The pulp fiber surface is typically negatively charged, a property that makes oxygen gas in combination with it a significant barrier. At a microscopic level, the repulsive force between the charges weakens the effective contact between the charges, so that oxygen is difficult to fully permeate into the fiber, and the mass transfer efficiency is greatly reduced. Taking the traditional process as an example, under the specific reaction condition, the mass transfer effect is poor, so that only partial lignin can be removed, a large amount of lignin remains, and the subsequent performance of the paper pulp is seriously affected.
In the existing oxygen delignification process, the oxygen utilization rate is generally low. On the one hand, the oxygen distribution in the reaction system is uneven, the partial area cannot fully participate in the reaction due to the too high oxygen concentration, so that waste is caused, and the partial area is difficult to thoroughly react due to insufficient oxygen. On the other hand, the unreasonable arrangement of the equipment structure and the technological parameters further aggravates the problem. For example, the design of the reaction vessel fails to fully consider the mixing effect of the gas and the paper pulp, so that the contact time and the contact area of the gas and the paper pulp are limited, resource waste is caused, and meanwhile, the production cost is increased.
The bleaching effect of current oxygen delignification processes is limited. The residual chromophores in the paper pulp cannot be effectively removed due to insufficient lignin removal, so that the whiteness of the paper pulp is difficult to improve. Even if the oxygen amount is increased or the reaction time is prolonged, the bottleneck of the bleaching effect is difficult to break, and the negative problems such as excessive degradation of fibers and the like can be caused, so that the physical properties such as pulp strength and the like are damaged. In addition, the existing technology has more severe requirements on reaction conditions, so that the stability of the production process is poor, and the high-efficiency and stable industrial production is difficult to realize.
Thus, there is a need to obtain a pulp bleaching process that can enhance the efficiency of oxygen delignification.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings of the prior art and provides a pulp bleaching method based on electric field gradient coupling oxygen nucleus
The aim of the invention is achieved by the following technical scheme:
a pulp bleaching method based on electric field gradient coupling oxygen nuclei, comprising the steps of:
(1) Adding paper pulp into a reaction kettle, adding alkali and a protective agent, stirring and uniformly mixing, and heating;
(2) When the temperature is heated to 90-100 ℃, maintaining the temperature, applying a direct current electric field into the reaction kettle and introducing oxygen under high-speed stirring, and reacting for 3-5 min;
(3) And (3) reacting for 30-120 min under low-speed stirring.
Further, the pulp in the step (1) is obtained by steaming and boiling a pulping raw material through a sulfate method, further, the pulping raw material comprises at least one of hardwood pulp, softwood pulp and bamboo pulp, and still further, the pulping raw material comprises bamboo pulp.
Further, the base in step (1) includes NaOH.
Further, the mass of the alkali in the step (1) is 1.8-4% of the absolute dry pulp mass of the paper pulp, and further, the mass of the alkali in the step (1) is 2% of the absolute dry pulp mass of the paper pulp.
Further, the protective agent in step (1) comprises magnesium salt, and further comprises MgSO 4.
Further, the mass of the protective agent in the step (1) is 0.4% -0.7% of the absolute dry pulp mass of the paper pulp, and further, the mass of the protective agent in the step (1) is 0.5% of the absolute dry pulp mass of the paper pulp.
Further, the base and the protecting agent described in step (1) are added in the form of a solution.
Further, the heating rate of the heating in the step (1) is 4-6 ℃ per minute, and further, the heating rate of the heating in the step (1) is 5 ℃ per minute.
Further, the heating in step (2) is to 90 ℃.
Further, the high-speed stirring in the step (2) is stirring at a rotating speed of 200-400 r/min, and further stirring at a rotating speed of 300 r/min.
Further, the electric field strength of the applied DC electric field in the step (2) is 200-1800V/m, further, the voltage between the electrodes of the applied DC electric field in the step (2) is 1000-1800V/m, and still further, the voltage between the electrodes of the applied DC electric field in the step (2) is 1000V/m.
Further, the electric field device for applying the direct current field in the step (2) comprises a power supply and an electrode;
Further, the output voltage of the power supply is adjustable and is 0-600V, 40-360V is provided for the electrode, and the electrode is a graphite electrode;
further, the length of the graphite electrode is 50% -90% of the axial length of the reaction kettle, the width of the graphite electrode is 20% -50% of the circumference of the bottom surface, and further, the length of the graphite electrode is 70% of the axial length of the reaction kettle, and the width of the graphite electrode is 25% of the circumference of the bottom surface.
Further, in the step (2), when oxygen is introduced, the oxygen pressure is controlled to be 0.4-0.8 MPa, and further, the oxygen pressure is controlled to be 0.5 MPa.
Further, the reaction described in step (2) is reaction 3 min.
Further, the low-speed stirring in the step (3) is stirring at a rotating speed of 100-180 r/min, and further stirring at a rotating speed of 180 r/min.
Further, the reaction described in step (3) is reaction 60 min.
Compared with the prior art, the invention has the following advantages and effects:
The invention solves the problems of low reaction efficiency and low oxygen utilization rate in the existing oxygen delignification process, and provides an improved process for enhancing oxygen delignification based on an electric field. Through applying a direct current electric field on the outer wall of the reaction kettle, the electric charge of oxygen molecules is separated by means of the electric field force, the bonding capability of the oxygen molecules and the surface of paper pulp fibers is improved, and the oxygen molecules react with the paper pulp fibers under the action of the electric field force, so that lignin is removed, and the whiteness and kappa number of paper pulp are improved. The process not only remarkably improves the lignin removal efficiency, but also has remarkable effect on improving the whiteness and kappa number of the paper pulp. The invention is suitable for the pulping and papermaking field, and has important significance for bleaching technology with high environmental protection requirement.
Drawings
FIG. 1 is a schematic diagram of an electric field device used in the method of the invention, wherein the number of the electric field device is 1, a reaction kettle, 2, an insulating heating sleeve, 3, an electrode, 4, a power supply, 5, a discharging pipe, 6, a stirrer, 7, a pulping raw material feeding pipe, 8, a reagent feeding pipe, 9, an air outlet pipe and 10, an oxygen air inlet pipe.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but embodiments of the present invention are not limited thereto.
The pulp used in the following examples was obtained by steaming bamboo pulp obtained by sulfate method, the whiteness of the pulp was 27.0% ISO, the viscosity was 1140 mL/g, and the kappa number was 25.7, and the bamboo pulp was obtained from Sichuan Yongfeng paper mill.
The schematic diagram of the electric field device for applying electric field in the following embodiment is shown in fig. 1, electric field devices are arranged on two sides of the reaction kettle, the type of a power supply of the electric field device is Siemens 6EP1336-3BA10 direct current power supply, the output voltage of the power supply is adjustable 0-600V, the precision is +/-1%, electrodes of the electric field device are graphite electrodes, in the following embodiment, the length of each graphite electrode is 70% of the axial length of the reaction kettle, and the width of each graphite electrode is 25% of the circumference of the bottom surface. The electrodes are isolated from the reactor wall by insulating materials to ensure that the electric field can be formed normally and act on the reaction area.
Example 1
A pulp bleaching method based on electric field gradient coupling oxygen nuclei, comprising the steps of:
(1) Adding paper pulp into a reaction kettle, adding NaOH solution and MgSO 4 solution, so that the mass of NaOH is 2% of the absolute dry pulp mass of the paper pulp, and the mass of MgSO 4 is 0.5% of the absolute dry pulp mass of the paper pulp, stirring and uniformly mixing, and heating at a heating rate of 5 ℃ per min;
(2) When the temperature is increased to 90 ℃, maintaining the temperature, increasing the stirring rotating speed to 300 r/min, applying a direct current electric field (the voltage between the electrodes of the electric field is 40V, the distance between the electrodes is 20cm, the electric field strength is 200V/m) into the reaction kettle, introducing oxygen (controlling the oxygen pressure to be 0.5 MPa), and reacting for 3 minutes;
(3) The stirring rate was reduced to 180 r/min and the reaction was carried out for 60 minutes.
After the reaction, washing the paper pulp by using quantitative water, and detecting the whiteness of the paper pulp according to the standard of ISO 2470-1:2016 (measurement of paper, paperboard and paper pulp-blue diffuse reflectance-part 1: indoor sunlight condition (ISO whiteness), and detecting the kappa number of the paper pulp according to GB/T1546-2018 (measurement of kappa number of paper pulp).
The pulp whiteness is 42.6% ISO and kappa number is 14.12.
Example 2
The difference between this example and example 1 is that the voltage between the electrodes of the electric field in step (2) was 120V, and the electric field strength of the electric field applied to the inside of the reaction vessel was 600V/m.
The pulp whiteness is 43.6% ISO and kappa number is 13.76.
Example 3
The difference between this example and example 1 is that the voltage between the electrodes of the electric field in step (2) was 200V and the electric field strength of the electric field applied to the inside of the reaction vessel was 1000V/m.
The whiteness of the paper pulp is 45.9% ISO and the kappa number is 13.22.
Example 4
The difference between this example and example 1 is that the voltage between the electrodes of the electric field in step (2) was 280V, and the electric field strength of the electric field applied to the inside of the reaction vessel was 1400V/m.
The pulp whiteness is 44.7% ISO and kappa number is 13.57.
Example 5
The difference between this example and example 1 is that the voltage between the electrodes of the electric field in step (2) was 360V and the electric field strength of the electric field applied to the inside of the reaction vessel was 1800V/m.
The whiteness of the paper pulp is 45.1% ISO and the kappa number is 13.34.
Comparative example
The comparative example differs from example 1 only in that no direct current electric field was applied.
The pulp whiteness is 38.9% ISO and kappa number is 14.81.
The results of the detection on the whiteness and kappa number of the paper pulp are shown in table 1, and experiments show that the whiteness of the paper pulp is improved to 45.9% ISO (38.9% ISO without electric field) under the electric field of 200V, the kappa number is reduced to 13.22 (14.81 without electric field), and the oxygen delignification efficiency is effectively improved. The method breaks through the bottleneck of the traditional process, obviously improves the bleaching efficiency under the condition of the same chemical consumption, and is widely applicable to pulp such as hardwood pulp, bamboo pulp and the like.
TABLE 1
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (10)
1. A pulp bleaching method based on electric field gradient coupling oxygen nuclei, which is characterized by comprising the following steps:
(1) Adding paper pulp into a reaction kettle, adding alkali and a protective agent, stirring and uniformly mixing, and heating;
(2) When the temperature is heated to 90-100 ℃, maintaining the temperature, applying a direct current electric field into the reaction kettle and introducing oxygen under high-speed stirring, and reacting for 3-5 min;
(3) And (3) reacting for 30-120 min under low-speed stirring.
2. The method of claim 1, wherein the step of determining the position of the substrate comprises,
The pulp in the step (1) is obtained by cooking pulp raw materials through a sulfate method.
3. The method of claim 1, wherein the step of determining the position of the substrate comprises,
The base in step (1) comprises NaOH;
The protective agent in step (1) comprises a magnesium salt.
4. The method of claim 1, wherein the step of determining the position of the substrate comprises,
The mass of the alkali in the step (1) is 1.8-4% of the absolute dry pulp mass of the paper pulp;
The mass of the protective agent in the step (1) is 0.4% -0.7% of the absolute dry pulp mass of the paper pulp.
5. The method of claim 1, wherein the step of determining the position of the substrate comprises,
The heating in the step (2) is to 90 ℃;
and (3) stirring at a high speed in the step (2) at a rotating speed of 200-400 r/min.
6. The method of claim 1, wherein the step of determining the position of the substrate comprises,
The electric field strength of the applied direct current electric field in the step (2) is 200-1800V/m.
7. The method of claim 6, wherein the step of providing the first layer comprises,
The electric field strength of the applied direct current electric field in the step (2) is 1000-1800V/m.
8. The method of claim 1, wherein the step of determining the position of the substrate comprises,
And (2) controlling the oxygen pressure to be 0.4-0.8 MPa when oxygen is introduced in the step (2).
9. The method of claim 1, wherein the step of determining the position of the substrate comprises,
The reaction described in step (2) is reaction 3min.
10. The method of claim 1, wherein the step of determining the position of the substrate comprises,
The low-speed stirring in the step (3) is stirring at the rotating speed of 100-180 r/min;
the reaction described in step (3) is reaction 60 min.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202510339141.4A CN120139012A (en) | 2025-03-21 | 2025-03-21 | A pulp bleaching method based on electric field gradient coupling oxygen nuclei |
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| CN202510339141.4A CN120139012A (en) | 2025-03-21 | 2025-03-21 | A pulp bleaching method based on electric field gradient coupling oxygen nuclei |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1296100A (en) * | 2000-12-27 | 2001-05-23 | 中国科学院广州化学研究所 | Method for bleaching waste water of paper making |
| DE102005049287A1 (en) * | 2005-06-16 | 2006-12-28 | Siemens Ag | Screening device for the production of paper and process for the treatment of unwoven fibers |
| CN101748631A (en) * | 2009-12-18 | 2010-06-23 | 华南理工大学 | Efficient and clean puling and bleaching method dissolving alpha-pulp by Chinese alpine rush |
| CN102066654A (en) * | 2008-04-30 | 2011-05-18 | 希乐克公司 | Paper product and method and system for making the same |
| CN119162752A (en) * | 2024-11-19 | 2024-12-20 | 江苏金夏纺织有限公司 | Bleaching device for textile material |
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- 2025-03-21 CN CN202510339141.4A patent/CN120139012A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1296100A (en) * | 2000-12-27 | 2001-05-23 | 中国科学院广州化学研究所 | Method for bleaching waste water of paper making |
| DE102005049287A1 (en) * | 2005-06-16 | 2006-12-28 | Siemens Ag | Screening device for the production of paper and process for the treatment of unwoven fibers |
| CN102066654A (en) * | 2008-04-30 | 2011-05-18 | 希乐克公司 | Paper product and method and system for making the same |
| CN101748631A (en) * | 2009-12-18 | 2010-06-23 | 华南理工大学 | Efficient and clean puling and bleaching method dissolving alpha-pulp by Chinese alpine rush |
| CN119162752A (en) * | 2024-11-19 | 2024-12-20 | 江苏金夏纺织有限公司 | Bleaching device for textile material |
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