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Application of chitosan as viscosity protective agent for ozone bleaching section of paper pulp

A technology of chitosan and protective agent, applied in the field of pulp bleaching, can solve immature problems, achieve low price, simple preparation process, and prevent invalid attacks

Inactive Publication Date: 2020-06-16
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Dou Hongyan and others have studied the application of chitosan in hydrogen peroxide bleaching. At present, the research on chitosan for pulp bleaching is still immature

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] After alkaline cooking, the pulp is subjected to ozone bleaching, the pulp concentration is 3% (wt), the viscosity protecting agent (chitosan solution with a molecular weight of 100,000) is used in an amount of 0.1wt% (for absolute dry pulp), and the configured viscosity protecting agent (chitosan solution ) The mass fraction concentration is 3%, the sulfuric acid dosage is 2wt% (for absolute dry pulp), after uniform mixing, the slurry is sent to the reaction kettle, and the mixer speed is adjusted until the slurry is completely mixed and stirred at a uniform speed, and the ozone generator is adjusted to control the reaction The ozone concentration at the inlet of the kettle is 118 g / Nm 3 , the amount of ozone introduced was 0.8wt% (for absolute dry pulp), and the reaction was carried out for 10 min. Record it as sample 1, and measure the whiteness and viscosity of the sample.

[0029] Preparation of the viscosity protecting agent used in this example (molecular weight...

Embodiment 2

[0031] After alkaline cooking, the pulp is bleached with ozone, the pulp concentration is 4% (wt), the viscosity protecting agent (chitosan solution with a molecular weight of 200,000) is used in an amount of 0.25 wt% (for absolute dry pulp), and the configured viscosity protecting agent (chitosan Solution) mass concentration fraction is 4%, the amount of sulfuric acid is 2.5 wt% (for absolute dry pulp), after uniform mixing, the slurry is sent to the reaction kettle, adjust the speed of the agitator until the slurry is completely mixed and stirred at a uniform speed, adjust the ozone generator, Control the ozone concentration at the inlet of the reactor to 120 g / Nm 3 , the amount of ozone introduced was 1wt% (for absolute dry pulp), and the reaction was carried out for 20 min. Record it as sample 2, and measure the whiteness and viscosity of the sample.

[0032] Preparation of the viscosity protecting agent used in this example (molecular weight: 200,000 oligomeric chitosan ...

Embodiment 3

[0034] After alkaline cooking, the pulp is bleached with ozone, the pulp concentration is 5% (wt), the viscosity protecting agent (chitosan solution with a molecular weight of 300,000) is used at 0.5 wt% (for absolute dry pulp), and the viscosity protecting agent (chitosan solution) ) mass fraction is 5%, sulfuric acid dosage is 3 wt% (for absolute dry pulp), after uniform mixing, the slurry is sent to the reactor, adjust the speed of the agitator until the slurry is completely mixed and stirred at a uniform speed, adjust the ozone generator, and control the reaction The ozone concentration at the inlet of the kettle is 122 g / Nm 3 , the amount of ozone introduced was 1.6wt% (for absolute dry pulp), and the reaction was carried out for 30 min. Record it as sample 3, and measure the whiteness and viscosity of the sample.

[0035] Preparation of the viscosity protecting agent used in this example (molecular weight 300,000 oligomeric chitosan solution): 50 g of chitosan with a de...

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Abstract

The invention belongs to the technical field of paper pulp bleaching, and particularly discloses an application of chitosan as a viscosity protective agent for an ozone bleaching section of paper pulp. Chitosan is used as a viscosity protective agent in paper pulp ozone bleaching, so that scaling, nondegradability of tert-butyl alcohol and the like formed by oxalic acid serving as the viscosity protective agent can be avoided, subsequent bleaching is not affected, and adverse effects on paper properties are avoided. Moreover, the chitosan is simple in preparation process, rich in raw materialsin nature, low in price, biodegradable and obvious in viscosity protection effect. Therefore, the application of the chitosan as the protective agent in ozone bleaching can promote the paper pulp industry to be further carried out on a full chlorine-free bleaching road, and has certain practical significance for industrial practical application of ozone.

Description

technical field [0001] The invention belongs to the technical field of pulp bleaching, and in particular relates to the application of chitosan as a viscosity protector in the ozone bleaching stage of pulp. Background technique [0002] As a strong oxidizing bleaching agent, ozone greatly destroys the lignin structure during the bleaching process, but the selectivity of ozone bleaching is poor, and it degrades lignin while causing great damage to carbohydrates and reducing pulp viscosity. At present, the protection of pulp viscosity in the process of ozone bleaching mainly includes pretreatment and adding additives. Pretreatment cannot be widely used in industry due to problems such as long time consumption and equipment investment. Currently, commonly used viscosity protection additives include oxalic acid, tert- Butanol, etc., and oxalic acid will form calcium oxalate that is not easy to peel off in actual production. The price of tert-butanol is too high, and it cannot be...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21C9/153
CPCD21C9/1026D21C9/1073D21C9/153
Inventor 刘明友王璐田霄飞何甜
Owner SOUTH CHINA UNIV OF TECH
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