Method for reducing AOX forming amount in chlorine dioxide bleaching process of bagasse pulp

A technology of chlorine dioxide and bagasse pulp, which is applied in pulp bleaching, post-treatment of cellulose pulp, textiles and papermaking, etc., can solve the problems of extra input cost and unsatisfactory input-output ratio, etc., to reduce AOX and save Usage amount, effect of reducing pollution

Inactive Publication Date: 2015-03-11
GUANGXI UNIV
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  • Summary
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In recent years, there have been many methods at home and abroad to try to reduce the amount of chlorine dioxide used in the bleaching process by reducing hemicellulose and hexenuronic acid in pulp, thereby reducing AOX emissions in wastewater, such as dilute acid leaching before bleaching, wood polymerization before bleaching, etc. Carbohydrase and laccase treatment methods and high-temp

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Method for reducing AOX formation in chlorine dioxide bleaching process

[0022] The washed and screened unbleached bagasse pulp is first sent to the pretreatment bleaching tower for two-stage pretreatment with high-temperature acid and enzyme, and then bleached with chlorine dioxide. The technological conditions of the high-temperature acid pretreatment section are: bleaching temperature 90°C, acid dosage 20kg / t 浆 , The reaction time is 60min. The unbleached pulp with a pulp concentration of 10% is preheated to 90°C and fully mixed with the acid solution in the slurry mixer, and then enters the pretreatment tower to start the reaction. The technological conditions of the biological enzyme pretreatment section are: bleaching temperature 60°C, enzyme dosage 20IU / g 浆 , The reaction time is 120min. After the slurry sprayed out from the high-temperature acid pretreatment tower is washed, the slurry concentration is adjusted to 10%, the reaction pH is controlled to be 6-9...

Embodiment 2

[0025] Method for reducing AOX formation in chlorine dioxide bleaching process

[0026] The washed and screened unbleached bagasse pulp is first sent to the pretreatment bleaching tower for two-stage pretreatment with high-temperature acid and enzyme, and then bleached with chlorine dioxide. The technological conditions of the high-temperature acid pretreatment section are: bleaching temperature 95°C, acid dosage 30kg / t 浆 , The reaction time is 75min. The unbleached pulp with a pulp concentration of 11% is preheated to 95°C and fully mixed with the acid solution in the slurry mixer, and then enters the pretreatment tower to start the reaction. The technological conditions of the biological enzyme pretreatment section are: bleaching temperature 75°C, enzyme dosage 30IU / g 浆 , The reaction time is 120min. After the slurry sprayed from the high-temperature acid pretreatment tower is washed clean, the slurry concentration is adjusted to 11%, the reaction pH is controlled to be 6...

Embodiment 3

[0029] Method for reducing AOX formation in chlorine dioxide bleaching process

[0030] The washed and screened unbleached bagasse pulp is first sent to the pretreatment bleaching tower for two-stage pretreatment with high-temperature acid and enzyme, and then bleached with chlorine dioxide. The technological conditions of the high-temperature acid pretreatment section are: bleaching temperature 98°C, acid dosage 50kg / t 浆 , The reaction time is 90min. The unbleached pulp with a pulp concentration of 15% is preheated to 98°C and fully mixed with the acid solution in the slurry mixer, and then enters the pretreatment tower to start the reaction. The technological conditions of the biological enzyme pretreatment section are: bleaching temperature 80°C, enzyme dosage 50IU / g 浆 , The reaction time is 120min. After the slurry sprayed out from the high-temperature acid pretreatment tower is washed, the slurry concentration is adjusted to 15%, the reaction pH is controlled to be 6-9...

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Abstract

The invention relates to a method for reducing an AOX forming amount in a chlorine dioxide bleaching process of a bagasse pulp. The method is characterized by mainly including the following steps: (1) high temperature acid pretreatment section; (2) biological enzyme pretreatment section; and (3) chlorine dioxide bleaching section. According to the present invention, high temperature acid pretreatment on the unbleached bagasse pulp is mainly to remove the hexenuronic acid in theunbleached pulp, and the use of biological enzyme is to remove the semi-cellulose on the fiber surface and to expose more residual lignin, so as to ensure the less usage of chlorine dioxide in the chlorine dioxide bleaching process, and reduce the AOX generated in the bleaching process. After high temperature acid pretreatment and enzyme pretreatment on the bagasse pulp, the usage amount of chlorine dioxide is saved by 15%-30%, and the forming amount of AOX is reduced by 20%-40%.

Description

technical field [0001] The invention relates to a method for cleaning pulp bleaching in a pulp and papermaking enterprise, in particular to a method for reducing the amount of AOX formed during chlorine dioxide bleaching of bagasse pulp. Background technique [0002] Pulp and paper companies can achieve the unity of environmental, economic and social benefits by using chlorine dioxide-based elemental chlorine-free (ECF) technology to bleach pulp. North America has fully completed the process of converting from conventional chlorine bleaching to ECF bleaching, and other regions are also converting from elemental chlorine bleaching to ECF bleaching. However, the ECF bleaching process still generates a small amount of adsorbable organic halides (AOX). AOX is the main persistent organic pollutant (POPs) in the ECF bleaching process, which is toxic, bioaccumulative and semi-volatile, and is difficult to degrade. Long-distance migration can occur. With the improvement of society...

Claims

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Application Information

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IPC IPC(8): D21C9/10D21C9/14
CPCD21C9/14D21C9/1005
Inventor 聂双喜王双飞姚双全宋雪萍牛芬洁覃程容
Owner GUANGXI UNIV
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