Bleaching stage using xylanase with hydrogen peroxide, peracids, or a combination thereof

a technology of hydrogen peroxide and bleaching stage, which is applied in the direction of multi-stage pulping process, cellulose treatment using microorganisms/enzymes, and inorganic base pulping, etc. it can solve the problems of inability to remove all lignin without, harsh pulp, and destruction of some cellulose fibers in pulp, so as to reduce the use of chlorine-containing bleaching chemicals and less costly bleaching operations

Inactive Publication Date: 2004-06-17
IOGEN BIO PRODUCKTS CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

0041] The method of the invention is an improvement over the separate treatments of xylanase and peroxyacids. The method of the invention uses only one bleaching tower rather than two. Surprisingly, the presence of the hydrogen peroxide and peracids do not destroy the acti...

Problems solved by technology

While pulping removes most of the lignin in the feedstock material, it is not capable of removing all the lignin without destroying the cellulose fibers of the feedstock.
Alkali-oxygen delignification reduces the amount of lignin in the pulp by 35-50%, but this process is harsh on the pulp and is often accompanied by destruction of some of the cellulose fibers in the pulp if the extent of delignification is greater than 50%.
However, beyond a certain low level of hydrogen peroxide, there is a significant possibility of damaging t...

Method used

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  • Bleaching stage using xylanase with hydrogen peroxide, peracids, or a combination thereof
  • Bleaching stage using xylanase with hydrogen peroxide, peracids, or a combination thereof
  • Bleaching stage using xylanase with hydrogen peroxide, peracids, or a combination thereof

Examples

Experimental program
Comparison scheme
Effect test

example 1

Determination of Kappa Number

[0077] The kappa number of the pulp is determined using the protocol described in: TAPPI method for Kappa number of pulp (T 236 cm-85) from TAPPI Test Methods 1996-1997, which is herein incorporated by reference. Briefly, the kappa number is the volume (in milliliters) of a 0.1 N potassium permanganate solution consumed by one gram of moisture-free pulp under the conditions specified in the method. The results are corrected to 50% consumption of the permanganate added.

[0078] The kappa number determination is performed at a constant temperature of 25.degree. C..+-.0.2.degree. C. with continuous agitation. However, it is possible to correct for variations in temperature as is described below.

[0079] The moisture content of the pulp is determined in accordance with TAPPI T 210 "Sampling and Testing Wood Pulp Shipments for Moisture" which is herein incorporated by reference. Briefly, the pulp specimen is disintegrated in about 800 mL of distilled water and st...

example 2

Standard Assay for the Measurement of Xylanase Activity

[0091] Xylanase Assay #1:

[0092] The endo-xylanase assay is specific for endo-1,4-beta-D-xylanase activity. On incubation of azo-xylan (oat) with xylanase, the substrate is depolymerized to produce low-molecular weight dyed fragments which remain in solution on addition of ethanol to the reaction mixture. High molecular weight material is removed by centrifugation, and the colour of the supernatant is measured. Xylanase activity in the assay solution is determined by reference to a standard curve.

[0093] Substrate: The substrate is purified (to remove starch and beta-glucan). The polysaccharide is dyed with Remazolbrilliant Blue R to an extent of about one dye molecule per 30 sugar residues. The powdered substrate is dissolved in water and sodium acetate buffer and the pH is adjusted to 4.5.

[0094] Assay: Xylanase is diluted in 0.5 M acetate buffer at pH 4.5. Two millilitres of the solution is heated at 40.degree. C. for 5 minutes....

example 3

Preparation of Chlorine Dioxide

[0098] Chlorine dioxide was made in the lab by the standard procedure of passing a mixture of chlorine gas and nitrogen through a series of columns containing sodium chlorite, and collecting the evolved gas in cold water. The chlorine dioxide was stored refrigerated at a concentration of 10.4 grams per litre in water. Further details regarding the preparation of chlorine dioxide may be found in Chlorine Dioxide Generation published by Paprican, Pointe Claire, Qubec (which is herein incorporated by reference).

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Abstract

The present invention discloses methods of bleaching chemical pulp that combine xylanase enzymes with hydrogen peroxide, peracids, or a mixture. The method comprises the steps of carrying out a chemical pulping operation, optionally followed by delignifying the pulp with oxygen, then combining xylanase enzymes with hydrogen peroxide, peracids, or a mixture to bleach the pulp. The method allows the mill to use both xylanase and peracids in a single bleaching tower to decrease the usage of chlorine dioxide and other bleaching chemicals. The pulp bleaching method of the present invention may be performed in a pulp mill as part of a complex pulp bleaching process.

Description

[0001] The invention relates to methods of bleaching pulp. More specifically the invention relates to methods of bleaching pulp using xylanase enzymes with hydrogen peroxide, peracids, or or a combination thereof.[0002] The production of bleached chemical pulp is a major industry around the world. More than 50 million tons of bleached pulp is produced annually. Bleached chemical pulp is the largest component of all types of white paper, including that used in photocopy paper, writing paper, and paper packaging. In addition, bleached chemical pulp is also used to impart strength to less expensive grades of paper, such as newsprint. Bleached chemical pulp has large markets because of its high degree of whiteness and cleanliness, the stability of the whiteness, its high strength, and the ease and uniformity of the printing surface it provides. These attributes are obtained when lignin, which is colored and decreases the interfiber bonding of the cellulose, is almost completely removed ...

Claims

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Application Information

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IPC IPC(8): D21C5/00D21C9/10D21C9/14D21C9/153D21C9/16
CPCD21C5/005D21C9/1057D21C9/16D21C9/153D21C9/14
Inventor TOLAN, JEFFREYSUCHY, MIRO
Owner IOGEN BIO PRODUCKTS CORP
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