HEMICELLULASES IN PULP BLEACHING PDF

HEMICELLULASES IN PULP BLEACHING PDF

Hemicellulase-aided bleaching is the first full-scale biotechnical application in the pulp and paper industry which truly exploits the unique specificity and safety of. () reported that the chlorine dosage can be reduced 25% for hemicellulase- assisted chlorine bleaching to obtain the similar bleached pulp. Paice et al. Elemental chlorine, while effective in bleaching pulp and low in both primary classes: hemicellulases (xylanase) and oxidases (laccase).

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It eases subsequent mechanical and chemical pulping. The hemicellluases hydrolyze some of the surface sugars on the pulp fiber and this releases the ink particles bound to the fiber.

Role Of Biotechnology In Pulp And Paper Industry

Visit for more related articles at Journal of Industrial Iin Control. The stability of the xylanase activity in the crude supernatant was checked at pH 7 and 9. As hleaching result, one would typically expect to find significant levels of residual Kraft black liquor in the pulp being sent to the pulp bleachery of an operating mill. Genetic plant engineering used to improve the strength, yield, and bleachability of mechanical and chemical pulps Merkle and Dean, In this regard, studies have reported linkages between hemicellulose, particularly xylan, and bleahcing in wood Eriksson, et al.

They save production costs and prevents formation of unwanted products during pulp bleaching process. Biermann, Handbook of Pulping and Papermaking, The method of claim 5 wherein weak black liquor is mixed with the acid or base and added to the delignified wood in step b.

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The culture supernatant was harvested by centrifugation rpm, min. It has also reduced chemical bleaching costs.

However, the treatment with chlorine is undesirable from an environmental standpoint because the resulting effluents contain a large number of toxic compounds e. Deforestation is a matter of concern for both the environmentalists and the paper industry this has forced.

In chemical hemivellulases, a majority of the lignin is removed from wood pulp e. The results are shown in FIG.

Hemicellulases in the bleaching of chemical pulps.

Unbleached softwood Kraft brownstock was obtained from a pulp mill in Eastern Canada. Any remaining ink is removed during a conventional flotation step. This option is only appropriate for new mills. In the absence of enzyme treatment, the bleached pulp bleavhing 71 ISO brightness. This cellulase enzyme can have very undesirable hemicellukases on pulp qualities such as pulp strength.

This invention preferably concerns the use of xylanase or other hemicellulase enzymes that have pH optima for hydrolysis of below 6. The region of an enzyme that specifically interacts with the substrate is called the active site. The enzymes that have shown benefit in bleaching include xylanase, arabinase and mannanase Paice, et al.

Process for treating hardwood pulp with an enzyme mixture to reduce vessel element picking. While the supernatant may be used as such, it is preferably concentrated prior to its use. An example of such a strain is T. In the present invention, a high level of brightness boosting activity is achieved at pH levels previously taught by Novo to inactivate the enzymes.

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The carbon source has been found to affect the xylanase isoenzyme pattern, i.

Biobleaching of pulp with enzymes have several advantages like: The method of claim 5 wherein said pulp is bleached with a bleaching agent selected from the group consisting of chlorine, chlorine dioxide, hypochlorite, ozone, oxygen, hydrogen peroxide, hydrosulphite and sodium sulphite. Thermostable hemicellulases from Bacillus steanothermophilus for pulp bleaching.

The process according to claim 1 wherein the pulp is contacted at an enzyme dosing ratio in the range of about 0. This invention relates to the use of thermostable enzyme systems obtained from Thermomonospora fusca strains and to a new bacterial strain, Thermomonospora fusca with the designation KW3, and its thermostable enzymes which are active over a wide pH range and at higher temperatures to modify wood pulp properties especially to reduce the lignin content.

Role Of Biotechnology In Pulp And Paper Industry | Open Access Journals

Topics Discussed in This Paper. Cellulases are used for drainage Foster,deinking Bhardwaj et al.

After being washed with water, the cooked material contains 1. Treatment of mechanical pulps with enzymes for improved drainability EP Karsila et al.