HEMICELLULASES IN PULP BLEACHING PDF

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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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This is applied before carrying out the normal mechanical or chemical pulping. Mannanase Activity The same procedure as that for endo-xylanase was used except that galactomannan Sigma No. The filtrate was discarded and the pulp cake was resuspended in 10 L of water and filtered a total of four times. Analysis of the culture supernatant by SDS polyacrylamide gel electrophoresis reveals a set of at least 6 isoenzymes with xylanase activity.

Use of enzymes can modify the fiber material. The extracted pulp is then washed with water to remove residual caustic.

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

It eases subsequent mechanical and chemical pulping. The influence of pH on enzymatic reactions may involve several different types of effects. Process for producing a concentrated sugar solution by enzymatic saccharification of polysaccharide enriched biomass.

The method of claim hemicellualses wherein the cooking process is followed by an oxygen delignification process. The trends, can be clearly seen in Fig.

US5591304A – Method for the use of enzymes in bleaching paper pulp – Google Patents

Enzymes, like other proteins, are ampholytes and possess many ionic groups. After enzyme treatment, each sample of pulp was washed with 3. The method of claim 12 wherein b and the addition of the enzyme are conducted substantially simultaneously. The use of enzymes to reduce chlorine requirements in pulp bleaching has been known and involves hemcellulases treatment of brownstock with a class of enzymes, known as hemicellulases, that hydrolyze the hemicellulose portion of wood pulp.

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The isolated xylan is therefore of similar structure to the indigenous xylan in wood pulp. It has been found, however, that the supernatants of T. This result is not surprising, because black liquor contains many aromatic and sulfide compounds that would be expected to be detrimental to enzyme hejicellulases.

International Pulp Bleaching Conference, Jun. 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. The method of claim pjlp wherein the enzyme preparation has a low cellulase content such that about FPU or less are added per ton of pulp. The amount of organochlorines discharged from a pulp mill is closely related to the bleaching process used and, in particular, to the amount of chlorine used for bleaching.

The present invention makes possible a three to four fold improvement in the “brightness boosting” power of the enzymes, to produce strong pulp that is light in color. Paper from bagasse Deforestation is a matter of concern for both the environmentalists and the paper industry this has forced Role of Biotechnology Bleachlng can be resourceful in: The amount of acid should be chosen so that the pH of the brownstock slurry will stabilize at roughly 7.

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Pulp that did not receive enzyme treatment was brought through the procedure, except enzyme was not added. Bleaching pulp with an enzyme system, containing thermostatic xylanose activity, obtained from a strain of Thermomonospora fusca and more specifically from a new strain with the designation KW3 and deposition number DSM Catalog X in the following manner.

Wood chips are debarked and then fed into a digester hemicdllulases they are cooked in a concentrated solution of sodium hydroxide and sodium sulfide.

The culture supernatant was harvested by centrifugation rpm, min. Hemicellulose in wood pulp consists of two types of structures with polysaccharide backbones: US USA en hemicellklases The inventors have found, for example that bleaching results using Trichoderma xylanase are three times better at pH 7. Joseleau, Svensk Papperstidn, While the supernatant may be used as such, it is preferably concentrated prior to its use. Washing and draining hemicellhlases the pulp remove most of the ink.

Biotechnology, silviculture, trees and other bioresources can be used to enhance the properties required in cellulose fibers Buschle-Diller and Ren. One highly convenient method of concentration involves a simple ultrafiltration designed to concentrate the supernatant fold and in any case recover for use yemicellulases concentrate containing essentially all enzymes which affect basic wood components, e.