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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The preferred range of pulp kappa numbers is between 20 and 40 for softwood and 10 to 20 for hardwood, however, the process of this invention can be applied to oxygen delignified pulps with even lower kappa numbers. Such extractants essentially solubilise the affected lignin component and suitable extractants include but are not limited to bases such as alkali metal hydroxides BleachinhDMF, dioxane, acetone, and alcohol.
Measurement of the cellulase and xylanase activities is described in Examples 1 and 2. In one embodiment of this invention, the process is carried out using a xylanase enzyme preparation produced by the fungus Trichoderma reesei. The key challenges are poor and technology obsolete, lacking ability in achieving economy scale and lack of skilled labor http: Sorghum straw for xylanase hyper-production by Thermomyces lanuginosus D2W3 under solid-state fermentation.
A process for the bleaching of a kraft pulp, a hardwood pulp or a softwood pulp in order to reduce the lignin content thereof which process includes the steps of: Inoculum Preparation Either spores or mycelium from an agar slant or a frozen test tube culture were added to ml of LB medium. The inventors have found, for example that bleaching results using Trichoderma xylanase are three times better at pH 7.
The method of claim 1 wherein the enzyme preparation has a low cellulase content such that not more than belaching 2, FPU are added per ton of pulp. A process for the bleaching of pulp which comprises the step of: In addition, the new strain KW3 shows a resistance towards crystal violet which is considered atypical for Thermomonospora fusca. Process for high consistency oxygen delignification of alkaline treated pulp followed by ozone delignification.
Biobleaching of pulp with enzymes have several advantages like: The treatment time will vary depending upon factors such as the result desired, the amount of substrate used, the amount of supernatant enzymes used, the specific activity of the supernatant, the type of pulp used, the temperature and the 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.
Hemicellulases in the bleaching of chemical pulps.
The resulting pulp is treated to remove the releasable lignin component using an appropriate extractant. Clearly, these alternatives incur significant costs.
The present inventors have discovered that incompletely or partially washed brownstock can be efficiently delignified with hemicellulase enzymes having a pH optima for activity below 6.
The C and E bleaching stages reduce the lignin content of the pulp to less than 0. The crude enzyme preparation obtained as described in example 1 was concentrated by use of an ultrafiltration membrane molecular weight cut off 10, to a concentration of xylanase units per milliliter. Topics Discussed in This Paper. While the well washed samples of brownstock used in our laboratory testing had residual soda levels below 1 Kg per ton, one often finds residual soda levels ten times this high in operating mills.
This, in turn, leads to a significantly reduced chlorine requirement to bleach pulp. Studies of the extracellular xylanase activity of some thermophilicactinonycetes.
Novo teaches that this compromise pH 6. A method of making a paper comprising selecting the wood pulp produced by the method of claim 5 and using said pulp to produce the paper. The degree of enhanced brightness due to enzyme treatment relative to an untreated control sample is shown in FIG.
Hemicellulose in wood pulp consists of two types of structures with polysaccharide backbones: The results are shown in Table 2. It enhances fibrillation to give stronger paper Eriksson, The process according to claim 1 wherein the pulp is selected from the group consisting of: The same procedure showed 4 mannanase isoenzymes.
US5591304A – Method for the use of enzymes in bleaching paper pulp – Google Patents
Modification of xylanase to improve thermophilicity, alkalophilicity and thermostability. After 2 hours time the pulp suspension was filtered through a Whatman No.
Moreover, in one preferred embodiment, this invention comprises the use of enzyme preparations with low contaminating cellulase levels, i. The procedures of Example 6 were carried out, except several samples of brownstock were adjusted to equilibrate at pH hemiclelulases to 8.
The enzyme boosted the brightness of the bleached pulp by 3 ISO points, as compared to 8 ISO points with pH 5 enzyme treatment on well-washed pulp. It also improves the runnability of the pulping, bleaching and papermaking processes. Paper is manufactured from pulp by sulphite and sulphate process.