Hardwood kraft pulping

Kirkpatrick, N. Reid, I.D. Ziomek, F. Paice, M.G. Biological bleaching of hardwood Kraft pulp using Trametes Coriolus) versicolor immobilized in pol3uirethane foam. Appl. Microbiol. Biotechnol. 1990, 33, 105-108. 

Paice, M.G. Jurasek, L. Ho, C. Bourbonnais, R. Archibald, F. Direct biological bleaching of hardwood kraft pulp with the fungus, Coriolus versicolor. Tappi J. 1989, 72, 217-221. 

Tran, A.V. Chambers, R.P. Delignification of an unbleached hardwood Kraft pulp by Phanerochaete chrysosporium. Appl. Microbiol. Technol. 1987, 25, 484-490. 

Other Reactions In addition to the direct stabilizing effect of the uronic acid groups, the relatively high yield of hardwood kraft pulp is also due to the readsorption of xylan on the fibers (Fig. 7-35). After kraft pulping of softwood, the glucomannan remaining in the pulp still contains traces of... 

Figure 6A. The effect of heating rate on the integral thermogram of a hardwood kraft pulp. All curves are for pulp BBC. Rate of heating from left to right 5°, 10°, 20°, 40 and 80°C/min.

This poses a question concerning deacidification. If a deacidification procedure does not remove aluminum from the cellulose carboxyls, will the paper have the stability that one would expect from a paper with an alkaline filler In an attempt to answer this question, a series of hand-sheets was made from a hardwood kraft pulp. This pulp was selected because (a) it had a carboxyl content of 5.75 mmol/100 g pulp, which is similar to that of some old papers (b) it was easy to beat in a laboratory beater and (c) the physical properties of the handsheets were in the "old... 

A hardwood kraft pulp was used for handsheets. This had a carboxyl content of about 5.75 mmols/100 g pulp. 

In this section, data are presented on the effects of deacidification on (a) oxidizable material extracted from some old papers (b) changes in physical properties of these old papers and (c) changes in physical properties of several multicolored maps. The results of some experiments on the interaction of metal ions with a hardwood kraft pulp are given, and discussed in relation to deacidification and probable stability. A series of handsheets made from a hardwood kraft pulp, after treatment of the pulp with various metal ions, were studied in relation to the effects of deacidification on the removal of aluminum and on stability before and after... 

The exact formation of salts with cellulosic carboxyls has never been resolved. The carboxyl content of the hardwood kraft pulp is about 0.0575 mmol/gram of pulp. If one adds up the meq of metals that have been sorbed by g cellulose, the milliequivalents of metals exceeds the milliequivalents of carboxlys. If one assumes that 1 mmol of metal reacts with 1 meq of carboxyl, then there is a surplus of carboxyls. It would appear that the reaction of metals with carboxyls is nonstoichio-metric. Using aluminum sulfate as an example, the product of the... 

In order to translate this into the real world of papermaking, and of deacidification, handsheets were made under controlled conditions from the hardwood kraft pulp. The pulp was first treated with calcium acetate solution to cover the carboxyls with calcium. Some of this pulp was then treated with A12(S04)3 solution. Handsheets were then made from the original pulp, from the calcium pulp, and from the aluminum pulp. Some of these handsheets were deacidified. The metals contents of these handsheets were then determined and the data are given in Table XVII. 

Neither magnesium acetate nor magnesium bicarbonate was able to remove aluminum from a hardwood kraft pulp in which the aluminum presumably was attached to the carboxyls. 

Sun, Y., and Argyropoulos, D. S., Fundamentals of high pressure oxygen and low pressure oxygen-peroxide (Eop) dehgnification of softwood and hardwood kraft pulps A comparison, J. Pulp Paper Sci. 21(6), 1185-190 (1995). 

Katagiri et al. [104] investigated the effects of MnP on pulp bleaching in a solid culture system in which P. chrysosporium and T. versicolor were incubated with unbleached hardwood kraft pulp. In five days cultures, the brightness increase was 30 and 15% ISO-points, respectively. 

In another study, when MnP from the fungus IZU-154 was incubated with softwood or hardwood kraft pulp in the presence of Mn +, glucose oxidase and glncose, the amount of effective chlorine needed to increase brightness was substantially lowered. After the enzyme treatment, chlorine consumption required to increase the brightness to 85% ISO decreased 51, 66, and 69% for normal-lignin-content softwood kraft pnlp, low-lignin-content softwood kraft pulp and hardwood kraft pulp respectively [109]. 

K Addleman, T Dumonceaux, MG Paice, R Bourbonnais, F Archibald. Production and characterization of Trametes versicolor mutants unable to bleach hardwood kraft pulp. Appl Environ Microbiol 61(10) 3687-3694, 1995. 

R Kondo, K Harazono, K Sakai. Bleaching of hardwood kraft pulp and manganese peroxidase secreted from Phanerochaete sordida YK-624. Appl Environ Microbiol 60(12) 4359-f363, 1994. 

N Kirkpatrick, I Reid, E Ziomek, MG Paice. Biological bleaching of hardwood kraft pulp using Trametes (Coriolus) versicolor immobilized in polyurethane foam. Appl Microbiol Biotechnol 33 105-109, 1990. 

R Kondo, K Kurashiki, K Sakai. In vitro bleaching of hardwood kraft pulp by extracellular enzymes excreted from white rot fungi in a cultivation system using a membrane filter. Appl Environ Microbiol 60 921-926, 1994. 

K Ehara, Y Tsutsnmi, T Nishida. Role of Tween 80 in hiohleaching of nnbleached hardwood kraft pulp with manganese peroxidase. J Wood Sci 46(2) 137-142, 2000. 

The isolation of enzymatic residual LCCs from unbleached softwood Kraft pulps is a well-established procedure producing preparations with high yields (estimated as lignin in isolated preparations per lignin in the original pulp) and relatively low enzyme impurities [46 8]. In contrast, significant problems are encountered when similar procedures are applied to the isolation of enzymatic residual LCCs from hardwood Kraft pulps and semi-bleached pulps [47]. Low yields (25-30%) make these preparations nonrepresentative for the whole pulp LCC. A very large amount of protein impurities... 

Aspen wood has a relatively low lignin content when compared with other pulped hardwoods, which makes the pulp easier to bleach. Typical aspen hardwood kraft pulp fibers have length 1.0-1.3 mm and width about 18-19 pm. The wall thickness is around 2-3 pm. 

Under alkaline cooking conditions some of the 4-0-MeGlcA residues present in hardwood and softwood xylans are converted into unsaturated hexenuronic acid residues (HexA) by -elimination of methanol. In an early study (4) employing MALDI-MS, we were able to identify a number of different HexA and 4-0-MeGlcA containing xylooligosaccharides in the hydrolysate obtained after endoxylanase treatment of an unbleached hardwood kraft pulp. 

Figure 8, MALDI mass spectrum (negative-ion mode) of the acidic xylooligosaccharides obtained by endoxylanase treatment of a hexenuronoxylan isolated from alkaline peroxide bleached hardwood kraft pulp. The spectrum consists of two series of peaks assigned to the molecular ions [M-Hf of xylooligosaccharides with varying chain lengths and containing one hexenuronic acid (HexA) residue or one 4-O-methylglucuronic acid ( 4-0-...

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