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phase of the cooking. Analogous to the alkaline processes, the impregna- tion of the wood chips during the acid sulfite pulping proceeds by two separate mechanisms: penetration as mass flow of liquid and solute into the chips and diffu- G. Koch et al.: Topochemical Characterisation of Delignification 611 Holzforschung / Vol. 57 / 2003 / No. 6 © Copyright 2003 Walter de Gruyter · Berlin · New York Holzforschung 57 (2003) 611–618 Topochemical Investigations on Delignification of Picea abies [L.] Karst. during Alkaline Sulfite (ASA) and Bisulfite Pulping by Scanning UV

CHEMICAL PULPING Nordic Pulp & Paper Research Journal Vol 31 no (3) 2016 379 Some process aspects on single-stage bisulfite pulping of pine Raghu Deshpande, Lars Sundvall, Hans Grundberg and Ulf Germgård KEYWORDS: Activation energy, Bisulfite pulping, Cellulose, Extractives, Glucomannan, Lignin, Pine, Spruce, Thiosulfate, Xylan SUMMARY: Sulfite pulping of pine is well-known to be a risky process because problematic lignin conden- sation reactions can occur resulting in poor pulp quality. However, sulfite pulping of pine is interesting of economic

Water sorption and surface composition of untreated or oxygen plasma-treated chemical pulps Gilbert Carlsson and Goran Strom, Institute for Surface Chemistry, Stockholm, Sweden Goran Annergren, SCA Research AB, Sundsvall, Sweden Keywords: Kraft pulps, Bisulfite pulps, Wettability, Water sorption, Plasma, Oxygen, Surface composition, ESCA. SUMMARY: Three kraft pulps and one bisulphite pulp have been studied. The surface chemical composition was deter- mined by means of ESCA, and water sorption was studied using a dynamic contact angle tester. The surface

Unconventional strength additives Makhlouf Laleg and Zvan I. Pikulik, Pulp and Paper Research Institute of Canada, Pointe Claire, Quebec, Canada Keywords: Additives. Wet webs, Wet strength, Dry strength, Cationic compounds, Aldehyde groups, Starch. Zirconium compounds. Bisulfite pulps. Kraft pulps. Thermomechanical pulps. SUMMARY: Unconventional additives for increasing the strength of never-dried wet webs, dry paper and rewetted paper were investigated. It was found that handsheets made from bisulphite pulps or kraft pulps can be reinforced by cationic

hemicellulose sugar residues ( Table 2 ). As the LS under study were extracted from softwood, most of the hemicellulose residues are in the form of galactoglucomannan. The major part of the residual sugars is recovered in the low MW fraction UF<1. This means that they are mostly in the form of monomers or oligomers, and not attached to the lignin, which allows them to pass across the membranes. This finding seems to be plausible as the hemicelluloses are easily hydrolyzed to monomers and oligomers under the acidic conditions of bisulfite pulping, whereas the ether and ester

the results obtained so far, it can be concluded that wet storage of beech wood logs efficiently prevents the formation of chromophore compounds which negatively affect acid bisulfite pulping. 1)Dedicated to Prof. Horst Nimz at his retirement as Editor-in- Chief of Holzforschung (1993–2003) Keywords: bisulfite process; dissolving pulp; Fagus syl- vatica L.; log storage; UV microspectrophotometry. Introduction For wood dissolving pulp production, only acid bisulfite cooking and the prehydrolysis kraft process are of major practical importance. Unlike paper grade

Abstract

Spent sulfite liquor derived from magnesium bisulfite pulping of beech was electrolyzed in a pilot-plantelectrolysis cell. During the electrochemical treatment (125 mA cm−2; 60°C; 180 min), desalination of the anolyte took place and the magnesium concentration was reduced to approximately 60%. In addition, the pH decreased from 5 to 1. Three differently treated liquors (SSL pH 5; SSLe pH 2.5; SSLe pH 1) were chosen for further analysis. The average molar mass of the fractions was determined by size exclusion chromatography. Extended electrolysis time increased the molar mass of the lignosulfonates (M w: SSL pH 5, 5700 g mol−1; SSLe pH 2.5, 6500 g mol−1; SSLe pH 1, 7400 g mol−1). The content of phenolic hydroxyl and sulfonic acid groups did not undergo significant changes. Nevertheless, lignosulfonates obtained after electrolysis showed higher charge densities than the unmodified product (SSL pH 5, 1590 μeq g−1; SSLe pH 2.5, 1760 μeq g−1; SSLe pH 1, 1920 μeq g−1). Separation of the liquors into five fractions was performed using four ultrafiltration membranes (100, 50, 10 and 1 kDa). This allowed detailed structural analysis of high- and low-molar-mass lignosulfonate fractions in terms of the modifications induced by electrolysis.

assumed that the degree of polymerisation äs well äs the molecular mass distribution of the native celluloses show about the same values independent of the age and kind of tree. \ \ Treiber/1009 A. Greune and D. Fengel: Elektronenmikroskopische Unter- suchungen zum Magnesiumbisulfit-Aufschluß von Kiefernholz. 1. Mitt. Tränkverhalten von Kiefernholz verschiedener Feuch- tigkeitsgehalte. (Electron microscopic investigations on mag- nesium bisulfite pulping of pine wood. Part I. Impregnation be- haviour of pine wood with various moisture contents.) Das Papier 42 (1988): 4

corresponding soda pulps. Treiber/1222 A.F.A. Wallis and R.H. Wearae: Preparation of chemical cellulose from radiata pine bisulfite pulps without using chlorine-containing reagents. Appita45 (1992): 4, 239-242. Cellulose suitable for a range of applications including derivatisa- tion (dissolving pulps) may be prepared by cold alkali extraction (4 -> 11% NaOH; 20 °C) of radiata pine tjisulfite pulp which had been bleached at 20-25% stock concentration with hydrogen peroxide (2-4%). Sequential treatment of the pulp with peroxide and alkali without interstage washing also gave

T. J. Smith et al: Chlorohydroxypyrone in Filtrates of Chlorine Bleached Pulps 423 Holzforschung 48 (1994) 423-428 An Ubiquitous Chlorohydroxypyrone in Filtrates from Chlorine Prebleaching of Alkaline Pulps By Terrence J. Smith, ROSS H. Wearne and Adrian F. A.Wallis Division of Forest Products, CSIRO, Clayton, Victoria, Australia Keywords Eucalyptus spp. P in us radiata Alkaline pulps Bisulfite pulps Chlorine Chlorine dioxide Bleaching effluents 4-Chloro-3-hydroxy- 2//-pyran-2-one Hemicelluloses 3-Deoxypentonic acid end-groups Summary An abundant chlorinated