Ozonation of conventional kraft and SuperBatch residual lignins in methanol/water and water
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P. Widsten
Abstract
The chemistry of ozone bleaching of chemical pulps was explored by ozonating residual lignins isolated from conventional kraft and SuperBatch pulps in methanol/water medium to detect possible differences in the reactivity of the two types of lignin. SuperBatch lignin was ozonated also in water to study the effect of ozonation medium on the lignin reactivity. The residual lignins were found to display similar reactivities in methanol/water, implying that ozonation should result in equal delignification rates for both conventional kraft and SuperBatch pulps unless the rates of reagent diffusion in the pulps are different. The lignins were partly oxidized to volatile and nonvolatile low-molecular weight oxidation products by the so-called “peeling mechanism”, according to which oxidation products go into solution and insoluble reaction products resemble the starting lignins. The reaction products obtained upon ozonation of SuperBatch lignin in neutral water resembled those formed in methanol/water, but their yield was much lower. This is probably due to the better solubility of lignin in methanol/water than in water and/or higher degradability of lignin by ozone than by radicals formed as ozone decomposition products.
Copyright © 2004 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- Bioactive phenolic substances in industrially important tree species. Part 1: Knots and stemwood of different spruce species
- Oligolignans in Norway spruce and Scots pine knots and Norway spruce stemwood
- Delignification mechanism during high-boiling solvent pulping. Part 6: Changes in lignin structure analyzed by 1H-13C correlation 2-D NMR spectroscopy
- Ozonation of conventional kraft and SuperBatch residual lignins in methanol/water and water
- Relationship between dissolution of fiber materials and development of pulp strength in alkaline peroxide bleaching of mechanical pulp
- Nondestructive estimation of tracheid length from sections of radial wood strips by near infrared spectroscopy
- Heat transfer model for estimating pinene emissions from hot-pressing softwood flakeboard
- Monitoring creep-rupture in oriented strandboard using acoustic emission: Effects of moisture content
- Adhesives made from isocyanates and pyrolysis oils for wood composites
- Effect of wood acidity and catalyst on UF resin gel time
- Estimation of green moisture content distribution in hemfir timber by stochastic simulation
- Theoretical exploration of factors affecting dielectric constants of masson pine
- Shrinkage stress of wood during drying under superheated steam above 100°C
- Exploratory evaluation of oscillation drying for thick hemlock timbers
- A biopulping mechanism: Creation of acid groups on fiber
- Enzymatically polymerized phenolic compounds as wood preservatives
- Evaluation of borate formulations as wood preservatives to control subterranean termites in Australia
