A new method for the titration of free phenolic groups in pulps
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Rabi Behrooz Eshkiki
Abstract
A fast and semi-quantitative wet chemical method was developed for the titration of free phenolic groups in residual lignins of pulps. The method is based on selective chlorine dioxide reaction with phenolic units of lignin at 0°C. A known amount of ClO2 is reacted for up to 30 min with various substrates and ClO2 consumption is measured. Experiments with monomeric lignin-like model compounds, a dioxane/HCl lignin (isolated from kraft pulp), kraft pulp, and one thermomechanical pulp (TMP) were performed. The ideal stoichiometric consumption of 1 mol of ClO2 per Ar-OH was approximated in a few cases. More model compound experiments are necessary to establish the possibilities and limitations of the method, but the results of these preliminary experiments are promising. First studies on pulps and comparison of the data with those obtained by 13C NMR analysis on dioxane/HCl lignins showed some deviations in the first instance, which were attributed to reaction of the intermediates HClO and Cl2 involved in the overall mechanism. However, using DMSO as HClO trapping agent improved the ClO2/Ar-OH stoichiometric ratio close to the theoretical value of 2, which essentially yielded better results. This improved stoichiometry was verified for three model compounds, one kraft pulp and one TMP, yielding results were similar to those obtained by 13C NMR analysis.
©2007 by Walter de Gruyter Berlin New York
Artikel in diesem Heft
- To all readers, authors and subscribers
- Vapor-phase diethyl oxalate pretreatment of wood chips: Part 1. Energy savings and improved pulps
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- Size exclusion chromatographic and UV-VIS absorption analyses of unbleached and bleached softwood kraft pulps using LiCl/1,3-dimethyl-2-imidazolidinone as a solvent
- A new method for the titration of free phenolic groups in pulps
- Adsorption of water-soluble organic dyes on ferrofluid-modified sawdust
- Mechanical properties and creep behavior of lyocell fibers by nanoindentation and nano-tensile testing
- Deformation behavior of wet lignocellulosic fibers
- Changes in physical, mechanical and chemical properties of wood during sterilisation by gamma radiation
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- Transverse mechanical behaviour and moisture absorption of waterlogged archaeological wood from the Vasa ship
- Determination of residual stress in bonded wood components
- Decohesion of glue bonds in wood connections
- Delamination assessment after drilling medium-density fibreboard (MDF) by digital image analysis
- Effects of thinning and fertilisation on tracheid dimensions and lignin content of Norway spruce
- Detection of β-1-4-galactan in compression wood of Sitka spruce [Picea sitchensis (Bong.) Carrière] by immunofluorescence
- Laboratory and outdoor water repellency and dimensional stability of southern pine sapwood treated with a waterborne water repellent made from resin acids
- Evidence of fungicidal and termicidal properties of Prunus africana heartwood extractives
- The effectiveness of silica treatments against wood-boring invertebrates
- Sap-staining fungi from logs and boards of two commercially important pines in Korea
- Improved quantitative determination of benzalkonium chloride in treated wood by liquid chromatography
- Obituary Anders Björkman (1920–2006)
Artikel in diesem Heft
- To all readers, authors and subscribers
- Vapor-phase diethyl oxalate pretreatment of wood chips: Part 1. Energy savings and improved pulps
- Vapor-phase diethyl oxalate pretreatment of wood chips: Part 2. Release of hemicellulosic carbohydrates
- Size exclusion chromatographic and UV-VIS absorption analyses of unbleached and bleached softwood kraft pulps using LiCl/1,3-dimethyl-2-imidazolidinone as a solvent
- A new method for the titration of free phenolic groups in pulps
- Adsorption of water-soluble organic dyes on ferrofluid-modified sawdust
- Mechanical properties and creep behavior of lyocell fibers by nanoindentation and nano-tensile testing
- Deformation behavior of wet lignocellulosic fibers
- Changes in physical, mechanical and chemical properties of wood during sterilisation by gamma radiation
- Penetration of poly(ethylene glycol) into wood cell walls of red pine
- Transverse mechanical behaviour and moisture absorption of waterlogged archaeological wood from the Vasa ship
- Determination of residual stress in bonded wood components
- Decohesion of glue bonds in wood connections
- Delamination assessment after drilling medium-density fibreboard (MDF) by digital image analysis
- Effects of thinning and fertilisation on tracheid dimensions and lignin content of Norway spruce
- Detection of β-1-4-galactan in compression wood of Sitka spruce [Picea sitchensis (Bong.) Carrière] by immunofluorescence
- Laboratory and outdoor water repellency and dimensional stability of southern pine sapwood treated with a waterborne water repellent made from resin acids
- Evidence of fungicidal and termicidal properties of Prunus africana heartwood extractives
- The effectiveness of silica treatments against wood-boring invertebrates
- Sap-staining fungi from logs and boards of two commercially important pines in Korea
- Improved quantitative determination of benzalkonium chloride in treated wood by liquid chromatography
- Obituary Anders Björkman (1920–2006)
