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Dissolution of fibre material in alkaline pre-treatment and refining of spruce CTMP

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Published/Copyright: January 17, 2006
Holzforschung
From the journal Volume 60 Issue 1

Abstract

The chemistry of chemithermomechanical pulping (CTMP) was assessed by chemical pre-treatment of spruce chips, followed by laboratory-scale refining. Pre-treatments with alkali, sulfite, alkaline sulfite and alkaline peroxide liquors were carried out at 40°C, 60°C and 80°C. The sodium hydroxide dosages were 1% and 2% and the sodium sulfite and hydrogen peroxide dosages were 2%, 4% and 6% on a dry wood basis. Process water samples were taken before and after refining. Alkali consumption in the pre-treatments and the amount and composition of released wood components were determined. A major part of the alkali was consumed in the alkaline and alkaline sulfite pre-treatments. In the alkaline peroxide pre-treatments, however, alkali consumption was considerably lower. Acetic acid was the main wood component released to the process waters in alkaline pre-treatments. Pectins, determined as galacturonic acid and rhamnose by acid methanolysis, were also released to some extent, as well as easily soluble polysaccharides. After fibre separation in refining, more hemicelluloses and pectins were released. There was a significant difference between the degree of demethylation for pectins and the degree of deacetylation for galactoglucomannans after the pre-treatments. The diffusion of chemicals into the secondary wall layers seemed to be slower than the liquor penetration into the porous middle lamella through the pit pores. Up to 10% of the pectins were dissolved in the process waters as a result of depolymerisation and extensive demethylation. The residual amount of pectins in the fibres, however, was determined to be as low as 65–70% of the initial pectin content.

Keywords: chemithermomechanical pulping; deacetylation; demethylation; hemicelluloses; pectins; Picea abies; sulfonation
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Corresponding author. Jonas Konn, Laboratory of Wood and Paper Chemistry, Åbo Akademi University, Porthansgatan 3, FI-20500, Turku/Åbo, Finland

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Published Online: 2006-01-17
Published in Print: 2006-01-01

©2006 by Walter de Gruyter Berlin New York

Articles in the same Issue

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  2. XPS in combination with mercurization – incorporation of mercury into different morphological parts of an unbleached softwood kraft pulp
  3. Comparison of different XPS methods for fiber surface analysis
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  5. Rapid analysis of transgenic trees using transmittance near-infrared spectroscopy (NIR)
  6. Calibration of NIR to assess lignin composition (H/G ratio) in maritime pine wood using analytical pyrolysis as the reference method
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  8. Creating water-repellent effects on wood by treatment with silanes
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  13. Machinability investigation of medium-density fibreboard
  14. Rolling shear modulus and damping factor of spruce and decayed spruce estimated by modal analysis
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  16. Distribution and characterisation of discolouring substances in Norway spruce (Picea abies L. Karst.) pulp wood stored under water sprinkling
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https://doi.org/10.1515/HF.2006.007
Keywords for this article
chemithermomechanical pulping; deacetylation; demethylation; hemicelluloses; pectins; Picea abies; sulfonation

Articles in the same Issue

  1. Morphological and chemical variations between juvenile wood, mature wood, and compression wood of loblolly pine (Pinus taeda L.)
  2. XPS in combination with mercurization – incorporation of mercury into different morphological parts of an unbleached softwood kraft pulp
  3. Comparison of different XPS methods for fiber surface analysis
  4. Antifungal diterpenes from the bark of Cryptomeria japonica D. Don
  5. Rapid analysis of transgenic trees using transmittance near-infrared spectroscopy (NIR)
  6. Calibration of NIR to assess lignin composition (H/G ratio) in maritime pine wood using analytical pyrolysis as the reference method
  7. Dissolution of fibre material in alkaline pre-treatment and refining of spruce CTMP
  8. Creating water-repellent effects on wood by treatment with silanes
  9. Rheology of latex films bonded to wood: influence of cross-linking
  10. Reinforcing potential of wood pulp-derived microfibres in a PVA matrix
  11. Diffusion of tritiated water into water-saturated wood particles
  12. Interrelationship between the severity of heat treatments and sieve fractions after impact ball milling: a mechanical test for quality control of thermally modified wood
  13. Machinability investigation of medium-density fibreboard
  14. Rolling shear modulus and damping factor of spruce and decayed spruce estimated by modal analysis
  15. Structural changes in activated wood-based carbons: correlation between specific surface area and localization of molecular-sized pores
  16. Distribution and characterisation of discolouring substances in Norway spruce (Picea abies L. Karst.) pulp wood stored under water sprinkling
  17. Decay resistance, extractive content, and water sorption capacity of Siberian larch (Larix sibirica Lebed.) heartwood timber
  18. Biological resistance of wood treated with zinc and copper metaborates
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