Alkaline Pre-Treatment of Softwood Chips Prior to Delignification

Scots pine (Pinus sylvestris) chips were pre-treated with alkaline solutions (alkali charges of 1, 2, 3, 4, 6, and 8% of NaOH on the oven-dried wood material) at 130°C and 150°C for various treatment times (30, 60, 90, and 120 minutes). Under these conditions, 2.0–13.6% of the wood d.s. was dissolve...

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Bibliographic Details
Published in:Journal of wood chemistry and technology 2015-03, Vol.35 (2), p.146-155
Main Authors: Lehto, Joni, Alén, Raimo
Format: Article
Language:English
Subjects:
Acids
aliphatic acids
Aliphatic compounds
Alkaline pre-treatment
Biodegradation
Carbohydrates
Carboxylic acids
Chips
Degradation
Dissolution
extractives
hemicelluloses
Hydrolysates
Lignin
Organic chemistry
pine wood
Temperature effects
Wood
Wood products
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Summary:Scots pine (Pinus sylvestris) chips were pre-treated with alkaline solutions (alkali charges of 1, 2, 3, 4, 6, and 8% of NaOH on the oven-dried wood material) at 130°C and 150°C for various treatment times (30, 60, 90, and 120 minutes). Under these conditions, 2.0–13.6% of the wood d.s. was dissolved into the aqueous hydrolysates. The soluble organic fraction was primarily characterized in terms of carbohydrates (monosaccharides and oligo-/polysaccharides) and their alkali-catalyzed degradation products: aliphatic carboxylic acids containing, besides non-volatile hydroxy carboxylic acids, volatile formic and acetic acids. With increasing alkali charge, temperature, and time, the enhanced formation of various hydroxy monocarboxylic acids was detected. Under the most drastic pre-treatment conditions, two-thirds of the total organic fraction dissolved was composed of various aliphatic carboxylic acids, the residual material being mainly degraded lignin and extractives. Only relatively small concentrations of carbohydrates and trace amounts of furans were found.
ISSN:1532-2319
0277-3813
1532-2319
DOI:10.1080/02773813.2014.902964