Pressurized hot water flow-through extraction of birch sawdust with acetate pH buffer

Petri Kilpeläinen*, Veikko Kitunen, Andrey Pranovich, Hannu Ilvesniemi, Stefan Willför

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

14 Citations (Scopus)


Birch sawdust was extracted with a pressurized hot water (PHW) flow-through system. The pH of the extract was controlled during extraction by the addition of acetic acid/sodium acetate buffer. Three different pH levels, 4.0, 4.2, and 4.6, were used. Extraction temperatures were 160, 170, and 180 °C, with a constant 4 mL/min flow rate through the 50 mL extraction vessel. During PHW extraction with plain water, the end pH of the extract dropped from 5 to below 3. Buffers kept the pH of the extracts constant during the first 30 min of extraction. Compared to plain water, the use of buffers resulted in a lower yield of xylans during the 170 °C extraction. However, with the buffered system it was possible to obtain xylans from sawdust with a higher molar mass than plain water extraction. Acetic acid/sodium acetate buffer enabled control of the hydrolysis rate of xylans during extraction.

Original languageEnglish
Pages (from-to)5202-5218
Number of pages17
Issue number4
Publication statusPublished - Nov 2013
MoE publication typeA1 Journal article-refereed


  • Birch
  • Flow-through
  • pH buffer
  • Pressurized hot water extraction
  • Sawdust
  • Xylan


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