Abstract
Hot water treatments (HWTs) of unbleached hardwood kraft
pulps under various process conditions were conducted to
extract the xylan and thus produce a high-purity
cellulosic pulp that could be used in dissolving
applications. Increasing treatment temperature up to 240
°C increased the removal of xylan over the degradation of
cellulose in birch pulp, but this effect was minor at
higher temperatures. Addition of acetic acid lowered the
treatment intensity needed to reach a certain degree of
pulp purity, but did not improve the selectivity in xylan
removal compared to water-only experiments. HWTs of
eucalyptus pulp, with lower xylan content than birch
pulp, produced cellulosic fibers with higher degree of
polymerization at a given pulp purity. Under selected
operational conditions (240 °C for 10 min) in a
flow-through reactor, and provided that the HWTs were
applied before bleaching, the chemical and macromolecular
properties of water-treated pulps may be suitable for
their conversion to viscose. Moreover, at high flow rates
(200-400 mL/min), the extracted xylan was recovered from
the aqueous hydrolysate in high yield and with relatively
high molar mass (~10 kDa). Based on the results of this
study, HWTs of hardwood kraft pulp are suggested as a
simple and green method to produce high-purity cellulose
and polymeric xylan for high value-added applications.
Original language | English |
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Pages (from-to) | 5133-5145 |
Number of pages | 13 |
Journal | Cellulose |
Volume | 24 |
Issue number | 11 |
DOIs | |
Publication status | Published - 1 Nov 2017 |
MoE publication type | A1 Journal article-refereed |
Keywords
- cellulose
- dissolving pulp
- hot water treatment
- kraft pulping
- viscose
- xylan