Abstract
Sodium sulphite pulping of Scots pine chips in the
initial pH range of 7.5-9 was investigated at 180°C and
165°C (for 120-240 min), using chemical charges between
25 and 50% and anthraquinone (AQ) charges 0-0.2%. As a
result, pulps with yields of 52-73% and kappa numbers of
35-106 were produced. Delignification was accelerated by
higher Na2SO3 charges and temperatures, and by AQ
addition, whereas the effect of initial pH was
negligible. The high pulp yields at a given kappa number
were attributable to high retention of hemicelluloses,
especially that of galactoglucomannan. The relatively low
viscosities of pulps were apparently caused by
depolymerisation of cellulose by sulphite. The sulphonic
acid groups in the pulps correlated well with the
residual lignin content, although some sulphonation of
polysaccharides may also be possible. The results
indicate that pulping of softwood in buffer-free (without
Na2CO3 and/or NaOH) sodium sulphite liquor may result in
pulps with tailored characteristics.
Original language | English |
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Pages (from-to) | 603-609 |
Journal | Holzforschung |
Volume | 70 |
Issue number | 7 |
DOIs | |
Publication status | Published - 2016 |
MoE publication type | A1 Journal article-refereed |
Keywords
- anthraquinone (AQ)
- galactoglucomannan (GGM)
- high yield pulp
- lignin
- neutral sulphite pulping (NS)
- neutral sulphite semi-chemical pulping (NSSC)
- sodium sulphite
- softwood
- sulphonic acid group