Improved yield and pulp properties by adding sodium dithionite in kraft pulping of spruce
(English)Manuscript (preprint) (Other academic)
The reductive effect of sodium dithionite (Na2S2O4) on sugar model compounds was investigated. Results revealed that parts of open aldehyde forms in the sugars were reduced to the corresponding alditols by Na2S2O4. The possibilities to improve yield and other properties of spruce kraft pulp by addition of Na2S2O4 were also investigated. The yield, carbohydrate compositions, Klason lignin, intrinsic viscosity, kappa number of pulp, tensile strength and optical properties of resultant paper sheets were analysed. Compare with the normal kraft pulp without Na2S2O4 addition, yield together with viscosity were increased, while Klason lignin and kappa number were decreased. The brightness and tensile strength of paper sheet were also improved. The only drawback for adding sodium dithionite to white liquor was higher reject content. This could be overcome by pre-impregnation with Na2S2O4 before kraft pulping process. The possibility of applying Na2S2O4 in industrial kraft pulp mill was discussed, including how to generate Na2S2O4 from black liquor thereby closing the process.
sodium dithionite, reductive reaction, peeling reaction, kraft pulping, pulp quality
Research subject Fibre and Polymer Science
IdentifiersURN: urn:nbn:se:kth:diva-150393OAI: oai:DiVA.org:kth-150393DiVA: diva2:742764
FunderKnut and Alice Wallenberg Foundation, 8102
QS 20142014-09-022014-09-022015-04-14Bibliographically approved