The impact of ionic strength on the molecular weight distribution (MWD) of lignin dissolved during softwood kraft cooking in a flow-through reactor
2016 (English)In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, no 6, 495-501 p.Article in journal (Refereed) PublishedText
The molecular weight distribution (MWD) of dissolved lignin as a function of time during kraft cooking of Scots pine (Pinus silvestris L) has been investigated, while the influence of sodium ion concentration ([Na+]) on the MWD was in focus. The kraft cooking was performed in a small scale flow-through reactor and the [Na+] was controlled by the addition of either Na2CO3 or NaCl. Fractions of black liquors (BL) were collected at different cooking times and the lignin was separated from the BL by acidification. The MWD of the dissolved lignin was analyzed by GPC. Results show that the weight average molecular weight (M-w) of dissolved lignin increases gradually as function of cooking time. An increase of [Na+] in the cooking liquor leads to M-w decrement. Findings from cooks with constant and varying [Na+] imply that the retarding effect of an increased [Na+] on delignification is related to the decrease in lignin solubility at higher [Na+].
Place, publisher, year, edition, pages
Walter de Gruyter, 2016. Vol. 70, no 6, 495-501 p.
flow-through reactor, lignin, molecular weight distribution (MWD), sodium ion concentration, softwood kraft cooking
Paper, Pulp and Fiber Technology
IdentifiersURN: urn:nbn:se:kth:diva-188715DOI: 10.1515/hf-2015-0103ISI: 000376680300002OAI: oai:DiVA.org:kth-188715DiVA: diva2:939837
QC 201606202016-06-202016-06-172016-06-20Bibliographically approved