The impact of ionic strength on the molecular weight distribution (MWD) of lignin dissolved during softwood kraft cooking in a flow-through reactor
Journal article, 2016

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+].

flow-through reactor

lignin

molecular weight distribution (MWD)

softwood kraft cooking

sodium ion concentration

Author

Binh Dang

Chalmers, Chemistry and Chemical Engineering, Chemical Technology, Forest Products and Chemical Engineering

Harald Brelid

Södra Innovation

Hans Theliander

Chalmers, Chemistry and Chemical Engineering, Chemical Technology, Forest Products and Chemical Engineering

Wallenberg Wood Science Center (WWSC)

Holzforschung

0018-3830 (ISSN) 1437-434X (eISSN)

Vol. 70 6 495-501

Subject Categories

Paper, Pulp and Fiber Technology

DOI

10.1515/hf-2015-0103

More information

Latest update

9/6/2018 1