The impact of ionic strength on the molecular weight distribution (MWD) of lignin dissolved during softwood kraft cooking in a flow-through reactor
Artikel i vetenskaplig tidskrift, 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+].

softwood kraft cooking

flow-through reactor


sodium ion concentration

molecular weight distribution (MWD)


Binh Dang

Chalmers, Kemi och kemiteknik, Kemiteknik, Skogsindustriell kemiteknik

Harald Brelid

Södra Innovation

Hans Theliander

Wallenberg Wood Science Center (WWSC)

Chalmers, Kemi och kemiteknik, Kemiteknik, Skogsindustriell kemiteknik


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

Vol. 70 495-501


Pappers-, massa- och fiberteknik