About structural changes of lignin during kraft cooking and the kinetics of delignification
Journal article, 2017

Wood meal was submitted to kraft cooking in a small-scale flow-through reactor and the structural changes of lignin have been investigated. The rate determining steps in kraft cooking were in focus. Based on two-dimensional nuclear magnetic resonance (2D-NMR) measurements on lignin fractions extracted at different cooking times from the black liquor, it was observed that the main lignin reactions occur within 10-20 min and thus the kinetics of the chemical reaction cannot be the rate-determining step. On the other hand, the molecular weight (MW) of lignin is shifted towards larger fragments in the course of cooking time but the MW decreases with increasing ionic strength. Obviously, the kinetics of the delignification are strongly dependent on solubility and/or mass transport at the cell wall level. At chip size level, the mass transport of cooking chemicals into the wood chip may influence the overall kinetics in the initial part of the cooking. At longer cooking times the concentration of chemicals becomes sufficiently high in the wood chips, and the delignification is progressively governed by solubility and/or mass transport of lignin molecules occurring at the cell wall level.

Size-Exclusion Chromatography

N-Dimethylacetamide

kraft

2D HSQC NMR

flow-through reactor

dissolved kraft lignin

C-13 NMR

ATR-IR

Lithium Chloride/N

Mobile-Phase

delignification

kinetics

Author

Cecilia Mattsson

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

Merima Hasani

Wallenberg Wood Science Center (WWSC)

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

Binh Dang

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

Maxim Mayzel

University of Gothenburg

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. 71 7-8 545-553

Subject Categories

Paper, Pulp and Fiber Technology

DOI

10.1515/hf-2016-0190

More information

Latest update

8/24/2018