Precipitation of lignin from softwood black liquor: An investigation of the equilibrium and molecular properties of lignin
Artikel i vetenskaplig tidskrift, 2015

Extracting lignin from black liquor is an attractive option in modern pulp mills as a unit process for a combined biorefinery. The lignin obtained can be utilized as solid fuel or other high-value added products. The precipitation equilibrium of kraft lignin from softwood black liquor was studied in this work. It was found that with decreasing pH and temperature, or increasing ion strength, the solid yield increases. Moreover, precipitated softwood kraft lignin has a higher molecular weight and contains lower amounts of carbohydrates and phenolic groups than lignin precipitated from mixed hardwood/softwood black liquor. The content of methoxyl groups in softwood kraft lignin was found to decrease with increasing precipitation yield. An empirical model for estimating the precipitation yield of lignin was proposed and evaluated.

LignoBoost process

Molecular weight of lignin

Carbohydrate analysis

1H and 13C NMR spectra of kraft lignin

Lignin precipitation

Softwood black liquor


Weizhen Zhu

Chalmers, Kemi och kemiteknik, Kemiteknik

Hans Theliander

Wallenberg Wood Science Center (WWSC)

Chalmers, Kemi och kemiteknik, Kemiteknik


1930-2126 (ISSN) 19302126 (eISSN)

Vol. 10 1 1696-1714


Hållbar utveckling


Fysikalisk kemi

Kemiska processer






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