Lignin separation from kraft black liquor by combined ultrafiltration and precipitation: a study of solubility of lignin with different molecular properties
Artikel i vetenskaplig tidskrift, 2016

Lignin from wood is by far the largest source of bio-based aromatic raw material. Today a vast amount of lignin is processes and incinerated in kraft pulp mills around the world. One possible option to utilize the energy surplus in a modern kraft pulp mill is to extract lignin from black liquor. Precipitation of lignin is one important step in an extraction process. This study investigates how the molecular size and functional groups of lignin influenced the precipitation yield. Cross-flow filtration was applied to fractionate lignin with different molecular weights from a black liquor, precipitation studies was made on the different fractions. The precipitated lignin was characterized by GPC, HPAEC-PAD and NMR analysis. The results show that it was possible to obtain a more homogenous lignin by fractionation using cross-flow filtration. It was found that the molecular properties of kraft lignin, i.e. molecular weight and functional groups, influenced the yield of lignin precipitation: at the same precipitation condition, lignin fraction with higher molecular weight has higher precipitation yield. Lignin fraction with lower molecular weight contains less amount of carbohydrates and methoxyl groups but higher amount of phenolic groups.

holzforschung

Lignin precipitation

fractionation

Lignin separation

1984

pulp

v38

Materials Science

llerstedt g

p151

c-13-nmr spectra

NMR analysis of kraft lignin

Ultrafiltration of black liquor

Författare

Weizhen Zhu

Kemi och kemiteknik, Kemiteknik, Skogsindustriell kemiteknik

Gunnar Westman

Kemi och kemiteknik, Kemi och biokemi, Organisk kemi

Wallenberg Wood Science Center (WWSC)

Hans Theliander

Wallenberg Wood Science Center (WWSC)

Kemi och kemiteknik, Kemiteknik, Skogsindustriell kemiteknik

Nordic Pulp and Paper Research Journal

0283-2631 (ISSN)

Vol. 31 270-278

Ämneskategorier

Pappers-, massa- och fiberteknik