Filtration properties of kraft lignin:The influence of xylan and precipitation conditions
Artikel i vetenskaplig tidskrift, 2017

LignoBoost lignin powder was dissolved together with xylan and re-precipitated. The influence of the (i) precipitation temperature, (ii) rate of acidification and (iii) final pH of the slurries on the resulting material and its filtration properties was investigated. In the case of slow acidification, larger agglomerates were obtained for slurries with higher precipitation temperatures as well as with higher ionic strengths. Fast acidification led to a more heterogeneous formation of particles, having a broader particle size distribution, compared to slow acidification. Chemical analysis of different layers of the filter cakes formed revealed that xylan was distributed evenly on the solid lignin, reinforcing the hypothesis that xylan is sorbed onto the lignin agglomerates when precipitated together with lignin. Furthermore, the resulting lignin-xylan mixtures were found to be more difficult to filter in the case of a higher final pH of the slurry (pH 4), close to the pKa values of the carboxylic acid groups of xylan, compared to lower pH values (pH 1-3). This is likely the result of an increase in electrostatic repulsive interactions between the particles/agglomerates at higher pH: a locally more porous solid structure is formed, leading to a larger solid/liquid surface area during filtration.

Kraft softwood lignin

Cake filtration

Xylan

Acid precipitation

Particle properties

Författare

Julie Durruty

Chalmers, Kemi och kemiteknik, Kemiteknik, Skogsindustriell kemiteknik

Tor Sewring

Chalmers, Kemi och kemiteknik, Kemiteknik, Skogsindustriell kemiteknik

H. Schneider

Unknown organization

L. Schneider

Unknown organization

Tuve Mattsson

Chalmers, Kemi och kemiteknik, Kemiteknik, Skogsindustriell kemiteknik

Wallenberg Wood Science Center (WWSC)

Hans Theliander

Chalmers, Kemi och kemiteknik, Kemiteknik, Skogsindustriell kemiteknik

Wallenberg Wood Science Center (WWSC)

Nordic Pulp and Paper Research Journal

0283-2631 (ISSN)

Vol. 32 4 508-526

Ämneskategorier

Materialteknik

Styrkeområden

Energi

DOI

10.3183/NPPRJ-2017-32-04-p508-526