Production of a pure lignin product part 2: Separation of lignin from membrane filtration permeates of black liquor
Journal article, 2014

Future high value lignin-based products, such as carbon fibers, require a lignin raw material with a high purity level. Lignin with low inorganic content can be separated from kraft black liquor by the LignoBoost process. This laboratory scale study focuses on the effect of micro- and ultrafiltration of black liquor on the content of impurities in the LignoBoost lignin. Two black liquors, obtained from pulping of eucalyptus and softwood, were used in this study. The black liquors were micro- and ultrafiltered and thereafter lignin was separated from these permeates according to the LignoBoost process. It was found that micro- and ultrafiltration significantly reduced the amounts of carbohydrate residuals in the separated lignin. Eucalyptus lignin separated from permeates contained similar amounts of Al, Mn, Mg, Fe and Si, but significantly less Ca than the reference sample separated from unfiltered black liquor, resulting in 50% lower ash content. Softwood lignin separated from permeates contained lower amounts of Al, Mn, Mg, Fe, Ca and Si than the reference. In both cases, the Na and K content were unaffected by the introduction of micro- and ultrafiltration.

microfiltration

precipitation

inorganic impurities

LignoBoost

ultrafiltration

black liquor

lignin

separation

Author

R. Ziesig

Innventia

P. Tomani

Innventia

Hans Theliander

Chalmers, Chemical and Biological Engineering, Forest Products and Chemical Engineering

Wallenberg Wood Science Center (WWSC)

Cellulose Chemistry and Technology

0576-9787 (ISSN)

Vol. 48 9-10 80 -811

Subject Categories

Paper, Pulp and Fiber Technology

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9/6/2018 1