Correlating lignin structural features to phase partitioning behavior in a novel aqueous fractionation of softwood Kraft black liquor

Ryan J. Stoklosa, Julian Velez, Shantanu Kelkar, Christopher M. Saffron, Mark C. Thies, David B. Hodge

Research output: Contribution to journalArticle

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Abstract

In this work, a set of softwood lignins were recovered from a Kraft black liquor using a novel pH-based fractionation process involving sequential CO 2 acidification and separation of the solvated aqueous lignin fraction. These recovered lignin fractions were characterized with respect to properties that may be responsible for their phase partitioning behavior as well as properties that may render the lignins more suitable for materials applications. Lignin fractions were recovered between a pH range of 12.8 and 9.5 with the bulk of the lignin (90%) recovered between a pH of 11.1 and 10.0. While all the fractions were found to consist primarily of lignin as validated by sample methoxyl content, the first fractions to phase separated were found to be especially enriched in aliphatic extractives and polysaccharides. From the bulk of the lignin that was recovered between a pH of 11.1 and 10.0 a number of noteworthy trends were discernible from the data. Specifically, the phenolic hydroxyl content was found to exhibit a strong negative correlation to the fractionation pH and exhibited a nearly 50% increase with recovery at decreasing pH, while the GPC-estimated molecular weights and 13C NMR-estimated β-O-4 content showed strong positive correlations to the pH at recovery. The aliphatic hydroxyl content exhibited minimal differences between recovery conditions. Overall, these results suggest that this fractionation approach can generate lignin fractions enriched in select physical or structural properties that may be important for their application as feedstocks for renewable chemicals or materials.

LanguageEnglish (US)
Pages2904-2912
Number of pages9
JournalGreen Chemistry
Volume15
Issue number10
DOIs
StatePublished - 2013

Profile

Softwoods
Lignin
Phase behavior
Fractionation
lignin
partitioning
fractionation
Recovery
Hydroxyl Radical
Acidification
Carbon Monoxide
Polysaccharides
polysaccharide
Feedstocks
acidification
nuclear magnetic resonance
Structural properties
Physical properties
Molecular weight
Nuclear magnetic resonance

ASJC Scopus subject areas

  • Environmental Chemistry
  • Pollution

Cite this

Correlating lignin structural features to phase partitioning behavior in a novel aqueous fractionation of softwood Kraft black liquor. / Stoklosa, Ryan J.; Velez, Julian; Kelkar, Shantanu; Saffron, Christopher M.; Thies, Mark C.; Hodge, David B.

In: Green Chemistry, Vol. 15, No. 10, 2013, p. 2904-2912.

Research output: Contribution to journalArticle

Stoklosa, Ryan J. ; Velez, Julian ; Kelkar, Shantanu ; Saffron, Christopher M. ; Thies, Mark C. ; Hodge, David B./ Correlating lignin structural features to phase partitioning behavior in a novel aqueous fractionation of softwood Kraft black liquor. In: Green Chemistry. 2013 ; Vol. 15, No. 10. pp. 2904-2912
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