Structural characterization of birch lignin isolated from a pressurized hot water extraction and mild alkali pulped biorefinery process

Lucas Lagerquist, Andrey Pranovich, Annika Smeds, S. von Schoultz, L. Vähäsalo, Jani Rahkila, I. Kilpeläinen, T. Tamminen, Stefan Willför, Patrik Christoffer Eklund

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14 Citations (Scopus)

Abstract

In this work we have characterized a mild soda pulped birch (betula pendula) lignin after a novel pressurized hot water extraction pilot process. In the process hemicelluloses are first isolated from woods chips with hot water at oxygen-starved conditions, followed by mild alkali pulping at oxygen-starved conditions to remove lignin from the cellulose. Lignin was precipitated, washed and fractionated from the black liquor and characterized by quantitative C-13 NMR, C-13 DEPT experiments, P-31 NMR, 2D HSQC, FTIR, size exclusion chromatography (SEC), elemental analysis, pyrolysis-gas chromatography-mass spectrometry (py-GC-MS), methoxyl group quantification and residual carbohydrate analysis after methanolysis. The structure was compared to a MWL of birch obtained from the same wood chips and the differences were an increase in phenolic hydroxyl groups, carboxylic groups, polydispersity index, and reduction of aliphatic hydroxyl groups. The process resulted in beta-O-4 cleavage and condensation of the structure. This lignin is therefore suitable to be used in its polymeric form, rather than for degradation of the structure to small building blocks.
Original languageUndefined/Unknown
Pages (from-to)306–316
Number of pages11
JournalIndustrial Crops and Products
Volume111
DOIs
Publication statusPublished - 2018
MoE publication typeA1 Journal article-refereed

Keywords

  • lignin characterization
  • Birch lignin
  • Condensed structures
  • Aryl glycerol
  • Milled wood lignin

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