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Acidic Depolymerization vs Ionic Liquid Solubilization in Lignin Extraction From Eucalyptus Wood Using the Protic Ionic Liquid 1-methylimidazolium Chloride

Antonio Ovejero-Pérez, Victoria Rigual, Juan Carlos Domínguez, M Virginia Alonso, Mercedes Oliet, Francisco Rodriguez

Int J Biol Macromol. 2020 Aug 15;157:461-469.

PMID: 32348860

Abstract:

Protic ionic liquids have been proposed as effective solvents for the selective extraction of lignin from wood. In this work, the protic ionic liquid 1-methylimidazolium chloride has been used to extract lignin at different biomass loadings, temperatures, and times to understand the influence of treatment severity on the lignin dissolution mechanism. The maximum lignin recovery (82.35 g lignin/100 g biomass lignin) was achieved at 10% (w/w) biomass loading, 135 °C, and 6 h. An increase in treatment severity leads to an acid cleavage of ether linkages, which increases the average molecular weight and thermal stability of lignins due to C-C repolymerization. HSQC-NMR analysis showed the effect of operating conditions on the predominant mechanism of lignin depolymerization. At mild conditions, there is a preferential degradation of G units (the typical depolymerization mechanism of ionic liquid treatments); but at the most severe conditions, S units are predominantly removed, as usually occurs in acidic treatments. This work contributes to better understanding the different lignin extraction mechanisms occurring with a protic ionic liquid depending on different operating conditions.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP35487173 1-Methylimidazolium chloride 1-Methylimidazolium chloride 35487-17-3 Price
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