A new and facile method for isolation of lignin from wood based on complete wood dissolution

Abstract

A new method for the isolation of lignin in high yield from wood and pretreated wood is presented, avoiding the liquid-solid extraction step of the classical milled wood lignin (MWL) isolation. Dissolved wood lignin (DWL) was obtained by total dissolution of ball milled wood in dimethylsulfoxide and N-methylimidazole (DMSO/NMI) followed by precipitation in dioxane/water in the course of which lignin and carbohydrate fractions were separated. The lignin fraction was purified. High lignin yields and the low number of separation steps belong to the advantages of the described method. DWL lignin was isolated from beech wood (Fagus sylvatica L.) and the sample was compared to MWL obtained by the classical Bjö rkman method. Elemental analyses, methoxyl group content, potassium permanganate oxidation, infrared spectroscopy, and 1D and 2D nuclear magnetic resonance spectroscopy indicated that both lignin preparations are quite similar. However, MWL contained significantly more phenolic hydroxyl groups than DWL. The results indicated that MWL contains higher amounts of smaller fractions with broken b-O-4 linkages than DWL.

HSQC-NMR analysis of lignin in woody (Eucalyptus globulus and Picea abies) and non-woody (Agave sisalana) ball-milled plant materials at the gel state 10th EWLP, Stockholm, Sweden, August 25–28, 2008

“…Other approaches are: 1) subjecting the milled wood to enzymatic treatment with cellulolytic enzymes to remove most of the carbohydrate components (Chang et al 1975;Wu and Argyropoulos 2003;Holtman et al 2004;Hu et al 2006); 2) completely dissolving ball-milled wood in a solvent system (dimethylsulfoxide, DMSO, and N-methylimidazol, NMI) followed by precipitation in dioxane/water in the course of which lignin and carbohydrate fractions are separated (Fasching et al 2008); or 3) isolating most of the lignin as lignin-carbohydrate complexes after endoglucanase treatment (Henriksson et al 2007). However, it is well recognized that these lignin preparations, in particular the MWL due to its low yield, represent only a part of the native lignin in the wood cell wall and may not be representative of the whole lignin present.…”

Review on Catalytic Cleavage of C–C Inter-unit Linkages in Lignin Model Compounds: Towards Lignin Depolymerisation

“…Using advanced NMR techniques the structures of complex native lignins, in whole cell wall, have been studied in great detail [31]. Another way to study the structure of native lignins is by careful chemical degradation techniques such as thioacidolysis or from milled wood lignin (MWL), which is usually considered to be more or less representative of native lignin [32,33]. Efforts are currently being made to separate native lignins from biomass with minimal structural changes [18,34].…”

Homogeneous Esterification Mechanism of Bagasse Modified with Phthalic Anhydride in Ionic Liquid, Part 3: Structural Transformation of Lignins

“…Several novel solvents or solvent systems could dissolve lignocellulosic materials (Lu and Ralph 2003;Fasching et al 2008;Luan et al 2013). Among these novel solvents, ionic liquids are attractive due to their recoverability, designability, extremely low vapor pressure, non-flammability, and high thermal and chemical stability (Zhu et al 2006).…”