Characterization of milled wood lignin and ethanol organosolv lignin from miscanthus

Ethanol organosolv lignin extracted from Miscanthus x giganteus (using the following conditions: T = 190 degrees C, t = 60 min, sulfuric acid = 1.2% w/w, EtOH/H2O = 0.65) and milled wood lignin from Miscanthus x giganteus were subjected to a comprehensive structural characterization by C-13, P-31 NMR, FTIR, UV spectroscopies and size exclusion chromatography. The results showed that Miscanthus lignin is an H/G/S type (4%, 52%, 44% respectively) with similar to 0.41 beta-O-4 linkage per aromatic ring and contains coumarylate linkages (0.1/Ar). It was shown that during organosolv treatment, cleavage of beta-O-4 linkages and of ester bond (acetyl and coumaryl residues) was the major mechanisms of lignin breakdown but the process did not significantly change the core of the lignin structure. (C) 2009 Elsevier Ltd. All rights reserved.