NMR Analyses and Thermal Stability of Ethanol-Dissolved Bamboo Lignin

Dendrocalamus sinicus, the largest bamboo species in the world, is one of the most potential renewable lignocellulosic feedstock for biorefinery. In this study, ethanol soluble lignin fraction was isolated from the dewaxed bamboo materials, and their structure features and thermal stability were characterized by NMR (C-13 NMR, 2D HSQC NMR) and thermogravimetic analysis. The obtained results indicated that the bamboo lignin was typical grass lignin, consisting of p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) units. The major inter-unit linkages presented in the isolated bamboo lignin were beta-O-4' aryl ether linkages, together with low amounts of beta-beta', beta-5', and beta-1' linkages. In addition, a small percentage of aliphatic hydroxyl was acetylated at the gamma-carbon in the side-chain of bamboo lignin. The thermal stability analysis results indicated that the violent degradation of bamboo lignin occurs at temperature range from 304 degrees C to 362 degrees C.