Understanding the chemical structural differences of key components at varying bamboo heights enhances knowledge of its biological properties and adaptive mechanisms, promoting its high-value utilization. In this study, lignin and lignin-carbohydrate complexes (LCC) were extracted from the base, middle, and top sections of bamboo culms, and the chemical composition, micro-regional distribution, and structural characteristics of key components were analyzed. Results showed that both lignin and hemicellulose contents followed the trend: top > base > middle. The size and number of fiber cells decreased progressively from the base to the top, with lignin content most abundant in the cellular tissues at the top, where the S/G structural unit ratio was also the highest. Lignin-ferulic acid (FA)-carbohydrate complexes were identified as major recalcitrant structures in LCCs across different bamboo heights. These findings offer key insights into the chemical structural differences of lignin and LCCs at various bamboo heights, providing a scientific foundation for understanding bamboo's biological characteristics and facilitating its high-value applications.
Si Gao,Ji Zhao,Xing Wang,Yanzhu Guo,Ying Han,Jinghui Zhou
This study focused on the structural differences of lignin after pyridine–acetic acid–water (PAW) and dioxane–acidic water (DAW) purification processes. These structural differences included the S/G ratio, condensed structure, weight-average (MW) molecular weights, β-O-4 linkages and sugar content. The chemical structure of the isolated crude lignin (CL), PAW purified lignin (PPL) and DAW purified lignin (DPL) was elucidated using quantitative13C NMR, 2D-HSQC NMR spectra, thermogravimetric analysis (TGA), gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR). The results showed that the PPL fractions contain fewer condensed structures, higher S/G ratios, more β-O-4 linkages, higher average MWand lower thermal degradation properties compared to the CL and DPL fractions. Furthermore, the PAW process was more selective in removing condensed units and enriching S-type lignin from CL compared to the DAW process. These results provide valuable information for understanding which purification process is more suitable to be applied for lignin.Keywords:lignin purification;structural recognition;condensed lignin;S/G ratio
危险品化学品经营许可证（带存储）