Heat-Induced Discoloration of Chromophore Structures in Eucalyptus Lignin

Materials

Yanxia Wei¹  Jianmin Gao¹  Yao Chen¹  Yongming Fan¹  Yang Liu¹  Peng Zhang¹ 

[1] MOE Key Laboratory of Wooden Material Science and Application, College of Materials Science and Technology, Beijing Forestry University, Beijing 100083, China;

关键词: heat-induced;    wood discoloration;    Eucalyptus;    lignin;    chromophore system;   

DOI  :  10.3390/ma11091686

来源: DOAJ

【 摘 要 】

The color changes corresponding to chromophore structures in lignin caused by exposure of Eucalyptus (Eucalyptus grandis and E. urophylla) to heat were investigated. Eucalyptus wood powders were heat treated under saturated steam atmospheres for 10 h at 110 °C, 130 °C and 150 °C. The lignin was isolated before and after heat treatment. The physicochemical properties of the lignin and changes in chromophore structures during heat treatment was evaluated through wet chemical analysis, Fourier transform infrared spectroscopy (FTIR), diffuse reflectance ultraviolet-visible spectroscopy (DRUV-Vis), gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS) and 13C Cross polarization magic angle spinning nuclear magnetic resonance (13C CPMAS NMR). Wood color darkened and reddened with the increase in pressure and temperature. Depolymerization and dehydration reactions occurred via demethoxylation with heat treatment in saturated steam at 110 °C or 130 °C. Lignin condensed to form insoluble compounds after heat treatment in saturated steam at 150 °C. G units increased and S units decreased through demethylation during heat treatment, as revealed by FTIR and 13C-NMR analysis.

【 授权许可】

Unknown