Gao Si, Zhao Ji, Wang Xing, Guo Yanzhu, Han Ying, Zhou Jinghui
Liaoning Key Laboratory of Pulp and Papermaking Engineering, Dalian Polytechnic University, Dalian 116034, China.
Jining Ming Sheng New Material Co., Ltd., Jinan 272100, China.
Polymers (Basel). 2018 Sep 1;10(9):967. doi: 10.3390/polym10090967.
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 (M) 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 quantitative C 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 M and 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.
本研究聚焦于木质素在吡啶⁻乙酸⁻水（PAW）和二氧六环⁻酸性水（DAW）纯化过程后的结构差异。这些结构差异包括S/G比、缩合结构、重均（M）分子量、β-O-4键和糖含量。使用定量碳核磁共振（C NMR）、二维异核单量子相干核磁共振光谱（2D-HSQC NMR）、热重分析（TGA）、凝胶渗透色谱法（GPC）和傅里叶变换红外光谱法（FTIR）对分离得到的粗木质素（CL）、PAW纯化木质素（PPL）和DAW纯化木质素（DPL）的化学结构进行了阐释。结果表明，与CL和DPL级分相比，PPL级分含有更少的缩合结构、更高的S/G比、更多的β-O-4键、更高的平均M和更低的热降解性能。此外，与DAW过程相比，PAW过程在从CL中去除缩合单元和富集S型木质素方面更具选择性。这些结果为理解哪种纯化过程更适合应用于木质素提供了有价值的信息。
