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首页> 外文会议>The Proceedings of International Conference on Chemical and Biological Utilization of Biomass Resources 2010. >Removing and Physico-chemical Characterization of Lignin from Ultrasound-assisted Extractions of Fast-growing Poplar Wood through Organic Solvents and Alkaline Solutions
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Removing and Physico-chemical Characterization of Lignin from Ultrasound-assisted Extractions of Fast-growing Poplar Wood through Organic Solvents and Alkaline Solutions

机译：通过有机溶剂和碱性溶液超声辅助提取速生杨木中木质素的去除及其理化性质

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摘要

Four organic and three alkaline lignin fractions were isolated by ultrasound-assisted extractions from fast-growing poplar wood. The seven lignin fractions obtained were comparatively studied by carbohydrate content, UV, alkaline nitrobenzene oxidation, GPC, FT-IR, quantitative 13C and 2D HSQC NMR spectroscopy as well as TGA. The results showed that the ultrasonic treatments and sequential extractions with three different concentrations of NaOH led to a release of 96.2% of the original lignin. The four organic lignin preparations were degraded significantly and contained more carbohydrate when compared with the three alkaline lignin preparations. The results from quantitative 13C NMR analyses of the highest yield lignin preparation (L5) demonstrated that it contained ～1.73/Ar of methoxyl groups and ～0.31/Ar of β-O-4’ moieties along with small amounts of β-β’ structures (～0.06/Ar). Furthermore, the HSQC NMR spectra of L5 showed a predominance of β-O-4’ aryl ether linkages (83% of all side-chains), followed by β-β’ resinol-type (16%) and β-5’ phenylcoumaran-type (1%) linkages. The S/G ratio of L5 was estimated to be 1.5 and 1.8 from the quantitative 13C and HSQC NMR spectra, respectively. The analyses also confirmed that L5 is highly acylated at the γ-carbon of the side-chain preferentially over syringyl units. The percentage of lignin acylation of β-O-4’ linkages was 22%, possibly with acetate and p-coumarate groups, while 40% of the β-β’ linkages was acylated with p-hydroxybenzoate. The ratio of p-hydroxybenzoate/p-coumarate was calculated to be 2.4.
机译：通过超声辅助提取从快速生长的杨木中分离出四个有机和三个碱性木质素部分。通过碳水化合物含量，UV，碱性硝基苯氧化，GPC，FT-IR，定量13C和2D HSQC NMR光谱以及TGA对得到的七个木质素级分进行了比较研究。结果表明，超声处理和依次萃取的三种不同浓度的NaOH导致原始木质素释放96.2％。与三种碱性木质素制品相比，四种有机木质素制品被显着降解并包含更多的碳水化合物。最高产率的木质素制剂（L5）的13C NMR定量分析结果表明，它含有甲氧基的〜1.73 / Ar和β-O-4'部分的〜0.31 / Ar，以及少量的β-β'结构（〜0.06 / Ar）。此外，L5的HSQC NMR谱图显示，β-O-4'芳基醚键占主导地位（占所有侧链的83％），其次是β-β'树脂醇型（占16％）和β-5'苯基香豆素。类型（1％）的链接。根据定量的13 C和HSQC NMR谱估计L5的S / G比分别为1.5和1.8。分析还证实，L5在侧链的γ-碳上比丁香基单元优先被高度酰化。 β-O-4′键的木质素酰化百分比为22％，可能是乙酸酯和对香豆酸酯基团，而40％的β-β′键被对羟基苯甲酸酯酰化。对羟基苯甲酸酯/对香豆酸酯的比例经计算为2.4。

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