Fractionation of five technical lignins by selective extraction in green solvents and characterisation of isolated fractions
Fractionation of five technical lignins by selective extraction in green solvents and characterisation of isolated fractions
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DOI：
10.1016/j.indcrop.2014.09.019
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发表时间：
2014-12-01
影响因子：
5.9
通讯作者：
Peter, Francisc
中科院分区：
文献类型：
--
作者：
Boeriu, Carmen G.;Fitigau, Firuta I.;Peter, Francisc
采用10%、30%、50%、70%和90% （v/v）丙酮和乙酸乙酯的绿色溶剂，在常温下对软木、硬木、草和麦秸中的木质素进行了选择性提取。从木质素提取率、木质素溶解度、分子量分布和官能团组成等方面对分离木质素馏分与未分离木质素馏分进行了比较。用乙酸乙酯和含30%丙酮的丙酮-水溶液萃取得到分散性较差的低分子量木质素馏分，其收率取决于木质素的种类和官能团含量。从乙酸乙酯中分离得到了大量（56%）低分子量（Mw = 1868 g/mol）、低分散性的硬木木质素有机溶剂。以低产率从含有50%、70%和90%丙酮的丙酮-水溶液中得到分子量很高（Mw在10和17 kg/mol之间）的不溶性馏分。与亲本木质素相比，低分子量木质素的缩合程度一般较低，脂肪羟基含量较低，而高分子量木质素的缩合羟基含量较高。从P-31核磁共振数据对木质素的化学成分和分离组分进行主成分分析，结果表明木质素具有高度的非均质性。建立了基于FT-IR光谱数据的偏最小二乘模型来预测技术木质素和木质素组分的定量P-31 NMR测定的官能团含量。该方法可用于开发简单、快速、准确的分析工具来监测和控制木质素的选择性分馏。(C) 2014 Elsevier B.V.版权所有
Lignins from softwood, hardwood, grass and wheat straw were fractionated by selective extraction at ambient temperature using green solvents like acetone/water solutions of 10, 30, 50, 70 and 90% (v/v) acetone and ethyl acetate. A comparison between the isolated fractions and unfractionated lignins was made in terms of extraction yield, lignin solubility factor, molecular weight distribution and functional group composition. Low molecular weight (LMW) lignin fractions with narrow dispersity are obtained by extraction with ethyl acetate and acetone-water solution containing 30% acetone, with yields depending on the type and the functional group content of lignins. A significant amount (56%) of the organosolv hardwood lignin with low molecular weight (Mw = 1868 g/mol) and low dispersity was isolated from ethyl acetate. Insoluble fractions with very high molecular weight (Mw between 10 and 17 kg/mol) are obtained in low yield from acetone-water solutions with 50, 70 and 90% acetone. LMW lignins are in general less condensed and have lower aliphatic hydroxyl content than parent lignins while the HMW fractions have a higher content of condensed hydroxyls. Principal component analysis on the chemical composition of lignins and isolated fractions determined from P-31 NMR data showed the high heterogeneity of the technical lignins. Partial least squares models based on FT-IR spectral data were developed to predict the functional group content determined by quantitative P-31 NMR analysis of technical lignins and lignin fractions. This approach can be used to develop simple, rapid and accurate analytical tools to monitor and control the selective fractionation of lignin. (C) 2014 Elsevier B.V. All rights reserved.