Fractionation by Sequential Antisolvent Precipitation of Grass, Softwood, and Hardwood Lignins Isolated Using Low-Cost Ionic Liquids and Water
Fractionation by Sequential Antisolvent Precipitation of Grass, Softwood, and Hardwood Lignins Isolated Using Low-Cost Ionic Liquids and Water
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DOI：
10.1021/acssuschemeng.9b06939
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发表时间：
2020-03-09
影响因子：
8.4
通讯作者：
Hallett, Jason P.
中科院分区：
文献类型：
--
作者：
Chambon, Clementine L.;Fitriyanti, Vivi;Hallett, Jason P.
本研究首次将序贯反溶剂沉淀法应用于离子溶剂木质素的分离。采用低成本的质子离子液体N，N-二甲基丁基硫酸氢铵（[DMBA][HSO4]， 80%的水）预处理芒草（草本）、柳树（硬木）和松树（软木），提取木质素。然后，加入水作为抗溶剂，依次沉淀木质素。分馏过程似乎受木质素聚合物分子量的控制。用最小水体积分离的馏分具有高分子量、多分散性、热稳定性和T-g（178℃）。后来的沉淀更加单分散，酚和总羟基含量高，热稳定性和T-g（136℃）较低。每克干白质加入1克水，可沉淀高达90%的木质素。分步沉淀是一种新的木质素分离技术，可以作为木质素回收过程的一部分，实现对木质素性质的高度控制。通过二维异核单量子相干核磁共振、凝胶渗透色谱、热重分析和差示扫描量热法，研究了木质素分馏对木质素结构、化学和热性能的影响，并与添加过量水获得的未分馏木质素沉淀物进行了比较。
In this study, fractionation by sequential antisolvent precipitation was applied to ionoSolv lignins for the first time. Pretreatment with the aqueous low-cost protic ionic liquid N,N-dimethylbutylammonium hydrogen sulfate ([DMBA][HSO4], 80 wt % in water) was applied to Miscanthus (herbaceous), willow (hardwood), and pine (softwood) to extract lignin. Then, lignin was sequentially precipitated by the addition of water as an antisolvent. Fractionation appeared to be controlled by the molecular weight of lignin polymers. Fractions isolated with minimal water volumes were shown to have high molecular weight, polydispersity, thermal stability, and T-g (178 degrees C). Later precipitates were more monodisperse and had high phenolic and total hydroxyl content and lower thermal stability and T-g (136 degrees C). Addition of 1 g of water per gram of dry IL was able to precipitate up to 90 wt % of lignin. Fractional precipitation represents a novel lignin isolation technique that can be performed as part of the lignin recovery procedure enabling a high degree of control of lignin properties. The effect of the fractionation on lignin structural, chemical, and thermal properties was thoroughly examined by two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance, gel permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry and compared to the unfractionated lignin precipitate obtained by addition of an excess of water.