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首页> 外文期刊>ACS Sustainable Chemistry & Engineering >Fractional Precipitation of Softwood Kraft Lignin: Isolation of Narrow Fractions Common to a Variety of Lignins
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Fractional Precipitation of Softwood Kraft Lignin: Isolation of Narrow Fractions Common to a Variety of Lignins

机译：软木牛皮纸木质素的部分沉淀：分离各种木素常见的窄馏分

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摘要

In a manner similar to crude oil, technical lignins need refining if their potential as reactive polyphenols of well-defined molecular weight polymers and oligomers is to be actualized. In this paper, we demonstrate that a continuum of narrow fractions can be isolated by the incremental addition of a nonpolar solvent (hexanes) in a polar (acetone) solution of softwood wood kraft lignin. Three distinct commercial samples of softwood kraft lignin were used to examine the validity of the developed protocol using detailed chromatographic and quantitative functional group analytical methods. It was shown that all samples contain a common relatively monodisperse fraction of a polyphenolic material that can be isolated from the different lignins in yields ranging between 10 and 20% w/w. The versatility of the developed fractional precipitation protocol was further validated by creating artificial physical mixtures of the examined lignins in different proportions and isolating from them precisely calculated fractions of nearly identical molecular weight distributions and composition. Overall, the fractional precipitation approach described here offers the possibility that representative specific narrow fractions, common to a variety of softwood kraft lignins, can be isolated irrespective of the manufacturing details of the pulping process. As such, the otherwise known heterogeneous kraft lignin material, whose composition is relatively unpredictable due to manufacturing variations in making pulp, may now offer consistently homogeneous lignin streams with significant commercial ramifications.
机译：以类似于原油的方式，如果要实现工业木质素作为明确定义的分子量聚合物和低聚物的反应性多酚的潜力，则需要对其进行精制。在本文中，我们证明了可以通过在软木牛皮纸硫酸木质素的极性（丙酮）溶液中增量添加非极性溶剂（己烷）来分离连续的窄馏分。使用详细的色谱和定量官能团分析方法，使用三个不同的商业针叶硫酸盐木质素样品检查开发的方案的有效性。结果表明，所有样品均含有多酚类材料的相对较常见的相对分散部分，可以从不同的木质素中分离出多酚类物质，其收率在10％至20％w / w之间。通过创建不同比例的被检查木质素的人工物理混合物，并从中分离出分子量分布和组成几乎相同的精确计算的馏分，进一步验证了所开发的分级沉淀方案的多功能性。总的来说，这里描述的分级沉淀法提供了这样的可能性，即可以分离出各种针叶木硫酸盐木质素所共有的代表性特定窄馏分，而与制浆工艺的制造细节无关。这样，由于制浆过程中的制造差异，其组成相对不可预测的本来已知的异质牛皮纸木质素材料现在可以提供具有显着商业意义的一致均质的木质素料流。

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