Chemical Engineering Department, Faculty of Science, University of Córdoba, Spain.
VTT Technical Research Centre of Finland Ltd., Finland.
Int J Biol Macromol. 2018 Jan;106:979-987. doi: 10.1016/j.ijbiomac.2017.08.102. Epub 2017 Aug 20.
Technical lignins are structurally heterogeneous and polydisperse. This work describes the use of a simple and green method for lignin fractionation, using different proportions of acetone (40 and 60%) in water. Lignins from three different sources (wheat straw organosolv lignin, wheat straw soda lignin and softwood kraft lignin) were used in this fractionation protocol. The obtained fractions showed different molar mass and functional groups. The lower molar mass fractions showed more phenolic hydroxyl groups and carboxylic acid moieties than higher molar mass fractions, which also possessed much higher amounts of carbohydrates. The chemical characterization of these fractionated lignins showed that the PREC fraction was exceptionally pure and homogeneous lignin. Its total lignin content was >96% for all three lignins and it was practically free from carbohydrates and inorganics (ash). Furthermore, PREC fraction possessed the highest carbon content for the three lignin samples (63.05-69.26%). These results illustrate that the proposed aqueous acetone fractionation protocol could indeed produce pure and uniform lignin fraction and it was applicable for lignins from different sources.
技术木质素在结构上具有异质性和多分散性。本工作描述了一种使用简单绿色方法进行木质素分级的方法，即在水中使用不同比例的丙酮（40%和 60%）。该分级方案使用了三种不同来源的木质素（麦草有机溶剂木质素、麦草苏打木质素和软木硫酸盐木质素）。所得级分的摩尔质量和官能团不同。较低摩尔质量级分的酚羟基和羧酸基含量高于较高摩尔质量级分，而较高摩尔质量级分的碳水化合物含量则高得多。对这些分级木质素的化学表征表明，PREC 级分是一种异常纯净和均匀的木质素。对于所有三种木质素，其总木质素含量均>96%，且实际上不含碳水化合物和无机物（灰分）。此外，PREC 级分对于三种木质素样品的碳含量最高（63.05-69.26%）。这些结果表明，所提出的含水丙酮分级方案确实可以产生纯净均匀的木质素级分，并且适用于不同来源的木质素。
