Beisl Stefan, Miltner Angela, Friedl Anton
Institute of Chemical, Environmental and Biological Engineering, TU Wien, 1060 Vienna, Austria.
Int J Mol Sci. 2017 Jun 10;18(6):1244. doi: 10.3390/ijms18061244.
Lignin is the second most abundant biopolymer after cellulose. It has long been obtained as a by-product of cellulose production in pulp and paper production, but had rather low added-value applications. A changing paper market and the emergence of biorefinery projects should generate vast amounts of lignin with the potential of value addition. Nanomaterials offer unique properties and the preparation of lignin nanoparticles and other nanostructures has therefore gained interest as a promising technique to obtain value-added lignin products. Due to lignin's high structural and chemical heterogeneity, methods must be adapted to these different types. This review focuses on the ability of different formation methods to cope with the huge variety of lignin types and points out which particle characteristics can be achieved by which method. The current research's main focus is on pH and solvent-shifting methods where the latter can yield solid and hollow particles. Solvent shifting also showed the capability to cope with different lignin types and solvents and antisolvents, respectively. However, process conditions have to be adapted to every type of lignin and reduction of solvent demand or the integration in a biorefinery process chain must be focused.
木质素是仅次于纤维素的第二丰富的生物聚合物。长期以来，它一直是纸浆和造纸生产中纤维素生产的副产品，但附加值应用相当有限。不断变化的纸张市场和生物精炼项目的出现，应该会产生大量具有增值潜力的木质素。纳米材料具有独特的性能，因此制备木质素纳米颗粒和其他纳米结构作为一种获得增值木质素产品的有前途的技术受到了关注。由于木质素具有高度的结构和化学异质性，方法必须适应这些不同类型。本综述重点关注不同形成方法应对各种木质素类型的能力，并指出哪种方法可以实现哪些颗粒特性。当前研究的主要重点是pH值和溶剂转移方法，其中后者可以产生实心和空心颗粒。溶剂转移还显示出分别应对不同木质素类型以及溶剂和抗溶剂的能力。然而，工艺条件必须适应每种类型的木质素，并且必须关注减少溶剂需求或融入生物精炼工艺链。
