An efficient separation technology for hydrolysates towards a full valorization of bamboo is still a tough challenge, especially regarding the lignin and lignin-carbohydrate complexes (LCCs). The present study aimed to develop a facile approach using organic solvent extraction for efficiently fractionating the main components of bamboo hydrolysates. The high-purity lignin with only a trace of carbohydrates was first obtained by precipitation of the bamboo hydrolysate. The water-soluble lignin (WSL) fraction was extracted in organic solvent through a three-stage organic solvent extraction process, and the hemicellulosic sugars with increased purity were also collected. Furthermore, a thorough characterization including various NMR techniques ( 31 P, 13 C, and 2D-HSQC), GPC, and GC-MS was conducted to the obtained lignin-rich-fractions. It was found that the WSL fraction contained abundant functional groups and tremendous amount of LCC structures. As compared to native LCC of bamboo, the WSL fraction exhibited more typical LCC linkages, i.e. phenyl glycoside linkage, which is the main type of chemical linkage between lignin and carbohydrate in both LCC samples. The results demonstrate that organic phase extraction is a highly efficient protocol for the fractionation of hydrolysate and the isolation of LCC-rich streams possessing great potential applications.

中文翻译：

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竹水解物的简便分级分离和分离的木质素和木质素-碳水化合物复合物的表征

有效的水解产物分离技术可实现竹子的完全增值，这仍然是一个艰巨的挑战，特别是对于木质素和木质素-碳水化合物复合物（LCC）。本研究旨在开发一种使用有机溶剂萃取的方法，以有效地分离竹水解产物的主要成分。首先通过竹水解产物的沉淀获得仅具有微量碳水化合物的高纯度木质素。通过三步有机溶剂萃取工艺在有机溶剂中萃取水溶性木质素（WSL）馏分，并且还收集了纯度更高的半纤维素糖。此外，对获得的富含木质素的馏分进行了包括各种NMR技术（31 P，13 C和2D-HSQC），GPC和GC-MS的全面表征。发现WSL级分包含丰富的官能团和大量的LCC结构。与天然LCC竹相比，WSL馏分显示出更典型的LCC键，即苯基糖苷键，这是两种LCC样品中木质素和碳水化合物之间化学键的主要类型。结果表明，有机相萃取是分离水解产物和分离富含LCC的物流的高效方法，具有巨大的潜在应用价值。