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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 (31P, 13C, 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. [ABSTRACT FROM AUTHOR]

Poplar sapwood chips were autohydrolyzed at three severity levels and subsequently treated with alkali for the production of chemi-mechanical pulp (CMP). The aim was to study the variation of the principal pathways for sodium hydroxide solution and the alkali concentration and distribution inside the autohydrolyzed chips as a function of autohydrolysis (AH) severity. The tyloses in the vessels and some pit membranes were partly dissolved after AH, while the skeletal structure of the fiber and vessel cell walls remained intact. AH had a positive influence on the diffusion and the uniform distribution of NaOH solution both in the axial and radial direction of the chips, but the axial direction was more favored than the radial one. [ABSTRACT FROM AUTHOR]