Lignin isolation in high yield and with specific functionality is important to utilize this natural polymer for value-added bioproducts. In this research, glycerol thermal processing (GTP) was adopted as a novel biomass pretreatment to denature plant cell wall for lignin mild isolation. Lignin extractability and structure changes were investigated as a function of pretreatment severity. After GTP pretreatment, up to 65% lignin was isolated from pretreated sweet gum (liquidambar styraciflua) samples in a well-controlled manner. The structural analysis of isolatied lignin using quantitative NMR and thioacidolysis indicated cleavage of �-O-4 bonds with formation of free syringyl hydroxyl groups occurred during the GTP pretreatment.  These structural changes were linked with lignin isolation. Correspondingly, molecular weight of isolated lignin decreased as the pretreatment severity increased. Minimum oxidation was observed on the isolated lignin even at high pretreatment severities. Utilization of two-dimensional NMR identified the residual bond types in isolated lignin. Additionally thermal analysis showed the lignin isolated from GTP pretreated sweet gum had excellent thermal stability. Overall, glycerol thermal processing provides a new way to facilitate lignin isolation with well-defined structure for further lignin based application.

Isolation and structural analysis of lignin from glycerol thermal pretreated (GTP) biomass

247th National Meeting (2014)

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