원문정보
초록
영어
Valuable applications of lignin are restricted by its heterogeneous features such as structural heterogeneity, high polydispersity, complex functional group distribution, solubility and etc. Solvent fractionation of lignin is one of the useful ways to increase its utilization by taking more uniform lignin. In this study, the crude lignin extracted from Quercus mongolica as treated in supercritical water oxidation was subjected to sequential fractionation with four organic solvents and five lignin fractions (F1~F5) were obtained. The yields of five fractions F1, F2, F3, F4, and F5 were 30.6%, 4.3%, 41.7%, 2.0%, and 3.7%, respectively. As fractionation proceeded, the carbon content gradually increased from 57.6% (F2) to 67.0% (F5). In addition, molecular weights and polydispersity (PDI) of fractionated lignins gradually decreased from F2 to F5. However, the content of methoxyl groups tended to be opposite to the molecular weights. The FT-IR spectra of crude lignin and fractionated lignins were very similar. Additional chemical structures of lignin such as phenolic hydroxyl and aliphatic hydroxyl content were investigated by 1H NMR. Moreover, TGA/DSC was conducted to analyze thermal stabilities and degradation behavior of the fractionated lignins.