Studies on the physical and chemical properties of lignins extracted from various pretreatment methods

초록

There are various pretreatment processes using lignocellulosic biomass to obtain lignin as a co-product. However, lignin has significantly different physical and chemical properties depending on the pretreatment process. Therefore, the characteristics of lignin must be clearly analyzed for the efficient utilization of lignin, In this study, four extracted lignins from different resources such as hardwood kraft lignin (L1), hardwood supercritical water oxidation lignin (L2), silver grass steam-explosion lignin (L3), and commercial lignin (L4), were subjected to several analyses to characterize their thermal as well as chemical structural properties. Molecular weight of L2 was higher than that of L1, however, PDI tended to be opposite to the molecular weight. The FT-IR spectra of four lignins were very similar. The methoxyl group contents of the four lignins L1 to L4 were 4.0 mmol/g, 3.1 mmol/g, 0.8 mmol/g, and 1.6 mmol/g, respectively. Regardless of lignin type, the methoxyl and phenolic hydroxyl group contents were lower as the molecular weight was higher. It was confirmed by Py-GC/MS that L4 was composed of only guaiacyl type lignins. As a result of the thermal analysis, L1 decomposition occurred by two steps but L4 was mainly decomposed at high temperature and L1 and L4, extracted from kraft pulping produced the largest amount of char residues. © 2018 Korean Technical Assoc. of the Pulp and Paper Industry. All rights reserved.

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