earticle

영어

Lignin is the second most abundant natural polymers and sustainable resource obtained as a co-product from either the pulping industry or the bioethanol production using the lignocellusic biomass. There are various pretreament processes using lignocellulosic biomass, among which kraft and sulfite pulping are the dominant processes to obtain lignin as a co-product. However, lignin has significantly different physical and chemical properties depending on the pretreatment process. Therefore, for the efficient utilization of lignin, characteristics of lignin must be clearly analyzed. In this study, four extracted lignins from different resources, 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. L1 revealed relatively low value of 1430 g/mol (Mn) and 4.0 (PDI) but the remaining three lignins showed similar molecular weights. The methoxyl group contents of four lignins L1 to L4 were 4.0 mmol/g, 3.1 mmol/g, 0.8 mmol/g, and 1.6 mmol/g, respectively. As results of DFRC analysis, L4 was found to have only quaiacyl type lignin, confirmed to be extracted from softwood. The FT-IR spectra of four lignins were very similar. Additional chemical structures of lignins 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 lignins.