Characterization of Organosolv Lignin Derived from Non-Woody Biomass; 비목질계 바이오매스 유래 유기용매 리그닌의 특성 분석

초록

As a potential fuel source, lignin promises to mitigate the environmental crises and depletion of natural resources caused by fossil fuel usage. This paper analyzes the properties of lignin extracted from non-woody biomasses (ramie, kenaf, and hemp) using a glycol ether-organosolv process. To recover the lignin, a 50-g sample of each non-woody biomass was soaked in a glycol ether/H2SO4 co-solvent (96:4 wt./wt.; ether: H2SO4 ratio of 1:10) for 24 h at room temperature. The mixture was reacted in an autoclave at 121°C and 0.15 MPa for 2 h, followed by vacuum filtration. The pulp and black liquor were separated through repeated washing with 1% NaOH and distilled water. The black liquor was adjusted to pH 2 or 5, allowed to settle for 24 h, centrifuged, and dried to obtain lignin at high yield. The lignin yields from hemp (bast) and kenaf were 32.6% and 31.7%, respectively, with Klason lignin contents of 52.4–62.9%. All samples contained hydroxyl groups (3–4 mmol/g) with sizeable proportions of phenolic hydroxyl groups (1.5–1.8 mmol/g). In antioxidant activity tests, hemp (hurd) exhibited the strongest activity and the lowest half-maximal inhibitory concentration (0.064 mg/mL). Principal component analysis classified the biomass constituents by their aromatic structures and clarified the remaining amount of polysaccharides in each biomass. These findings indicate the high functionality and strong commercial potential of non-woody biomass-derived lignin as an eco-friendly material and a viable alternative to fossil fuel-based resources.

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