In this study, a two-step process based on steam explosion pretreatment and alkali/alkaline ethanol post-treatments was applied to separate the degraded bamboo lignins. Steam explosion (1.8 and 2.0 MPa for 5 min, and 2.0 MPa for 8 min) combined alkali/alkaline ethanol treatments resulted in the dissolution of 28.9, 53.3 and 60.1% of the degraded acid-insoluble lignins, respectively. The structural features of the degraded lignins were comparatively and comprehensively investigated by FT-IR and NMR techniques. The degraded lignins were found to be predominantly composed of the type �-O-4' along with minor amounts of other substructures such as �-�', �-5', and a, �-diaryl ethers linkages. The degraded lignins showed low molecular weights (Mw, 860�1190 g/mol), narrow polydispersities (Mw/Mn, 1.46�1.92), and a high content of phenolic hydroxyl groups (0.53�1.79 mmol/g). Antioxidant activities investigation showed that the radical scavenging index (RSI) of the extracted lignins (2.02�5.56) were higher than BHT (0.19) but lower than that of BHA (11.11). The relatively high antioxidant activity of the degraded lignins suggested that they may be a potential antioxidant in food and other industries.

Structural characterization of the degraded lignin from steam exploded bamboo stem

247th National Meeting (2014)

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