Organosolv fractionation of waste biomass for lignin production enhanced by oxygen

An oxygen-enhanced organosolv fractionation method to produce lignin from waste biomass was investigated. In this novel biorefinery process, mild conditions, i.e., temperature at 80 to 100 °C and pressure < 0.8 MPa, were employed to alleviate energy input and to retain the original lignin structure as much as possible. The results showed that the lignin yield was increased with increasing process temperature, ethanol concentration, and ratio of liquid to solid. Although little structural changes were observed, the normalized Infrared transmittance results revealed quantitative differences. Moreover, a basic kinetic study was conducted, and the results showed that there existed two stages with fast and slow rates during the delignification processes. Analysis of the fibers’ micro-structure also demonstrated the effectiveness of oxygen-enhanced organosolv fractionation. However, a phenol-based inducer could possibly further improve the efficiency based on the delignification mechanism of reactive oxygen species, which will be studied in future research.