Hydrothermal separation of lignin from bark of Japanese cedar

• Published in: The Journal of supercritical fluids 2018-03, Vol.133, p.696-703
• Main Authors: Watanabe, Masaru, Kanaguri, Yukihiro, Smith, Richard L.
• Format: Article
• Language: English
• Subjects: Bark; Hemicellulose-lignin complex; Hydrolysis; Hydrothermal; Lignin; Solubilization
• ISSN: 0896-8446; 1872-8162
• DOI: 10.1016/j.supflu.2017.09.009

[Display omitted] •Lignin yields of 65wt% from Japanese cedar bark in 10min treatment at 598K.•Recovered lignin composed mainly of guaiacyl units with average 1000Da.•Hydrothermal treatment promotes hemicellulose-lignin hydrolysis without additives.•Bark solubilization (BS) and lignin recovery (LR) both depend on hydrolysis.•Severity analysis applied as a two-reaction process to describe BS and LR. Hydrothermal treatment was used to study the separation of lignin from bark derived from biomass. A coupled-system of two batch reactors was used to treat Japanese cedar bark (ca. 45% lignin) with water at 473K–573K without additives and to collect lignin fractions at given times. Hydrothermal treatment of bark at a temperature of 548K and a treatment time of 10min allowed 65wt% of the lignin to be separated, which means that it is possible to obtain about 0.3kg-lignin per kilogram of Japanese cedar bark. From the characterization, it was revealed that the hydrothermal-soluble lignin had a simple structure with a molecular mass of about 1000Da. The yield of lignin decreased for treatment temperatures higher than 548K that is attributed to carbonization. Hydrothermal treatment of bark can be used to recover lignin and has potential application to biorefineries.