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Physicochemical characterization of lignin fractions sequentially isolated from bamboo (Dendrocalamus brandisii) with hot water and alkaline ethanol solution

Authors

  • Zheng-Jun Shi,

    1. Institute of Biomass Chemistry and Technology, Beijing Forestry University, Beijing 100083, China
    2. College of Material Science and Technology, Southwest Forestry University, Kunming 650224, China
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  • Ling-Ping Xiao,

    1. Institute of Biomass Chemistry and Technology, Beijing Forestry University, Beijing 100083, China
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  • Jia-Deng,

    1. Institute of Biomass Chemistry and Technology, Beijing Forestry University, Beijing 100083, China
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  • Feng Xu,

    1. Institute of Biomass Chemistry and Technology, Beijing Forestry University, Beijing 100083, China
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  • Run-Cang Sun

    Corresponding author
    1. Institute of Biomass Chemistry and Technology, Beijing Forestry University, Beijing 100083, China
    2. State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510641, China
    • Institute of Biomass Chemistry and Technology, Beijing Forestry University, Beijing 100083, China
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Abstract

Nine lignin fractions from bamboo (Dendrocalamus brandisii) were sequentially isolated with hot water at 80, 100, and 120°C for 3 h and 60% aqueous ethanol containing 0.25, 0.5, 1.0, 2.0, 3.0, and 5.0% NaOH at 80°C for 3 h. Molecular weight and purity analysis revealed that the lignin fractions isolated by hot water (L1, L2, and L3) had lower weight-average molecular weights (between 1350 and 1490 g mol−1) and contained much higher amounts of associated hemicelluloses (between 9.26 and 22.29%), while the lignin fractions isolated by alkaline aqueous ethanol (L4, L5, L6, L7, L8, and L9) had higher weight-average molecular weights (between 2830 and 3170 g mol−1) and contained lower amounts of associated hemicelluloses (between 0.63 and 1.66%). Spectroscopy (UV, FTIR, 13C-NMR, and HSQC) analysis showed that the bamboo (Dendrocalamus brandisii) lignin was typical grass lignin, consisting of p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) units. The major interunit linkages presented in the alkaline aqueous ethanol extractable bamboo lignin were β-O-4′ aryl ether linkages (about 74.3%), followed by β-β′ resinol-type linkages and β-1′ spirodienone-type linkages (both for 7.8%), together with small amounts of β-5′ phenylcoumaran (6.8%) and p-hydroxycinnamyl alcohols end groups (3.1%). In addition, a small percentage (1.0%) of the lignin side-chain was found to be acetylated at the γ-carbon, predominantly over syringyl units. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

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