Isolation and Structural Characterization of Lignin Polymer from Dendrocalamus sinicus
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Isolation and Structural Characterization of Lignin Polymer from Dendrocalamus sinicus Zheng-Jun Shi & Ling-Ping Xiao & Jia Deng & Run-Cang Sun
# Springer Science+Business Media New York 2013
Abstract Dendrocalamus sinicus, which is the largest bamboo species in the world, has broad prospects in the fields of bioenergy and biorefinery application. In this study, dewaxed D. sinicus samples were sequentially treated with 80 % ethanol containing 0.025 M HCl, 80 % ethanol containing 0.5 % NaOH, and aqueous alkaline solutions (containing 2.0, 5.0, and 8.0 % NaOH, respectively) at 75 °C for 4 h, in which 9.63, 8.71, 21.83, 21.09, and 13.09 % of the original lignin were isolated, respectively. The lignin fractions obtained were comparatively characterized by chemical composition, molecular weights, and structural features by wet chemical and instrumental analysis methods. It was found that the bamboo lignin fractions isolated by ethanol had lower weight-average molecular weights (1,360–1,380 gmol−1) and contained much higher amounts of associated hemicelluloses, while the lignin fractions isolated by aqueous alkaline solutions had higher weight-average molecular weights (5,300–6,040 gmol−1) and contained lower amounts of associated hemicelluloses. Spectroscopy analyses indicated that the bamboo lignin was a typical grass lignin, consisting of p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) units. A small percentage of the lignin side-chain was found to be acetylated at the γcarbon, predominantly at syringyl units. The major interunit linkages present in the bamboo lignin obtained were β-O-4′ aryl ether linkages, together with lower amounts of β-β′, β-5′, and β-1′ linkages. Z.-J. Shi College of Material Science and Technology, Southwest Forestry University, Kunming 650224, China Z.-J. Shi : R.-C. Sun (*) State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China e-mail: [email protected] Z.-J. Shi : L.-P. Xiao : J. Deng : R.-C. Sun Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China
Keywords Bamboo . Dendrocalamus sinicus . Lignin . Isolation . Characterization
Introduction In ages of depleting fossil reserves and increasing emission of greenhouse gases, it is obvious that utilization of renewable feedstock is one necessary step towards a sustainable development of our future [1]. Therefore, the efforts to exploit a variety of potential plant feedstocks for the energy, chemical, and food ingredients have been made particularly from agricultural and forestry biomass resources [2–4]. Dendrocalamus sinicus, the world’s largest bamboo species, belonging to Bambusoideae of Gramineae, with strong woody stems (maximal diameter 30 cm and maximal height 33 m), is mainly distributed in the southwest region of China [5]. Due to its easy propagation, fast growth, and high productivity, D. sinicus is considered as one of the most potential renewable non-woody lignocellulosic feedstocks for bioenergy and biorefinery. Given
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