Dendrocalamus sinicus, which is the largest bamboo species in the world, has broad prospects in the fields of pulp and paper making as well as 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 oC for 4 h, and their structural properties were examined. It was found that the bamboo lignin fractions isolated by ethanol had lower weight-average molecular weights (1360-1380 g mol–1), while the lignin fractions isolated by aqueous alkaline solutions had higher weight-average molecular weights (5300-6040 g mol–1). The isolated bamboo lignin was a typical grass lignin, consisting of p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) 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. In addition, the hemicelluloses isolated by ethanol had lower weight-average molecular weights (ranging from 17380 to 19620 g/mol), while the hemicelluloses isolated using alkaline aqueous solutions had higher weight-average molecular weights (ranging from 22510 to 42150 g/mol). The soluble bamboo hemicelluloses were mainly composed of arabinoglucuronoxylans, followed by minor amount of starch. The isolated arabinoglucuronoxylans from bamboo could be defined as a linear (1→4)-β-linked-xylopyranosyl backbone to which α-L-arabinofuranose and/or 4-O-methyl-glucuronic acid units were attached as single-unit side chains via α-(1→3) and/or α-(1→2) linkages. These abundant natural components isolated from bamboo, which has polyhydroxy structure, can therefore be used as a platform for preparation of more advanced materials by structural modification or polymerization with functional branch, including hydrogel, drug delivery, nutrition carrier, nanoscale systems.

Lignin and hemicelluloses isolated from the largest bamboo species: Dendrocalamus sinicus

2019 Fall National Meeting

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