Inhomogeneities in the Chemical Structure of Sugarcane
Bagasse Lignin
Jing-Xia Sun
Xaio-Feng Sun
Run-Cang Sun
Paul Fowler
Mark S. Baird
10.1021/jf034633j.s001
https://acs.figshare.com/articles/journal_contribution/Inhomogeneities_in_the_Chemical_Structure_of_Sugarcane_Bagasse_Lignin/3360634
Sequential treatments of dewaxed bagasse with distilled water, 0.5 M NaOH, 0.5, 1.0, 1.5, 2.0, and
3.0% H<sub>2</sub>O<sub>2</sub> at pH 11.5, and 2 M NaOH at 55 °C for 2 h solubilized 2.8, 52.5, 14.9, 3.3, 5.5, 5.0, 2.8,
and 2.2% of the original lignin, respectively. The eight isolated lignin fractions were subjected to a
comprehensive structural characterization by UV, FT-IR, and <sup>1</sup>H and <sup>13</sup>C NMR spectroscopies and
thermal analysis. The nitrobenzene oxidation method was also applied to the in situ lignins. The
seven lignin fractions, isolated successively with alkali and alkaline peroxide, were all SGH-type lignins,
with a small amount of esterified <i>p</i>-coumaric acid and mainly etherified ferulic acid. No significant
differences were found in the weight-average molecular weights (1680−2220 g/mol) of the seven
alkali and alkaline peroxide dissolved lignins. However, the first four lignin fractions, isolated with 0.5
M NaOH and 0.5, 1.0, and 1.5% H<sub>2</sub>O<sub>2</sub> at pH 11.5, were rich in syringyl units and contained large
amounts of noncondensed ether structures, whereas the last three lignin fractions, isolated sequentially
with 2.0 and 3.0% H<sub>2</sub>O<sub>2</sub> at pH 11.5 and 2 M NaOH at 55 °C for 2 h, had a higher degree on
condensation and were rich in guaiacyl lignins.
Keywords: Bagasse lignins; sugars; molecular weight; UV; FT-IR; <sup>1</sup>H and <sup>13</sup>C NMR; nitrobenzene
oxidation; phenolic acids
2003-11-05 00:00:00
13 C NMR spectroscopies
etherified ferulic acid
lignin fractions
noncondensed ether structures
nitrobenzene oxidation method
0.5 M NaOH
1 H
UV
2 M NaOH
13 C NMR
Sugarcane Bagasse Lignin Sequential treatments