|
Title
Spectroscopic comparison of organosolv lignins isolated from wheat straw
Authors
E. SABERIKHAH J. MOHAMMADI-ROVSHANDEH and M. MAMAGHANI
Received
June 25, 2012
Published
Volume 47 Issue 5-6 May-June
Keywords
organosolv, wheat straw, lignin, FT-IR, NMR
Abstract
Glycerol lignin (LIG-Gly), dimethylformamide lignin (LIG-DMF) and mixed solvents (glycerol and
dimethylformamide) lignin (LIG-Gly, DMF) were isolated from wheat straw by organosolv pulping. The physical
characterization of three different lignins isolated under laboratory conditions from wheat straw was performed. The
structures of lignins were studied by three non-destructive (FT-IR, 1H and 13C NMR spectroscopy) methods. The
examination of FT-IR and 1H NMR spectra did not show changes in the main structure of lignins, but based on 13C
NMR spectra of lignin obtained from glycerol (LIG-Gly), C-α, C-β and C-γ in β-O-4 and carbon–carbon bonds, such as
β-β, β-5, were observed. In the case of lignin that was obtained from mixed solvents (LIG-Gly, DMF), the signals for
C-β and C-γ in β-O-4 and β-1, β-5 and 5-5 type structures were detected. In the 13C NMR spectra, signals relating to the
ester groups obtained from the linkage of p-coumaric acids, ferulic acids and an ether linkage from ferulic acid and
lignin were observed. In the lignin obtained from DMF (LIG-D), no fractures occurred.
Link
|
