Structural characterization of lignin from wheat straw
Enzyme/mild acidolysis lignin (EMAL) was isolated from wheat straw. The structural characterization of wheat straw EMAL was investigated by FT-IR, 1H NMR, quantitative 31P NMR and DFRC, and DEPT CH (θ = 135C°) techniques. The wheat straw EMAL was a GSH-lignin with β-O-4′ structures and several condensed units (β-5′, β-β′, β-1′, 5-5′) and vinyl ether moieties; the contents of DBDO substructures and total β-aryl ether in the wheat straw EMAL were 0.257 mmol·g−1 and 0.818 mmol·g−1, respectively. Meanwhile, the structure features of the hemicelluloses residues attached to lignin were also investigated using DEPT CH (θ = 135C°) spectra.