This paper presents a complete structural investigation of three lignin samples (crude, purified and hydrolyzed) isolated from Tunisian alfa lignin by CIMV process. Spectroscopic techniques (FTIR, NMR 1H and 13C) were used for characterising the structures of these lignins. Size exclusion chromatography and MALDI-TOF/MS were employed for analysing molecular weight distribution (Mn, Mw, Ip) and identifying lignin fragments. Lignins were also characterized by determining phenolic and aliphatic groups. The results showed the presence of S-H-G-H-G, S-H-G-H, S-H-G, S-H-H, S-H and S-G oligomers incorporating mainly (β-O-4), (β-5) and (γ-O-γ) bonds. Phenolic OH fraction is higher than that of alcoholic OH.
F. Abdelkefi, H. Ammar, B. Mlayeh, S. Abid, R. El Gharbi
Lignin, Alfa, Biopolymers