Characterization and comparison of two ligno-cellulosic substrates by (13)C CP/MAS NMR,XPS, conventional pyrolysis and thermochemolysis

Ligno-cellulosic substrates (LCSs) isolated from wheat straw and bran exhibit high complexing capacities and may have important applications for metal removal from industrial effluents. These two LCSs were examined in the present work by spectroscopic and pyrolytic methods (solid state cross polarization magic angle spinning (CP/MAS) (13)C NMR, XPS, conventional Curie pyrolysis (Cupy)/GC/MS, and TMAH thermochemolysis/GC/MS). This combined study highlighted the limitation of some of the above methods when applied to ligno-cellulosic materials and the resulting biases and the usefulness of TMAH thermochemolysis. A large difference in composition was observed between bran- and straw-LCS due to a much higher contribution of alkyl moieties in the former. These moieties correspond to fatty acids esterified to the ligno-cellulosic macromolecular structure and such carboxylic functions should play an important role for metal complexation.