Characterization of lignin isolated from some nonwood available in Bangladesh

Lignins isolated from cotton stalks, jute stick and dhaincha by acidolytic dioxane were characterized using alkaline nitrobenzene oxidation, elemental analysis, methoxyl analysis and molecular weight analysis and UV, IR 1H NMR spectroscopy. The C9 formulas for cotton stalks, jute stick and dhaincha (Sesbania aculeata) lignin were C9H9.36O4.50(OCH3)1.23, C9H9.02O4.57(OCH3)1.35 and C9H8.88O4.65(OCH3)1.50, respectively. All three lignins were of the guaiacyl–syringyl type. Cotton stalks lignin contained more p-hydroxy phenyl unit than dhaincha and jute stick lignins as observed by alkaline nitrobenzene oxidation products. The β-O-4 units in these nonwood lignins had predominately erythro stereochemistry type.