Antioxidant activities of lignin extracted from sugarcane bagasse via different chemical procedures.

Lignin was extracted from sugarcane bagasse via different chemical procedures with ethanol and alkaline solutions. The products (EL, AL) were characterized by UV, FT-IR, (13)C NMR, TGA, GPC and potentiometric titration. The results indicated AL had more phenolic hydroxyl (PhOH) and methoxyl groups (OCH(3)), and larger molecular mass and better thermal stability than EL. The lignins were further evaluated as potential antioxidants. The results demonstrated the radical scavenging activity (RSA) of AL was 79.0%, 91.3% higher than EL at the concentration of 300 mg L(-1). The stronger antioxidant activity of AL was due to its higher quantities of PhOH and OCH(3) groups.