Impact of catalytic oil palm fronds (OPF) pulping on organosolv lignin properties

This article sheds light on the structural characteristic and antioxidant activity of the ethanol organosolv lignin extracted from oil palm fronds (OPF) via incorporation of 1,8-dihydroxyanthraquinone during the delignification process. The resulting modified organosolv lignin (DEOL) was studied by 31P NMR, HSQC, HMBC and GPC. It was proposed that addition of a catalytic amount of 1,8-dihydroxyanthraquinone during pulping process; (1) enhanced the dissolution of lignin and the delignification rate, (2) improved the solubility of the resulting modified lignin (DEOL) by reducing its hydrophobicity properties and (3) improved its antioxidant activity compared to untreated organosolv lignin (EOL) (DEOL: 78% and EOL: 53% of Oxygen Uptake Inhibition (OUI) respectively). It was shown that antioxidant activity was closely related to its average molecular weight and phenolic hydroxyl content.