This article reports on the structural characteristics and antioxidant activity of unmodified autohydrolyzed ethanol organosolv lignin (AH EOL) extracted from oil palm fronds (OPF) and modified autohydrolyzed ethanol organosolv lignin via incorporation of p-nitrophenol (AHNP EOL). The isolated lignin were analyzed by FTIR, (1)H and (13)C NMR spectroscopy, 2D NMR; HSQC and HMBC, CHN analysis, molecular weight distribution using GPC analyzer, thermal analysis; TGA and DSC. The chemical modification by utilizing an organic scavenger during delignification process provided smaller lignin fragments and enhanced the solubility of lignin by reducing its hydrophobicity properties. It was revealed that the antioxidant properties increased as compared to the unmodified organosolv lignin. Additionally, the modified lignin has better solubility in water (DAHNP EOL=35%>DAH EOL=25%).
Lignin extracted from oil palm fronds (OPF) underwent chemical modification by incorporating m-cresol into the lignin matrix. This study reports on the physicochemical properties and antioxidant activity of unmodified autohydrolyzed ethanol organosolv lignin (AH EOL) and the modified autohydrolyzed ethanol organosolv lignin (AHC EOL). The lignin samples were analyzed by FTIR, 1H and 13C NMR spectroscopy, 2D NMR: HSQC spectroscopy, CHN analysis, molecular weight distribution analysis; GPC and thermal analysis; DSC and TGA. The lignin modification has reduced the hydrophobicity of its complex structure by providing better quality lignin with smaller fragments and higher solubility rate in water (DAHCEOL: 42%>DAHEOL: 25%). It was revealed that the modification of lignin has improved their structural and antioxidant properties, thus venture their possible applications.