The isolation and characterization of lignin of kenaf fiber

Abstract

Abstract In this article, milled wood lignin (MWL) was isolated and purified from retted kenaf fiber, the lignin obtained was characterized by elemental analysis, FTIR, 1 H‐NMR, and 13 C‐NMR spectroscopy. The C 9 formula is calculated for kenaf fiber MWL as C 9 H 9.32 O 3.69 (OCH 3 ) 1.30 . The spectra of FTIR, 1 H‐NMR, and 13 C‐NMR show the kenaf fiber lignin to be of the G/S type with high proportion of syringyl (S) unit. The numbers of phenolic and aliphatic hydroxyl groups in the kenaf fiber MWL are estimated to be 0.14 and 1.31, respectively, per C 9 unit. The OH aliph is 90.3% in total numbers of hydroxyl groups of kenaf fiber MWL, and the OH ph is 9.7%. It is evident that the β‐O‐4 structures are mainly linkage in the MWL of kenaf fiber, which contain more erythro stereochemistry type in β‐O‐4 units than thero stereochemistry type. In general, the characteristics of lignin of kenaf fiber are similar to that of hardwood. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009