ISOLATION AND FRACTIONAL CHARACTERIZATION OF BALL-MILLED AND ENZYME LIGNINS FROM OIL PALM TRUNK

Ball-milled and enzyme lignins were isolated from the trunks of oil pa lms and subsequently studied. The lignins were fractionated into pure milled lignin (PML), pure enzyme lignin (PEL), lignin rich enzyme lign in (LREL), hemicellulose rich milled lignin (HRML), and solubilized li gnin obtained during enzyme treatment (SLET) fractions by a two-step p recipitation method. The chemical and structural composition of the fi ve lignin preparations was determined by using UV, GPC, FT-IR, 1 degre es C NMR spectroscopy and nitrobenzene oxidation. Pure milled lignin a nd pure enzyme lignin fractions were found to contain rather low amoun ts of neutral sugars, 2.2-3.1%. The lignin fractions contained a high proportion of noncondensed syringyl units with small amounts of noncon densed guaiacyl and p-hydroxyphenyl units. Trace amounts of p-coumaric and ferulic acids were also found to be associated with linin in the oil palm trunk cell walls.