Fractional and Physico-Chemical Analysis of Soda-AQ Lignin by Successive Extraction with Organic Solvents from Oil Palm EFB Fiber

A soda-anthraquinone (AQ) lignin, derived from oil palm empty fruit bunch (EFB), was fractionated by successive extraction with dichloromethane, n-propanol, and methanol-dichloromethane (7/3, v/v). The fractionation resulted in four lignin fractions of increasing molecular weight from 2630 (fraction 1) to 4380 g mol-1 (fraction 4). The lower-molecular-weight fractions showed high contents of carbonyl groups and high molar ratio of noncondensed syringyl/guaiacyl units, while the higher-molecular-weight fractions appeared to have high thermal stability.