Fractionation of Oil Palm Fiber Using Green Solvent for Lignin Separation

Abstract

Oil palm processing produces more than 70-wt% of its lignocellulosic content as by-product, the bulk of which is empty fruit bunches (EFB). EFB contains cellulose, hemicellulose, and lignin which makes it a potential source of bio-based chemicals. This research explores the utilization of ethanol as a potentially green, sustainable, and low-cost organic solvent (organosolv) for EFB fractionation. Organosolv processes target extraction of lignin (delignification). Conventional delignification use an acid hydrolysis process with lignin yields of approximately 18-wt%. In this study the EFB was treated in 2 stages, (1) soaking EFB for 1 hour followed by (2) delignification using ethanol as the organic solvent under variable process conditions. Temperature (140°C, 170°C), liquid-to-solid ratio (L/S-w/w) (6:1, 15:1), and wt%-ethanol (20-wt%, 50-wt%) were varied while residence time was constant at 30 minutes (experiments were run in duplicate). Data analysis using 2k Factorial Design Method showed the significant variables were temperature, L/S-ratio, wt%-ethanol, interaction of L/S ratio and temperature, temperature and %wt-ethanol interaction, and L/S-ratio and %wt-ethanol. The optimum operating conditions (170°C, 15:1, 20wt%-ethanol) produced a lignin yield of up to 31%wt. This preliminary study shows ethanol in an organosolv process is a potential delignification option.