The Effect of Steam and Glycerol Pretreatment on Chemical Contents of Oil Palm Empty Fruit Bunch (EFB)

Abstract

This research aimed to evaluate the effect of the type of solvent, pH, substrate loading, and reaction time on the chemical components of palm empty fruit bunches (EFB). Steam pretreatment was set up at a temperature of 121 °C and pressure of 1.18 bar, using an autoclave with substrate loading of 5, 10, 15 and 20 % w/v at reaction times of 15 and 60 min. Distilled water, waste glycerol, alkaline glycerol and acidic glycerol were compared as solvents during steam pretreatment. The results showed that with distilled water, better pretreatment was achieved at 5 % and 10 % loading for 60 min. During the pretreatment with waste glycerol at 5 % loading an increase on the reaction time from 15 to 60 min reaction resulted in a remarkable increase in reducing sugar in the liquid phase. Overall, the best steam pretreatment conditions were observed using alkaline glycerol at 5 % w/v and 15 min reaction time, resulting in holocellulose (cellulose plus hemicellulose) increase to 87.98 % and a lignin decrease to 9.17 %. However, pretreatment with glycerol for 15 min was better than those for 60 min using either glycerol or distilled water. The results suggest that waste glycerol during steam pretreatment of EFB can be utilized effectively at short reaction times and at an increased pH to achieve a high output of cellulose and hemicellulose for sugar conversion in the bioethanol fermentation process.