Paper Title
Potential Fermentation Inhibitors formed during Dilute-Acid Hydrolysis of Oil Palm Lignocellulosic Wastes and their Detoxification Methods

Empty fruit bunches (EFBs) are lignocellulosic wastes from palm oil industry. Due to their low cost and domestic availability, they are potential raw materials to be used for bioethanol production. This study aimed to determine the potential fermentation inhibitors formed during acid hydrolysis of the EFBs and to study the efficiency of their detoxification methods. The dilute-acid hydrolysis process was performed using 2% and 6% sulfuric acid at 121oC for 30-60 min. The results showed that various sugars including glucose, mannose, galactose, rhamnose, xylose and arabinose were found in the hydrolysate of EFBs. The maximum total sugars obtained were 19.77 g/L when the EFBs were hydrolyzed with 6% sulfuric acid at 121oC for 45 min. The hydrolysates contained xylose as a major sugar, followed by arabinose, and glucose. The inhibitors formed during hydrolysis stage were acetic acid, furfural and phenolic compounds. The levels of all inhibitors increased with the increased reaction time and acid concentration. The detoxification methods, namely evaporation, activated charcoal treatment and over-liming could effectively remove the inhibitors but in the different extents.