Effects of Various Pretreatment Variables on Hydrolysis of Lignocellulose to Produce Sugar in Bioethanol Production

Abstract

This research intends to explore the effect of pretreatment on lignoselulose to be used as raw material for bioethanol production. Pretreatment prepares lignocellulose compounds to be more easily hydrolyzed. Several variables were tested on oil palm empty fruit bunch (OPEFB) i.e. temperature, NaOH concentration, and particle size. According to the method of size reduction, there are two types of pretreatment which were milling and cutting. The first pretreatment type consisted of milling and screening resulting -+10-30, -30+40, -40+80, and-80 mesh. Each size fractions were then soaked in water at 90 °C for 2 hours. Meanwhile the second type consisted of cutting to 1 cm length followed by soaking in NaOH solutions for 2 hours. The operating temperatures at the second type were varied at 90 °C, 120 °C, 150 °C, 170 °C while the NaOH concentrations applied were 0%, 0.5%, 1%, 2%, 5%, 10%.The pretreated OPEFB was then hydrolyzed using cellulase produced by Aspergillusniger grown in situ. It was revealed that the relatively good pretreatment condition was milling to-80 mesh followed by soaking in hot water at 90 °C. It gave the highest produced sugar concentration at 15 g/L while other type resulted only 5.8 g/L.