Effect of Alkaline Pretreatment on Properties of Lignocellulosic Oil Palm Waste

As a biggest palm oil producer in the world, Indonesia also produces a huge amount of oil palm waste, like oil palm empty fruit bunch (EFB) and oil palm fronds (OPF). Oil palm EFB and OPF contain cellulose that can be converted to bioethanol through pretreatment, saccharification, and fermentation processes. The pretreatment is required to liberate the cellulose from lignocellulosic matrix. One of pretreatment method is chemical pretreatment process using alkaline solution at high pressure and temperature. This paper reports the influence of alkaline pretreatment to chemical composition, cellulose crystallinity index, and morphology of oil palm EFB and OPF. The results show that increasing of alkaline concentration causes decreasing of lignin content from 25.83% to 13.61% for oil palm EFB and from 30.92% to 19.23% for OPF at 10% of NaOH solution. The lowest cellulose crystallinity index of oil palm EFB and OPF are achieved at 10% and 8% of NaOH solution, respectively. The result also indicates the changing of oil palm EFB and OPF morphology. After alkaline pretreatment, the surface of oil palm EFB and OPF look rougher than the raw material, some holes are formed on them.