Sample preparation
Freshly cut oil palm fronds were obtained from the Oil Palm Estate owned by Universiti Kebangsaan Malaysia, located at Bangi, Selangor. The leaflet was left in the estate and only petiole part was taken for the characterization purpose. Sugarcane machine model SCM, 6.5HP Elephant brand was used to squeeze and extract the juice from the raw OPF biomass. The remaining biomass was in the form of OPF bagasse, was also kept for further compositional characterization using NREL procedures [23]. The OPF baggase was naturally sun-dried until the moisture content dropped from the initial of 69 to below 20%. OPF baggase was grinded to a particle with diameter size of 2 mm. The grounded sample was sieved through 0.5 mm mesh to remove the powdery tiny particles (powder) that could be overhydrolyzed during acid hydrolysis [26]. The meshed sample was further dried at 45 °C in an oven until the moisture content dropped below 10% before it could be used in water extraction.