Ball milling pretreatment and diluted acid hydrolysis of oil palm empty fruit bunch (EFB) fibres for the production of levulinic acid

Oil palm empty fruit bunch (EFB) fibres were pretreated by ball milling (BM) at different durations of times. The pretreated fibres were characterised by wide angle X-ray diffraction analysis, particle-size distribution and scanning electron microscopy while the effectiveness of the pretreatment was correlated with the yield of acid hydrolysis to produce levulinic acid (LA). The obtained results showed that the highest yield of LA (10.4 g/L, 52.08%) can be achieved from the 12 h BM pretreated EFB fibres. Further BM pretreatment exceeding 12 h has no significant effect on the LA yield. Optimisation process was further carried out by applying central composite with rotatable design to verify the optimum parameter (H2SO4 concentration, temperature, and time) to produce LA. The optimal conditions for the LA production from the EFB fibres were 0.57 N H2SO4, 185.98 °C, and 195.77 min for producing 10.77 g/L (53.93 %) of LA.