Optimization of microwave assisted dilute ammonia pretreatment of oil palm empty fruit bunch using response surface methodology

Indonesia is the largest producer of palm oil in the world. Around one-fifth of the palm oil processing, weight end up as solid waste, named as oil palm empty fruit bunch (OPEFB). OPEFB is lignocellulosic biomass which contains cellulose, hemicellulose, lignin and minerals. The utilization of cellulose and hemicellulose requires pretreatment to open the lignin bond. This study examines the pretreatment of OPEFB using microwave assisted dilute ammonia. The OPEFB (30 - 40 mesh) was pretreated by ammonia solution with solid-liquid ratio of 1:10 under variated parameters such as ammonia concentration (7.5; 10; 12.5 %), microwave power (280; 560; 840 Watt) and reaction time (3; 6; 9 minutes).The hemicellulose content of all samples was characterized according to SNI 01-1561-1989. The results were optimized using response surface methodology with Box-Behnken model. The model showed that the highest hemicellulose content of 27.3% can be reached at pretreatment conditions of 665-Watt microwave power at 7.5 % ammonia concentration for 3 minutes.