Optimization of Pretreatment Conditions for Microwave-assisted Alkaline Delignification of Empty Fruit Bunch by Response Surface Methodology

Abstract

Oil palm empty fruit bunch (OPEFB) is one of the prominent lignocellulosic wastes from the oil palm industry, and it has the potential for feedstock in biobased products. However, delignification must be applied. This study investigated the effect of microwave-assisted alkaline pretreatment of OPEFB by using response surface methodology with Box-Behnken design (BBD) to find the optimum pretreatment conditions. OPEFB (30-mesh) was treated with various concentrations of aqueous sodium hydroxide. The effect of three variables, microwave power (280-840 W), NaOH concentration (1-3% w/v), and reaction time (3-9 min), was evaluated to improve lignin removal. The quadratic model indicated that microwave power of 832.9 W, NaOH concentration of 2.7% (w/v), and a reaction time of 8.9 min resulted in the highest lignin removal: 88.10%. FTIR and SEM analysis was also conducted on the untreated and treated OPEFB to evaluate the effectiveness of the pretreatment. These results showed that microwave-assisted alkaline pretreatment of OPEFB could effectively remove the lignin under a relatively short time period and low alkaline concentration.

Keywords

• alkaline pretreatment
• lignin
• microwave
• oil palm empty fruit bunch
• response surface methodology