Evaluation of fractionation and delignification efficiencies of deep eutectic solvents on oil palm empty fruit bunch

Deep eutectic solvent (DES) has been introduced as a new generation green solvent for lignocellulosic biomass pretreatment in recent years. In the current study, six DES varying from acidic to basic nature were synthesized and applied on oil palm empty fruit bunch (EFB) in a single step fractionation and delignification process. The effect of the properties of DES on its fractionation performance was assessed. Mass balance performed on the pretreatment process reveals that pH of DES has a significant impact on biopolymer fractionation efficiency. The dissolution trend of acidic and basic DES resembles those in the conventional acid and alkaline pretreatments. The pretreatment energy requirement for the DES used ranged from 2087 to 2451 J/g. The acidic choline chloride:lactic acid DES succeeded in achieving 100% hemicellulose extraction, 88% delignification and 50% lignin pellet extraction from EFB. Thus, it is feasible for acidic DES to be considered in a biorefinery scheme for biomass fractionation.