| The rise in the price of crude oil in recent years has greatly increased the interest in liquid biofuel as a transportation fuel. Second generation biofuel produced from non-food biomass has the potential to replace over half of the gasoline used annually in the United States, considering the amount of cellulosic biomass that could be produced every year. Unlike corn ethanol, cellulosic ethanol production requires that biomass be pretreated to reduce recalcitrance due to the presence of lignin and hemicellulose. Pretreatment serves to enhance the digestibility of lignocellulosic biomass. There are different pretreatment methods for the treatment of biomass, each with a varied extent of success and short-comings. Among the leading pretreatment methods are ionic liquids, which are considered as green solvents. However, the high cost of ionic liquids and the adverse environmental effects of many ionic liquids have put a constraint on its use as a pretreatment solvent. The current research demonstrates the use of deep eutectic solvent (DES) as an alternative solvent to ionic liquid for the pretreatment of switchgrass. Deep eutectic solvent (DES) was prepared by mixing 1:2 molar-ratio of choline chloride and trifluoroacetamide. The first goal of this research was the determination of chemical composition of our chosen biomass, switchgrass. The second goal was the selection of a green, stable deep eutectic solvent. The third goal of this research was to carry out a low temperature (50 °C) pretreatment of switchgrass with the selected deep eutectic solvent (DES), dilute sulfuric acid and deionized water. Fourthly, enzymatic hydrolysis of all pretreated switchgrass was carried out to compare total reducing sugar yield. Finally, structural changes as a result of pretreatment were investigated with Scanning electron microscope (SEM) image and with the Attenuated total reflection-Fourier transform spectroscopy (ATR-FTIR) spectra. Results showed that deep eutectic solvent (DES) pretreated switchgrass recorded the highest level of delignification and digestibility, reaching a 6.63% lignin removal and attaining up to 95% cellulose digestibility within 24 hr. hydrolysis. |
PDF Full Text Request