ARS | Publication request: Comparison of Dilute Acid and Ionic Liquid Pretreatment of Switchgrass: Biomass Recalcitrance, Delignification and Enzymatic Saccharification

Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 23, 2009
Publication Date: November 30, 2009
Repository URL: http://hdl.handle.net/10113/45259
Citation: Li, C., Knierim, B., Manisseri, C., Arora, R., Scheller, H.V., Auer, M., Vogel, K.P., Simmons, B., Singh, S. 2009. Comparison of Dilute Acid and Ionic Liquid Pretreatment of Switchgrass: Biomass Recalcitrance, Delignification and Enzymatic Saccharification. Bioresource Technology. 101:4900-4906. doi:10.1016/j.biortech.2009.10.066.

Interpretive Summary: The efficiency of two biomass pretreatment methods, dilute acid hydrolysis and dissolution by an ionic liquid were compared for their efficiency in producing fermentable sugars from switchgrass biomass. Ionic liquids pretreatment significantly increased the rate of enzyme activity resulting in almost 96% of theoretical glucose yield from cell wall cellulose in 24 hours. Although ionic liquids have unique advantages when compared to the dilute acid pretreatment process, currently the cost of the ionic liquid needs to be considered.

Technical Abstract: The efficiency of two biomass pretreatment technologies, dilute acid hydrolysis and dissolution in an ionic liquid, are compared in terms of delignification, saccharification efficiency and saccharide yields with switchgrass serving as a model bioenergy crop. When subject to ionic liquid pretreatment (dissolution and precipitation of cellulose by antisolvent) switchgrass exhibited reduced cellulose crystallinity, increased surface area, and decreased lignin content compared to dilute acid pretreatment. Pretreated material was characterized by powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and chemistry methods. Ionic liquid pretreatment enabled a significant enhancement in the rate of enzyme hydrolysis of the cellulose component of switchgrass, with a rate increase of 16.7-fold, and a glucan yield of 96.0% obtained in 24 h. These results indicate that ionic liquid pretreatment may offer unique advantages when compared to the dilute acid pretreatment process for switchgrass. However, the cost of the ionic liquid process must also be taken into consideration.