Lignocellulosic biomass is abundant in nature as well as has the potential to play a major role in generation of renewable biofuels through its conversion to bio-ethanol. Unfortunately, lignocellulosic biomass is a complex biological composite material that shows significant recalcitrance towards the structural breakdown into sugars that is necessary for fermentation to bio-ethanol, making it a cost-ineffective feedstock. Small-angle neutron scattering (SANS) and wide-angle X-ray diffraction (WAXD) were used to obtain a better understanding of the morphology of the cellulose/lignin composite across atomic to sub-micron length scales during the industrially-relevant dilute acid pretreatment method on switchgrass and poplar. Results from dilute acid pretreatment demonstrate: (1) increase in the cross-sectional radius of the crystalline cellulose domains until encompasses the entire elementary cellulose fibril; (2) decrease in the interconnectivity of the fibrils and formation of 300 � diameter lignin aggregates; and (3) at length scales larger than 1000 �, smooth domain boundaries observed that undergo no change to dilute acid pretreatment. Preliminary results from in-situ dilute acid pretreatment study will also be presented. This ex-situ study clearly demonstrates that the dilute acid pretreatment increases cellulose crystallinity while opening the fibril network to allow easier enzyme penetration and the fate of lignin, which precipitates into aggregates within the material.

Effect of chemical pretreatment on lignocellulosic biomass

247th National Meeting (2014)

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