Monday, April 30, 2012: 2:00 PM
Rhythms Ballroom, 2nd fl (Sheraton New Orleans)
Treatment of biomass with alkaline hydrogen peroxide (AHP) can be used as a chemical pretreatment or alternatively as a post-treatment. This work will present research results of AHP pretreatment scaled-up from the bench scale for pretreating grasses including switchgrass and corn stover. The effect of AHP on the carbohydrate and lignin compositional changes after pretreatment and fiber swelling behavior of corn stover and switchgrass will be shown as a function of hydrogen peroxide loading as well as the formation of potential fermentation inhibitors at the bench scale. Scale-up results will show the results of pretreatment performed at higher solids loadings ranging from 15-55% (wt/wt) and the impact of solids loading and pretreatment time on subsequent digestibility. It was found that hydrolysis yields are improved for high solids pretreatment and that the maximum yield is achieved at significantly shorter pretreatment times. We hypothesize that the digestibility improvement resulting from AHP pretreatment may be attributed to mild oxidation or solubilization of the lignin remaining in the cell wall and, for grasses, destruction of ferulate crosslinks between cell wall polymers which would have the net effect of increasing the hydrophilicity to allow improved water and enzyme penetration into the cell wall. To test this hypothesis, we will correlate the hydrophilicity of the cell wall as measured indirectly by lignin and cell wall carboxylic acid content to water swelling capacity, water activity at limiting free water, and digestibility.