11-14: Comparison of carbohydrate recovery from wood of high and low specific gravity Populus deltoides clones after dilute acid pretreatment and enzymatic hydrolysis

Monday, April 30, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Elizabeth M. Martin1, Angele C. Djioleu1, Jim A. Smith1, D. Julie Carrier1, Matthew Pelkki2 and Anju Arora3, (1)Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR, (2)School of Forest Resources, University of Arkansas, Monticello, Monticello, AR, (3)Division of Microbiology, Indian Agricultural Research Institute, New Delhi, India
Populus sp. are one of several forest species that are of interest in cellulosic ethanol production since they are fast growing and drought resistant, therefore an interesting candidate for short rotation crop.  In an earlier publication from our lab, it was reported that xylose recovery, by dilute acid pretreatment (DA) of 160 °C for 60 min, yielded higher percentages from wood of a low specific gravity clone that had not been irrigated, than from wood of a high specific gravity clone that had been irrigated.  The objective of this present study was to repeat the DA parameters of 160 °C for 60 min in unstirred batch stainless steel reactors, and continue the procedure through enzymatic hydrolysis such that carbohydrate mass balances can be calculated.  Based on our compositional analysis, xylose recovery from DA and enzymatic hydrolysis was 93% for wood from high specific gravity, and 91% for wood of low specific gravity clones.  Glucose percent recovery, also based on our compositional analysis, was 52% from wood of high specific gravity clones and 60% from wood of low specific gravity clones.  Presence of degradation products was also analyzed.  Compounds such as furfural, hydroxymethylfurfural, formic acid and acetic acid were present in all samples, with formic acid being significantly higher in DA pretreatment samples compared to the compositional analysis.  These results indicate that the low specific gravity clone (non-irrigated) yielded more carbohydrate than the higher specific gravity clone (irrigated). These findings could be interesting from a feedstock sustainability perspective. 
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