Sunday, May 4, 2008
3-22

Effect of varying feedstock-pretreatment chemistry combinations on the production of potentially inhibitory degradation products in biomass hydrolysates

Bowen Du1, Lekh Nath Sharma2, G. Peter Van Walsum3, and C. Kevin Chambliss2. (1) Environmental Studies, Baylor University, One Bear Place #97266, Waco, TX 76798-7266, (2) Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348, (3) Chemical Engineering, University of Maine, 5737 Jenness Hall Rm. 117, Orono, ME 04469

A variety of degradation products, many of which are inhibitory in downstream microbial processes, are produced upon pretreatment of lignocellulosic biomass under different thermochemical conditions. Production and release of degradation products is highly affected by the pH and redox potential of pretreatment reactions. In a previous study, samples of poplar wood and corn stover were subjected to eight different chemical conditions, representing several leading pretreatment methods. The resulting hydrolysates were analyzed using recently developed analytical methodology involving the application of liquid chromatography in combination with UV spectroscopy and tandem mass spectrometry. While qualitative aspects of this study were definitive, the influence of co-extracted matrix components on the mass spectral response of a number of analytes precluded sound quantitative conclusions.  As a result, the pretreatment study has been repeated, and an improved quantitative protocol that alleviates limitations caused by matrix effects has been applied to determine analytical concentrations of degradation products in hydrolysates.  The scope of previous work has also been expanded to include pine wood as a representative softwood.  Tested pretreatment conditions included: 0.7% H2SO4, 0.07% H2SO4, liquid hot water, neutral buffer solution, aqueous ammonia, lime, lime with oxygen pressurization, and wet oxidation. All reactions were carried out at 180 degrees for 8 minutes. Accumulation trends for 39 potentially inhibitory degradation products will be presented as a function of tested feedstock-pretreatment chemistry combinations.

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