Monday, April 30, 2007

Quantitation of organic degradation products resulting from varying pretreatment chemistry applied to poplar and corn stover

Bowen Du1, Lekh Nath Sharma2, C. Kevin Chambliss2, and G. Peter Van Walsum1. (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

A variety of degradation products 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 the pretreatment reactions. To date, the complexity of these samples has significantly limited the scope of efforts to perform summative analyses of degradation products.  Qualitative and quantitative interrogation of hydrolysates is also paramount to identifying potential correlations between pretreatment chemistry and microbial inhibition in downstream bioconversion processes. 
Samples of poplar wood and corn stover were pretreated under eight different chemical conditions representative of several pretreatment methods that have been investigated in recent years. All samples were reacted in batch mode for eight minutes at 180ºC. Chemical conditions included: 0.7% H2SO4, 0.07% H2SO4, liquid hot water, neutral buffer solution, aqueous ammonia, lime, lime with oxygen pressurization, and wet oxidation. Pretreatment liquids were then filtered, extracted with MTBE and analyzed by LC-PDA-MS/MS (liquid chromatography-photodiode array-tandem mass spectrometry). Compounds quantified include aromatic acids, aliphatic acids, aldehydes and phenolic degradation products.