Spectroscopic and chemical characterizaton of biomass

Spectroscopic characterization of both untreated and treated material is being performed in order to determine changes in the biomass and the effects of pretreatment on crystallinity, lignin content, selected chemical bonds and depolymerization of hemicellulose and lignin. The methods used are X-Ray diffraction for determination of cellulose crystallinity (CrI); diffuse reflectance Fourier transform infrared (DRIFT) for changes in C-C and C-O bonds; and fluorescence to determine lignin content. Changes in spectral characteristics and crystallinity are statistically correlated with enzymatic hydrolysis results to identify and better understand the fundamental features of biomass that govern its enzymatic conversion to monomeric sugars. Raman spectroscopy was also used to create a statistical model that relates the spectral characteristics of poplar to its enzymatic hydrolysis results. DRIFT can be used to compare various pretreatments and their effect on the biomass along with their parameters. The PCR model gives not only better correlation, but also better prediction for initial rate and 72-hr conversion for poplar samples. On the other hand, MLR gives a better correlation and prediction for the AFEX pretreated corn stover. This difference in model applicability is due to the nature of the samples. The models for 72-hr conversion give a better correlation and prediction than the initial rate models indicating that factors, other than lignin, biomass crystallinity and acetyl content, affect enzymatic hydrolysis. The pretreated corn stover MLR model indicates that the factor that most affects the initial rate is the aldehyde content or the bonds between the lignin and hemicellulose. However, for the 72 hr conversion the model indicates that lignin is the primary factor affecting hydrolysis. The PCR model indicates that both initial rate and 72-hr conversion is more affected by O-H content.