(603h) Identification of Nucleophilic Reactions in Detoxification of Phenolic Model Compounds for Bioethanol Fermentation

Biomass pretreatment is typically needed to break down the recalcitrant structure of plant cell wall in bioconversion process. However, during the pretreatment, considerable amount of inhibitors are generated from the degradation of carbohydrates, lignin and extractives; many of these inhibitors significantly reduce the microbial growth and biofuels productivity during the subsequent fermentation process. Overliming detoxification and ammonia conditioning have been widely used for detoxifying biomass hydrolysate. However, gypsum and ammonium salts generated in detoxification will be significant issues for the subsequent processes. Therefore, new detoxification approaches should be investigated for developing cost-effective processes for producing biofuels from lignocellulosic biomass.

In this study, we will use several nucleophiles to detoxify phenolic model compounds and real biomass hydrolysate for bioethanol fermentation with Saccharomyces cerevisiae. We have found addition of nucleophiles improved the volumetric ethanol productivity significantly from 0.17 g/L.h to 1.81 g/L.h. This nucleophiles treatment did not change the concentrations of organic acids in hydrolysate, but decreased the furan derivatives by 20%. We will investigate the effects of pH, temperature and reaction time on this nucleophilic reaction. Further research will also be focused on the reaction mechanism between nucleophiles and phenolic model compounds.