In Situ Extraction of Fermentation using Ionic Liquids

University Of Kansas Center For Research Inc, Lawrence KS

Investigators

Abstract

Principal Investigator: Aaron M Scurto Proposal No: 1034433 Intellectual Merit The production of alcohol-based biofuels from fermentation of renewable biomass feedstocks is one route for securing a sustainable source of transportation fuels. Most fermentations produce alcohols in relatively dilute aqueous solutions that are currently separated by energy-intensive downstream processes such as distillation. However, if the alcohols could be removed in situ from the fermentation broth by solvent extraction, then product inhibition of the microorganisms could be overcome, and downstream energy consumption could be reduced, leading to more efficient alcohol recovery. Optimal solvents must possess three main characteristics. First, the solvent must possess thermodynamic and mass transfer characteristics that facilitate alcohol separation and solvent recovery. For example, the solvent must be immiscible in water, have high solubility for the target biofuel, and possesses a large volatility difference with the biofuel. Second, the solvent must be biocompatible with the fermentation microorganisms. Finally, solvent should be environmentally benign with low impact on humans and the environment. Ionic liquids (ILs) have the potential meet all these requirements. The overall goal of this research is to provide fundamental understanding of the extraction of alcohol-based biofuels from fermentation broths using molecularly-adaptable ionic liquids. Ionic liquids are liquid organic salts with no volatility. The design of ionic liquids as materials for in situ product recovery of alcohols from fermentation broths will be realized by simultaneous optimization of phase equilibrium thermodynamics, mass transfer, and biocompatibility. Model systems of candidate nonvolatile ionic liquids and volatile alcohol biofuels will be investigated according to their partitioning and mass transfer in aqueous systems, aqueous systems with model fermentation compounds, and actual fermentation broths. S. cerevisiae will serve as the model organism for ethanol fermentation, and C. acetibutylicum will serve as the model organism for butanol fermentation. The molecular and phase toxicity of the ionic liquids to these fermentation microorganisms will be determined. Life-cycle analysis will be used to compare the long-term impact of conventional solvents vs. ionic liquids. Overall, this research plan is designed to elucidate the structure-property relationships that will assess the potential of ionic liquids to accomplish the low-energy separation of alcohol-based biofuels from fermentation broths. Broader Impacts Overall, the proposed research seeks to assess alternatives to distillation to lower the energy consumption associated with biofuel production from renewable resources. Educational and outreach activities based on the research are also proposed. Specifically, case studies based on new processes which could result from the research will be developed and used in three current courses at the University of Kansas: Biocatalysis, Environmentally-Benign Reaction Engineering, and Environmental Assessment of Chemical Processing. In collaboration with a local high-school science teacher, incorporation of eco-toxicology experiments with solvents, including ionic liquids, will be incorporated into the science curriculum. These activities will be adapted for curriculum materials at Project Discovery, a summer camp for female high-school students interested in chemical engineering.