ABSTRACT
ABST R AC T Biomass production of chemicals and fuels by fermentation, biocatalysis, and related techniques implies energy-intensive separations of organics from dilute aqueous solutions, and may require use of hazardous materials as entrainers to break azeotropes. We consider the design feasibility of using ionic liquids as solvents in liquid-liquid extractions for separating organic compounds from dilute aqueous solutions. As an example, we focus on the extraction of 1-butanol from a dilute aqueous solution. We have recently shown [Chapeaux et al. (2008), Green Chemistry, 10, 1301] that 1-hexyl3-methylimidazolium bis(triuoromethylsulfonyl)imide shows signicant promise as a solvent for extracting 1-butanol from water. We will consider here two additional ionic liquids, 1-(6-hydroxyhexyl)-3-methylimidazolium bis(triuoromethylsulfonyl)imide and 1-hexyl-3-methylimidazolium tris (pentauoroethyl)triuoro-phosphate, as extraction solvents for 1-butanol. Preliminary design feasibility calculations will be used to compare the
CONTENTS
Introduction ......................................................................................................... 372 Methodology ........................................................................................................ 373
Experimental............................................................................................... 373 Modeling ..................................................................................................... 374
Results ................................................................................................................... 375 Experimental............................................................................................... 375 Modeling ..................................................................................................... 375
Conclusions .......................................................................................................... 377 Acknowledgments .............................................................................................. 377 References ............................................................................................................. 377
three ionic liquid extraction solvents considered. The ability to predict the observed ternary liquid-liquid equilibrium behavior using selected excess Gibbs energy models, with parameters estimated solely using binary data and pure component properties, will also be explored
1-Butanol is used as a feedstock for making many common chemicals. It is also used as solvent in many applications, such as re-crystallization processes in the pharmaceutical industry. Furthermore, there is growing interest in 1-butanol as a fuel. For any current and potential use of 1-butanol, it is important to look to renewable sources for its synthesis. Thus, there is much current research focused on the fermentation of biomass, resulting in a broth composed of mainly water and alcohols, from which 1-butanol can be separated. Conventionally, separating alcohols and water requires a series of distillation columns. This method is energetically costly, and much room for improvement exists. It has been shown that ionic liquids (ILs) have the potential for separating alcohol/water mixtures with simple liquid-liquid extraction (Fadeev and Meagher, 2001; Chapeaux et al., 2008), which could be less energetically costly than distillation.
