Submitted to: Separation and Purification Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2010
Publication Date: 3/31/2010
Citation: Offeman, R.D., Franquivillanueva, D.M., Cline, J.L., Robertson, G.H., Orts, W.J. 2010. Extraction of ethanol with higher carboxylic acid solvents and their toxicity to yeast. Separation and Purification Technology. 72: 180-185. Interpretive Summary: Currently the energy required to distill a gallon of ethanol from a fermentor and dehydrate it is equivalent to 18-22% of its total fuel value. Solvent extraction is a less energy-intensive alternative to distillation. This paper is the fifth in a series that searches for better solvents for recovering ethanol from aqueous solutions, and seeks to develop a better understanding of solvent molecular properties that enhance extraction. This paper presents new data for C12 – C18 carboxylic acid solvents, and evaluates the toxicity of the solvents to a commercial yeast used in fuel ethanol production. Improvements in extraction solvents could lead to reduction in energy required to produce ethanol from grain and biomass sources.
Technical Abstract: In a screening exercise for ethanol-selective extraction solvents, partitioning of ethanol and water from a 5 wt% aqueous solution into several C8 – C18 carboxylic acids was studied. Results for the acids are compared with those from alcohols of similar structure. In all cases studied, the acids exhibited higher separation factor, but lower capacity than their alcohol analogs. Solvent toxicity to a commercial yeast commonly used in fuel ethanol production was evaluated for selected solvents. For the acids studied, those containing 12 or fewer carbons were toxic or inhibitory to the yeast; those containing 16 or more carbons were nontoxic and non-inhibitory.