Solvent Extraction of Ethanol from Aqueous Solutions. I. Screening Methodology for Solvents

The evaluation of the potential for separation of aqueous ethanol mixtures by liquid-liquid solvent extraction has been complicated by inconsistent results and differing experimental methodologies among researchers developing distribution coefficient data. A screening method for measuring equilibrium distribution coefficients for solvent extraction of ethanol from dilute aqueous solutions is presented to minimize potential sources of variation. These include entrainment, incomplete equilibration, impurities, and temperature changes during the preparation of samples for analysis. Multiple literature sources of data exist for each of 10 solvents. Results for these 10 solvents are compared among sources and to results generated from this method. The method also has general utility for the screening of solvents for extraction of other useful fermentation products.