Salting‐out extraction of bio‐based isobutanol from an aqueous solution

Abstract

AbstractBACKGROUNDMore efficient downstream separation technologies need to be explored due to the low concentration of bio‐based isobutanol in the fermentation broth. The salting‐out extraction of isobutanol from its aqueous solution by employing nine salts (K4P2O7·3H2O, K2HPO4·3H2O, K3PO4·3H2O, K2CO3, K2SO4, KCl, Na2CO3, Na2SO4, NaCl) as salting‐out agents and three organic solvents (2‐ethyl‐1‐hexanol, cyclopentanol, 2‐methyl‐2‐butanol) as extractants were investigated at 298.15 K.RESULTSThe recovery was greatly influenced by the salt concentration and types of salts and organic solvents. When the initial molar K4P2O7 concentration was equal to or higher than 1.01 mol kg‐1 and the mass ratio of aqueous isobutanol solution to 2‐ethyl‐1‐hexanol was 1:1, the recovery of isobutanol reached 100%, and more than 91.62% of water was removed from the organic phase.CONCLUSIONThe salting‐out effects of different anions in nine salts were ordered in the sequence: Cl‐ < SO42‐ < HPO42‐ < CO32‐ < PO43‐ < P2O74‐ at the same initial molar salt concentration and using the same organic solvent. 2‐Ethyl‐1‐hexanol was verified to be the most suitable extractant. The distribution behavior and salting‐out extraction effects can be evaluated by tie‐line correlations and solubility correlation. © 2017 Society of Chemical Industry