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

Abstract

BACKGROUND More 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. RESULTS The 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. CONCLUSION The 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

Assessment of extraction options for a next‐generation biofuel: Recovery of bio‐isobutanol from aqueous solutions

“…When the initial salt concentration of K 2 CO 3 is 350 g/kg, all isobutanol in the aqueous phase can be extracted into the organic phase, and the recovery of isobutanol is as high as 100%. When K 2 CO 3 is used as the salting‐out agent, and the recovery rate of isobutanol is 100%, the amount of the salting‐out agent used in the salting‐out method is a little higher than that of the salting‐out extraction method (250 g/kg) [40].…”

“…[26, 34–39] In the previous study, the effects of extractant types, concentration and extraction temperature on the extraction efficiency of isobutanol from aqueous solutions were studied when cyclopentanol, tert‐pentanol, n‐valeraldehyde and isooctyl alcohol were used as extractants. [28] The salting‐out extraction of isobutanol from aqueous solutions was also investigated by employing nine salts (K 4 P 2 O 7 ·3H 2 O, K 2 HPO 4 ·3H 2 O, K 3 PO 4 ·3H 2 O, K 2 CO 3 , K 2 SO 4 , KCl, Na 2 CO 3 , Na 2 SO 4 , NaCl) as salting‐out agents and three organic solvents (2‐ethyl‐1‐hexanol, cyclopentanol, 2‐methyl‐2‐butanol) as extractants at 298.15 K [40]. Higher recovery of isobutanol and dehydration ratio was achieved simultaneously with the K 2 CO 3 as the salting‐out agent.…”

Microbial engineering for the production of isobutanol: current status and future directions

“…Among different extractants 2-ethyl 1 hexanol served as best host. Isobutanol recovery of 100% was achieved by this method [ 55 ].…”

Isopropanol, n‐butanol and ethanol recovery from IBE model solutions by salting‐out using potassium pyrophosphate

“…The four salting‐out agents that have achieved phase separation for ethanol aqueous solution and the salting‐out effects are arranged in the order: K 4 P 2 O 7 > K 3 PO 4 > K 2 HPO 4 > K 2 CO 3 . In the study of salting‐out agents on the separation of the isobutanol + water system, it was found that potassium pyrophosphate (K 4 P 2 O 7 ) had the best phase separation ability among these salts . Therefore, K 4 P 2 O 7 was expected to recover IBE from the fermentation broth.…”

“…17 In the study of salting-out agents on the separation of the isobutanol + water system, it was found that potassium pyrophosphate (K 4 P 2 O 7 ) had the best phase separation ability among these salts. 18 Therefore, K 4 P 2 O 7 was expected to recover IBE from the fermentation broth.…”