Extraction of 2,3-Butanediol with Aqueous Two-Phase Systems Formed by Water-Miscible Organic Solvents and Inorganic Salts

Abstract

2,3-Butanediol is one of the bulk chemicals that exhibits a wide range of potential uses in cosmetics and transport fuels as well as being a precursor of synthetic rubbers. During the last few decades, considerable efforts have been made to improve the production of 2,3-butanediol from fermentation. However, major difficulties still exist in downstream processing because 2,3-butanediol has a high boiling point and a high affinity for water. In this study, aqueous two phase systems composed of water-miscible solvents and salts could be used to extract 2,3-butanediol from a model solution. We used t-butanol, tetrahydrofuran and 2-propanol as water-miscible solvents, and dipotassium hydrogen phosphate, tripotassium phosphate, potassium carbonate, potassium fluoride and tripotassium citrate as salts. The phase separation abilities of water-miscible solvents and the salting-out abilities of salts were evaluated by the difference in the binodal curves and salting-out of 2,3-butanediol. t-Butanol and tetrahydrofuran showed high phase separation abilities, and potassium carbonate showed as high a salting-out ability as conventional phosphate salts. The concentration in the top phase and recovery ratio of 2,3-butanediol reached 184.3 g/L and 92.2%, respectively, when the system was composed of tetrahydrofuran and potassium carbonate. This process provided the possibility of a simple and economical process for the separation of 2,3-butanediol from fermentation broth.