Separation of bio-based acetoin from model fermentation broths by salting-out with high-solubility inorganic salts

Abstract

The downstream separation of acetoin from microbial fermentation broths is a complex process, which has become the bottleneck of large-scale production. In this study, salting-out was proved to be an effective separation method. Three high-solubility potassium salts, K4P2O7, K2CO3 and K2HPO4, were used to recover acetoin from three different concentrations of model acetoin fermentation broth at 298.15 K. Under the optimized conditions, the recovery of acetoin in the model aqueous solution could reach 99.7 %, which was obviously higher than other separation methods. The residual amount of water in the organic phase was 7.67 wt%, while only 0.026 wt% acetoin remained in the aqueous phase. The salting-out ability of the three high-solubility inorganic salts to acetoin model fermentation broth showed the following sequence: K4P2O7 > K2HPO4 > K2CO3. In addition, the content of acetoin in the aqueous phase and the residual amount of water in the organic phase could be calculated by the total linear regression equation in the range of 5 wt% to 10 wt% acetoin concentration. Because inorganic salts have strong stability, low cost and non-toxic, this process shows a good prospect of industrial application.