Understanding the dehydration of acetone, 1-butanol, and ethanol fermentation-based biofuel

Abstract

ABSTRACT Removing most of the water in the acetone + n-butanol + ethanol (ABE fermentation broth can reduce energy consumption and improve the biobutanol market competitiveness. Understanding the dehydration process of ethanol, acetone, and n-butanol can guide the fermentation process for the subsequent separation, which led to an investigation into the salting-out effects of K2CO3 on aqueous ethanol solution, aqueous acetone solution and n-butanol+water system at various temperatures. Elevating the salt concentration has the potential to decrease the water content of these solutes as well as the content of ethanol or acetone and n-butanol in the salt-free aqueous phase. The distribution and selectivity coefficients of ABE were also enhanced. As a result, the recovery and dehydration ratio of ethanol or acetone, or n-butanol, was also improved. The strong hydrophilicity of acetone and ethanol makes the recovery and dehydration ratio of n-butanol difficult. On the same basis(50% K2CO3), the dehydration ratios of ethanol, acetone, and n-butanol were 91.43%, 96.21%, and 97.52%, respectively. Thus, the dehydration capacity gave the following trend: n-butanol>acetone>ethanol. By raising the temperature，it was possible to increase the amount of ethanol，acetone，or n-butanol in the organic phase while decreasing their amounts in the aqueous phase. The ratio of n-butanol’s recovery and dehydration can be improved by raising the temperature.