REMOVAL OF ACETIC ACID WITH AMINE EXTRACTANTS FROM FERMENTATION BROTH USING HYDROPHOBIC HOLLOW-FIBER MEMBRANE CONTACTOR

Abstract

The organic solvent with a high partition coefficient toward acid extraction must be selected to increase the efficiency of extraction of acetic acid in aqueous phase. Amine extractant plays a major role in the reactive extraction process at the interface between aqueous phase/organic phases. Therefore, it has been investigated that an effect of addition of various amines such as di-ethylamine (DEA), tri-ethylamine (TEA), and tri-n-octylamine (TOA) to organic phase could increase the extraction performance due to increasing partition coefficient. The effect of temperature with TOA content of 0 to 40 wt-% on extraction process of acetic acid was observed. The removal efficiency of acetic acid in aqueous phase increased with temperature. However, the maximum value of extraction performance was different according to experimental conditions, such as the choice of organic solvent, temperature, and TOA content. In the case of methyl isobutyl ketone (MIBK)/TOA system and chloroform/ TOA used in organic phases, the maximum value of removal of acetic acid showed 64 wt-% and 53 wt-% at 40 wt-% TOA content and 25°C, respectively. In 2-octanol/TOA system, the maximum removal efficiency of acetic acid was 67 wt-% at 30 wt-% TOA and 50°C. On the basis of the energy efficiency, the optimal condition of organic phase for the extraction of acetic acid in aqueous phase was determined to be 40 wt-% MIBK/TOA at 25°C. Using the membrane extraction process with a hollow-fiber membrane contactor, the overall mass transfer coefficient was calculated by Wilson-plot method under the assumption of constant partition coefficient. These values show a significant increase in mass transfer rate with increasing the TOA content. Additionally, an improvement of extraction performance was established by multiplying the diffusion coefficient and partition coefficient of solutes.