SALT EFFECTS IN EXTRACTION OF ETHANOL, 1-BUTANOL AND ACETONE FROM AQUEOUS-SOLUTIONS

Experimental studies were performed to assess the effect of salt addition on the extraction of 1-butanol, ethanol and acetone from dilute aqueous solutions using cyclopentanol, n-valeraldehyde, tert-amyl alcohol, and Adol 85NF as extractants. The liquid-liquid partitioning was examined for a few strong electrolytes in a broad range of concentrations. Results demonstrate that the distribution coefficient and selectivity in systems with reduced water activity resulting from salt addition were markedly increased. These observations can be qualitatively explained on the basis of the hydration theory. It was also determined that strong electrolytes added to the aqueous feed reduced extractant solubility in the aqueous phase, thus contributing to lower solvent losses. The results showed that the extraction efficiency was not significantly affected by increasing salt content beyond a level that reduces the water activity to a value of 0.92.