Solvent selection for separation of biologically derived 1,3-propanediol

For the recovery of 1,3-propanediol from aqueous solution, a suitable solvent was selected and the experimental equilibrium data on 1,3-propanediol-water-solvent mixture was investigated. The theoretical solvent screening using Hansen model was applied to select the possible solvents for extracting 1,3-propanediol from aqueous solution. Then the experimental data were determined for evaluating the solvent based on the distribution coefficients and mutual solubility of the solvent and were compared with the calculating data by unifac equation. The tie line data were correlated using the methods of Othmer-Tobias and Hand and their correlation coefficient (R2) were 0.94 and 0.99, respectively. This results revealed that ethyl acetate would be suitable solvent and the distribution coefficient of 1,3-propanediol is 0.22 at temperature of 303.15 K. Furthermore, the effects of temperature (303.15 to 323.15 K) and glycerol addition in feed aqueous stream (4, 8, 12 g/L) were studied. For this results, the distribution coefficient of 1,3-propanediol increases with decrease in temperature; moreover, the distribution coefficient of 1,3--propanediol increases when the amount of glycerol increases. In order to decrease the amount of solvent, the solvent mixtures were also investigated. It was found that the distribution coefficient increases to 0.31 using the solvent mixture between ethyl acetate and ethanol at volume ratio of 90:10. The number of theoretical stages decreases from 7.6 to 5.8 stages at S/F of 10 for extracting 1,3-propanediol from aqueous phase with solvent mixture.