Liqiud-Liquid Extraction as an Alternative Separation Technique for Ethanol-Water Solutions

Michael Pirc

This thesis has been withdrawn as it is a duplicate, the original can be found here:


The feasibility of liquid extraction as an economic alternative to the ternary azeotrope distillation of an ethanol-water fermenta tion mixture was studied. Experimentation included the determination of the attractiveness of the potential solvents "Freon" TF, 1-pentene, ethyl ether, unleaded gasoline, and #2 diesel fuel. Selectivities and distribution coefficients for these solvents were determined. Analysis included generation of a process flowsheet and the resultant energy requirements and process economics.

Unleaded gasoline was selected aver #2 diesel fuel as the more attractive solvent based on the distribution coefficients, and "Freon" TF, 1-pentene, and ethyl ether were ruled out as potential solvents.

A fermentation plant incorporating a gasoline extraction process and a beer still to separate the fermentation mixture, with an ethanol recovery rate of 96 wt%, was found to yield an energy savings of 15.6% over a fermentation plant equipped with only a ternary azeotrope dis tillation separation process. Annual cost for this extraction scheme was found to be $3,998,600, as compared to an annual cost of $1,501,400 for the distillation process. Increasing the recovery rate of ethanol to greater than 99 wt% for the extraction process was suggested as a means to vastly improve its economics.

An extraction scheme that did not include the beer still to preconcentrate the alcohol was found to be uneconomical.