Separation of azeotropic mixture acetone + hexane by using polydimethylsiloxane membrane

• The possibility of separation acetone + hexane with low environmental effect.
• Sorption and pervaporation techniques are considered.
• Hexane exhibits significantly higher sorption into PDMS than acetone.

We report on possibilities of separation of the azeotropic mixture of acetone + hexane via sorption and pervaporation techniques using polydimethylsiloxane (PDMS) membrane. Acetone + hexane mixtures were studied at the temperature of 25 °C over the whole concentration range. The equilibrium and preferential sorption experiment were performed. Furthermore, the original physicochemical properties of acetone + hexane mixtures such as the excess surface tensions were determined and correlated using the Redlich-Kister equation. Determined differences in hexane and acetone sorption in PDMS, as well as in Flory-Huggins interaction parameters, are consistent with the differences in Hildebrand solubility parameters of pure liquids compared to PDMS, i.e. hexane and PDMS have identical value (14.9) which corresponds to higher sorption and higher rate of interaction with PDMS exhibited by hexane compared to acetone with 19.6. The pervaporation experiments confirmed that PDMS is able to separate this liquid mixture at the azeotropic point composition.

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