Apparent and intrinsic properties of commercial PDMS based membranes in pervaporative removal of acetone, butanol and ethanol from binary aqueous mixtures

The performance of three commercial poly(dimethylsiloxane) based membranes (Pervatech, Pervap 4060 and PolyAn) was studied in pervaporation of removal of acetone, butanol and ethanol from binary aqueous mixtures at 25 °C. Physicochemical properties of solvents and PDMS were applied to describe affinities and interactions between transported mixture components and membrane. It was shown that high vapour pressure of acetone causes the most pronounced transport of this component through all investigated membranes. In terms of apparent properties, all membranes show high separation towards organic component of the binary mixture. Separation factors ( β i / w ) determined for aqueous mixture containing 0.01 mol fraction of acetone are equal to 30, 62 and 39 for Pervatech, Pervap 4060 and PolyAn, respectively. Comparing these values to β BuOH / w values of water–butanol mixture (9, 31, 9 for Pervatech, Pervap 4060 and PolyAn, respectively), it seems that acetone is the most preferentially transported compound. In contrast, the intrinsic membrane properties discussed in terms of permeances and selectivities reveal that investigated membranes are selective towards butanol (intrinsic membrane selectivity α BuOH / w is equal to 3.6, 11.6 and 3.4 for Pervatech, Pervap 4060 and PolyAn, respectively). However, these membranes are nonselective or water selective ( α i / w ≤1) in contact with water–acetone and water–ethanol mixtures.