Solubility of binary mixtures of n-heptane with C4 to C6 alcohols in polymeric membranes

• The measurements are performed by gravimetric and dilatometric techniques.
• The sorption diagram compares the sorption and the distillation.
• The results enable to estimate the membrane suitability for separation processes.

Sorption gravimetric and volumetric techniques performed at 25 °C and at atmospheric pressure were employed to study the preferential and total sorptions from binary liquid mixtures of heptane + alcohols (butan-1-ol, pentan-1-ol, hexan-1-ol) in a polydimethylsiloxane membrane and to study the volumes of the swollen membrane. The experimental volume of the swollen membrane was compared with that calculated under the assumption that interactions between the polymer and liquid mixture were negligible. The sorption extents of binary liquid mixture butan-1-ol + heptane into three membranes (Nafion, low-density polyethylene, and polydimethylsiloxane) were compared. Polydimethylsiloxane and low-density polyethylene sorb preferentially heptane, Nafion prefers butan-1-ol. Because there is an azeotropic point on the vapour-liquid equilibrium curve of the system heptane + butan-1-ol, the distillation is not suitable as a separation technique. Sorption curve, however, exhibits no azeotrope; membrane separation could be a suitable alternative.

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