Studies on the state of permeant in the membrane and its effect on pervaporation phenomena

Pervaporation experiments of pure water and 2‐propanol through poly‐dimethylsiloxane membranes were carried out in order to study the effect of the interaction between permeant and membrane material on pervaporation phenomena. From the effect of downstream pressure on the pervaporation rate, the saturation vapor pressure of water in the membrane was determined to be 2.799 × 103 Pa (21.0 mmHg), which is the same as the literature value, whereas that of 2‐propanol in the membrane was estimated to be 5.865 × 103 Pa (44.0 mm Hg), which is 8.53 × 102 Pa (6.4 mmHg) higher than that of pure 2‐propanol. In the differential scanning calorimetry analyses of permeants in the membrane, it was evident that the state of 2‐propanol in the polydimethylsiloxane membrane was different from that of bulk 2‐propanol. On the other hand, the state of water in the membrane was assigned to that of bulk water. Throughout the present study, it was observed that the interaction between permeant and membrane material plays an important role in determining pervaporation phenomena.