HOMEWORK 6
1. Name two most important polymers for commercial pervaporation applications.
2. Name 2 most important commercial pervaporation applications.
3. In a pervaporation experiment at 20°C, the water flux measured at zero permeate
pressure through a 100-micron membrane was 6 g/(cm2.h). The equilibrium water
sorption in the membrane was 0.15 g/g. A water diffusivity of 6 x 10-9 cm2/s for the
membrane was obtained from a desorption experiment at zero permeate pressure.
1) Calculate the plasticization constant of water.
2) Draw / Sketch the concentration profiles of water in the pervaporation
experiment.
4. Ethanol and water mixtures can be separated by pervaporation membranes. A
composite membrane with a top, the selective layer thickness of 4 microns at 50°C
showed the permeabilities of 40 x 10-5 and 200 x 10-5 g.m/(m2.h.cm Hg) for ethanol
and water, respectively. For a 50/50 by weight ethanol/water mixture at 50°C, the
activity coefficients are 1.7 and 1.2 for ethanol and water, respectively. At this
temperature, the saturation vapor pressures are 220 and 93 mm Hg for ethanol and
water, respectively. Calculate
1) The ethanol flux and
2) The ethanol wt. % in the permeate at this temperature for a 20 mm Hg
permeate pressure.
,
1. Name two most important polymers for commercial pervaporation applications.
2. Name 2 most important commercial pervaporation applications.
3. In a pervaporation experiment at 20°C, the water flux measured at zero permeate
pressure through a 100-micron membrane was 6 g/(cm2.h). The equilibrium water
sorption in the membrane was 0.15 g/g. A water diffusivity of 6 x 10-9 cm2/s for the
membrane was obtained from a desorption experiment at zero permeate pressure.
1) Calculate the plasticization constant of water.
2) Draw / Sketch the concentration profiles of water in the pervaporation
experiment.
4. Ethanol and water mixtures can be separated by pervaporation membranes. A
composite membrane with a top, the selective layer thickness of 4 microns at 50°C
showed the permeabilities of 40 x 10-5 and 200 x 10-5 g.m/(m2.h.cm Hg) for ethanol
and water, respectively. For a 50/50 by weight ethanol/water mixture at 50°C, the
activity coefficients are 1.7 and 1.2 for ethanol and water, respectively. At this
temperature, the saturation vapor pressures are 220 and 93 mm Hg for ethanol and
water, respectively. Calculate
1) The ethanol flux and
2) The ethanol wt. % in the permeate at this temperature for a 20 mm Hg
permeate pressure.
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