ポリプロピレン製多孔質中空糸膜を用いたエタノ-ル水溶液の浸透気化濃縮分離

概要

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Concentration of aqueous ethanol solutions by pervaporation was carried out using porous polypropylene hollow-fiber of which dimensions were 0.083μm as pore diameter, 262μm as outer diameter, 20.6μm as membrane thickness l and 0.44 as porosity ε. The aqueous solutions were fed on the outer side of the hollow-fiber membrane and the pressure of the inner side was kept lower than atmospheric pressure. Ethanol is concentrated in the permeate than the retentate. Concentration and flux of permeate increased with the increase of feed concentration and temperature, but kept almost constant (total permeation flux : 4×10-4 mol/ (m2·s), concentration of ethanol in permeate : 30wt% at 9.5wt% 25°C, 15mmHg) with the change of feed flow rate on the outer side of the membrane. Nitrogen gas was introduced in the inner side of the membrane to reduce pressure of ethanol and water, p2E and p2W so as to increase their pressure differences over membrane (P1E-P2E), (P1W-P2W). With the increase of flow rate of nitrogen gas, permeation flux increases, but the concentration of ethanol in the permeate kept constant about 30wt% (at 9.5wt%, 25°C, 15mmHg). Permeation rates of ethanol and water, JE and JW are expressed by the following equations. JE=KE· (P1E-P2E) /RT JW=KW· (P1W-P2W) /RT KE=1.31·DEM/εl KW= (0.09t+6.6) ·DWM/εl where DEM and DWM are diffusion coefficients. KE and KW depend on temperature of feed solution and downstream pressure.
日本膜学会の論文