Abstract
A two-stage membrane separation process composed of one step using a silicone rubber membrane hollow-fiber module and another step using a polyimide hollow-fiber module for effective separation of alcohol from a low-concentration alcohol–water solution was proposed and its effectiveness was experimentally confirmed.
The first step is a pervaporation through the silicone rubber into a carrier gas, and the second is a gas-phase separation through the polyimide membrane. By use of these two steps in series, 99% and 1% solutions were separated from 5–10 mol% ethanol solution.
This effective separation must be due to the high permeation rate of water vapor through the polyimide membrane, 200-fold that of ethanol vapor as shown by the experimental data.
