Pervaporation of Ethanol/Water and Acetic Acid/Water Mixtures through PDMS Membranes

The effects of feed concentration and feed temperature on the flux and selectivity of polydimethylsiloxane (PDMS) pervaporation membrane for separating ethanol and acetic acid from ethanol/water and acetic acid/water mixtures were investigated. The swelling properties of PDMS membrane in ethanol and acetic acid were also examined for exploring the possible separation mechanism in the pervaporation process. The results indicated that pervaporation was quite different for ethanol and acetic acid. Compared with the preferential pervaporation of ethanol through PDMS, the low diffusion rate of acetic acid in PDMS membrane was observed, which made water pass through PDMS membrane prior to acetic acid if the operation temperature was lower than 60℃.