Abstract
The separation of ethanol from low ethanol-content aqueous solutions by supercritical CO 2 in the presence of a hydrophilic reverse osmosis polyamine membrane was investigated. The separation was carried out in a membrane module that consisted of two chambers divided by the membrane. The supercritical CO 2 and aqueous solution flowed in parallel into one chamber, while the other chamber was empty and kept at 1 atm. By introduction of supercritical CO 2 into the reverse osmosis operation at a proper time, the ethanol rejection of the present method was significantly enhanced over the reverse osmosis separation and the supercritical CO 2 extraction method. The ethanol rejection could be 70% higher than the best result obtained with reverse osmosis separation at an operating temperature and pressure near that of the critical point of CO 2 and at relatively higher ratios of CO 2 flow rate to solution flow rate. The effects of liquid and CO 2 flow rates, ethanol and salt contents of the feed solution, as well as pH on ethanol rejection were also examined.
Published Version
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