Pervaporation–Membrane Process for Bioethanol Recovery

The traditional separation process, fractional distillation accounts for abou 40% of the cost for corn to ethanol production. A relatively new technology called "pervaporation" may provide considerable energy savings over traditional distillation technologies. Pervaporation is a membrane-based process used to separate and concentrate volatile compounds from a liquid mixture by selective permeation through a non-porous membrane into a vacuum permeate stream. The remaining liquid thus becomes depleted in the compound that permeates the membrane.

A US patent "Pervaporation process of separating a liquid mixture" disclosed an invention withe the abstract: " A pervaporation process for separating at least one component from a mixture of liquids, for example for separating ethanol from a fermentation mass, by a series of three separation steps: separating the mixture by a first pervaporation to form a first permeate vapor enriched in the component to be separated; fractionating the first permeate vapor, for example by temperature condensation, to form a high concentration fraction twice enriched in the component to be separated; and either distilling the high concentration fraction or a second pervaporation to form a distillate or retentate liquid thrice enriched in the component to be separated".