Patent ID: 7955506

Claim:
A system for dewatering an aqueous ethanol solution, comprising: a) a source of feed solution comprising ethanol and water, the feed solution having a water activity; b) a reservoir containing a draw solution comprising an osmotic agent selected from inorganic salts and acetate salts and water, the draw solution having a water activity lower than the water activity of the feed solution, wherein solar energy concentrates the draw solution to a desired concentration within the reservoir; c) a membrane having a water/ethanol selectivity greater than 4-50 and an osmotic agent rejection rate greater than 95%, the membrane having a draw solution side and a feed solution side; d) a means for delivering the feed solution to the feed solution side of the membrane whereupon the feed solution is dewatered; e) a means for delivering the draw solution from the reservoir to the draw solution side of the membrane whereupon the draw solution is diluted; f) a means for delivering the diluted draw solution from the draw solution side of the membrane to the reservoir; and g) a means for removing the dewatered ethanol solution from the feed solution side of the membrane.