Due to an emerging scarcity of oil resources and an associated increase of oil prices, biofuels (e.g., ethanol) play an important role in the energy crisis. Fermentation is a common process for producing ethanol from renewable biomass. Pervaporation is an attractive technique for the recovery of ethanol from the fermentation systems. Separation membrane is the key element in the pervaporation separation equipments. In this article, the pervaporation performances of ethanol-permselective membranes presented in the recovery of ethanol from dilute ethanol aqueous solution are reviewed. An analytical overview on the challenges and opportunities, and the prospect of ethanol-permselective membranes by pervaporation is also discussed.

In this article, the composite polydimethylsiloxane (PDMS) membranes supported by cellulose-acetate (CA) microfiltration membrane were successfully prepared by adding nano-fumed silica particles modified with a silane coupling reagent, NH₂-C₃H₆-Si(OC₂H₅)₃. The effects of silica content, feed concentration, and feed temperature on the pervaporation performances of the nano-composite PDMS membranes were investigated for recovering ethanol from aqueous solution by pervaporation. It was found that adding the modified silica particles significantly improved the pervaporation performances of the composite membranes. When the silica content in the membrane was 5 wt%, for a 5 wt% ethanol/water mixture at 40°C, the permeation flux of the membrane maintained about 200 g · m⁻² · h⁻¹ and separation factor reached the maximum value of 19.