Document Type: Review Paper
Organophilic membranes provide a method of recovering organic compounds by pervaporation, which exploits the selective transport of the organic phase. The main application is in the extraction of bio-alcohols from aqueous solution. The eﬀect of membrane composition on performance in transporting alcohols and not water at improved rates is the focus of this review. In this way the minor fraction, the bio-fuel, is removed rather than the usually large volume of water. A more economical process is then obtained. The most successful membranes are non-polar in character, and can be purely organic, inorganic or organic-inorganic polymer hybrids. For ethanol recovery, ﬂux rates are best for polydimethylsiloxane (PDMS) when used as a very thin layer on a supporting base. Zeolites give the best separation factors along with reasonable ﬂuxes, and supported silicalite performs well. For butanol recovery, ﬂux rates are best for PDMS mixed matrix membranes. A styrene copolymer membrane gives a reasonable result for benzene/cyclohexane separation, while metal-organic frameworks have potential in the separation of organic isomers, where pore geometry becomes important.
• Organophilic membranes can selectively recover organic compounds by pervaporation
• Non-polar structures preferred, whether organic, inorganic, or a mixture of same
• For ethanol recovery, a thin supported layer of silicone rubber gives highest ﬂux rates
• For butanol recovery, ﬂux rates best for silicalite on alumina support
• Metal-organic frameworks have great potential in the separation of organic isomers