ABSTRACT
Pervaporation (PV) is the most promising technology in molecular-scale liquid-liquid separations existing in biorenery, petrochemical, and pharmaceutical industries, as the process is highly selective, economic, safe, and ecofriendly. It is a rapidly developing technology. PV is a very mild process and hence very effective for the separation of less stable compounds. It is a method for separating mixtures of liquids by partial vaporization through a very dense nonporous membrane. The name of this membrane-based process is derived from the two basic steps of the process: rst, the permeation through the membrane by the permeate and then its evaporation into the vapor phase. The concept of PV has been recognized for a long time (Mitchell 1831). However, only in the past 50 years has the development of this technology as a process taken place. Binning et al. (1961a,b) were the rst to suggest, based on their experiments with organic liquid mixtures, that PV had commercial potential. During the following two decades, most of the work on PV was focused on ethanol (EtOH)–water separation. The reason was that PV could achieve improved separation-something that was not possible by ordinary distillation-breaking of the EtOH-water azeotrope. In the 1980s, SETEC and GFT (now part of Le CarboneLorraine) in Germany commercialized PV membrane systems based on composite polyvinyl alcohol (PVA) membranes for EtOH-water separation (Bruschke et al. 1985). At present, by using this technology, there are numerous commercial facilities around the world with capacities as large as 150,000 l/day. Fleming (1992) suggested that PV is also good for solvent dehydration.
