Hybrid organic-inorganic pervaporation membranes for desalination

Membrane desalination using reverse osmosis (RO) has been the leading candidate technology for supplying fresh water in recent years. However, there is a strong motivation for improving the established membrane process and/or developing alternative membrane technologies to overcome the limitations of high energy cost and brine discharge problems of RO technology. In the later context, pervaporation is a potential membrane technology as it has the advantage that the energy need is essentially independent of the concentration of the salt feed water. The pervaporation process combines the evaporation of volatile components of a mixture with their permeation through a nonporous polymeric membrane under reduced pressure conditions. In desalination applications, pervaporation has the advantage of near 100% of salt rejection. The pervaporation of an aqueous salt solution can be regarded as separation of a pseudo-liquid mixture containing free water molecules and bulkier hydrated ions formed in solution upon dissociation of the salt in water. Previous studies have demonstrated the possibility of applying pervaporation to produce distilled water from aqueous salt solutions. However, the water flux reported in the literature so far is generally quite low (