Membrane technologies high efficiency reverse osmosis

It is the rate of separation rather than the efficiency of salt retention that is the primary practical issue in the development of reverse osmosis desalination. In addition to a variety of other factors, the rate of reverse osmotic flow depends on the excess pressure across the membrane. Therefore the problem of rapid flow is tied into the technology of developing membranes capable of withstanding high pressures. The osmotic pressure of sea water at 25 °C is about 25 atm. This means that no reverse osmosis will occur until the applied pressure exceeds this value. This corresponds to a water column about 840-ft high at this temperature. 

In recent years reverse osmosis membranes have become the most popular desalination technology because of their high energy efficiency. To improve the separation features of polyamide films, typically used as a selective layer, different fillers have been dispersed in the polymer phase. The in situ dispersion of the nanoparticles during the interfacial polymerization reaction of the polyamide layer is reported to be able to achieve a suitable dispersion. 

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