Reverse osmosis toluene-water

Interfdci l Composite Membra.nes, A method of making asymmetric membranes involving interfacial polymerization was developed in the 1960s. This technique was used to produce reverse osmosis membranes with dramatically improved salt rejections and water fluxes compared to those prepared by the Loeb-Sourirajan process (28). In the interfacial polymerization method, an aqueous solution of a reactive prepolymer, such as polyamine, is first deposited in the pores of a microporous support membrane, typically a polysulfone ultrafUtration membrane. The amine-loaded support is then immersed in a water-immiscible solvent solution containing a reactant, for example, a diacid chloride in hexane. The amine and acid chloride then react at the interface of the two solutions to form a densely cross-linked, extremely thin membrane layer. This preparation method is shown schematically in Figure 15. The first membrane made was based on polyethylenimine cross-linked with toluene-2,4-diisocyanate (28). The process was later refined at FilmTec Corporation (29,30) and at UOP (31) in the United States, and at Nitto (32) in Japan. 

Figure 3.21 Idealized structure of polyethyleneimine crosslinked with toluene 2,4-diiso-cyanate. This was called the NS-100 membrane. The chemistry was first developed by Cadotte to make interfacial reverse osmosis membranes with almost twice the water flux and one-fifth the salt leakage of the best reverse osmosis membranes then available. Even better membranes have since been developed by Cadotte and others [47]...

Toluene-Water Reverse Osmosis Data. Data for the reverse... 

Membranes based on PEI were introduced for use in reverse osmosis to desalinate water. These membranes, known as NSlOO and NSlOl, are made by forming a PEI skin on polysulfone support and insolubilizing it by treatment with toluene di-isocyanate or phthaloyl dichloride to produce a polyurea or polyamide (Figure 5.65). 

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