Reverse osmosis thin-film composite membranes

Thin Film Composite Reverse Osmosis Membranes 

A thin film composite reverse osmosis membrane can be defined as a multilayer membrane in which an ultrathin semipermeable membrane layer is deposited on a preformed, finely microporous support structure. This contrasts with asymmetric reverse osmosis membranes in which both the barrier layer and the porous substructure are formed in a single-step phase inversion process and are integrally bonded. 

Fabrication of a thin film composite membrane is typically a more expensive route to reverse osmosis membranes because it involves a two-step process versus the one-step nature of the phase inversion film casting method. However, it offers the possibility of each individual layer being tailor-made for maximum performance. The semipermeable coating can be optimized for water flux and solute rejection characteristics. The microporous sublayer can be optimized for porosity, compression resistance and strength. Both layers can be optimized for chemical resistance. In nearly all thin film composite reverse osmosis membranes, the chemical composition of the surface barrier layer is radically different from the chemical composition of the microporous sublayer. This is a common result of the thin film composite approach. 

The term thin film composite has the connotation that the barrier layer is extremely thin, and hence quite fragile. Indeed, the barrier layer may be quite thin, varying to as low as 200 angstroms depending on the nature of the particular reverse osmosis membrane and its method of manufacture. But this does not necessarily result in fragility. Some of these membranes may be considerably 

There are several potential routes to the preparation of composite reverse osmosis membranes, whereby the ultrathin semipermeable film is formed or deposited on the microporous sublayer.1 2 The film can be formed elsewhere, then laminated to the microporous support, as was done in the earliest work on this membrane approach. Or it can be formed in place by plasma polymerization techniques. Alternatively, membrane polymer solution or polymer-forming reactants can be applied in a dipcoating process, then dried or cured in place. The most attractive approach from a commercial standpoint, however, has been the formation of the semipermeable membrane layer in situ by a classic non-stirred interfacial reaction method. Several examples of membranes made by this last approach have reached commercial status. 

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Thin-Film Composite Reverse-Osmosis Membranes Origin, Development, and Recent Advances... 

The origin of thin-film-composite reverse osmosis membranes began with a newly formed research institute and one of its first employees, Peter S. Francis. North Star Research and Development Institute was formed in Minneapolis during 1963 to fill a need for a nonprofit contract research institute in the Upper Midwest. Francis was given the mission of developing the chemistry division through support, in part, by federal research contracts. At this time the Initial discoveries by Reid and Breton ( ) on the desalination capability of dense cellulose acetate membranes and by Loeb and Sourlrajan (,2) on asymmetric cellulose acetate membranes had recently been published. Francis speculated that improved membrane performance could be achieved, if the ultrathin, dense barrier layer and the porous substructure of the asymmetric... 

In 1977 the North Star membrane research group was spun off by Midwest Research Institute, forming FilmTec Corporation. Two new thin-film-composite reverse osmosis membranes have been under development at FilmTec Corporation since that time, the NS-300 and the FT-30 membranes. 

Y. Kamiyama, N. Yoshioka, K. Matsui and E. Nakagome, New Thin-film Composite Reverse Osmosis Membranes and Spiral Wound Modules, Desalination 51, 79... 

R.J. Petersen and J.E. Cadotte, Thin Film Composite Reverse Osmosis Membranes, in Handbook of Industrial Membrane Technology, M.C. Porter (ed.), Noyes Publications, Park Ridge, NJ, pp. 307-348 (1990). 

M., "Recent Developments in Thin-Film Composite Reverse Osmosis Membrane Systems." Desalination. 1981, 36, 207-233. 

Thin Film Composite Reverse Osmosis Membranes... 

Kulkarni A., Mukherjee D., Gill W.N. (1996), Flux enhancement by hydrophilization of thin film composite reverse osmosis membranes. Journal of Membrane Science, 114, 39-50. 

Kang G, Liu M, Lin B, Cao Y, and Yuan Q, A novel method of surface modification on thin-film composite reverse osmosis membrane by grafting poly(ethylene glycol). Polymer 2007, 48, 1165-1170. 

Kim, H.I. and Kim, S.S. 2006. Plasma treatment of polypropylene and polysulfone supports for thin film composite reverse osmosis membrane. 

J. Lee, J.H. Jang, H.-R. Chae, S.H. Lee, C.-H. Lee, P.-K. Park, Y.-J. Won, I.-C. Kim, A facile route to enhance the water flux of a thin-film composite reverse osmosis membrane incorporating thickness-controUed graphene oxide into a highly porous support layer, Journal of Materials Chemistry A (44) (2015). 

Perera, D.H.N., Nataraj, S.K., Thomson, N.M., Sepe, A., Hiittner, S., Steiner, U., Qiblawey, H. Sivaniah, E. (2014) Room-temperature development of thin film composite reverse osmosis membranes from cellulose... 

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