Composite membrane preparation

Composite membranes combine two or more different materials with different characteristics to obtain optimal membrane performance. Basically, the preparation involves (i) preparation of porous support that is usually made by a phase-separation process (cf. Section 2.4.2), and (ii) deposition of a selective barrier layer on this porous 

Other methods derived from surface modification, including heterogeneous graft copolymerization or in situ radical polymerization and deposition of polyelectrolyte 

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Tavalaro, A. and Tavolaro, P. (2007) LTA zeolite composite membrane preparation, characterization and application in a zeohtic membrane reactor. Catal. Commun., 8, 789-794. 

Table II displays several thousand hours data on various samples of Quantro II tested against synthetic seawater at 15-20°C. Routine samples exhibit a flux in excess of 1 gfd at rejection of 98-99%. It is possible with composite membrane preparation to trade rejection for flux within certain limits. The objective of present work is to maintain a rejection of 99+ against seawater while modifying formulation in order to achieve a higher flux.

The technology to fabricate ultrathin high-performance membranes into high-surface-area membrane modules has steadily improved during the modem membrane era. As a result the inflation-adjusted cost of membrane separation processes has decreased dramatically over the years. The first anisotropic membranes made by Loeb-Sourirajan processes had an effective thickness of 0.2-0.4 xm. Currently, various techniques are used to produce commercial membranes with a thickness of 0.1 i m or less. The permeability and selectivity of membrane materials have also increased two to three fold during the same period. As a result, today s membranes have 5 to 10 times the flux and better selectivity than membranes available 30 years ago. These trends are continuing. Membranes with an effective thickness of less than 0.05 xm have been made in the laboratory using advanced composite membrane preparation techniques or surface treatment methods. 

Liu B., Dai W., Wu G., Deng J.-F. Amorphous alloy/ceramic composite membrane preparation, characterization and reaction studies. Catalysis Letters 1997 49 181-188. 

Figure 34.13 Reverse osmosis characteristics of composite membranes prepared by plasma polymerization of benzene/H20/N2 compared with those from acetylene/H20/ N2 represented by the solid line porous polysulfone film as the substrate, 3.5% NaCl at 1500 psi.

Figure 34.20 The influence of different substrate hollow fibers on (a) air enrichment factor, and (b) air flux of composite membranes prepared by deposition of plasma polymerization coating of 1,1,3,3-tetramethyldisiloxane.

FIGURE 25.8 SEM images of the ferromagnetic composite membranes prepared by impregnation of porous substrates (a) silica-coated y-FejOj (b) Fe2Co04. 

Sun F and Ruckenstein E. Sorption and pervaporation of benzene-cyclohexane mixtures through composite membranes prepared via concentrated emulsion polymerization. J Membr Sci 1995 99 273-284. 

Tavolaro A. VS-1 composite membrane Preparation and characterization. Desalination 2002 147 333-338. 

Meng Dong Jia, K.V. Peinemann and R.D. Behling, Ceramic zeolite composite membrane preparation, characterisation and gas permeation. /. Membr. Sci., 82 (1993) 15-26. 

In conclusion, some of the high salt rejection properties found with interfacial polypiperazineamide membranes in the laboratory could not be attained by a machine-made membrane. However, the machine-formed membrane may still find applications where high rejection of monovalent salts is not required but where high flux and rejection of larger solutes are useful. A limited effort to replace piperazine in the reaction with piperazine-terminated oligomers did not appear to resolve the membrane reproducability problem. Recent studies made on the use of piperazine terminated oligomers in composite membrane preparation were reported by R. Sudak et al at Membrane Systems, Inc. (46) and by J.F. Wolfe et al at Stanford Research Institute (47). 

Chen, Y., Xiangli, F., Jin, W., Xu, N. (2007). Organic-inorganic composite membranes prepared by self-assembly of polyelectrolyte multilayers on macroporous ceramic supports. J. Membr. Sci., 302, 78-86. 

A composite membrane prepared, e.g., by lamination of a cation exchange membrane with an anion exchange membrane, called a bipolar ion exchange membrane, shows interesting properties, for example water splitting to generate hydrogen ions and hydroxide ions at the interface of both membranes in electrodialysis, or a rectifier effect.110 When the current is passed from one direction. 

Composite membranes prepared from anion exchange membranes and pyrrole are also effective in preventing the increase in electrical resistance of the... 

T. Sata, Anti-organic fouling properties of composite membranes prepared from anion exchange membrane and polypyrrole, J. Chem. Soc., Chem. Commun., 1993, 1122. 

Figure 5.9 Photograph from a microscope of a composite membrane prepared from NEOSEPTA CM-1 and pyrrole. One surface of a ferric ion form cation exchange membrane, NEOSEPTA CM-1, was contacted with an aqueous 0.745 N pyrrole solution for 4 h.

M. Josowitz, J. Janata, K. Ashley and S. Pons, Electrochemical and ultraviolet-visible spectroelectrochemical investigation of selectivity of potentiometric gas sensors based on polypyrrole, Anal. Chem., 1987, 59, 253 T. Sata. Possibility for potentiometric humidity sensor of composite membranes prepared from anion-exchange membrane and conducting polymer, Sensor Actuators, B, 1995, 23, 63 K. Ogura, H. Shiigi, T. Oho and T. Tonosaki, A C02 sensor with polymer composites at ordinary temperature, J. Electrochem. Soc., 2000,147, 4351. 

T. Sata, Y. Ishii, K. Kawamura and K. Matsusaki, Composite membranes prepared from cation exchange membranes and polyaniline and their transport properties in electrodialysis, J. Electrochem. Soc., 1999,146, 585. 

T. Sata, Properties of composite membranes prepared from ion exchange membranes and conducting polymers. II. Electrical potential generation from cell composed of a cation exchange membrane-polypyrrole composite membrane and ferric ion form cation exchange membrane, J. Membr. Sci., 1993, 82, 247-253. 

Accordingly, Fig. 4 shows the X-ray diffraction profiles of Nafion 117 and the composite membranes, prepared as described in the experimental section, in the protonic form and dry state. The broad diffraction peaks at 26 = 12-20° result from a convolution of amorphous (20 = 16) and crystalline (20 = 17.50) scattering from the polyfluorocarbon chains of Nafion . 

Similar degrees of inhibition due to CO exposure were reported by Hughes and coworkers [17] for a Pd composite membrane prepared by electroless plating. At 380°C and 50 psig feed pressure, a CO concentration of 12mole% caused a reduction in the H2 flux of about 20%. 

Composite membranes prepared by casting Nafion 15 on films made from PPE and phosphomolybdic acid show a lower methanol permeability in comparison to pure Nafion 15. The composite membranes have a potential application as electrol5d es in direct methanol fuel cells. 

Commonly Used Monomers and Newly Reported Monomers for Thin-Film Composite Membrane Preparation... 

Performances of Several Thin-Film Composite Membranes Prepared from Newly Developed Monomers... 

Wang, H., Li, L., Zhang, X., and Zhang, S. 2010. Polyamide thin-fihn composite membranes prepared fiom a novel triamine 3,5-diamino-N-(4-aminophenyl)-benzamide monomer and m-phenylenediamine. Journal of Membrane Science 353 78-84. 

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