Multilayer composite membrane

Figure 3.24 Method developed by Ward, Browall and others at General Electric to make multilayer composite membranes by the water casting technique [55]...

Figure 3.26 Schematic and scanning electron micrograph of a multilayer composite membrane on a microporous support. (Courtesy of Membrane Technology and Research, Inc.)...

Peter, J. and Peinemann, K-V. 2009. Multilayer composite membranes for gas separation based on crosslinked PTMSP gutter layer and partially crosslinked Matrimid 5218 layer. 340 62-72. 

Fig. 15. Schematic drawing and scanning electron micrograph of a multilayer composite membrane.

Multilayer composite membrane can have low resistance by thinner thickness and low methanol crossover by impermeable substrate. The correlation between impregnated ionomer and substrate are the factors that control performance of PEM in DMFC. Process is also an important design factor to obtain good fuel cell performance. 

The most widely used chemically modified PPO in the development of thin film composite membranes is sulfonated polyphenylene oxide (SPPO). The polymer in the acid form as well as salt form has been used by Bikson to produce multilayer composite membranes. These types of membranes have been described to have at least two chemically distinct layers deposited on a porous substrate in a single coating step process. The outer layer forms a protective defect-sealing surface whereas the inner layer is the selective SPPO layer. This layer is adjacent to the porous support membrane. The two top layers are formed simultaneously on top of porous polysulfone support hollow fibers. A coating solution of SPPO in the lithium salt form (SPPO-Li ) and amine functional silicone fluid was coated on top of the polysulfone fibers. These coated fibers were used to construct a hollow fiber separator permeator. 

Figure 5.25 — Flow-through ion-selective optrode based on a multilayer lipidic membrane prepared by the Langmuir-Blodgett method. (A) Cross-sectional view of the composite six-layer membrane (four layers of arachidic acid/ valinomycin covered by an arachidic acid and rhodamine dye bilayer). (B) Optical arrangement integrated with the sensor, which is connected to a flow system. LS light source Ml and M2 excitation and emission monochromator, respectively FI and F2 primary filters M mirror LB lipid-sensitive membrane in a glass platelet FC flow-cell A amplifier D display P peristaltic pump. (Reproduced from [107] with permission of the Royal Society of Chemistry).

Another type of gas separation membrane is the multilayer composite structure shown in Figure 8.9. In this membrane, a finely microporous support membrane is overcoated with a thin layer of the selective polymer, which is a different material from the support. Additional layers of very permeable materials such as silicone rubber may also be applied to protect the selective layer and to seal any defects. In general it has been difficult to make composite membranes with... 

During the last few years, ceramic- and zeolite-based membranes have begun to be used for a few commercial separations. These membranes are all multilayer composite structures formed by coating a thin selective ceramic or zeolite layer onto a microporous ceramic support. Ceramic membranes are prepared by the sol-gel technique described in Chapter 3 zeolite membranes are prepared by direct crystallization, in which the thin zeolite layer is crystallized at high pressure and temperature directly onto the microporous support [24,25],... 

A third type of membrane reactor combines the functions of contactor and separator. An example of this combination membrane reactor is shown in Figure 13.16(c), in which the membrane is a multilayer composite. The layer facing the organic feed stream is an immobilized organic liquid membrane the layer facing the aqueous product solution contains an enzyme catalyst for the deesterification reaction... 

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 novel organic (chitosan) and inorganic (tetraethyl orthosilicate) composite membrane has been prepared, which is pH sensitive and drug permeable [258]. The latter possibly involved in ionic interactions. By plasma source ion implantation technique, the adhesion between linear low-density polyethylene and chitosan could be improved [259]. Such bilayer films showed 10 times lower oxygen permeability, a property of use in food packaging applications. These multilayer films were easily recyclable. 

McCool B, Xomeritakis G, Lin YS. Composition control and hydrogen permeation chara-teristics of sputter deposited palladium-silver membranes. J Memb Sci. 1999 161 67-76. Moss TS, Peachey NM, Snow RC, Dye RC. Multilayer metal membranes for hydrogen separation. Int J Hydrogen Energy. 1998 23(2) 99. 

W.R. Browali, Method for sealing breaches in multilayer ultrathin membrane composites, US Patent 3,980,456, 1976. 

Multilayer composite surfaces prepared by an electrostatic self-assembly of quaternary ammonium salt or tetramethyl ammonium chloride and polyacrylic acid onto poly (acrylonitrile-co-acrylic acid) membrane... 

Special attention deserves Nafion layered membrane prepared by the LBL self assembly of polyelectrolytes [25, 167-171]. A high selectivity membrane was prepared by Tang et al. [25] by self-assembling multi-layer Pd nanoparticles onto Nafion, using poly(diallyl dimethylammonium chloride) (PDAC) for charging the Pd particles. A Nafion 112 membrane was immersed in a Pd/PDDA dispersion and then in a Nafion dispersion. The process was repeated five times to obtain a multilayer self-assembly Nafion composite that shows a small decrease in conductivity (from 112 mS.cm for Nafion 112 to 81 mS.cm for the composite). However, the reported methanol permeability was reduced by a factor 0.0085 (out of scale in Fig. 6.22), leading to k 85. This composite membrane, whose strucmre is depicted in Fig. 6.24, was not tested in a DMFC. 

Kuznetsov et al. (2001) used composite membranes, coated with poly(2-dimethyl-amino ethyl)methacrylate (PDMA) and ladder polyorganosiloxane (LP) onto micro-porous aromatic PAI support and PAN, as PV membranes for separating mixtures of methanol and MTBE. It was noticed that the PAI and PAN supports of the multilayer m branes have opposite effects on the total selectivity. High membrane permeability of the multilayer membranes was attained by virtue of the thinness of the interlayer or coating diffusion layer of PDMA with ultrahigh molecular weight. 

The composite membrane significantly surpassed the limit of pure PDMS selectivity for EtOH, with the total flux decreasing a little compared with the single-layer PDMS/PVDF membrane. The maximum separation factor of the multilayer PDMS/ PVDF composite membrane was obtained at 60°C, and the total flux increased exponentially along with the increase in temperature. The composite membrane gave the best PV performance with a separation factor of 15 and a permeation rate of 450 g/m h with a 5 wt% EtOH concentration at 60°C. 

FIGURE 9.9 Schematic diagram of a multilayer PDMS/PVDF composite membrane. 

Meier-Haack, J., Lenk, W., Lehmann, D. and Lunkwitz, K. 2001. Pervaporation separation of water/alcohol mixtures using composite membranes based on polyelectrolyte multilayer assemblies. 184 233-243. 

Zhan, X., Li, J., Huang, J. and Chen, C. 2010. Enhanced pervaporation performance of multilayer PDMS/PVDF composite membrane for ethanol recovery from aqneous solution. Ami. Biochem. Biotechnol. 160 632-642. 

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