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Membrane flat-sheet microporous

A separator is a porous membrane placed between electrodes of opposite polarity, permeable to ionic flow but preventing electric contact of the electrodes. A variety of separators have been used in batteries over the years. Starting with cedar shingles and sausage casing, separators have been manufactured from cellulosic papers and cellophane to nonwoven fabrics, foams, ion exchange membranes, and microporous flat sheet membranes made from polymeric materials. As batteries have become more sophisticated, separator function has also become more demanding and complex. [Pg.181]

In the supported liquid membrane process, the liquid membrane phase impregnates a microporous solid support placed between the two bulk phases (Figure 15.1c). The liquid membrane is stabilized by capillary forces making unnecessary the addition of stabilizers to the membrane phase. Two types of support configurations are used hollow fiber or flat sheet membrane modules. These two types of liquid membrane configuration will be discussed in the following sections. [Pg.653]

Of the existing flat-sheet RO membranes, cellulose acetate membranes of the Loeb-Sourirajan type give the best results because their open microporous substrate minimizes internal concentration polarization. Conventional interfacial composite membranes, despite their high water permeabilities and good salt rejections, are not suitable for PRO because of severe internal concentration polarization. [Pg.90]

Polymer precipitahon by cooling to produce microporous membranes was hrst developed and commercialized by Akzo [33,37], which continues to market microhltration polypropylene and poly(vinylidene fluoride) membranes produced by this technique under the trade name Accurel . Flat sheet and hollow fiber membranes are made. Polypropylene membranes are prepared from a solution of polypropylene in N, A-bis(2-liydroxyethyl)tal lowamine. The amine... [Pg.110]

Concurrently with the work on carbon dioxide and hydrogen sulfide at General Electric, Steigelmann and Hughes [27] and others at Standard Oil were developing facilitated transport membranes for olefin separations. The principal target was the separation of ethylene/ethane and propylene/propane mixtures. Both separations are performed on a massive scale by distillation, but the relative volatilities of the olefins and paraffins are so small that large columns with up to 200 trays are required. In the facilitated transport process, concentrated aqueous silver salt solutions, held in microporous cellulose acetate flat sheets or hollow fibers, were used as the carrier. [Pg.455]

Membranes are polymeric microporous materials in hollow-fiber or flat-sheet configurations. The membrane properties control the contactor and the membrane contactor system performance and economy. The most important membrane properties are ... [Pg.500]

The experimental results reported in this chapter are related to membrane contactors manufactured by GVS S.P.A by using microporous polymeric flat-sheet... [Pg.500]

Membranes can be classified as porous and nonporous based on the structure or as flat sheet and hollow fiber based on the geometry. Membranes used in pervaporation and gas permeation are typically hydrophobic, nonporous silicone (polydimethylsiloxane or PDMS) membranes. Organic compounds in water dissolve into the membrane and get extracted, while the aqueous matrix passes unextracted. The use of mircoporous membrane (made of polypropylene, cellulose, or Teflon) in pervaporation has also been reported, but this membrane allows the passage of large quantities of water. Usually, water has to be removed before it enters the analytical instrument, except when it is used as a chemical ionization reagent gas in MS [50], It has been reported that permeation is faster across a composite membrane, which has a thin (e.g., 1 pm) siloxane film deposited on a layer of microporous polypropylene [61],... [Pg.215]

Asymmetric Microporous Nonporous, skinned on microporous substrate Flat-sheet, tubular, hollow fiber Flat-sheet, tubular, hollow fiber Phase-inversion casting or spinning Phase-inversion casting or spinning Microfiltration, ultrafiltration, membrane reactors Reverse osmosis, gas separation, pervaporation, perstraction, membrane reactors... [Pg.354]

Liquid Continuous Liquid immobilized in microporous substrate Flat-sheet, hollow fiber Impregnation Membrane extraction, gas separation, coupled transport... [Pg.354]

From outward appearance membrane contactors look similar to other membrane devices. However, functionally the membranes used in contactors are very different. They are mostly nonselective and microporous. Membrane contactors can be made out of flat sheet membranes and there are some commercial apphcations. Most common commercial membrane contactors are, however, made from small-diameter microporous hollow fiber (or capillary) membranes with fine pores (illustrated in Figure 2.1) that span the hoUow fiber wall from the fiber inside surface to the fiber outside surface. The contactor shown as an example in Figure 2.1 resembles a tube-in-sheU configuration with inlet/outlet ports for the shell side and tube side. The membrane is typically made up of hydrophobic materials such as Polypropylene, Polyethylene, PTFE, PFA, and PVDF. [Pg.8]

Most commercial systems like Mustang from Pall and Sartobind from Sartorius make use of functionalized microporous membranes. The fibrils reinforced membranes are (pleated) layered around a porous core. The feed is forced to permeate through the membranes in radial direction. This approach results in high area to volume ratio. The 3M and Mosaic Systems approach is different. Instead of functionalization of a porous support they make use of already functionalized beads, which are embedded in a porous support. In this approach, the beads are responsible for the capacity and selectivity where the porous matrix controls the hydrodynamics. The 3M modules consist of stacked flat sheet or pleated membranes, while Mosaic Systems makes use of porous fibers in which the active particles are embedded (Figure 3.23). [Pg.52]

The first composite reverse osmosis membrane reported in the technical literature was developed by Peter Francis of North Star Research Institute in 1964 (4). This membrane was formed by float-casting an ultrathin film of cellulose acetate (CA) upon a water surface, removing the membrane from the water surface by lamination onto a pre-formed microporous support film and drying to bond the membrane to the support. This float-casting procedure has since been described in the technical literature for both flat sheet and tubular membranes ( 5, 6, T). [Pg.275]

A further requirement of a CCRO membrane is that it should have an open, microporous sublayer structure. Such membranes allow effective diffusion of ethanol into the membrane from a recirculation solution supplied on the permeate side of the membrane. In our survey of various flat-sheet and hollow-fiber membranes, a monomer-derived polyamide composite membrane designated 3N8 was identified which satisfied this requirement. Other membranes tested either exhibited small or no measurable flux increases with permeate-side recirculation and are thus not suited to CCRO applications. [Pg.427]

Liquid impregnated (or immobilized) in the pores of a thin microporous sohd support is defined as a supported liquid membrane (SLM or ILM). The SLM may be fabricated in different geometries. Flat sheet SLM is useful for research, but the surface area to volume ratio is too low for industrial applications. Spiral-wound and hoUow-fiber SLMs have much higher surface areas of the LM modules (103 and 104 m /m, respectively [23]). The main problem of SLM technology is the stability the chemical stability of the carrier, the mechanical stability of porous support, etc. [Pg.6]


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See also in sourсe #XX -- [ Pg.237 ]




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