Composite membranes schematic illustration

FIG. 14 Schematic illustration of an archaeal cell envelope structure (a) composed of the cytoplasmic membrane with associated and integral membrane proteins and an S-layer lattice, integrated into the cytoplasmic membrane, (b) Using this supramolecular construction principle, biomimetic membranes can be generated. The cytoplasmic membrane is replaced by a phospholipid or tetraether hpid monolayer, and bacterial S-layer proteins are crystallized to form a coherent lattice on the lipid film. Subsequently, integral model membrane proteins can be reconstituted in the composite S-layer-supported lipid membrane. (Modified from Ref. 124.)... 

Figure 5. Schematic illustration for the SECM operation using a Pt UMP tip (A), and the topographical images for the bare Nafion 417 (B) and NPyc composite membrane (C) (side-1) (the scales x andp = distance, z = current).

When a DC pulse is applied to a couple of fluid-phase vesicles, which are in contact and oriented in the direction of the field, electrofusion can be observed. Vesicle orientation (and even alignment into pearl chains) can be achieved by application of an AC field to a vesicle suspension. This phenomenon is also observed with cells [164, 165] and is due to dielectric screening of the field. When the suspension is dilute, two vesicles can be brought together via the AC field and aligned. A subsequent application of a DC pulse to such a vesicle couple can lead to fusion. The necessary condition is that poration is induced in the contact area between the two vesicles. The possible steps of the electrofusion of two membranes are schematically illustrated in Figure 7.8a. In Sections 7.5.2.1 and 7.5.2.2, consideration will be given to the fusion of vesicles with different membrane composition or different composition of the enclosed solutions. 

The molecular structure of a conventional polymer used for a PFSA membrane is shown in Fig. 1. Membranes registered as Nafion (DuPont), Flemion , (Asahi Glass), and Aciplex (Asahi Chemical) have been commercialized for brine electrolysis and they are used in the form of alkali metal salt. Figure 4 shows a schematic illustration of a membrane for chlor-alkali electrolysis. The PFSA layer is laminated with a thin perfluorocarboxylic acid layer, and both sides of the composite membrane are hydrophilized to avoid the sticking of evolved hydrogen and chlorine. The membrane is reinforced with PTFE cloth. The technology was applied to PEFC membranes with thickness of over 50 xm [14]. 

The procedure for preparing fibrillar/microporous polypyrrole membranes is illustrated schematically in Figure 2.. The membrane-coated convex Pt disk working electrode (Figure 3) is immersed into a solution containing the monomer (pyrrole), which is electropolymerized as described above. Ideally (see below) polypyrrole is only synthesized in the pores of the host membrane a Nuclepore/polypyrrole conductive composite membrane is obtained (Figure 2). Polymerization was terminated before the conductive polymer fibrils reached the Nuclepore/solution interface. 

GFCSS, a German company, developed a composite membrane on the basis of the above principle, a composite membrane that is illustrated schematically in Figure 10.27 [328]. The membrane consists of three layers. The first layer is a non woven polyester backing material. A porous membrane of polyetherimide (Ultem, General Electric) material is cast on the backing material by the phase-inversion technique. The porous membrane is further coated with... 

Fig. 12.3 (a) Schematic diagram illustrating the fabrication of PA-66 nanofiber/net membranes on nonwoven PP scaffold, (b) and (c) Filtration properties of composite membranes variation versus thickness of NFN membranes ((a-c) Reprinted with permission from [11]. 2012 Royal Society of Chemistry)... 

Fig. 17.6 (a) Typical SEM cross-sectional image of PVA nanofibrous composite membrane, (b) Relations of permeate flux and solute rejection of the nanofibrous composite membranes with the degree of cross-linking in the PVA hydrogel coating for separation of oil-water emulsion, (c) Schematic illustration of the fabrication process for thin-film nanofibrous composite membianes based on PAN electrospun nanofibrous substrate and cross-linked PVA barrier layer ((a-b) Reprinted with permission from Ref [70]. Copyright 2006, Elsevier, (c) Reprinted with permission from Ref. [74]. Copyright 2010, Elsevier)... 

Schematic illustration interfacial polymerization to fabricate RO TABLE 4.1 Composite membranes produced by interfacial polymerization. 

FIGURE 15.27 Schematic illustration of dip-coating (a) dry porous support hollow fiber membrane, (b) coating bath, (c) oven, (d) hollow-fiber composite membrane. (Adapted from M. Mulder, Basic Principles of Membrane Technology, 2nd edn., Kluwer Academic, Dordrecht, the Netherlands/Boston, MA, 1996.)... 

The schematic diagram of a gas-sensing electrode is illustrated in Figure 16.8, that comprises of essentially a reference electrode (E), a specific-ion electrode (B), and an internal electrolyte solution (F) contained in a cylindrical plastic tube (G). One end of the plastic tubing is provided with a thin, replaceable, gas-permeable membrane that separates the internal electrolyte solution from the external solution containing gaseous analyte. However, the exact composition and specifications of this gas-permeable membrane is usually described by its respective manufacturers. It is normally made up of a thin microporous film fabricated from a hydrophobic plastic material. 

The first composite reverse osmosis membrane to be developed and described consisted of an ultrathin film of secondary cellulose acetate deposited onto a porous Loeb-Sourirajan membrane.3 The ultrathin film of cellulose acetate was fabricated by a water surface float-casting technique. This has been described to some extent in the published technical literature,4 5 and in considerable detail in several reports on government-funded research projects.3 6 Figure 5.2 illustrates this process schematically. 

Figure 9.17 illustrates the general schematic of the membrane unit used in permeation measurements. Experimental permeation runs were performed with CO2 and N2 in a composite PES/PI (polyethersulfone Sumikaexcel/polyimide Matrimid 5218) hollow-fiber membrane. The single-component permeances were measured using a standard variable-pressure method and the binary ratios converted into the corresponding ideal selectivities. A specified feed pressure was applied to the upstream shell-side, while the permeate side was initially under vacuum. The permeation rates were calculated from the pressure increase as a function of time, in a downstream calibrated volume. The permeation stopped when equalization between pressures on both sides of the membrane was achieved. The main physical properties of the membrane are listed in Table 9.2. 

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