Supported liquid membrane schematic

The typical concentration profile of solute in an SLM system with quaternary ammonium salt as carrier is schematically shown in Fig. 6. To model the facilitated transport within a supported liquid membrane [58,59], the following assumptions are usually made ... 

Figure 8.3 Schematic representation of copper concentrations relevant to freshwater studies and analytical windows of several analytical techniques. ASV, anodic stripping voltammetry CSV, cathodic stripping voltammetry ISE, ion selective electrode SLM, supported liquid membrane SWASV, square wave anodic stripping voltammetry LC50, lethal concentration for 50% of the population [Cu]t, total metal concentration (adapted from Langford and Gutzman, 1992).

However, ELMs are quite difficult to prepare and after transport, the oil droplets have to be separated and broken up to recover the receiving phase. Compared to the ELM, the BLMs are easier to operate. The supported liquid membranes (SLM) are categorized into two types of supports, namely, a flat-sheet supported liquid membrane (FSSLM) or a hollow fiber supported liquid membrane (HFSLM). Here a polymeric filter with its pores filled with the organic phase acts as membrane. The three different types of liquid membranes have already been schematically represented in Chapter 29. A schematic representation of a hollow fiber semp is shown in Figure 31.2. 

Scheme 8-6 Schematic diagram of enantioselective transport of (S)-i buprofen through a lipase-facilitated support liquid membrane.

FIG U R E 2 7.9 Schematic diagram of a spiral-type supported liquid membrane (SLM) module 1, microporous hydrophobic membrane (support) 2, mesh spacer 3, inlet pipe of feed solution 4, inlet pipe of receiver solution 5, inlet tube of organic membrane solution 6, feed solution 7, organic membrane solution and 8, receiver solution. (Reprinted from Teramoto, M. et al., Sep. Sci. TechnoL, 24, 981-999,1989. With permission from Taylor Francis Ltd.)... 

Figure VI - 30. Schematic drawing of two types of liquid membrane, left supported liquid membrane (SLM) and right emulson liquid membrane (ELM)...

Figure VT - 42. Schematic representation of the emulsification of the organic phase in supported -liquid membranes[69].

FIGURE 4.7 Schematic view of hollow fiber supported liquid membrane run in recycling mode. (1) hollow fiber contactor, (2,3) feed and strip pump, (4,5) feed and strip reservoir, respectively. (From A. Kumar and A. M. Sastre, Ind. Eng. Chem. Res., 39,146, 2000. With permission.)... 

In liquid-phase microextraction (LPME), a liquid membrane is used to enrich and isolate analytes from a complex sample. The liquid membrane, which is immiscible with water and the sample matrix, is immobilized in the pores of a porous hollow fiber. Such a liquid membrane is referred to as a supported liquid membrane (S LM). Immobilization of the SLM is achieved by simply dipping the hollow fiber in an organic solvent allowing the pores to be filled. Figure 9.11 shows a schematic representation of LPME. 

Schematic diagram of the manifold used for extraction by the supported liquid membrane. (From BogiaUi, S. et al.. Food Toxicants Techniques, Strategies and Developments, ch. 9 Extraction Procedures, 2007, 269-298 edited by Yolanda Pico, Elsevier, Amsterdam. With permission.)...

F igure 8.3. Schematic representation of a hollow fiber contactor set up used for supported liquid membrane applications. Flow directions in a hollow fiber module (a), single fiber (b), and hollow fiber set up for simultaneous extraction and stripping. (Reproduced with permission from Ansari etal, 2011a). 

Figure 1. Schematic Representation of Different Liquid Membrane Configurations (a) Bulk Liquid Membrane, (b) emulsion liquid membrane, (c) flat-sheet supported liquid membrane, (d) hollow fiber supported liquid membrane.

Figures 12 and 13 show the effects of CO2 feed partial pressures, pc02 on Rc02 and a for dry and water-containing membranes, respectively. In both cases, as the CO2 feed pressure increased, Rco2 decreased while Rn2 was nearly constant. The decrease in Rc02 observed for both dry and water-containing membranes suggests that CO2 permeates by the carrier transport mechanism in both conditions. However, the mechanism may be different for the two cases. In the dry membranes, the facilitated transport of CO2 is expected to be attributable to the weak acid-base interaction between CO2 and amine moiety, as suggested by Yoshikawa et al. (27). Therefore, the dry membrane is a fixed carrier membrane. On the other hand, tertiaiy amine groups in the wet membrane are considered to act as catalyst for the hydration of CO2 as in the case of triethanolamine in a supported liquid membrane (28). The mechanism is schematically represented as follows ...

Figure 2. Schematic Diagram of a Transport Process Which Uses Composite Supported Liquid Membranes in Series.

Figure 28.2 Schematic of supported liquid membrane with strip dispersion.

Separations in two-phase systems with one immobilized interface(s) are much newer. The first paper on membrane-based solvent extraction (MBSE) published Kim [4] in 1984. However, the inventions of new methods of contacting two and three liquid phases and new types of liquid membranes have led to a significant progress in the last forty years. Separations in systems with immobilized interfaces have begun to be employed in industry. New separation processes in two- and three-phase systems with one or two immobilized L/L interfaces realized with the help of microporous hydrophobic wall(s) (support) are alternatives to classical L/L extraction and are schematically shown in Figure 23.1. Membrane-based solvent extraction (MBSE) in a two-phase system with one immobilized interface feed/solvent at the mouth of microspores of hydrophobic support is depicted in Figure 23.1a and will be discussed... 

Figure 3 is a schematic representation of a tortuous pore in a liquid membrane support. Lee et al. (33) define the tortuosity, T, as the following ... 

Liquid membranes are prepared from immiscible, liquid ion exchangers, which are retained in a porous inert. solid support. As. shown schematically in Figure 23-8. a porous, hydrophobic (that is. water-repelling), plastic disk (typical dimensions 3 X 0.15 mm) holds the organic layer between the two aqueous solutions. For divalent cation determinations, the inner tube contains an aqueous standard soittt ion of MCI, where M is the cation whose activity is to be determined. This solution is also saturated with AgCI to lorm a Ag-AgCI reference electrode with the silver lead wire. 

Figure 25 Schematic of the concept of the supported liquid-phase catalytic membrane reactor...

Apart from hydrocarbons and gasoline, other possible fuels include hydrazine, ammonia, and methanol, to mention just a few. Fuel cells powered by direct conversion of liquid methanol have promise as a possible alternative to batteries for portable electronic devices (cf. below). These considerations already indicate that fuel cells are not stand-alone devices, but need many supporting accessories, which consume current produced by the cell and thus lower the overall electrical efficiencies. The schematic of the major components of a so-called fuel cell system is shown in Figure 22. Fuel cell systems require sophisticated control systems to provide accurate metering of the fuel and air and to exhaust the reaction products. Important operational factors include stoichiometry of the reactants, pressure balance across the separator membrane, and freedom from impurities that shorten life (i.e., poison the catalysts). Depending on the application, a power-conditioning unit may be added to convert the direct current from the fuel cell into alternating current. 

A schematic of a typical fuel-cell catalyst layer is shown in Figure 9, where the electrochemical reactions occur at the two-phase interface between the electrocatalyst (in the electronically conducting phase) and the electrolyte (i.e., membrane). Although a three-phase interface between gas, electrolyte, and electrocatalyst has been proposed as the reaction site, it is now not believed to be as plausible as the two-phase interface, with the gas species dissolved in the electrolyte. This idea is backed up by various experimental evidence, such as microscopy, and a detailed description is beyond the scope of this review. Experimental evidence also supports the picture in Figure 9 of an agglomerate-type structure where the electrocatalyst is supported on a carbon clump and is covered by a thin layer of membrane. Sometimes a layer of liquid water is assumed to exist on top of the membrane layer, and this is discussed in section 4.4.6. Figure 9 is an idealized picture, and... 

Currently, most solution-coated composite membranes are prepared by the method first developed by Riley and others [45,56,57], In this technique, a polymer solution is cast directly onto the microporous support. The support must be clean, defect-free and very finely microporous, to prevent penetration of the coating solution into the pores. If these conditions are met, the support can be coated with a liquid layer 50-100 xm thick, which after evaporation leaves a thin selective film 0.5-2 xm thick. A schematic drawing of the meniscuscoating technique is shown in Figure 3.25 [58], Obtaining defect-free films by this technique requires considerable attention to the preparation procedure and the coating solution. 

Fig. 20. Schematic representation of a composite membrane (Figs. 1 and 7) at liquid saturation showing a single gelled particle enmeshed in PTFE microfibers as described in the text. The bold straight lines represent the PTFE fibers. The entangled network of curved lines represent the crosslinked polymer that supports the liquid saturated gel. Each empty circle (o), superimposed on the curvy lines, represents a set of molecules (

Two reactor concepts may be distinguished [209], which are schematized in Figure 9.30. One consists of the gas-phase and the liquid-phase flowing, respectively, on each side of the membrane (Figure 9.30a). In this case, one reactant is dissolved in the liquid phase, which is sucked by capillary forces into the catalytic membrane layer, getting the reactant in contact with the catalytic sites. The gaseous reactant is fed on the other side through the porous support of the membrane. As a result, a gas-liquid-phase boundary was established, which is determined by the pressure difference between the gas and the liquid side. The pressure must be controlled in order to have the phase boundary in the membrane layer where catalytic active sites are located so that the contact between the liquid reactant, the gas reactant, and... 

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