Transport mechanisms schematic

A different approach is the use of an ultrafiltration membrane with an immobilized chiral component [31]. The transport mechanism for the separation of d,l-phenylalanine by an enantioselective ultrafiltration membrane is shown schematically in Fig. 5-4a. Depending on the trans-membrane pressure, selectivities were found to be between 1.25 and 4.1, at permeabilities between 10 and 10 m s respectively (Fig. 5-4b). 

Fig. 7.21 Schematic diagram of automated pH conductivity instrument, showing the sample transport mechanism.

There are four well-known types of diffusion in solids [10] gaseous or molecular diffusion [75], Knudsen diffusion [76-80], liquid diffusion [10], and atomic diffusion. In Figure 5.27, the possible transport mechanisms in porous media are schematically shown [77], Gaseous flow (Figure 5.27a)... 

Complex mathematical formulae will be minimized here for the purpose of simplicity since there are numerous texts that deal with detailed theory of mass transport in chromatography1[2,1,22 The flow of mobile phase through a packed column bed is shown schematically in Figure 2.1. There are two transport mechanisms in progress. Firstly, the convectional flow around the particles and secondly, the diffusion in and out of the pores of the stationary phase. 

Figure 4. Schematic representation of transport mechanisms in porous media (a) Poiseuille flow (b) Knudscn diffusion (c) surface diffusion (d) capillary condensation (e) molecular sieving...

Fig. 7.23. Schematic fllustratioii of the tempieiature dependence of the conduction energy showing the ects of different transport mechanisms. The peak of the band tail electron distribution is also shown. The energy is referenced to the top of the exponential band taU.

General properties of liquid membrane systems have been a subject of extensive theoretical studies. Six basic mechanisms of transport are schematically shown in Figure 13.2. In a simple transport (Figure 13.2a), solute passes through due to its solubihty... 

In carrier-mediated transport studies, two terms are used, namely, facilitated transport and coupled transport. Facilitated transport is generally referred to as the case where the transport mechanism is independent of any other ion, while in case of coupled transport the transport rate of a particular ion is dependent on the concentration of another ion. The mechanism of facilitated transport is shown in Figure 31.3 a, while those of the two different types of coupled transport (cotransport and counter-transport) are schematically explained in Figure 31.3b and 31.3c. In case of cotransport, the metal ion is transferred along with a counter-anion, while simultaneous transport of another ion from receiver phase to source phase occurs in case of counter-transport. 

The membranes used in the present study contained 50.0 wt% PVA (60 mol % cross-linked by formaldehyde), 20.7wt% AIBA-K, 18.3wt% KOH, and 11.0wt% poly(allylamine), unless otherwise stated. Figure 9.3 presents a schematic of the C02 transport mechanism in the membranes. The membranes synthesized contained both AIBA-K and KHCO3-K2CO3 (converted from KOH) as the mobile carriers, and poly(allylamine) as the fixed carrier for C02 transport. AIB A is a sterically hindered amine, and its reaction with C02 is depicted in Equation 9.12.49 Poly(allylamine) is a nonhindered amine, and its reaction is shown in Equation 9.13. The reaction mechanism of the C02 with KHC03-K2C03 is presumably similar to that of hindered amine-promoted potassium carbonate described in Equation 9.14 50... 

Figure 9.3. Schematic of C02 transport mechanism in the membranes synthesized.

Fig. 7 Schematic diagram of charge-transport mechanism in PFO/PEO20/cathode. The gray region of the PEO20 layer is the Cs2C03-rich region (taken from [86])...

The SSF membranes are produced by carbonization of polyvinyhdene chloride (PVDC) [29]. They contain nanopores (5—7 A in diameters) which allow all of the molecules of the feed gas mixture to enter the pore structure. However, the larger (higher polarizability) and the more polar molecules are selectively adsorbed on the pore walls at the high-pressure side. Then they selectively diffuse on the pore surface to the low-pressure side, where they desorb into the gas phase. The adsorbed molecules effectively block the transport of the smaller molecules through the void space within the pores, if any. Figure 22.7(b) schematically depicts the transport mechanism through an SSF membrane. 

According to the transport mechanisms, the LM techniques may be divided into six basic mechanisms of transport, schematically shown in Fig. 1.2. 

Several possible current transport mechanisms are illustrated in Fig. 3. The schematic represents a Schottky barrier on an undoped sample under forward bias. The three arrows for electron transport are drawn for comparison with crystalline semiconductors in which thermionic emission, tunneling via thermionic field emission, or field emission represent the usual mechanisms. 

Fig. 3. Schematic of the Schottky barrier on a-Si H showing the different transport mechanisms.

When low molecular substance or solvent molecules migrate through solid plastics this process is called permeation. Basically, substance transport in permeation takes place in three steps adsorption, diffusion, and desorption of the migrating molecule [3, 21, 22]. Figure 30 provides a schematic presentation of the transport mechanism involved in permeation. 

Figure 7 Schematic illustration of the two possible transport mechanisms (a) reverse micellar and (b) lamellar thmning transport of marker from the inner aqueous phase to the continuous aqueous phase.

FIGURE 22.3 Schematic view of transport mechanism of Fe(III) from sulfuric acid media with the IL (PJMTH ij (S04 ) by PEHFSD with single hollow-fiber module. 

F. 2.12 Schematic representation of the transport mechanisms within a plug. (Ghaini et al. 2011)... 

FIGURE 9.3 Schematic representation of the pervaporation transport mechanism (a) solution-diffusion model and (b) pore flow model. 

Figure 4.3 Schematic of the counter-current oxygen transport mechanism of a symmetric (dense) MIEC membrane exploited for oxygen separation applications (a) and the change in oxygen permeation flux with the membrane thickness (b). fSource Reproduced from Ref [ 10], with permission from Elsevier)...

These equations are applicable only in cases where solubihty and diffusion of the permeating gas molecule are constant and not influenced by interaction between the gas and the IL media. For some gases in ILs, especially CO2, this is not the case, as the so-called facilitated transport mechanism appHes [57]. Here, chemical complexing of CO2 occurs with the carrier IL, forming ionic compounds such as, for example, COj . These [IL-CO2] ions diffuse through the IL at a high rate and evolve at the permeate side, as schematically depicted in Figure 21.11. 

FIGURE 16.4 (a) Transport mechanisms during drying of supported catalysts (b) schematic of metal adsorption on an oxide support. 

Figure 7.3 Schematic representation of the transport mechanism through mixed matrix membranes with (a) conventional and (b) high aspect ratio permeable particles.

In membrane-based gas separation, the movement of penetrant gases is driven by the pressure gradient imposed between upstream and downstream. A membrane will separate gases oidy if some components pass through the membrane more rapidly than others, as shown in Fig. 3.3. There are three general transport mechanisms for membrane-based gas separation Knudsen diffusion, solution-diffusion, and molecular sieving [156,163]. A schematic representation of the mechanisms of membrane-based gas separations is shown in Fig. 3.4. 

Figure 3.11 Schematic of pervaporation transport mechanism (solution-diffusion model).

In the Grotthus mechanism, protons hop from one hydrolyzed ionic site (S03-H30 ) to another through the membrane [244]. Protons at the anode side adhere to water molecules and produce hydronium ions, and one different proton from the hydronium ion hops onto the other water molecule. It involves the conversion of H-bonds to covalent bonds between water molecules, and vice versa, and the proton is transported. A schematic representation of the hopping mechanism is shown in Fig. 3.16 [245]. According to this mechanism, hydrophilic ionic clusters are... 

The transfer of thermal energy occurs via three mechanisms. They are via solid conductivity, gaseous conductivity, and infrared radiation. Figure 6.14 shows a schematic presentation of various modes of thermal transport mechanisms in the GSA-SDS/FMWNT. In addition, the GSA-4SDS and GSA-SDS/FMWNT exhibit mechanical properties similar to that of polymeric foam, and thus thermal convection within the cells shall be considered as an additional component in deriving total thermal conductivity, which can be represented by Eq. 6.15. 

Fig. 6.14 Schematic representation of the various modes of thermal transport mechanisms in GSA-SDS and GSA-SDS/FMWNT composites...

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