Coupled transport membranes characteristics

A second characteristic of coupled transport membranes is that the membrane flux usually increases with increasing metal concentration in the feed solution, but is usually independent of the metal concentration in the product solution. This behavior follows from the flux Equations (11.6) and (11.8). In typical coupled... 

A second characteristic of coupled transport membranes is that the membrane flux usually increases with increasing metal concentration in the feed solution but is usually independent of the metal concentration in the product solution. This behavior follows from the flux Equations 13 and 15. In typical coupled transport experiments, the concentration of the driving ion A in the product solution is very high. For example, in coupled transport of copper, the driving ions are hydrogen ions and 100 g/ sulfuric acid is used as the product solution. As a result, the term [MRn] g is very small compared to [MRn] 0 and Equation 15 reduces to ... 

K-I Inui, T Okano, H Maegawa, M Kato, M Takano, R Hori. H+ coupled transport of p.o. cephalosporins via dipeptide carriers in rabbit intestinal brush border membranes diffefence of transport characteristics between cefixime and cephadrine. J Pharmacol Exp Ther 247 235—241, 1988. 

In this section, we will discuss the major characteristics of coupled transport systems. The discussion will be illustrated with results obtained with supported liquid membranes. However, the same principles apply to emulsion membranes. We use supported liquid membrane results because the geometry of supported membranes is well-defined and it is possible to maintain the conditions of the feed and product solutions constant. This allows parametric studies to be per-... 

Mass transfer properties of species are affected by various parameters. These are dependent on the membrane characteristics and the species. Simon et al. [115] explained theoretically how the coupling of various parameters affects the effective separation efficiency of membranes. Mass transport was found to be strongly affected by these coupling effects that involve coupling between flows of one character and forces of another as well as coupling between the flows of various solutes. These effects can affect significantly the efficiency of the membrane separation. The relationships among the mass fluxes, forces, and their interdependency have also... 

Parameters that Affect Diffusion-Limited Transport. Brown et aL varied the length of the alkyl chain of alkyl o-nitrophenyl ether membrane solvents and examined its influence on the proton-coupled transport of alkali metal cations by a crown ether derivative. By comparison of solvent characteristics, such as the dielectric constant, viscosity, and surface tension, they concluded that hexyl o-nitrophenyl ether is a better membrane solvent than NPOE (43), The effect of the solvent on the transport of NaC104 by carrier 4 has been studied by Visser et al (44), Transport parameters and were determined. A series of octyl phenyl ethers containing an electron withdrawing group (NO2, CN) of various positions on the phenyl ring were used. Data are presented in Table 5. 

ABC transporters are multidomain systems that translocate substrates across membranes. A common characteristic is the well-conserved ATP binding cassette (ABC) domain that couples ATP hydrolysis to transport. Members of this group of proteins constitute the largest superfamily of transport components, and they are found in all organisms from Archaea to humans. According to the work of Dassa, who developed a classification based on the ATPase components, the ABC systems can be divided into a number of subfamilies (for details see http //www.pasteur.fr/recherche/unites/pmtg/abc/) [136]. 

T. Yoshikawa, N. Muranushi, M. Yoshida, T. Oguma, K. Hirano, and H. Yamada, Transport characteristics of ceftibuten (7432-S), a new oral cepham, in rat intestinal brush-border membrane vesicles Proton-coupled and stereoselective transport of ceftibuten, Pham. Res., 6 302-307 (1989). 

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