Membrane system with

Shfe, C.W., Wang, E., Hunter, R., Wang, S., Burgess, C., Liotta, D.C., and Merrill, A.H.Jr., 1989, Free sphingosine formation from endogenous substrates by a liver plasma membrane system with a divalent cation dependence and a neutral pH optimum. J. Biol. Chem. 264 10371-10377. 

Cd in natural water using a liquid membrane system with 2-acetylpyr-idine benzoylhydrazone as carrier. Transport processes across the membrane were optimised... 

M. D. Granado-Castro, M. D. Galindo-Riano and M. Garcia-Vargas, Separation and preconcentration of cadmium ions in natural water using a liquid membrane system with 2-acetylpyridine benzoylhydrazone as carrier by flame atomic absorption spectrometry, Spectrochim. Acta, Part B, 59(4), 2004, 577-583. 

Gram-negative tougher peptidoglycan layer extensive internal membrane system with photosynthetic pigments... 

Fig. 17. Model of the synthetic glycolipid obtained from the biantennary decasaccharides incorporated in a membrane system with a) a high and b) a low concentration of the glycolipid in the membrane. Determination of the distance of the membranes yields the proposed conformations of the iV-type biantennary oligosaccharides...

In Fig. 4.10, the DDPV curves corresponding to a membrane system with two polarizable interfaces (solid lines) and also to a system with a single polarizable interface (dashed lines), obtained for two values of the pulse amplitude AE, are shown. The current A/DDPV has been plotted in all the cases versus the... 

Besides previously described examples of integrated membrane systems and much more reported in the literature, including applications in gas separation and the petrochemical industry [29], a special case of integrated or hybrid membrane systems, with a lot of interest in the logic of the sustainable growth, is represented by the catalytic membranes reactors (CMRs). 

One long-term objective of this research is to utilize the finest attributes associated with the worlds of both biological and synthetic materials to create nanomechanical systems powered by biological motors. Important fields of application include miniaturized (nanofluidic) analytical systems,131 molecular sorting,132 controlled adaptation of materials on a molecular to mesoscopic scale,133 and engineering lipid and polymer membrane systems with cellular processes.134... 

Figure 8.1 Shows the projected performance of an RO membrane system with ideal, marginal and inadequate pretreatment.1 After an initial period over which time new membranes stabilize performance, a system with ideal performance will show only a slight decline in performance with time due to compaction and the inevitable fouling and scaling that will occur despite good pretreatment and system hydraulics. Marginal pretreatment exhibits more rapid decline in performance than the system with ideal pretreatment. Initial cleaning may be able to revive most of the performance, but after time, foulants and scale that were not removed become irreversibly attached to the membrane and cannot be cleaned away. The RO system with inadequate pretreatment will show very rapid decline in performance that typically cannot be recovered by cleaning the membranes. An RO system with less than ideal pretreatment faces frequent cleaning intervals and short membrane life. Frequent cleaning and membrane replacement costs money, time, and the environment.

Ralf Kuriyel (Millipore Corporation) addressed some of the issues related to the use of Dean vortices, formed during the flow of fluids in curved conduits, to enhance the performance of cross-flow filters by increasing the back transport of solutes. Results were presented on coiled hollow fibers with a varying radius of curvature, fiber diameter, and solution viscosity, to characterize the relationship between the back transport of solutes and hydrodynamic parameters. A performance parameter relating back transport to the Dean number and shear rate was derived, and a simple scaling methodology was developed in terms of the performance parameter. The use of Dean vortices may result in membrane systems with less fouling and improved performance. 

Example 10.1 Membrane equilibrium An aqueous solution (phase A) of 100 mmol/L of NaCl is in equilibrium across a protein-tight membrane with an aqueous solution (phase B) of NaCl and protein. The protein concentration is 5 mmol/L with a negative ionic valency of 10. Determine the difference in electric potential and hydrostatic pressure across the membrane when both solutions are assumed to be ideal and the temperature is 25°C. Figure 10.1 shows the membrane system with the phases A and B. 

The feasibility of the palladium membrane system with an oxidation reaction on the permeation side and 1-butene dehydrogenation reaction on the reaction side in a membrane reactor has been successfully demonstrated. The palladium and its alloy membrane not only can withstand high temperature but also are selectively permeable to hydrogen... 

Figure 5.8 Flux decline of a porous alumina membrane system with Lime due to fouling [Gumming and Turner, 1989]...

Wodzki R and Szczepanska G. Design of integrated membrane system with liquid and polymer membranes. Zeszyty Naukowe Politechniki Slaskiej (Chemia in English), 2001 146 231-234. 

Scaling up of the processes to large surface areas (i.e. to obtain asymmetric membrane systems with several layers) as is necessary for large-scale operations has been successfully demonstrated for micro/ultrafiltration and bioseparation processes, but not for other applications such as gas/vapour separation and membrane reactors, for which only small-scale laboratory equipment is available. 

Finally functional groups can be introduced also in a membrane system with inorganic-organic composites. Care should be taken in this case to select combinations which add advantages of both components and avoid too many of the disadvantages. 

Membrane systems with pore diameters in the micropore range (gas separation, nanofiltration) are not yet commercially available but are produced for development and marketing purposes by, e.g., Velterop B.V. (Enschede, Netherlands) and Media and Process Technology Inc. (Pittsburgh, USA). These systems have an a-alumina support combined with multilayered y-alumina (mesoporous) layers and a silica (microporous) separation layer. 

Transport phenomena in porous solids have been the subject of many studies [1-6,10]. Quantitative solutions are obtained however only in a number of limiting cases of generally formulated problems or in relatively simple cases. Such a case is, e.g., the permeation of a single gas in a membrane system with a relatively simple pore architecture and under conditions when a single mechanism is predominantly operating. 

Transport of mixtures is more complicated, especially in membrane systems with a more complex architecture and operated with large pressure gradients. In such cases quantitative solutions for permeation and separation efficiency (selectivity) are not available in a generally applicable form. Specific solutions have to be obtained by approximations and by combiiung solutions for limiting cases. The description in this chapter takes account of this situation. 

Fig. 4 Facilitated transport in a liquid membrane system with complexing agent in the membrane phase and acid in the receiving phase.

In cases of extreme temperamre instability, evaporative methods of concentration have not been feasible because distillation temperatures at even the lowest feasible pressures are still too high (e.g., distilling water at 25°C may be possible but this temperature may be still too high for the extended time cycle required). Alternative means of concentration are reverse osmosis for aqueous systems and some membrane systems with molecular weight cutoffs compatible with the compound in question. Obviously, these systems preclude crystallization during operation. An example of an antibiotic with severe temperamre restrictions is presented in Example 11-1. 

Lee, S.C. (2004). Comparison of extraction efficiencies of penicUHn Gat different w/o ratios in the emulsion liquid membrane systems with dilute polymer solutions. J. Membr. Sen, 237, 225-32. 

Boyadzhiev L, Bezenshek E, Lazarova Z. Removal of phenol from waste water by double emulsion membranes and creeping film pertraction. J Membr Sci 1984 21 137-144. Ohki A, Takagi M, Takeda T, Ueno K. Thioether-mediated copper transport through hquid membranes with the aid of redox reaction. J Membr Sci 1983 15 231-244. Wodzki R, Szczepanska G. Design of integrated membrane system with hquid and polymer membranes. Zeszyty Naukowe Pohtechniki Slaskiej, Chemia 2001 146 231-234 (in English). 

Shalygin MG, Vorobieva EV, i cplyakov VV. Gas transport in combined membrane system with moving liquid carrier. Sep Purif Technol 2006 57 466-472. 

Shalygin M, Teplyakov V, Roizard D, Favre E. CO2 transport study in combined membrane system with aqueous potassium carbonate as a hquid carrier. Desahnation, 2006 V 200(1-3) 106-108. 

In the next sections, the main gas separation applications using facilitated liquid membranes are reported. The gas permeability and selectivity in various membrane systems with facilitated transport properties are summarized in Table 7.5. 

Table 7.5 Summary of gas permeability and selectivity in various liquid membrane system with facilitated transport by mobile carrier... 

M. G. Shalygin, A. Yu. Okunev, D. Roizard, E. Favre, V. V. Teplyakov, Gas permeability of combined membrane systems with mobile liquid carrier. Colloid J. 68 (2006) 518-525. 

Lin, S. H., Pan, C. L., Leu, H. G. (1999). Liquid membrane extraction of 2-chlorophenol from aqueous solution. Journal of Hazardous Materials 65 289-304. Raghuraman, B.J., Tirmizi, N.P., Kim, B.-S., Wiencek, J. M. (1995). Emulsion Liquid Membranes for Wastewater Treatment Equihbrium Models for Lead- and Cadmium-di-2-ethylheyl Phosphoric Acid Systems. Environmental Science and Technology 29 979-984. Liu, H. J., Wu, Q. S., Ding, Y. P., Liu, L. (2004). Biomimetic synthesis of metastable PbCrO4 nanoparticles by emulsion liquid membrane system with carrier and coupled treatment of Pb(II) and Cr(VI) wastewaters. Hrtij Chimica Sinica 62 946-950. 

Measurements of partitioning of drugs into lipid vesicles, liposomes or cell membranes as predictive models for drug absorption are also described in the literature (Hillgren et al. 1995 Balon et al. 1999 Stewart et al. 1997). This may be due to the similarity of these systems to biological membranes and the wish for a pure membrane system with the correct lipid and protein composition, but without enzymes and carrier proteins. 

---