Thin channel module

Figure 12.5 Different membrane modules used in MD (a) a Lewis ceU, (b) flat-sheet or tangential-flow module, (c) hollow-fiber module, and (d) a thin channel module.

Tubular systems can also be converted to thin-channel devices with the use of "volume displacement rods". In one such design ( 7), manufactured by Amlcon and Romicon, a splined core has the membrane wrapped around it, sealed, and braided to form thin-channels between the core and the membrane (Figure 17). These braided tubes are then potted in a shell and tube module where the permeate is collected on the shell side (Figure 18). 

In FLM, the LM organic solution flows in a thin channel between two hydrophobic microporous membranes separating the LM phase from an aqueous feed and strip solutions. The FLM differs from the HLM and MHS modules with hydro-phobic membranes by application of a spiral-type module. A schematic diagram of the spiral-type FLM module is shown in Figure 13.11. 

Kaur, J. Agrawal, G.P. Studies on protein transmission in thin channel flow module the role of Dean vortices for improving mass transfer. J. Membr. Sci. 2002, 196, 1-11. 

The present contribution describes a novel low pressure, high flux system which utilizes an "in situ" dynamically formed silica membrane particularly suited for the ultrafiltration of emulsions. The support for this selective layer of silica was a pleated, thin channel crossflow module il (tradename "Acro-flux", Gelman Sciences, Inc.) containing 0.1 m of 0.2 urn pore size acrylonitrile copolymer membrane. 

If the gel layer is not the limiting resistance to flow, the layer will continue to grow until the channel is completely full of 75% solid material-resulting in a drop in recirculation rate with time. Thin channel tubes and spiral flow modules running continuously at constant latex feed concentration and pressure drop for periods approaching one year have shown no decreases in recirculation rate or accumulation of polymer latex in the channels. 

Often preventive measures may be taken to avoid fouling the membrane. Prefilters or screens can be used to remove large particles which block thin channels or accumulate in stagnant areas of the module. High cross-flow velocities tend to sweep deposits away. Low pressures avoid compaction of gels on the membrane. Some polymers have a higher susceptibility to fouling and chemical modification of the membrane surface can have a profound effect on the propensity to foul. 

The concentration of latex emulsions was one of the early applications suggested for UF. Unfortunately, not all latexes are amenable to processing with UF. Many latexes are unstable under the high shear induced by pumps or even in the thin channels of UF modules. However, the use of diaphragm pumps and careful control of hydrodynamic shear within the module helps prevent coagulation. 

Filtration is required in some UF and in NF/RO processes. This is mainly because spiral wound modules cannot tolerate large particulates due to their very thin channels. Also, coarse particles may damage membranes under high shear conditions. Filters applied are usually in the 1 -25 pm range, aimed at suspended solids (Suratt (1993)). 

Tanny, G. B. and Hauk, D. "Filtration of Particulates and Emulsions with a Pleated, Thin Channel, Cross-Flow Module," Separation Science and Technology. Vol. 317-337, 1980. 

As illustrated by the examples given in Table 3, the application of labs-on-chips to real samples is still limited. This is partly due to the fact that the analytical assay is only the final step of the whole procedure, which includes sample pretreatment protocols such as filtration, analyte cleanup, or analyte preconcentration. However, also the integration of corresponding microfabricated elements is described. Filtration was achieved by porous membranes or arrays of thin channels preventing particulates to enter the analytical device. Analyte preconcentration in combination with removal of other sample constituents is achieved by solid-phase extraction modules, which are either capillaries or beads coated with a suitable adsorbent, such as a Cl 8 phase originating from coating with octa-decyltrimethoxysilane, from which the analyte is... 

A numerical study of the effect of area ratio on the flow distribution in parallel flow manifolds used in a Hquid cooling module for electronic packaging demonstrate the useflilness of such a computational fluid dynamic code. The manifolds have rectangular headers and channels divided with thin baffles, as shown in Figure 12. Because the flow is laminar in small heat exchangers designed for electronic packaging or biochemical process, the inlet Reynolds numbers of 5, 50, and 250 were used for three different area ratio cases, ie, AR = 4, 8, and 16. 

Bertolino M., Baraldi M., Parenti C., Braghiroli D., DiBella M., Vicini S., and Costa E. (1993). Modulation of AMPA/kainate receptors by analogues of diazoxide and cyclothiazide in thin slices of rat hippocampus. Receptors Channels 1 267-278. 

In US-A-4618763 a detector module is disclosed which is formed of stacked multi-channel integrated circuits, a detector array and a module header interface. The detector array and the module header interface are disposed transverse to the plane of the integrated circuits on opposite edge portions of the integrated circuits. Each integrated circuit is formed in a semiconductor material which has been deposited upon a thin sapphire wafer. 

This review has attempted to put hydrodynamic modulation methods for electroanalysis and for the study of electrochemical reactions into context with other electrochemical techniques. HM is particularly useful for the extension of detection limits in analysis and for the detection of heterogeneity on electrode surfaces. The timescale addressable using HM methodology is limited by the time taken for diffusion across the concentration boundary layer, typically >0.1 s for conventional RDE and channel electrode geometries. This has meant a restriction on the application of HM to deduce fast reaction mechanisms. New methodologies, employing smaller electrodes and thin layer geometries look to lift this restraint. 

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