Silica membranes module

Fig. 16.9 Photograph of a high temperature stable silica membrane module. The membrane module is fully made of ceramic materials (Courtesy Noriuike Company LTD., Aichi, Japan)...

Yacou, C., Smart, S. and Dinizda Costa, J.C. (2012) Long term performance cobalt oxide silica membrane module for high temperature H2 separation. Energy and Environmental Science,5,5820-5832. 

Yoshino, Y., Suzuki, T., Nair, B.N., Taguchi, H., and Itoh, N., Development of tubular substrates, silica based membranes and membrane modules for hydrogen separation at high temperature, Journal of Membrane Science, 267, 8-17, 2005. 

Kusakahe K, Shihao F, Zhao G, Sotowa K-I, Watanabe K, and Saito T. Surface modification of silica membranes in a tubular type module. J. Membr. Sci. 2003 215 321-326. 

Schleger M, Sommer S, and Melin T. Module arrangement for solvent dehydration with silica membranes. Desalination 2004 163 281-286. 

Fig. 13 High flux pervaporation module for silica membrane. (View this art in color at www.dekker.com.)...

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. 

Pessimism exists about the ability to fabricate cost effective modules from microporous membranes. Specific concerns include the stability of the membranes (especially for silica membranes in humid, high temperature environments), the ability to produce large uniform membrane areas, the effect of thermal cycling (especially for applications that require operation at elevated temperature), the ability to form tubesheets, and the ultimate cost of manufacture. 

As an immobilization method, both for whole cells or enzymes, membrane bioreactors provide the advantages and drawbacks common to entrapment or adsorption methods. They nevertheless present particular assets. Mass transfer in the porous supports generally used (alginate, k-carrageenan, zeolites, silica) is a diffusion-controlled process, often becoming the overall rate-limiting step. This maybe overcome by the use of membrane modules. This equipment also avoids... 

Kusakabe K., Shibao F., Zhao G., Sotowa K.-L, Watanabe K., Saito T. Surface modification of silica membranes in a tubular type module. J. Membr. Sci. 2003 215 321-326 Lacan P., Guizard C., Le Gall P., Wettling D., Cot L. Facilitated transport of ions through fixed-site carrier membranes derived from hybrid organic-inorganic materials. J. Membr. Sci. 1995 100 99-109... 

Fig. 12 The appearance of a thin membrane module of porous silica-alumina as the support for the gel and SEM photomicrograph of the membrane cross-section.

The main building block of a membrane reactor system is the module, which as a unit operation bears more resemblance to a membrane unit than to a traditional reactor. For commercial apphcations, it is desirable to fabricate membranes into a modular form that maximizes both productivity and selectivity. The most common commercial membrane geometries are flat sheet and tubular, and currently there are five module types namely, plate-and-frame and spiral-wound modules, based on flat membranes, and tubular, capillary and hollow-fibre modules, based on tubular membrane geometries. The module types of most relevance to siUca membrane modules and membrane reactors are the plate-and-frame and tubular types. The inflexibility of silica membranes prevents them from being used in a spiral-wound set-up and the technology to produce capillary and hoUow-fibre membrane geometries has not been adequately explored for sihca membranes. Plate-and-frame modules are easily constructed by... 

A recent development is to combine filtration with solid-phase extraction separation. These filter modules contain a unique silica gel membrane that binds up to 20 pg of DNA in the presence of a high concentration of chao-tropic salt and allow eventual elution in a small volume of low-salt buffer. They also contain an asymmetric laminar membrane with a gradation of pore sizes for efficient removal of material precipitated in the lysate. Such membrane filters eliminate time-consuming phenol-chloroform extraction and alcohol precipitation. The impregnation of silica in the membrane matrix also prevents the problems associated with loose resins and slurries. High-purity plasmid DNA eluted from such modules is ready to use and often needs no further precipitation, concentration, or desalting. 

Membrane Formation. In earlier work. 2.) it was found that fumed silica particles could be dispersed in aqueous suspension with the aid of ultrasonic sound. Observations under the electron microscope showed that the dispersion contained disc-like particles, approximately 150-200 1 in diameter and 70-80 1 in height. Filtration experiments carried out in the "dead-end" mode (i.e., zero crossflow velocity) on 0.2 urn membrane support showed typical Class II cake formation kinetics, i.e., the permeation rate decreased according to equation (12). However, as may be seen from Figure 7, the decrease in the permeation rate observed during formation in the crossflow module is only t 1, considerably slower than the t 5 dependence predicted and observed earlier. This difference may be expected due to the presence of lift forces created by turbulence in the crossflow device, and models for the hydrodynamics in such cases have been proposed. 

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