Membrane techniques

membrane separation processes are finding an extensive and ever-increasing use in the pharmaceutical, food, and petrochemical industries, as well as in environmental applications. Membrane separation processes present some advantages over more classical separation processes since they are less energy-consuming and more compact, and generally require less initial capital investment 

Homogeneous Catalysis in the Aqueous Phase as a Special Unit Operation 

Membranes can be classified according to the type of material their film is made of (organic or inorganic materials) or to the porosity of the thin layer (porous or dense). Choosing between a porous or a dense film as well as choosing the type of 

Membranes are manufactured in a wide range of geometries they include flat, tubular, and multi-tubular, hollow-fiber, and spiral-woimd. The type of geometry of the membrane depends on the material the membrane is made of. Ceramic membranes generally come in tubular, multi-tubular and flat geometries, whereas most spiral-wound and hollow-fiber membranes are made of polymers. 

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Membrane techniques have already been combined with two-phase liquid catalysis. The main function of this method is to perform fine separation of undesirable constituents from the catalytic system after phase decantation has already performed the coarse separation of the catalyst from the products. This technique can be applied to ionic liquid systems as a promising approach for the selective removal of volatile solutes from ionic liquids [20]. 

The use of reverse osmosis (RO), electrodialysis reversal (EDR) and other membrane techniques, and evaporation or demineralization may be applicable when a reduction in the TDS content of the MU water source is required. 

As with ED, RO, and other membrane techniques, the primary operational cost of EDR is that of pumping water through the system, and pumping costs are proportional to the TDS of the incoming water. Cost for the actual electrodialysis is low. 

Meissner et al. proposed a monograin-membrane technique with which short circuits can be avoided at the suspended particles and which makes it possible in principle to separate the anodic and cathodic reactions. The membrane consists of... 

The separation of the reaction products from the catalyst solution by membrane techniques (Figure 5.8, [52]) ... 

The latter concept implies providing local life support systems for unfriendly environments. By now, Ukrainian scientists and engineers have developed a variety of processes for potable water treatment by adsorption, electrochemical oxidation, electrocoagulation, electro-coprecipitation, electrodialysis, electrofloatation, floatation, membrane techniques etc. Each family must get small units for water purification, air cleaning and removal of hazardous substances from the food as soon as possible, for it may take decades to introduce cleaner production on a national scale. Here, we should follow the example of Western business people who bring with them to Ukraine devices enabling a safe existence in this unfriendly environment. 

Weng L, Temminghoff EJM, van Riemsdijk WH. Determination of the free ion concentration of trace metals in soil solution using a soil column Donnan membrane technique. Ear. J. Soil Sci. 2001 52 629-637. 

Alcohol is a clean energy source that can be produced by the fermentation of biomass. However, it needs to be highly concentrated. In general, aqueous alcohol solutions are concentrated by distillation, but an azeotrope (96.5 wt% ethanol) prevents further separated by distillation. Pervaporation, a membrane separation technique, can be used for separation of these azeotropes pervaporation is a promising membrane technique for the separation of organic liquid mixtures such as azeotropic mixtures [34] or close-boiling point mixtures. 

The preparation of food for consumption, as well as manufacturing of various products from different raw materials, usually involves the application of several discrete unit operations and processes. Many operations, such as washing, trimming, milling, leaching, disintegrating, mechanical separation, and use of membrane techniques, may decrease the natural toxicity of some raw materials by eliminating specific undesirable components. Examples include the removal of most of the fluorine compounds from Antarctic krill... 

Membrane techniques Microfiltration, Oxidation Aerobic, wet oxidation. Ion-exchange... 

Membrane Processes [109,110]. Depending on the desired application, membrane techniques can be divided into ... 

In order to develop the liquid membrane techniques, i.e., emulsion Hquid membrane (ELM), supported liquid membrane (SLM), non-dispersive extraction in hollow fiber membrane (HFM), etc., for practical processes, it is necessary to generate data on equilibrium and kinetics of reactive extraction. Furthermore, a prior demonstration of the phenomena of facilitated transport in a simple liquid membrane system, the so-called bulk liquid membrane (BLM), is thought to be effective. Since discovery by Li [28], the liquid membrane technique has been extensively studied for the separation of metal ion, amino acid, and carboxyHc acid, etc., from dilute aqueous solutions [29]. 

The membrane technique being developed at the University of Maine is a powerful tool to study intermolecular interactions when one of the solutes is a macromolecule or in a separate phase. 

Direct elimination of proteins and other matrix constituents from food samples can also be accomplished with matrix solid-phase dispersion or diphasic dialysis membrane techniques. A matrix solid-phase dispersion technique was used for the determination of chloramphenicol in meat (66) and milk (67) using... 

Less gas-liquid chromatographic interference occurs when protein in plasma and serum is precipitated with picric acid than with trichloroacetic acid or sulfosalicylic acid. Ultracentrifugation or membrane techniques could be used. The cation-exchange columns should be washed with water until no visible picric acid remains. 

Belafi-Bako, K., Nemestothy, N., and Gubicza, L. 2004. A study on applications of membrane techniques in bioconversion of fumaric acid to L-malic acid. Desalination 162, 301-306. 

Since the last 15 years, membrane techniques like ultrafiltration, nanofiltration, or reverse osmosis have been also applied (Serkiz and Perdue, 1990 Abbt-Braun... 

From the point of view of soil and water quality, Al speciation has gained high interest. Donnan membrane technique on gibbsite suspension can be used to study... 

Weng, L., Temminghoff, E. J. M., and Van Riemsdijk, W. H. (2002). Aluminum speciation in natural waters measurement using Donnan membrane technique and modeling using NICA-Donnan. Water Res. 36, 4215-4226. 

Trocewicz, J (1996). Determination of herbicides in surface water by means of a supported liquid membrane technique and high-performance liquid chromatography. J. Chromatogr. A, 725 121-127. 

Papantoni, M., Djane, N.-K., Ndung u, K., Jonsson, J.A. and Mathiasson, L. (1995) Trace enrichment of metals using a supported liquid membrane technique. Analyst, 120, 1471-1477. 

Membrane Techniques in which the Mass Transfer Equations are Used... 

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