Emulsion liquid membrane

Fig. 5-2. Three types of the liquid membrane eonfiguration (a) emulsion liquid membrane (b) supported liquid membrane (e) elassieal bulk liquid membrane set-up.

An survey of recent developments in membrane processes, involving reverse osmosis (RO), ultrafiltration (UF), microfiltration (MF), electrodialysis (ED), dialysis (D), pervaporation (Pr), gas permeation (GP), and emulsion liquid membrane (ELM), has been provided by Sirkar (1997). 

Mahdi C, Oualid H, Fatiha A, Christian P (2010) Study on ultrasonically assisted emulsification and recovery of copper(II) from wastewater using an emulsion liquid membrane process. Ultrason Sonochem 17(2) 318-325... 

Datta S, Bhattacharya PK, Verma N (2003) Removal of aniline from aqueous solution in a mixed flow reactor using emulsion liquid membrane. J Membr Sci 2269(1-2) 185-201... 

As discussed by Frankemfeld and Li(28) and del Cerro and Boey(29), liquid membrane extraction 28,29) involves the transport of solutes across thin layers of liquid interposed between two otherwise miscible liquid phases. There are two types of liquid membranes, emulsion liquid membranes (ELM) and supported liquid membranes (SLM). They are conceptually similar, but substantially different in their engineering. 

Figure 8.22. Schematic diagram of emulsion liquid-membrane...

In the emulsion liquid membrane configuration, the liquid membrane is formed by dispersing into the feed (phase 1) an emulsion of the stripping... 

The emulsion liquid membrane (Fig. 15.1b) is a modification of the single drop membrane configuration presented by Li [2] in order to improve the stability of the membrane and to increase the interfacial area. The membrane phase contains surfactants or other additives that stabilize the emulsion. 

Figure 15.3 illustrates schematically the different stages of a continuous separation process using the emulsion liquid membrane. There are four main stages in the flow sheet (1) emulsification of the stripping phase... 

All the novel separation techniques discussed in this chapter offer some advantages over conventional solvent extraction for particular types of feed, such as dilute solutions and the separation of biomolecules. Some of them, such as the emulsion liquid membrane and nondispersive solvent extraction, have been investigated at pilot plant scale and have shown good potential for industrial application. However, despite their advantages, many industries are slow to take up novel approaches to solvent extraction unless substantial economic advantages can be gained. Nevertheless, in the future it is probable that some of these techniques will be taken up at full scale in industry. 

In this paper an overview of the developments in liquid membrane extraction of cephalosporin antibiotics has been presented. The principle of reactive extraction via the so-called liquid-liquid ion exchange extraction mechanism can be exploited to develop liquid membrane processes for extraction of cephalosporin antibiotics. The mathematical models that have been used to simulate experimental data have been discussed. Emulsion liquid membrane and supported liquid membrane could provide high extraction flux for cephalosporins, but stability problems need to be fully resolved for process application. Non-dispersive extraction in hollow fib er membrane is likely to offer an attractive alternative in this respect. The applicability of the liquid membrane process has been discussed from process engineering and design considerations. 

Bulk Liquid Membrane. . . Emulsion Liquid Membrane. Supported Liquid Membrane Dispersion Free Extraction. ... 

The emulsion liquid membrane for cephalosporins relies essentially on facilitated transport. There are basically, however, two types of facilitated transport in emulsion liquid membrane system, i. e.. Type I and Type II facilitation. In the first type, the concentration gradient of the membrane soluble solute/permeate... 

Emulsion liquid membrane extraction of cephalosporins conform to the type II facilitated transport. Here the solute transport is either associated with a cotransport or counter-transport of an anionic species depending on whether ion-pair or ion-exchange extraction is exploited in the ELM system. 

Two principal approaches for the demulsification of the loaded emulsion are chemical and physical treatments. Chemical treatment involves the addition of a demulsifier to the emulsion. This method seems to be very effective. However, the added demulsifier will change the properties of the membrane phase and thus inhibits its reuse. In addition, the recovery of the demulsifier by distillation is rather expensive. Therefore, chemical treatment is usually not suitable for breaking emulsion liquid membrane, although few examples of chemical demulsification have been reported for certain liquid membrane systems [88]. 

Demulsification with electrostatic fields appears to be the most effective and economic way for breaking of W/0 emulsion in ELM processes 190, 91]. Electrostatic coalescence is a technique widely used to separate dispersed aqueous droplets from nonconducting oils. Since this type of technique is strictly a physical process, it is most suitable for breaking emulsion liquid membranes to recover the oil membrane phase for reuse. 

A form of liquid membrane that received a great deal of attention in the 1970s and 1980s was the bubble or emulsion membrane, first developed by Li at Exxon [11-13], Figure 11.14 is a schematic illustration of an emulsion liquid membrane process, which comprises four main operations. First, fresh product solution is emulsified in the liquid organic membrane phase. This water/oil emulsion then enters a large mixer vessel, where it is again emulsified to form a water/oil/water emulsion. Metal ions in the feed solution permeate by coupled... 

Coupled transport with supported and emulsion liquid membranes has made very little real progress towards commercialization in the last 15 years. In addition, it is now apparent that only a few important separation problems exist for which coupled transport offers clear technical and economic advantages over conventional technology. Unless some completely unexpected breakthrough occurs, it is difficult to imagine that coupled transport will be used on a significant commercial scale within the next 10-20 years. The future prospects for coupled transport are, therefore, dim. 

Berrama T, Pareau D, Stambouli M, Durand G. Purification and concentration of lactic acid by emulsion liquid membrane extraction. In Cox, Hidalgo M, Valiente M, eds. Solvent Extraction for the 21st Century, Proceedings of ISEC 99, Barcelona. London Society of Chemical Industry, 2001 983-987. 

Partitioning of components between two immiscible or partially miscible phases is the basis of classical solvent extraction widely used in numerous separations of industrial interest. Extraction is mostly realized in systems with dispergation of one phase into the second phase. Dispergation could be one origin of problems in many systems of interest, like entrainment of organic solvent into aqueous raffinate, formation of stable, difficult-to-separate emulsions, and so on. To solve these problems new ways of contacting of liquids have been developed. An idea to perform separations in three-phase systems with a liquid membrane is relatively new. The first papers on supported liquid membranes (SLM) appeared in 1967 [1, 2] and the first patent on emulsion liquid membrane was issued in 1968 [3], If two miscible fluids are separated by a liquid, which is immiscible with them, but enables a mass transport between the fluids, a liquid membrane (LM) is formed. A liquid membrane enables transport of components between two fluids at different rates and in this way to perform separation. When all three phases are liquid this process is called pertraction (PT). In most processes with liquids membrane contact of phases is realized without dispergation of phases. 

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