Emulsion liquid membrane extraction

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. 

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. 

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. 

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. 

Fouad, E.A. and Bart, H. (2008) Emulsion liquid membrane extraction of zinc by a hollow-fiber contactor. Journal of Membrane Science, 307, 156. 

Hu, S.Y.B. and Wiencek, J.M. (1998) Emulsion-liquid-membrane extraction of copper using a hollow-fiber contactor. AICHE Journal, 44, 570. 

Emulsion Micellar Microdroplets Single- or multistage emulsification Emulsified liquid membrane extractions... 

FIGURE 19 Liquid membrane extraction, (a) Emulsion membrane extraction, (b) supported membrane extraction. 

Yurtov EV and Koroleva MY. Emulsions for liquid membrane extraction Properties and peculiarities. In Bartsch RA, Way JD, eds. Chemical Separations with Liquid Membranes, Washington, DC American Chemical Society, ACS symposium series 642, 1996 89-102. 

Raghuraman, B. and Wiencek, J.M., Extraction with emulsion liquid membranes in a hollow-fiber contactor, AIChE J., 39, 1885, 1993. 20a. Hu, S.Y. and Wiencek, J.M., Emulsion-liquid-membrane extraction of copper using a hollow-fiber contactor, AIChE J., 44, 570, 1998. 20b. Wiencek, J.M. and Hu, S.Y., Emulsion liquid membrane extraction in a hollow-fiber contactor, Chem. Eng. TechnoL, 23, 551, 2000. 

SchoUer, C., Chaudhuri, J.B. and Pyle, D.L. (1993). Emulsion liquid membrane extraction of lactic acid from aqueous solutions and fermentation broth. Biotechnol. Bioeng., 42, 50-8. 

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. 

Figure 2. Flowsheet of an emulsion liquid membrane extraction process.

The liquid membrane (LM) concept combines solvent extraction (SX) and membrane-based technologies, enabling both extraction and back-extraction in a single step with reduced consumption of extractants and diluents. For these reasons, separation based on LMs can be viewed as a promising alternative to traditional SX. The LM separation approach involves mass transfer of a target chemical species between two solutions (i.e., feed and receiver solutions) separated by an immiscible LM [1]. The main types of LMs are bulk liquid membranes (BLMs), emulsion liquid membranes (ELMs), supported liquid membranes (SLMs), and polymer inclusion membranes (PIMs). 

Emulsion Liquid Membranes. The emulsion liquid membrane (ELM) was developed by U and Cussler in the late 1960 s and early 1970 s (65-66), A water-in-oil emulsion is formed by an organic solvent and water, often containing acid. The emulsion can be stabilized by the addition of a surfactant. This emulsion is then stirred into an aqueous source solution, and transport occurs across the extremely thin membrane bubbles (Figure 8b). When extraction is complete the emulsion is collected and broken to obtain the concentrated target substance. 

Emulsions for Liquid Membrane Extraction Properties and Peculiarities... 

Emulsion Liquid Membranes. Extraction and stripping of metals are traditionally performed in separate operations. By use of emulsion liquid membranes (ELMs), the two steps can be accomplished in a single step. ELMs, first invented by li (3), arc made by forming a surfactant-stabilized emulsion between two immiscible phases. A water-in-oil emulsion, consisting of an oil phase with a metal extractant and an aqueous... 

Much effort has been expended in our labs over the last few years investigating the use of emulsion liquid membranes to carry out such wastewater treatment schemes with a special focus on the removal of mercury ions from water. Both coarse or macroemulsions as well as microemulsions were studied and compared. The advantage of emulsion liquid membrane extraction is the large surface area available for mass transfer which results in fast separations. Because the volume ratio of the feed to internal receiving phase is high, the separated metal is concentrated by factors as high as... 

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. 

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