Use of emulsion liquid membranes

Use of Emulsion Liquid Membrane Systems in Chemical and Biotechnological Separations... 

A new time in the development of the liquid-membrane technology began in the 1960s when Li and coworkers patented the use of emulsion liquid membrane (ELM) systans... 

This paper reviews the use of emulsions and microemulsions as liquid membranes with sp ial emphasis placed on the separation of mercury, as Hg(N03)2, from water using oleic acid as the extractant Although emulsion (either macro- or micro-) liquid membranes offer advantages in terms of fast rates of separation, new modes of creating a stabilized liquid membrane utilizing hollow fiber contactors offer comparable flux in a more stable format. The paper wiU start with a review of the basic types of liquid membranes as currently used in research. The discussion will then focus on the author s experience with emulsified liquid membrane systems. The last section of the paper will discuss the obvious next step in liquid membrane technology, the use of emulsion liquid membranes in hollow fiber contactors. 

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... 

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... 

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... 

The concept of emulsion liquid membranes (ELM) was first proposed by Li in 1968 [1]. Since their inception in the late 1960s they have been referred to as surfactant liquid membranes, double emulsion membranes or ELM. Regardless of the terminology used, the workings of such systems are as follows they consist of an emulsion formed by an organic solvent and water, which can be stabilized by the addition of surfactant. This emulsion is then contacted with a continuous phase containing the desired solute, stirred to yield globules, and transported across the extremely thin membrane layer that separates internal phase droplets... 

Bayraktar, E. (2001). Response surface optimization of the separation of dl-tryptophan using an emulsion liquid membrane. Process Biochem., 37, 169-75. 

Jarudilokkul, S., Tanthapanichakoon, W. and Boonamnuayvittaya, V. (2007). Synthesis of hydro.xyapatite nanoparticles using an emulsion liquid membrane system. CoUoids Surf. A, 296, 149-53. 

Pickering, P. J., Chaudhuri, J. B. (1997). Enantioselective extraction of (D)-phenylalanine from racemic (D/L)-phenylalanine using chiral emulsion liquid membranes. Journal of Membrane Technology 127 115-130. 

Although microemulsions offer many potential advantages when used as emulsion liquid membranes, their effective usefulness in an industrial setting is questionable. Studies on a variety of systems have shown some disadvantages of microemulsions as opposed to coarse emulsions ... 

Hirai T, Orikoshi T. Preparation of yttrium oxysulfide phosphor nanoparticles with inffared-to-green and -blue upconversion emission using an emulsion liquid membrane system. J Colloid Interface Sci 2004 273(2) 470. 

Nakashio et al. reported the use of lipophilic dialkyIdimethlylammonium bromides as surfactants in the formation of emulsion liquid membrane systems (22). The two long alkyl chains provided a good hydrophilicity-lipophilicity balance (HLB) to form a stable emulsion membrane. This finding led us to attempt the use of such quaternary ammonium salts in an emulsion liquid membrane system for which the ammonium salt functions not only as the emulsifying agent but also as the carrier for heavy metal halide complexes (Figure 5). 

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... 

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