ABSTRACT
Greek Symbols ............................................................................................................................................................ 733 References ................................................................................................................................................................................ 734
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
can a emulsion dispersed in an aqueous phase (W=O=W) or an oil-in-water emulsion dispersed in an oil phase (O=W=O) [2]. According to Ho et al. [3], in general the internal phase droplets are small, with diameters in the order of 1-10 mm. The emulsion globules, however, are much larger usually 0.1-2.0 mm in diameter. On completion of the extraction process, the emulsion needs to be broken=demulsified to recover the internal phase containing the concentrated solute.
