ABSTRACT
Dispersion-free contact between immiscible liquids can be obtained by the aid of a porous solid support such as a membrane contactor, a supported liquid membrane (SLM), or a contained or flowing liquid membrane, or simply mem brane-based liquid-liquid extraction [15,40]. In SLM mode, the carrier is ab sorbed in the microporous wall of the polymeric support shaped as a flat sheet or tiny hollow tubes (i.d. 0.5-1 mm). Usually the feed solution is circulated through the lumen and the strip solution on the shell side of the hollow fiber. In such a case, extraction and back-extraction of the metal species take place simultaneously in one hollow-fiber (HF) module. The details of the SLM mode, its various configurations, different applications, potentials, advantages and dis advantages, latest improvements, and current status are described elsewhere [4]. Therefore, this chapter does not furnish details of SLM techniques. In a DFME mode, aqueous and organic solutions flow continuously as just described, with both phases coming into contact through the pores of the fiber wall. Flere, only one separation is realized, either extraction or back-extraction. To obtain extraction and stripping together, an integrated process is used with two FIF modules, one for extraction and one for stripping.
