Chapter 15 Liquid membrane techniques

Abstract

Publisher Summary This chapter focuses on extraction systems with liquid membrane phases and trapping in the acceptor. Both two- and three-phase systems are considered. These types of system have been successfully applied to a number of analyte and sample types and can be important alternatives to more orthodox approaches to sample preparation. A common type of a liquid membrane format is the supported liquid membrane (SLM). A two-phase membrane extraction system with a porous membrane that separates one aqueous and one organic phase is called microporous membrane liquid liquid extraction (MMLLE). In principle, there are two approaches: with a hydrophobic or a hydrophilic porous membrane. There are a number of other ways for arranging a three-phase liquid membrane extraction—for example, as a bulk liquid between semipermeable membranes or in completely unsupported forms. These types are commonly called bulk liquid membranes (BLM). This principle leads to slow mass transfer and long extraction times. Membrane extraction can also be arranged in the form of an emulsion. The ELM is useful for removal of compounds from the feed solution, but the quantitative recovery of the extract is difficult.