Liquid Membrane Technology

Abstract

Liquid membrane technology is introduced and is identified as a subset of membrane science. A tutorial section discusses configurations, transport mechanisms, experimental techniques, and a survey of basic theoretical approaches. The concepts of reactive liquid membranes which combine traditional unit operations such as extraction or absorption with stripping are discussed. The chapters to follow in this volume are summarized and the subject of each is placed in perspective to the field of liquid membrane technology. TutorialA membrane can be viewed as a semi-permeable barrier between two phases. This barrier can restrict the movement of molecules across it in a very specific manner. The membrane must act as a barrier between phases to prevent intimate contact. The semi-permeable nature is essential to insuring that a separation takes place.There are two points to note concerning this definition. First, a membrane is defined based on what it does, not what it is. Secondly, a membrane separation is a rate process. The separation is accomplished by a driving force, not by equilibrium between phases (JO.By extending our definition of a membrane, we can include liquids. If we view a membrane as a semipermeable barrier between two phases, then an immiscible liquid can serve as a membrane between two liquid or gas phases. Different solutes will have different solubilities and diffusion coefficients in a liquid. The product of these two terms is a measure of the permeability. A liquid can yield selective permeabilities and, therefore, a separation. Because the diffusion coefficients in liquids are typically orders of magnitude higher than in polymers, a larger flux can be obtained.

Effect of organic solvent type on the removal of nitrate ion using liquid membrane technique

“…In liquid membrane systems transportation phenomena are enforced by driving force and the driving force is generally chemical potential gradient changing with concentration. Separation process occurs in liquid film due to difference between diffusion and solubility (Noble and Way 1989). Liquid membranes are well known as one of the most powerful tools for separation and enrichment purposes (Ulbrich and Marr 1994).Carrier mediated transport through liquid membranes is not only an important technique for concentration, separation, and recovery, but is also of fundamental importance from the environmental engineer's point of view (Winston and Sirkkar 1992;Mulder 1990).…”

Triethanolamine–cyclohexanone supported liquid membranes study for extraction and removal of nickel ions from nickel plating wastes

“…A number of mathematical models, which describe the behaviour of supported liquid membrane separation processes, have been proposed [9][10][11][12][13][14][15]. The system under study consists of two aqueous phases and an organic phase, which contains the carrier, triethanolamine (TEA), confined within the membrane pores by capillary action.…”

Emulsion liquid membranes for chiral separations: Selective extraction ofrac-phenylalanine enantiomers

“…In practice it leads to greatly reduced solvent and carrier inventories, as well as significantly faster mass transfer rates, which are uninhibited by the equilibrium constraints encountered in solvent extraction. 22 The two most common configurations are emulsion (ELM) and supported liquid membranes (SLM), as shown in Figures 2 and 3, respectively. In the former configuration, droplets of the receiving phase are stabilised within an organic membrane phase, in the form of a water-in-oil emulsion.…”