Important variables governing the permeation of copper ion through liquid membranes and their effects on the separation process are described. These variables are membrane viscosity, treatment ratio (volume ratio of emulsion to feed in mixer), complexing agent concentration, internal droplet size, internal phase leakage, and copper concentration in the internal phase. The information is needed for scaling-up of equipment and further process development. The economic evaluation based on bench-scale pilot plant runs shows this process is 40% cheaper than solvent extraction.

Extraction of Copper by Liquid Membranes

The potential for liquid emulsion membrane (LEM) systems in biochemical applications and their advantages over conventional systems are discussed. Examples are cited where LEMs have been used to successfully separate organic acids, amino acids, and antibiotics. The use of LEMs to immobilize cells and enzymes to synthesize antibiotics and amino acids as well as decontaminate biological waste streams is described. Enzyme systems immobilized in LEMs are quantitatively evaluated via traditional engineering approaches. In light of the above analysis, the potential LEM process difficulties of membrane breakage, swell, and selectively are examined. New biological applications for LEMs are suggested.

Liquid Emulsion Membranes and Their Applications in Biochemical Processing

Publisher Summary Liquid pertraction or liquid membranes appeared as a new and prospective separation method relatively recently. Due to its advantages over solid membranes and liquid-liquid extraction, liquid pertraction attracted the attention of many scientists and engineers. Liquid pertraction reflects the transfer process involved as well as the mulfi-(three) phase structure of the system. The term "liquid membranes" also represents the essential feature of the process, but the conventional image of a membrane—a thin, solid (in this case also semipermeable) barrier—could hardly be adapted to the multiple emulsions for which the term was actually introduced. It explores a very simple idea: two homogeneous, completely miscible liquids, which may be referred to as donor solution (F), and an acceptor solution (R) are spatially separated by a third liquid, immiscible and practically insoluble in the former two liquids—the membrane phase (S). Liquid membranes have two considerable advantages over solid membranes: as is known, molecular diffusion in the liquids (except in super-viscous ones) is, by several orders of magnitude, faster than that in solids.

Chapter 7 Liquid membranes (liquid pertraction)

Transport of alkali metal cations across liquid membranes by crown ether carboxylic acids

The carrier transport of U(VI) has been studied by means of the liquid membrane of LIX 63 (HR) held on a porous support. U was effectively transported from the dilute feed solution (pH = 4–5) to the product solution of 0.1 M H2SO4. Its concentration in the feed decreased according to [U]f, t = [U]f, o exp (-k obs t). The apparent rate constant (k obs) increased with an increase in carrier concentration up to 0.05 M, but it became nearly constant in the range of [HR] = 0.05–0.2 M. The rate of transport was inversely proportional to the feed volume. More than 99% of U was recovered and the final concentration ratio in the product to the feed ([U]p/[U]f) exceeded 103.

J. Strzelbicki

Papers

Separation of copper by liquid surfactant membranes