Separation of metal ions by ligand-accelerated transfer through liquid surfactant membranes

Abstract

The rate of extraction of heavy-metal ions is greatly accelerated by the presence of a ligand in the aqueous solution containing the metal ions. The ligand effect on interfacial mass-transfer rates has been defined by measuring the rate of extraction of cobalt by di-2-ethylhexyl phosphoric acid using sodium acetate as ligand in a modified Lewis cell. The effect of a surfactant such as polyamine on mass transfer at liquid/liquid interfaces has been investigated and is found to be quite significant. This interfacial resistance to metal extraction by surfactant-membrane processes must be taken into account when modelling such systems.

Selective Extraction of Cadmium from Multicomponent Acidic Leach Solutions by Emulsion Liquid Membrane using Amberlite LA-2 as Extractant

“…This is in agreement with the results reported in various studies, that is, the membranes incorporated with Span 80 shows less resistance to mass transfer than those with other surfactants, but it suffers from some drawbacks: osmotic swelling, poor chemical stability due to hydrolysis, and macroemulsion formation (36). It is also reported that ECA 4360 J can form very stable emulsions compared to Span 80 (38), but it has also some shortcomings, such as higher interfacial mass transfer resistance (39) and interactions with organic. From here, SPAN 80 was chosen as surfactant for further studies.…”

Extraction and concentration of cobalt from acidic leach solutions containing Co–Ni by emulsion liquid membrane using TOA as extractant

“…This is in agreement with the results reported in various studies which indicate that the membrane formed with Span 80 shows less resistance to mass transfer than that formed with other surfactants, but it suffers from some drawbacks: as osmotic swelling, poor chemical stability due to hydrolysis, and macroemulsion formation [28][29][30][31][32][33]. It is also reported that ECA 4360J can form very stable emulsions compared to Span 80 [34][35][36][37][38], but it has also some shortcomings, such as higher interfacial mass transfer resistance [36,37] and interactions with organic and inorganic acids [30]. Examination of these results indicates that ECA4360J is more favorable than Span 80 as emulsifier.…”

Analysis of the effect of internal phase leakage on liquid membrane separations

“…In the second mechanism, called type II facilitation, a carrier is incorporated in the membrane phase to augment the transfer rates. Solvent extraction of metal ions using ion-exchange reagents is an example of carriermediated transport (Hochhauser and Cussler, 1975;Strzelbicki andCharewicz, 1978a,b, 1980;Volkel et al, 1980;Cahn et al, 1981;Teramoto et al, 1983a;Wasan et al, 1984).…”