Use of liquid membrane systems for selective ion transfer

Abstract

In a liquid membrane process for removing ions from solution which comprises contacting a feed solution containing a first ion with an emulsion, said emulsion comprising an external phase which is immiscible with said solution and contains a complexing agent, said complexing agent being capable of forming a first complex with said first ion, which is soluble in said external phase, and an internal phase, the improvement which comprises providing a second ion, in the internal phase, of the emulsion, said second ion being capable of converting said first complex to a second complex by replacing said first ion in said first complex, said second complex being also soluble in said external phase, whereby the first ion diffuses from said solution into said internal phase, and said second ion diffuses from said internal phase into said solution. More particularly, the instant invention comprises maintaining the concentration of the second ion, in the feed solution, at a sufficiently low level to allow formation of the first complex at the interface of the external phase of the emulsion and the solution, and maintaining the concentration of the second ion, in the internal phase of the emulsion at a concentration, sufficiently high, to convert said first complex into a second complex. Preferably, the first ion is a metal ion--for example, copper, or a complex ion, such as H.sub.g Cl.sub.4 =comprising a metal constituent and said second ion is either hydrogen or hydroxyl ion.