A Novel Liquid Emulsion Membrane Containing TODGA as the Carrier Extractant for Am Recovery from Acidic Wastes

Abstract

The recovery of Am has been investigated by Liquid Emulsion Membrane (LEM) containing 0.1 M N,N,N 0 ,N 0 -tetraoctyl-3-oxapentane diamide (TODGA) þ 0.5 M di-n-hexyloctanamide (DHOA) in n-dodecane as extractant. Span 80 (sorbitan monooleate) was used as the surfactant for making the emulsion while 3 M HNO 3 and 0.1 M acetate buffer (at pH 4.75) were used as the external and internal phases, respectively. Optimized conditions indicated 2% Span 80 was required for making the emulsions. The effect of different experimental conditions such as varying feed acidity, varying volume ratio, different strippants, and varying TODGA concentration have been studied for the quantitative removal of Am from acidic solution. The higher transport rate has been observed which can be attributed to the higher surface area per unit volume available for mass transport. Demulsification was possible by heating the emulsions to 80 C.Actual acidic radioactive waste has also been tested for the recovery of americium. The results show the applicability of ELM for the removal of Am(III) from waste solutions with a faster rate of transport as compared to those reported previously.

Selective Recovery of Rare Earth Elements from Coal Fly Ash Leachates Using Liquid Membrane Processes

“…Liquid Emulsion Membrane. The LEM process was based on methods by others 23,25,35,36 and entailed first a preparation of a water-in-oil emulsion. The oil-phase comprised of 10% (v/v) DEHPA and 1% or 3% (v/v) Span 80 in either kerosene or mineral oil with a total final oil-phase volume of 50 mL.…”

“…Liquid membrane processes use nonaqueous solvents with dissolved chelating agents to physically separate the aqueous leachate and acidic strippant phases while simultaneously recovering REEs. The aqueous strippant may be stabilized within an emulsion (LEM process), or the nonaqueous solvent may be impregnated in a physical membrane (SLM process). − These processes differ from standard solvent extraction as both REE extraction and recovery occur in the same step. Moreover, the advantage of liquid membrane process configurations is they maximize interfacial area of REE mass transfer while also reducing the required volumes of nonaqueous solvent and chelating agent.…”

Mass transfer and equilibrium characteristics of defluorination from groundwater by emulsion liquid membrane

“…Many chemical techniques have been investigated for purifying FCG, such as precipitation, ion exchange, adsorption and membrane separation . Experimental and technical results show that defluorination by emulsion liquid membrane is a practical and promising method for purification of FCG due to its high interfacial surface area for mass transfer, simultaneous extraction and stripping operations in one stage, high solute transfer flux and recyclability of raw materials.…”