Diglycolamide functionalized calix(4)arene based hollow fiber supported liquid membrane: a judicious choice for recovery of Am(III) from acidic feed solution

Though solvent extraction is a widely accepted technique for the separation of metal ions in the nuclear industry, generation of large volumes of spent solvent as the secondary waste, particularly for the treatment of dilute solutions, encourages the use of other techniques where the waste generation is several orders of magnitude lower. One such alternative technique is the liquid membrane (LM), which is a combination of membrane separation and solvent extraction techniques, that offers a promising approach for the separation of metal ions from dilute aqueous solutions. The important features of LMs are: (i) possibility of simultaneous extraction and stripping of the metal ions, (ii) diffusion controlled transport, and (iii) low secondary waste. Two types of LMs, viz. flat sheet supported liquid membrane (FSSLM) and hollow fiber supported liquid membrane (HFSLM), have been extensively studied for the treatment of nuclear waste. Recently, we have demonstrated the extraordinary extraction ability of a diglycolamide-functionalized calix(4)arene (C4DGA) ligand for Am(III) from acidic feed solutions. The study performed in FSSLM at 20 ml scale yielded very encouraging results. However, the small surface area in FSSLM (3.14 cm²) does not allow any practical application of the method. In this context, use of the HFSLM technology seems to be a feasible way due to increased throughput associated with the large surface area of the membrane. In this paper, the separation of Am(III) by C4DGA-HFSLM has been studied. The effect of feed acidity and lanthanide concentration of feed on the permeation of Am(III) was investigated