Unique Eu(III) transport selectivity seen using a supported liquid membrane containing a diglycolamide dendrimer ligand

Abstract

ABSTRACT Dendrimers are exotic multi-functional ligands and are expected to give rise to better extraction/transport results as compared to the mono-functional ligands. Diglycolamide (DGA) based dendrimers are scarcely reported and literature on their transport studies are very limited. Transport of Am(III) and Eu(III) across a PTFE (polytetrafluoroethylene) based flat sheet supported liquid membrane containing a generation 1 dendrimer of tris(2-aminoethyl)amine (TREN), containing six diglycolamide (DGA) pendent arms (termed as TREN-G1-DenDGA) was investigated from nitric acid feed solutions. The transport studies involved 5.75 × 10−4 M ligand solution in 5% isodecanol modified n-dodecane. Am(III) transport was slower than that of Eu(III) under identical conditions. The transport of both Am(III) and Eu(III) increased with increasing nitric acid concentration from 1 to 6 M HNO3 suggesting a solvation extraction mechanism with nitrate ions playing a significant role. A unique preferential Eu(III) transport over Am(III) was seen at 3 M HNO3 with a transport selectivity factor (ratio of permeability coefficient values) of 6.2 which decreased upon changing the acid concentration. Carrier ligand concentration also played a significant role in transport selectivity. Membrane parameters such as permeability coefficient and effective diffusion coefficient (D eff) values were determined experimentally. The liquid membrane stability studies were also carried out.