Study on synergistic carriers facilitated transport of uranium(VI) and europium(III) across supported liquid membrane from phosphoric acid media

Abstract

Uranium(VI) and europium(III) transports across the supported liquid membrane ((SLM) have been studied to understand the chemical conditions that affect the selective preconcentration of U(VI) from phosphoric acid feed. The SLM was prepared by impregnating the PTFE microporous membrane with an organic phase consisting of di(2-ethyl)hexylphosphoric acid (D2EHPA) and a neutral organophosphorous oxodonor dissolved in n-dodecane. The different organophosphorous oxodonors studied for synergism were tri- n-butyl phosphate (TBP), di-butyl butyl phosphonate (DBBP), tri- n-octyl phosphine oxide (TOPO), and Cyanex 923 (a mixture of four trialkyl phosphine oxides viz. R 3PO, R 2R′PO, RR′ 2PO and R′ 3PO where R: n-octyl and R′: n-hexyl chain). SLMs thus prepared were evaluated for U(VI) and Eu(III) transport from phosphoric acid feed having different compositions to receiver compartment containing (NH 4) 2CO 3. In order to enhance the driving force, the U(VI) complexing reagents like NaF and EDTA were also used along with (NH 4) 2CO 3 as the receiving phase. The phosphoric acid feed composition was also varied to examine the applicability of SLMs studied in the present work for the preconcentration of U(VI) from the analytical waste containing phosphoric acid. The experimental data obtained in the present work seems to suggest that the SLM formed by tri- n-octyl phosphine oxide with D2EHPA is best suited for U(VI) transport from phosphoric acid feed with a good selectivity over Eu(III). However, the increase in feed acidity (6 mol L − 1 H 3PO 4) found to retard the transport rate of U(VI) across SLM.