Carrier facilitated transport of uranium across supported liquid membrane using dinonyl phenyl phosphoric acid and its mixture with neutral donors

Carrier facilitated transport of U(VI) from nitric acid medium across supported liquid membrane (SLM) has been studied under varying experimental conditions, namely feed, carrier, receiver phase compositions, pore size and membrane thickness etc. Microporous polytetrafluoroethylene (PTFE) membranes were used as a solid support and dinonyl phenyl phosphoric acid (DNPPA) either alone or in combination with neutral donors dissolved in n-paraffin was used as carrier. Receiver phases like H2SO4, Oxalic acid, Citric acid and Na2CO3 were evaluated. 2 M H2SO4 appeared to be most effective as receiver for U(VI) transport across SLM under the conditions of these studies. The permeability coefficient (P) evaluated for 0.1 M DNPPA in combination with 0.05 M neutral donors showed the U(VI) transport order: Cyanex 923 similar to TOPO>TBP>TEHP. The permeability (P) of U(VI) decreased with increase in HNO3 concentration and with metal ion concentration in feed solution. The variation of Cyanex 923 concentration at fixed DNPPA concentration (0.1 M) revealed that U(VI) permeation across SLM was maximum at 1:2.5 mole ratio. The synergistic mixture of 0.1 M DNPPA + 0.05 M Cyanex 923 was used for uranium recovery from uranyl nitrate raffinate (UNR) solution. (C) 2012 Elsevier B.V. All rights reserved.