Performance of some extractants used for ‘actinide partitioning’ in a comparative hollow fibre supported liquid membrane transport study using simulated high level nuclear waste

The performance of different extractants used for ‘actinide partitioning’, viz. TRUEX, DIAMEX and TODGA is compared in hollow fibre supported liquid membrane (HFSLM) technique for the separation of trivalent lanthanides/actinides from simulated high level waste solutions. In the case of TODGA solvent (0.1 M TODGA + 0.5 M DHOA), quantitative transport of Nd(III) and Am(III) was achieved in 30 min from 500 mL of feed solution containing 0.6 g/L Nd at 3 M HNO3 as well as from pressurized heavy water reactor-simulated high level waste (PHWR-SHLW). In the case of TRUEX solvent (comprising of 0.2 M CMPO as the extractant + 1.2 M TBP as the modifier in normal paraffin hydrocarbon), only 50% transport was observed which was attributed to the significant amount of acid transport, which in turn affected the dissociation of metal–ligand complex at the membrane–aqueous strip interface. However, quantitative transport of metal ions was even possible for TRUEX solvent after neutralization of feed acidity. On the other hand, DIAMEX solvent (1 M DMDBTDMA) resulted in about 85% transport under identical conditions which was explained on the basis of relatively lower DAm value under HLW conditions.