¢arrier-facilitated transport of plutonium(IV) through tributyl phosphate/ dodecane liquid membranes

Abstract

Selective transport of Pu⁴⁺ over other long-lived fission product contaminants has been accomplished from aqueous acidic solutions through an organic bulk liquid membrane (BLM) and flatsheet immobilized liquid membrane (LLM) containing tributyl phosphate (TBP) as the mobile carrier and dodecane as the membrane solvent Extremely dilute to moderately concentrated plutonium nitrate solutions (10^-5 mol dm^-3) in about 2 mol dm^-3 HNO₃ are used as the source phase. With increase in carrier concentration in the organic membrane both, the amount of plutonium that can be extracted into the membrane and the viscosity of the organic solution increase. These opposing effects result in maximum plutonium permeation with about 30% TBP in dodecane while enhanced acidity, of the strip side adversely affects the partitioning of the cation into the product side Among the several aqueous reagents tested, 0.5 mol dm^-3 ascorbIc acid is found to be the most efficient strippant. The stoichiometry of the Pu⁴⁺-TBP complex in the liquid membrane system has been established as Pu(NO₃)₄.2TBP. The lack of any contamination from even appreciable amounts of possible fission product contaminants is a feature of this novel separation technique.