Phosphine oxide and quaternary ammonium extraction of americium(III) from concentrated chloride solutions

Abstract

The extraction of Am(III) and Eu(III) by tri- n-octylphosphine oxide (TOPO) and methyl trialkyl(C 8C 10) ammonium chloride (Adogen 464) from HCl and slightly acidic LiCl solutions was investigated. Linear extraction isotherms showed that macro Eu(III) specoes exist with the same degree of assocition in both organic and aqueous phases suggesting the same behavior for the actinide analog Am(III). Reagent dependences indicated the extraction of primarily AmCl 3·TOPO and AmCl 3·3TOPO from 1 and 5 M LiCl, respectively, and the extraction of only R 4NAmCl 4 (where R 4N + is the quaternary ammonium cation of Adogen 464) from both 1 and 5 M LiCl. However, detailed studies of the TOPO-LiCl and Adogen 464-LiCl systems showed wide variations in lithium and water extraction as a function of aqueous LiCl molarity, so that these systems are not suitable for investigating the aqueous chloride complex equilibria.