Functionalized ionic liquids based on DODGA with enhanced Eu(III)/U(VI) separation efficiency in highly acidic environment

Abstract

Lanthanides/actinides separation is of importance in many modern industrial engineering fields, e.g. the circulation of the nuclear fuel and rare earth. N,N-dioctyl diglycol amic acid (briefly as DODGA) is known as an effective extractant for extraction of rare earth metal. In this work, two extractants, [N1888][DODGA] and [N4444][DODGA], were developed by using quaternary ammonium as cations and DODGA as anion. The resultant ionic liquids were used to separate europium from europium-uranium binary component system. The influence of several factors (nitric acid concentration, contact time, temperature, metal ions, extractant concentration, salting agent concentration and stripping) were analyzed. The coordination chemistry of Eu(III) with [N1888][DODGA] and [N4444][DODGA] were investigated by the mole-ratio method. The experimental results confirmed that the separation factors (SF) of Eu(III)/U(VI) were reached 55.44 and 60.35 for [N1888][DODGA] and [N4444][DODGA]. The stoichiometry of the complex of Eu(III) and [N1888][DODGA] or [N4444][DODGA] were determined as 1:3. Excellent extraction of the target metals and prominent separation factors using these ionic liquids showed that they were viable to separate lanthanides from actinides.