Solvent extraction and separation of europium (III) using a phosphonium ionic liquid and an organophosphorus extractant-A comparative study

In this paper, the comparative study between an ionic liquid (Cyphos IL 104) and an acidic extractant (D2EHPA) on europium (III) extraction from chloride medium has been reported. Effect of different extraction parameters such as equilibrium pH, extractant and metal ion concentration, salt, diluent and temperature effect has been investigated. Quantitative extraction of europium is achieved with 0.02 M Cyphos IL 104 and with 0.05 M D2EHPA and the loading capacity of 0.01 M Cyphos IL 104 is found to be 0.004 mol and that of 0.01 M D2EHPA is 0.0027 mol, respectively showing Cyphos IL 104 is a better extractant than D2EHPA. The extraction occurred via ion association mechanism for Cyphos IL 104 and cation exchange mechanism for D2EHPA. Stripping studies have been carried out using H2SO4 and HNO3. The effect of thermodynamic parameters, stability and reusability test of both the extractants studied in detail. The loss of extractants while stripping with nitric acid is negligible for both the extractants. The extraction behavior of europium is studied in presence of some transition elements. Separation studies of europium in presence of yttrium, cerium and lanthanum from a mixed solution indicate that D2EHPA is more suitable than Cyphos IL 104 for Y(III)/Eu(III) separation but the selectivity of Eu(III)/La(III) and Eu(III)/Ce(III) are better with Cyphos IL 104 than D2EHPA.