Synergistic Extraction of Europium (III) using Di-n-Butylsulfoxide and PicrolonicAcid

Abstract

Aim and Objective: Europium (Eu(III))isa rare-earth metal, the softest, least dense, and most volatile member of lanthanides. It is greatly applied in control rods of nuclear reactors. Although various extraction methods of Eu(III)have been reported, we present a novel mixture ofeasily available extractants in optimizedexperimental conditions to extract it efficiently, quickly, and cost-effectively. Materials and Methods: Physical-chemical conditions (e.g. pH, equilibration time, temperature, europium concentration, extractants concentration, presence of specific metal ions) were optimized. The extractantspicrolonic acid (HPA) and di-n-butylsulfoxide (DBSO) were thoroughly mixed at equal concentrationin chloroform. Standard Eu(III) solution was used for method accuracy.Reagent blank was prepared under identical conditions but without metal ions.Using the metallochromic dye arsenazoIII as blank, absorbance of Eu(III) was measured spectrophotometricallyat 651 nm. Distribution ratio (i.e.Eu(III) concentration in aqueous phase before and after extraction) defined the extraction yield. Results: HPA/DBSO mixture (0.01 M)had a synergistic effect on Eu(III) extraction (1.19×10-5 mole/dm3) achieving a maximum yield (≥99%) at pH2, during 5 minutes equilibration,atroom temperature.Eu(III) extraction was reduced depending on the nature but not on the metal ions concentration. Extractants could be recycled four times without consequent degradation. Deionized water (dH2O) was the best strippantbesides its availability and low-cost. The composition of the extracted adduct was defined as Eu(PA)3.2DBSO. Conclusion: This alternative method was stable, simple, rapid, cost-effective, reliable, accurate and sensitive.It could be used forEu(III) extraction and refining on a pilot plant scale.