Separation of americium (III) and strontium (II) using TEHDGA and 18-crown-6

Abstract

Abstract This work describes extraction of Am(III) and Sr(II) together with tetra(2-ethylhexyl) diglycolamide (TEHDGA) and selective back-extraction of strontium with a strontium complexant, 18-crown-6, leading to their separation from each other. 0.3 M TEHDGA+5% isodecyl alcohol/ n -dodecane was used to extract Am(III) and Sr(II) from 4 M nitric acid into organic phase with very high D ( D Am =1000, D Sr =22) and 0.1 M 18-crown-6 dissolved in 4 M nitric acid is used for selective stripping of Sr(II) from loaded extract phase. Am(III) left in the extract phase was then stripped with 0.01 M nitric acid. Stripping of Sr(II) was found to increase with increase in 18-crown-6 concentration, at 0.1 M 18-crown-6 dissolved in 4 M nitric acid, 83% of the loaded strontium ( D Sr =0.20) was back-extracted in a single contact while loss of Am(III) was 0.8% ( D Am =122.45). Stoichiometry limit of 1:1 was observed between strontium and 18-crown-6. Strontium was precipitated and separated from the complexant by Na 2 SO 4 or Na 2 CO 3 . This process was tested with simulated solution of high level waste and found suitable for quantitative recovery of strontium with high purity.