Applicability of certain organo phosphorus extractants to environmental and biological radioactivity surveys

Abstract

The applicability of certain organo phosphorus extractants to environmental and biological radioactivity surveys has been demonstrated. Specifically, a solution of mono 2-ethyl hexyl phosphoric acid, H 2MEHP, in a hydrocarbon and/or chlorinated hydrocarbon diluent has been shown to extract radioactive Ce(III), Pm(III), Y(III), Am(III), Pu(III), Th(IV), Np(IV), Pu(IV) and U(VI) from acidified human urine with sufficiently high K values to permit basing a scheme of analysis for such radioelements upon liquid-liquid extraction. The specific K value is strongly dependent upon the valence of the element, permitting a partial mutual separation of the above set of elements through use of the H 2MEHP (hydrocarbon and/or chlorinated hydrocarbon) vs. HCl system. These separation possibilities are multiplied by introduction of negative synergist, specifically 2-ethyl hexanol-1, which serves to progressively inactivate H 2MEHP. Consequently, under certain conditions, M(III) may be scrubbed from an extract leaving M(IV) and M(VI) in the organic phase; but under another set of conditions involving a greater relative concentration of negative synergist, M(VI) may be scrubbed from the extract leaving M(IV) in the organic phase. Further mutual separation is accomplished by means of extraction with di 2-ethyl hexyl phosphoric acid, HDEHP, this extractant serving to separate Y from Pm, Ce(III) and Am and to separate Ce(IV) from Pm and Am. Finally, extraction with tri n-octyl phosphine oxide, TOPO, is utilized in the separation of U(VI) from Pu(III). Through use of selected diluents of different densities, the organic phase has been made the upper or lower phase in accordance with maximum ease of manipulation. Flow sheets have been devised and tested. Advantages of the techniques are discussed, and other areas of application are suggested.