Extraction of selected trivalent lanthanide and actinide cations by bis(hexoxy-ethyl) phosphoric acid

Abstract

The extraction of Eu(III) and Am(III) from aqueous chloride and perchlorate media into benzene and cyclohexane solutions of ( n-C 6H 13OCH 2CH 2O) 2PO(OH), HDHoEP, has been shown to be 2·5 power dependent upon the formality of HDHoEP in the organic phase and inversely third-power dependent upon the concentration of hydrogen ion in the aqueous phase. The extracted entity, in the benzene system, is postulated as M(Y)(HY 2) 2, where (HY) 2 represents the dimer of HDHoEP, shown to be dimeric in dry benzene in the concentration range considered. In dry cyclohexane, HDHoEP is “empirically” trimeric and tetrameric, respectively, at 0·02 F and 0·2 F concentrations. The extractant is tentatively considered to exist as a mixture of trimers and tetramers in the “wet” cyclohexane of the system investigated. No attempt to formulate the extracted entity in Eu(III) and Am(III) extractions has been made. Under comparable conditions, both Eu(III) and Am(III) are extracted by HDHoEP with distribution ratio, K, values approximately 500 times greater in cyclohexane than in benzene.