AGGREGATION OF COMPLEXES FORMED IN THE EXTRACTION OF SELECTED METAL CATIONS BY P,P'-DI(2-ETHYLHEXYL) METHANEDIPHOSPHONIC ACID*

* Work performed under the auspices of the Office of Basic Energy Science, Divisions of Chemical Science and Material Science, U.S. Department of Energy, under contract number W-31-109-ENG-38. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.

ABSTRACT

The aggregation of several metal complexes formed during solvent extraction with P,P'-di(2-ethylhexyl) methanediphosphonic acid, H₂DEH[MDP], in deuterated toluene, has been investigated by small angle neutron scattering (SANS). The SANS results show that the Ca(II)-, Al(ni)-, La(III)- and Nd(III)-H₂DEH[MDP] compounds exhibit little or no tendency to aggregate. Uranyl complexes of H₂DEH[MDP] at high metal loading form small aggregates with an aggregation number of approximately 14. This behavior is in sharp contrast with the Th(IV)-H₂DEH[MDP] system which forms large aggregates in the organic phase under high metal loading conditions. The aggregation behavior of the various metal-H₂DEH[MDP] compounds is discussed in light of the information obtained from earlier solvent extraction, vapor pressure osmometry, and infrared spectroscopy studies.

Notes

* Work performed under the auspices of the Office of Basic Energy Science, Divisions of Chemical Science and Material Science, U.S. Department of Energy, under contract number W-31-109-ENG-38. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.