EXTRACTION EQUILIBRIUM OF YTTERBIUM(III) WITH SULFOXIDES AND THEIR MIXTURES

The extraction equilibria of Yb-175 from thiocyanate solutions with di -n-pentyl sulfoxide (DPSO), di-n-octyl sulfoxide (DOSO), tri-n-octylph osphine oxide (TOPO) and their mixtures in carbon tetrachloride has be en investigated. A relatively small synergistic enhancement has been o bserved with mixtures of dialkyl sulfoxides (DPSO + DOSO) and also wit h mixtures of DPSO + TOPO. These extraction data have been analyzed wi th the aid of a computer by taking into account complexation of the me tal in the aqueous phase by inorganic ligands and assuming a set of pr oduct species in the organic phase and adjusting their formation const ants through an iterative non-linear least-squares procedure to obtain the best fit to the data. The extraction of the metal is inversely an d linearly dependent upon the dielectric constant of the solvent and t emperature of the system.