ZIRCONIUM EXTRACTION INTO OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYLMETHYLPHOSPHINE OXIDE AND TRIBUTYL-PHOSPHATE

Classical slope analysis techniques were used to determine the octyl(p henyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) and nitrat e stoichiometries for the extraction of zirconium by CMPO diluted with diisopropylbenzene (DIPB). The equilibrium constant for the extractio n of zirconium by CMPO was also determined using classical slope analy sis techniques. The extraction of zirconium by TBP in n-dodecane was u sed as a control to verify the zirconium species as Zr+4, and to verif y the experimental methodology. Equilibrium [CMPO](org) and [TBP](org) concentrations were determined by accounting for the extraction of HN O3 into both TBP and CMPO solvents. Nitric acid dissociation and aqueo us phase activity coefficients were also taken into consideration. Org anic activity coefficients, Zr+4 activity coefficients, Zr+4 hydrolysi s, and consumption of TBP oi CMPO by water were neglected. Nitrate and CMPO dependencies for the extraction of zirconium have been determine d from this work to be: Zr-aq(+4) + 4NO(3) (-)(aq) + 2CMPO(org) --> Zr (NO3)(4) . 2 CMPOorg An equilibrium constant of 1.13 x 10(5) +/- 1.48 x 10(4) at 25 degrees C was also determined for this reaction.