The solvent extraction of Pr(III) and Sm(III) with trialkyl phosphine oxide (Cyanex 923) in chloroform, carbon tetrachloride, n-octane, cyclohexane, 1,2-dichloroethane, benzene, toluene, xylene and nitrobenzene from acidic nitrate medium was investigated. On the basis of slope analysis data, the composition of the extracted species was determined as (M(NO3)3·2CY923), CY923 refers to Cyanex 923. The values of the equilibrium constants and the separation factors were calculated. The effect of the diluents on the metal extraction and separation was discussed and correlated to the physical constants of the diluents. The results showed that with increasing dielectric constant of the diluent, the extraction percent decreased while the separation factors did not change considerably.
Cyanex 923 , rare earths , extraction , diluents , Praseodymium , Samarium