Separation of cerium(IV) and yttrium(III) from citrate medium by solvent extraction using D2EHPA in kerosene

Abstract

The extraction and separation of cerium(IV) and yttrium(III) from citric acid solution using Di-2-ethylhexyl phosphoric acid, D2EHPA, in kerosene was investigated. The effects of the different parameters on the extraction process, including the shaking time, extractant concentration, phase ratio, acid concentration as well as, temperature, were separately investigated to achieve the maximum possible separation between Ce(IV) and Y(III). The extraction constant was modeled based on the most predominant citrate cationic species at pH 4.0. The stoichiometry of the extracted species was found to be [Ce(H2Cit)2·2A(HA)] and [Y(H2Cit)·2A(HA)], (where HA denotes D2EHPA), based on the slope analysis method applied on the obtained results. The mean conditional extraction constants values KC.ex were found to be 4.15 × 102 ± 0.05 and 5.36 ± 0.28 × 103 for Ce(IV) and Y(III), respectively. The thermodynamic functions associated with the extraction reaction were evaluated and discussed. It was found that the extraction process is spontaneous and exothermic for both metal ions. Possible separation of Y(III) from Ce(IV) was given in terms of the separation factors at different extraction conditions.