Solvent extraction of Ce(IV) from sulfuric acid solutions using Cyanex 921 and its mixtures with D2EHPA

With the rapid development of science and technology, cerium and cerium oxide are widely used in various fields, including in the manufacture of aluminum, aluminum alloys, some steels and in permanent magnets, catalysts, Polishing powder, Glass, Cinema, and Ceramic Technology. Solvent extraction is one of the effective techniques for extraction, separation, and purification of cerium.

The extraction of cerium (IV) from sulfuric acid solutions using Cyanex 921 in kerosene was investigated. The different parameters affecting the extraction process of cerium(IV) such as pH of aqueous solutions , reagent, metal ion concentration, contact time as well as temperature, are separately investigated. Experiments in the pH range of 0.5 to 5.5, at 25±1 oC , using Cyanx 921 in the concentration range of 0.06 to 0.4 mol L-1, and a mixture of Cyanx 921 and D2EHPA was performed in different ratios.

From the temperature study, the extraction reaction for Ce (IV) was found to be exothermic in nature. The results indicated that the effective extraction of cerium(IV) from sulfuric acid solutions cannot be achieved in a single equilibration because the solubility of Cyanex 921 in aliphatic diluents is limited at ambient temperature. To rectify this issue, the possibility of using a synergistic mixture of Cyanex 921 and D2EHPA as extractant system to recover cerium(IV) from sulfuric acid solutions was investigated. Mixtures of Cyanex 921 and D2EHPA resulted in synergistic extraction of cerium (IV) from sulfuric acid solutions. The results indicated that, under experimental conditions, the maximum synergistic coefficient was obtained at the molar ratio of (0.6M D2EHPA / 0.2 M Cyanex 921) 3.0, and cerium(IV) was extracted into organic phase in the form of Ce(SO4)(HSO4)2. Cyanex 921.