Study on separation of Eu(II) from trivalent rare earths via electro-reduction and ion exchange

Separation of Eu(II) from trivalent rare earths was carried out in 0.01 mol dm^-3 hydrochloric acid medium. Eu(III) was selectively reduced to Eu(II) at glassy carbon cathode in flow type electrolyzer. For Eu(II) separation strong acid cation exchanger based on sulfonated polystyrene/DVB copolymer impregnated into porous silica beads was used. Breakthrough and chromatography curves were measured. Eu(II) exhibited lower affinity towards the sorbent than trivalent rare earths and therefore it was the first species to breakthrough the column. Excellent separation from middle rare earths was achieved while the separation from heavy rare earths was difficult. The back-oxidation of Eu(II) was a problem despite all the measures that were taken to prevent oxidation by dissolved oxygen and photo-oxidation.