A new approach was proposed for grouping separation of 14 lanthanide rare-earth ions from their coexisting mixed aqueous solutions

by performing liquid-column elution using the aqueous solution containing 14 lanthanide rare-earth ions as the stationary phase and the dispersed organic oil droplets containing P507 extractant as the mobile phase. It was revealed that 14 lanthanide rare-earth ions could be separated into four groups

according to the lanthanide tetrad effect

respectively eluting out from the liquid column at different time in a certain order. Various effects including the saponification degree of P507

the concentration of P507 in organic phase

the length and inner diameter of the extraction column on the performance of grouping separation of rare-earth ions were discussed. The changes of the mass transfer coefficients were also investigated. The separation efficiency of the four groups of rareearth elements (REEs) was evaluated based on the elution resolution

Rs

of the elution peaks of La(III)

Gd(III)

Ho(III) and Lu(III)

the four representative elements respectively from each of the four groups of REEs. Experimental results demonstrated that the separatio

n of REEs by liquid-column elution mainly depended on the competitive adsorption of different rare-earth groups onto the surface of ascending P507 oil droplets. The affinity of different rare-earth groups with P507 extractant and a limited adsorption capacity of P507 molecules at the surface of the oil droplets ascending in liquid column play the important role. The present work highlights a promising technique for grouping separation of multiple lanthanide elements co-existing complex systems.