CHARACTERISTICS OF CENTRIFUGAL PARTITION CHROMATOGRAPHY FOR LANTHANOID SEPARATION IN HDEHP EXTRACTION SYSTEM

Separation of light lanthanoids with centrifugal partition chromatogra phy (CPC) was investigated in extraction system of 30% HDEHP/CCl4/n-pa raffin and HNO3. Since separation factors between lanthanoids, Ce, Nd, Pr, Sm, Eu and Gd, were independent of volume ratio of CCl4 and n-par affin diluents, difference in the density between the mobile phase and the stationary phase was controlled by varying the volume ratio of tw o diluents in order to operate at reasonable pump-pressure. The effect s of volume of the stationary phase and rotational speed on the separa tion characteristics of CPC were examined to find the optimum operatio n conditions. The effect of chain length of n-paraffin (number of carb on atoms: 6 - 15) as diluents was also examined. The best separation e fficiency was obtained with the longest, n-pentadecane. On the basis o f the above results, mutual separation of lanthanoids was successfully performed in 30% HDEHP/15% CCl4/55% n-pentadecane and 0.5 mol/dm(3) H NO3 extraction system at a low pump pressure of 4.5 kgf/cm(2).