Comparison of the Extraction and Separation Behavior of La, Ce, Pr, Nd, Sm from Light Rare Earth Mixed Solutions by PC88A and Cyanex 572

摘要

Solvent extraction of La, Ce, Pr, Nd and Sm from chloride solutions was studied using PC88A and Cyanex 572 as the extractants. Our results indicated that the acidity of the aqueous solution and saponification degree had some effect on the percentage extraction of metal ions. The distribution coefficient of the metal ions increased with increasing aqueous solution pH in both of PC88A and Cyanex 572. But the pH(50) value was lowered by about 0.05 similar to 0.34 in PC88A. In extraction with saponified Cyanex 572 with NaOH, the distribution coefficients of the metal ions were independent of the degree of saponification, and did little to improve the separation behavior of these metal ions. With Cyanex 572 as the extractant, the separation factor of the binary La/Ce and Nd/Sm was enhanced about 5.0, but Ce/Pr and Pr/Nd showed no difference in separation factor as compared with PC88A. The group separation factor of La/(Pr, Nd, Sm) and (Pr, Nd)/Sm was increased by 3.0 similar to 8.0, but for (La, Ce)/(Pr, Nd) and Ce/(Pr, Nd) it was only increased by 0.2 similar to 0.7 in the Cyanex 572 system.