以酸性萃取劑萃取稀土元素鑭(III)和鈰(III)之平衡研究

Abstract

In this study, the equilibrium of the separation of Lanthanum(III) and Cerium(III) by solvent extraction methods were investigated at 25°C；meanwhile, the acidic extractants D2EHPA was used. It began with the extraction equilibrium of Lanthanum(III) and Cerium(III) in extractants-kerosene solution and extractants-aqueous solution, and eventually the mixed Lanthanum(III) and Cerium(III) extractants-aqueous solution was studied. The experimental results indicated that the extraction distribution ratio of Lanthanum(III) and Cerium(III) increased with either of rising concentrations of extractant in the organic phase or equilibrium pH values in the aqueous phase. Moreover we could realize the composition of the extractants through the graphical and numerical analysis. The composition of LaCl3/D2EHPA complex formed in the organic phase were found to be LaA3(HA)2, LaA3(HA)3, and at the same time the respective corresponding equilibrium constants were KLa32 = 0.0013 (kmol/m3)0.5, KLa33 = 0.029 ; The composition of CeCl3/D2EHPA complex formed in the organic phase were found to be CeA3(HA)2, CeA3(HA)3, and furthermore the respective corresponding equilibrium constants were KCe32 = 0.0202 (kmol/m3)0.5, KCe33 = 0.075. The composition of LaCl3, CeCl3/D2EHPA complex formed in the organic phase were found to be LaA3(HA)2, LaA3(HA)3；CeA3(HA)2, CeA3(HA)3, and simultaneously the respective corresponding equilibrium constants were KLa32 = 0.0023 (kmol/m3)0.5, KLa33 = 0.014；KCe32 = 0.0198 (kmol/m3)0.5, KCe33 = 0.033；separation factor：αCeLa = 3.0625[H2A2]-0.16