H2C2O4对TODGA萃取Nd3+的影响

以N,N,N′,N′-四辛基-3-氧戊二酰胺(TODGA)为代表的酰胺荚醚类萃取剂可以有效萃取高放废液中的An(Ⅲ)和Ln(Ⅲ)，为防止Zr⁴⁺、Pd²⁺等裂片元素萃入有机相，通常需要加入H₂C₂O₄作为水相络合剂，目前，H₂C₂O₄对TODGA萃取Ln(Ⅲ)的影响尚未报道。本工作研究了HNO₃、H₂C₂O₄浓度对TODGA或TODGA+TBP体系萃取Nd³⁺的影响，同时测定了有机相中的H₂C₂O₄浓度，并用紫外-可见吸收光谱分析了有机相中的H₂C₂O₄与有机相中Nd³⁺的配位情况。研究结果表明：HNO₃浓度在1.0~3.0 mol/L的范围内，Nd³⁺的分配比D(Nd³⁺)随HNO₃浓度的增加而增加；H₂C₂O₄浓度在0.1~0.5 mol/L的范围内，D(Nd³⁺)随H₂C₂O₄浓度的增加而增加。HNO₃浓度在1.0~3.0 mol/L的范围内，萃入有机相中H₂C₂O₄浓度随HNO₃浓度的增加而减小，且存在于有机相中的H₂C₂O₄并未与有机相Nd³⁺配位。

Influences ofH2C2O4 on TODGA Nd3+ Extraction Process

Amidopodands, such as N, N, N′, N′-tetraoctyldiglycolamide(TODGA) have been evaluated as an efficient extractant for the separation of actinides(Ⅲ) and lanthanides(Ⅲ) from high level liquid waste(HLLW). Oxalic acid, which was treated as an aqueous complexing agent, was employed to prevent the extraction of some important fission products (e.g. Pd, Zr). However, the influences ofH₂C₂O₄ on the TODGA-Ln(Ⅲ) extraction process remained unexplored. With TODGA or the mixture of TODGA and tributyl phosphate(TBP) as extractant, the extraction performance of Nd³⁺ was studied according to the varied amount of oxalic acid and nitric acid. The concentration ofH₂C₂O₄ in organic phase was determined and the coordination ofH₂C₂O₄ with Nd³⁺ in organic phase was studied using the method of UV-Vis absorption spectrum analysis. The results show that the distribution ratios of Nd³⁺ increase with the concentration of nitric acid at the range of 1.0-3.0 mol/L and increase withH₂C₂O₄ concentration at the range of 0.1-0.5 mol/L. The extracted oxalic acid in the organic phase decrease with the concentration of nitric acid at the range of 1.0-3.0 mol/L without coordination with Nd³⁺.