40%正辛醇/煤油中DMDODGA对硝酸环境中铈(Ⅲ)的萃取机理研究

为进一步研究N,N′-二甲基-N,N′-二辛基双酰胺（DMDODGA）对镧系和锕系元素的萃取过程，以40%正辛醇/煤油作为稀释剂，研究了DMDODGA对硝酸环境中Ce(Ⅲ)的萃取行为。结果表明，DMDODGA在40%正辛醇/煤油中表现出对Ce(Ⅲ)很好的萃取能力，但Ce(Ⅲ)的萃取趋势随硝酸浓度而变化，且分配比随硝酸浓度变化的峰值随萃取剂浓度的上升而向低酸度方向移动。使用斜率法，在0.1 mol/L和0.5 mol/L酸度下，均得到配合物中Ce(Ⅲ)与DMDODGA的化学计量数之比为1∶3。Ce(Ⅲ)和DMDODGA形成带正电的1∶3的络合物，该络合物再与NO^-₃相结合形成电中性的分子团。另外，红外光谱分析结果证实，Ce(Ⅲ)和DMDODGA中的CCDS1]O基团存在强相互作用。反萃实验结果表明，由于DMDODGA与Ce(Ⅲ)结合得非常紧密，3种常用反萃剂并不能很好地从有机相中将Ce(Ⅲ)反萃入水相。

Extraction of Ce(Ⅲ) with N,N′-dimethyl-N,N′-dioctyl-diglycolamide in 40% Octanol/Kerosene

The extraction of Ce(Ⅲ) nitrate was investigated by using N,N′-dimethyl-N,N′-dioctyl-diglycolamide (DMDODGA) as extractant with 40% octanol/kerosene as diluent. DMDODGA shows good extraction ability for Ce(Ⅲ), but the trends are quite different depending on the concentrations of nitric acid in aqueous phase, and the peak value of distribution ratio varying with the concentration of nitric acid and moves towards low acidity with the extractant concentration increasing. The slope analysis method was used to obtain the stoichiometric ratio of the extracted complexes. The results show that 1∶3 complexe of Ce(Ⅲ) to DMDODGA is formed in DMDODGA-octanol/kerosene system. The expected charged 1∶3 complex of Ce(Ⅲ) is formed in the 40% octanol/kerosene, and the complex is a neutral complex with three DMDODGA molecules directly bonding to Ce(Ⅲ) and three nitrate anions. In addition, the stronger interaction between the C＝O groups of DMDODGA and Ce(Ⅲ) in the 40% octanol/kerosene system is confirmed by IR spectroscopy. The results of the back extraction show that the stripping of Ce(Ⅲ) is difficult from organic phase using three common stripping agents, due to a strong interaction between Ce(Ⅲ) and DMDODGA.