Study On The Extraction Of Zirconium And Lanthanides With N,N’-dimethyl-N,N’- Dioctyldiglcolamide

In spent fuel reprocessing,the significant fission products in High Level Waste（HLLW）has high radioactivity,strong toxicity,and high heat release rate because of long-lived nuclides and actinides.It is vital propation to separate them from HLLW.In the separation process,it is easy to involve the co-extraction of actinides and chemically similar lanthanides.Diglycolamides（DGAs）has good extraction affinity of An（Ⅲ）、Ln（Ⅲ）and other fission products、and have some advantages because of the stability of chemical properties、radiation resistance、the combustion products not producing secondary pollution through the study of various style extractants towards lanthanides,The extraction properties of Zr（Ⅳ）and Ln（Ⅲ）from nitric acid medium are studied using N,N’-dimethyl-N,N’-dioctyl-3-oxa-diglycolamide（DMDODGA）in 40/60（V/V）%1-octanol/kerosene.Effects of HNO₃ concentrations of initial aqueous phase、concentration of extractant and temperature on the distribution ratio D of lanthanides are investigated.The results indicate through the extraction of Zr（Ⅳ）:（1）The extraction distribution ratio D of Zr（Ⅳ）increases gradually with the increase of HNO₃ concentration and when HNO₃ concentration reaches 3.0 mol/L,（2）The extraction distribution ratio D of Zr（Ⅳ）increases gradually with the increase of DMDODGA concentration.The extraction mechanism of metal ion is studied by the slope analysis,and the number of extractant molacular in extracted species is different at various aqueous acidity.When HNO₃ concentration is 0.3mol/L,1.0mol/L,3.0mol/L and 5.0mol/L,the number of extractant molacular for Zr（Ⅳ）is 2.3,1.1,1.0 and 0.7,respectively.（3）The extraction process of Zr（Ⅳ）is exothermic reaction.The extraction distribution ratio D of Zr（Ⅳ）increases with the increase of temperature,which means lower temperature favoring extraction.The results indicate through the extraction of Ln（Ⅲ）:（1）The extraction distribution ratio D of La（Ⅲ）,Pr（Ⅲ）and Tb（Ⅲ）increases gradually as HNO3 concentration increases and when HNO3 concentration reaches 3.0 mol/L,the distribution ratio D decreases.However,the distribution ratio of Tb（Ⅲ）increases gradually with the increase of HNO₃ concentration.（2）The distribution ratio D of Ln（Ⅲ）increases with the increase of atomic number in the same extraction condition.（3）The extraction distribution ratio D of Ln（Ⅲ）increases gradually with the increase of DMDODGA concentration.The extraction mechanism of metal ion is studied by the slope analysis,and the number of extractant molacular in extracted species is different at various aqueous acidity.When HNO₃ concentration is 0.3mol/L,1.0mol/L,and 3.0mol/L,the number of extractant molacular for La（Ⅲ）is 1.2,2.2 and 1.9,and for Pr（Ⅲ）is 2.5,2.5,and 2.7,and for Sm（Ⅲ）is 1.8,2.8,and2.9,and for Tb（Ⅲ）is 3.4,2.5 and 2.7,respectively.（4）The extraction process of Ln（Ⅲ）are exothermic reaction.The extraction distribution ratio D of Ln（Ⅲ）increases with the increase of temperature,which means lower temperature favoring extraction.