Research On The Extraction Behavior Of Cerium(Ⅲ) With Dmdodga In 1-Octanol/Kerosene And Ionic Liquid

High-level waste liquid is a waste liquid with high radioactivity,strong toxicity,high heat release rate and strong acidity.It is necessary to reduce the radioactivity of high-level radioactive waste liquid,shorten the monitoring time of the final geological disposal,and increase the U and Pu utilization rate.In recent years,bisamido oxime ether extractants as one of the tridentate ligands,have been extensively studied due to their high extraction rates for trivalent/tetravalent lanthanides and actinides in the separation of high-level waste liquids.Ionic liquids is applicated by the separation of high-level liquid waste due to their high radiation stability,thermal stability,high extraction efficiency for metal ions,and good selectivity.In this paper,N,N’-dimethyl-N,N’-dioctyldiglcolamide（DMDODGA）extraction mechanism of Ce（Ⅲ）in nitric acid media is studied with 40/60%（V/V）n-octanol/kerosene and[Bmim][PF₆]as diluents,respectively.The extraction time and the initial aqueous phase are considered by the extraction behaviors of Ce（Ⅲ）in nitric acid medium with 40/60%（V/V）n-octanol/kerosene and[Bmim][PF₆]as diluents.Then,these influence factors of extraction Ce（Ⅲ）are disccussed,such as the nitric acid concentration,extractant concentration,concentration of imidazolium ions in the aqueous phase,ultimate loading yielded DMDODGA-40/60%（v/v）n-octanol/kerosene and DMDODGA-[Bmim][PF₆].Furthermore,the structure of the complex is analyzed by the fourier transform infrared spectrometer.And the extraction mechanism and average number of complexes for Ce（Ⅲ）are proposed.The stripping efficiency of Ce（Ⅲ）is studied with[Bmim]Cl,H₂O and HNO₃ as stripping agents.The results show that DMDODGA has a good extraction performance for Ce（Ⅲ）.The concentration of the original aqueous phase nitric acid and extractant have a great influence on the distribution ratio of Ce（Ⅲ）.At the same extractant concentration,when the concentration of nitric acid in the aqueous phase was about 2 mol/L,the distribution ratio has a maximum value;when the concentration of nitric acid in the aqueous phase was about 4mol/L,the distribution ratio had a minimum value.DMDODGA is coordinated with Ce（Ⅲ）via C=O bond,and the molar ratio of Ce（Ⅲ）to DMDODGA in the complex is 1:3.In 40/60%（v/v）n-octanol/kerosene system,the medium extraction mechanism is neutral complexation,while the extraction mechanism in the[Bmim][PF₆]system is cation exchange.Furthermore,the recovery rates of Ce（Ⅲ）are high with low concentrations of nitric acid and water in the40/60%（v/v）n-octanol/kerosene system,and recovery rates of Ce（Ⅲ）in the[Bmim][PF₆]system by different stripping agents are in the order of HNO₃>mixture of HNO₃ and[Bmim]Cl>[Bmim]Cl>H₂O.