Asymmetric diglycolamide in BmimNTf 2 as an effective solvent system for the uranyl extraction
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Asymmetric diglycolamide in BmimNTf2 as an effective solvent system for the uranyl extraction Zheng Wei1 · Chuan Lu2 · Yu Zhou1 · Caishan Jiao1 · Meng Zhang1 · Hongguo Hou1 · Yang Gao1 · Guoxin Tian1,3 Received: 11 May 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The extraction behavior of uranyl from the nitric acid medium using an asymmetric diglycolamide, DMDODGA, in BmimNTf2 was studied. The effects of the concentration of HNO3, DMDODGA and temperature on the distribution ratio were discussed. The distribution ratio of uranyl into BmimNTf2 liquid is much higher than that into hydrocarbon diluents. The extraction mechanism was investigated by UV-visible spectroscopic and extraction experiments that all agree the cationexchange mechanism. Formation of the 1:2 U/DMDODGA complexes was analyzed using the slope analysis method. In addition, uranyl can be effectively separated from perrhenate using DMDODGA-BmimNTf2 system. Keywords Asymmetric diglycolamides · Ionic liquid · Uranyl extraction
Introduction Separation of uranium from liquid waste generated in the reprocessing of the spent nuclear fuel has always been a significant task with regard to both the environmental problems and nuclear fuel cycle [1]. In the context, numerous different extractants have been studied and put into use for the partitioning of uranium, of which tri-n-butyl phosphate (TBP) based on the PUREX process still remains the preferred extractant. There are yet some drawbacks in TBP solvent system, as e.g. vast amount of secondary waste produced during incineration of the spent solvent and the poor radiation resistance etc. [2]. Therefore, it is urgent to search for a better alternative in order to get over the problems related to the utilization of TBP.
* Yang Gao [email protected] 1
Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, College of Nuclear Science and Technology, Harbin Engineering University, Harbin 150001, Heilongjiang Province, China
2
Science and Technology on Reactor System Design Technology Laboratory, Nuclear Power Institute of China, Chengdu 610041, Sichuan Province, China
3
China Institute of Atomic Energy, P. O. Box 275 (126), Beijing 102413, China
Among these extractants used for the uranium separation, diglycolamides (DGAs) have been found to be especially outstanding because of their performance advantages. DGAs compounds only consist of C, H, O, N, and are therefore completely combusted and will noteworthily reduce the amount of the secondary waste production during combustion. And compared to TBP, DGAs exhibit better radiolytic stability [2, 3]. So far, N,N,N’,N’-tetraoctyldiglycolamide (TODGA), as one of the most studied representative of DGAs, has been extensively evaluated. Sasaki et al. [4] investigated the extraction of various metals by TODGA from nitric acid to n-dodecane and attained the distribution ratios of 75 elements. However, unfavorable factors also exist in the use of TODGA as it tends to form a third phase. Until very recently asymmetri
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