Obtaining high-purity 90Sr is crucial because it is the parent radionuclide of the 90Sr/90Y generator. However, 90Sr products recovered from high-level liquid waste (HLLW) often fail to meet the stringent purity requirements. This necessitates the development of a novel extraction system that can seamlessly connect with existing separation processes to achieve the required purity level. A novel diglycolamide (DGA) ligand was designed and synthesized. The distribution ratios (D) of several traditional organic diluents and ionic liquids (ILs) as diluents were compared under the same experimental conditions; 1-butyl-3-methylimidazolium bis(trifluoromethanesulphonyl)imide (C4mimNTf2) was chosen as the optimal diluent. The HNO3 concentration, ligand concentration, C4mim+ concentration, etc., were assessed. The extraction mechanism was confirmed to ensure that the extraction proceeded mainly via the C4mim+ and H+ exchange mechanisms. Slope analysis and the ESI-MS results revealed that the novel ligand N,N-diphenyl-N′,N′-dibutyl diglycolamide (DPDBDGA, L) in C4mimNTf2 formed a 1:3 complex with Sr2+. The experiments on Sr2+ indicated that it can be recovered completely with 1 M mineral acid within two stages. Furthermore, we predicted that the novel DGA ligand would provide a good extraction capacity for Sr2+ in dilute nitric acid in the C4mimNTf2 system. This system can be linked to the separation process of extracting Sr2+ from HLLW using N,N,N′,N′-tetraoctyl-diglycolamide (TODGA) or crown ethers as extractants. Consequently, high-purity 90Sr products can be obtained.
Ma et al. (Sat,) studied this question.