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A recyclable IL separation strategy is provided, which simplifies the separation process of Th and RE, reduces chemical consumption, and provides a new idea for the treatment of IATREO waste residue. [Display omitted] • Efficient and sustainable separation of thorium and rare earth achieved using a novel ionic liquid. • The separation factor of Th/REs is as high as 22114. • Functionalization of cations provides more coordination sites to form an ion pair. • Stripping and recycling process of [OB2DTA][CA12] is easier to implement. • REs loss was limited to less than 0.3%, with Th and Fe extraction efficiencies of 99.5% and 100%, respectively. Thorium (Th) containing radioactive waste generated by ion-adsorbed rare earth ore (IATREO) separation plants poses a threat to the environment. The waste residue contains a much higher content of rare earth (RE) than the original IATREO. This study describes novel ionic liquids (ILs) containing cationic functionalization and evaluates their effectiveness in recovering Th and RE from the waste residue leaching solution (WRLS). Di-functionalization of the cation in ILs is more advantageous than mono-functionalization and non-functionalization, providing more coordination sites and achieving higher extraction and separation performance. In the simulated solution at an initial pH of 3, [OB2DTA][CA12] is able to extract 99.0% of Th and only 0.4% of RE, the Th/RE separation factor reaches 22114. The extraction reaction is carried out by an ion association mechanism. After 5 cycles of extraction-stripping-regeneration, the extraction and separation abilities of ILs remain stable. For the HCl leaching solution of waste residue, 99.5% of Th is separated in two extraction stages, while the total loss of RE is only about 15 mg/L. The recyclable separation strategy based on ILs simplifies the separation process of Th and RE, reduces chemical consumption, and provides a new idea for the treatment of IATREO waste residue. [ABSTRACT FROM AUTHOR]

[Display omitted] • HDESs were used for removing Al impurity to produce high-purity GdCl 3. • The separation factor of Al/Gd extracted by the HDES is higher than 400. • No emulsification and third phase formation after HDES extraction of Al. • High purity of GdCl 3 products was obtained by HDES extraction system. • HDESs can be easily stripped and remains stable after 5 cycles. In the current industrial production of high-purity gadolinium (Gd) products, aluminum (Al) is enriched into GdCl 3 solution as the main impurity element. It is urgent to develop a new process to effectively remove Al3+ from GdCl 3 solution. In this paper, a novel strategy for separating Al3+ and Gd3+ based on hydrophobic deep eutectic solvent (HDES) is reported. The main physical properties of HDESs were characterized, including density (<0.90 g/cm3), viscosity (<30 mPa·s), water content (<3.5 %) and water solubility (TOC < 300 mg/L). The extraction performances of HDESs for separating of Al3+ from GdCl 3 solution were systemically investigated. Compared with other HDESs, N,N-diethyldodecanamide (DM):ibuprofen (BF) (3:1) HDES has a better separation performance, with the maximum separation factor of Al/Gd (β Al/Gd) being greater than 400. It was found that DM:BF (3:1) HDES could quantitatively remove Al3+ (E% > 99 %) from the original GdCl 3 solution (853.9 mg/L Al3+ and 5466.2 mg/L Gd3+) in three continuous counter-current extraction stages. The co-extraction rate of Gd3+ was only 2.43 %, and the purity of GdCl 3 in the raffinate was 99.9 %. After the loaded HDES was scrubbed one more time, the comprehensive yield of Gd exceeded 99 %. The loaded HDES could be easily stripped, regenerated and sustained stability over five regeneration cycles. The HDES studied in this paper has the advantages of simple preparation, low toxicity, low viscosity, good hydrophobicity and excellent separation effect, which is conducive to the sustainable preparation of high-purity GdCl 3. [ABSTRACT FROM AUTHOR]