Solvent extraction of Th(IV) from aqueous solution with methylimidazole in ionic liquid

Abstract

Abstract An extraction of Th(IV) was performed using 1- methylimidazole (1-MIM) or 2-methylimidazole (2-MIM) as the extractant in imidazolium type ionic liquids (ILs) or n-pentanol. The extractability for Th4+ in ILs was by far higher than that obtained in n-pentanol. The extraction mechanism was determined by slope analysis and ESI-MS. The transfer of Th4+ with MIM into ILs proceeded through both a cationic exchange and a neutral solvation mechanism, whereas the partitioning of Th4+ with MIM into n-pentanol only underwent a neutral solvation mechanism. The thermodynamic parameters values (ΔH, ΔS and ΔG) for extraction of Th4+ with 1-MIM in IL were calculated and the results indicated the extraction reaction was spontaneous and went through endothermic process. Separation of Th4+ from the solution of lanthanides (III) and uranium was also carried out by 1-MIM in ILs and n-pentanol.