The extraction of SR2+ with dicyclohexano-18-crown-6 in conventional organic solvent and ionic liquid diluents

Abstract

90Sr (t1/2 = 28.8 a), one of the most significant fission products in high-level radioactive liquid waste (HLLW), contributes to a large part of the heat load and radiation. Removal of 90Sr from the HLLW is beneficial for the final treatment of nuclear waste. In this paper, the extraction of Sr2+ was carried out using dicyclohexano-18-crown-6 (DCH18C6) in a variety of diluents including conventional organic solvents and novel ionic liquid solvents. The effect of several factors, such as nitric acid concentration, crown ether concentration and initial strontium concentration on the extraction of Sr2+ have been studied comprehensively. The higher distribution ratio and the stripping efficiency of Sr2+ were obtained with the binary diluents consisted of n-octanol and acetylene tetrachloride, which were compared with that using pure n-octanol as diluent. As for the CnmimNTf2 (n = 2, 4, 6) ionic liquid solvent systems, the distribution ratio of Sr2+ was much higher in the nitric acid medium with low concentration than in the traditional solvent systems. The results showed that DC2mimNTf2 > DC4mimNTf2 > DC6mimNTf2, which indicated that shorter carbon chain benefits the extraction of Sr2+.