Pradeep Kumar^1,* and Ashok Khanna²

¹Department of Chemical Engineering, Institute of Engineering and Technology, Lucknow-226021, India

²Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur-208016, India

*Corresponding author: E-mail: pradeepkumar@ietlucknow.ac.in

In present study, tri-n-butylphosphate (TBP), a classical complexing agent for metallic cations, has been studied for the extraction of uranium into ionic liquids (ILs): 1-butyl-3-methylimidazolium-bis( tri-fluoromethylsulfonyl)imide ([BMIM][TF2N]) and trihexyl-tetradecylphosphonium-bis(tri-fluoromethylsulfonyl) imide ([P_(14)666][TF2N]). Increasing HNO₃ acidity of aqueous solution from 0.01 to 1 M the distribution ratio, D_U decreases from 16 to 1.2 for 1.1 M TBP in [BMIM][TF2N] and the corresponding extraction efficiency (% E) varies from ~94 to 55. In the acidic range of 1 to 8 M D_U and % E shows reversal trend of giving a local maximum at 8 M. This behaviour is compared and validates by literature. In contrast, on increasing in aqueous acidity from 0.01 to 8 M the extraction of uranium into [P_(14)666][TF2N] ionic liquid, D_U enhances from 2 to 39 and (%E) goes up from ~ 51 to 95. Since, [P_(14)666][TF2N] works better than [BMIM][TF2N] in the acidic range > 0.1. This ionic liquid has been used for selective separation of uranium from strontium giving a D_U of 63 and D_Sr of 2 with 98% E of uranium at 8 M acidity. To confirm the various species and groups in the formed complex, FTIR studies have been conducted.

Distribution ratio, Extraction efficiency, Ionic liquid, Tributyl phosphate, Solvent extraction.