Extraction of U(VI) by Tri-n-Amyl Phosphate Under High Solvent Loading Conditions

Tri-n-butyl phosphate (TBP) is being employed as the extractant for the processing of nuclear materials all over the world. However, some of its limitations such as third-phase formation, aqueous solubility, chemical and radiation degradation, etc., affect the performance of TBP-based extraction processes. Hence, there is a need to identify alternative extractants that do not possess the disadvantages of TBP but retain the desirable properties of TBP. In this connection, higher homologues of TBP such as tri-n-amyl phosphate (TAP) and some of its isomers are considered to be important for various solvent extraction processes. Batch extraction studies have been carried out on the extraction of U(VI) by 1.1 M solutions of TBP and TAP in n-dodecane as well as heavy normal paraffin (HNP), and the results are reported in this paper. Extraction of U(VI) by 1.1 M TAP/HNP under high solvent loading conditions and subsequent stripping of U(VI) by 0.01 M HNO₃ from loaded 1.1 M TAP/HNP in a countercurrent mode were also carried out with an ejector mixer-settler. This paper describes the results of these mixer-settler runs. Results revealed the suitability of higher homologues of TBP for reprocessing applications.