Extraction of ternary beta-diketonates of uranyl ion using some substituted monoamides

The extraction behavior of uranyl ion from dilute nitric acid medium employing 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP)/2-thenoyl-trifluoroacetone (HTTA) in toluene and their mixture with several structurally modified monoamides viz. di-2-ethylhexyl acetamide (D2EHAA), di-2-ethylhexyl propanamide (D2EHPrA), di-2-ethylhexyl isobutyramide (D2EHiBA), and di-2-ethylhexyl pivalamide (D2EHPvA) was investigated. The species of the type UO2(A)(2) and UO2(A)(2) (.) B were extracted for the binary and ternary extraction systems respectively where A = PMBP/TTA and B = D2EHAA, D2EHPrA, D2EHiBA, or D2EHPvA. The extraction constants (log K-ex) for the binary species UO2(A)(2) were determined to be -2.32 +/- 0.03 for HTTA and 0.21 +/- 0.02 for HPMBP, which was an inverse function of their pK(a) value. The overall extraction constants (log K) for the ternary species UO2(A)(2) (.) B were determined as 4.70, 4.22, 4.00, 3.61, 2.65, 2.39, 2.32, and 1.76 for UO2(PMBP)(2) (.) D2EHAA, UO2(PMBP)(2) (.) D2EHPrA, UO2(PMBP)(2) (.) D2EHiBA, UO2(PMBP)(2) (.) D2EHPvA, UO2(TTA)(2) (.) D2EHAA, UO2 (TTA)(2) (.) D2EHPrA, UO2(TTA)(2) (.) D2EHiBA, and UO2(TTA)(2) (.) D2EHPvA, respectively. A linear correlation was observed between the basicity of the amide and the corresponding adduct's formation constants.