Thermodynamics of Extraction of Uranium(VI) and Plutonium(IV) with some Long-chain Aliphatic Amides

Abstract

Distribution data for U(VI) and Pu(IV) from 3.5 M nitric acid medium with 0.5 M N,N-dihexyl derivatives of hexanamide (DHHA), octanamide (DHOA) and decanamide (DHDA) in n-dodecane have been obtained in the temperature ränge 20-50 °C. From these data, the enthalpy, entropy and free energy changes associated with their extraction reactions were evaluated by the temperature coefficient method. Results indicate that the extraction reactions of U(VI) and Pu(IV) with all the three amides are predominantly enthalpy stabilised.

SOLVENT EXTRACTION STUDIES ON U(VI), Pu(IV), AND FISSION PRODUCTS USING N,N-DIHEXYLOCTANAMIDE

“…These considerations led us to carry out a systematic study of the extraction ability of different long-chain dialkyl aliphatic amides. We have recently reported investigations on extraction behaviour of actinides and fission products using dihexylhexanamide (9).…”

“…(2) 0.51\1 OIlOA -1I-IIoII«alle and KPu ----------------------------...... (9) The aqueous nitrate ion complexation factors (1 + L~n[N03-n for UO," and Pu" in 3.5 M HNO, were determined by cation exchange method as well as TTA extraction method (20). The values obtained are 2.23±O.03 and 2093±72 for U(VI)and PU(lV) respectively(9). Neglecting the consumption of DHOA by UO," or Pu" (tracer concentration) the equilibrium concentration of the free amide was calculated using the following equation.…”

Extraction of U(vi) From Nitrate and Thiocyanate Media With Monoamides

“…The equilibrium constant values of UO 2 2þ for several amide systems from nitric acid medium have been reported in literature [9,17,18] but the values from NO 3 À medium at pH 2.0 and the SCN À medium are being reported for the first time.…”

“…The log K ex values evaluated at all the temperatures for the NO 3 À and SCN À systems are given in Table 4 and a plot of log K ex vs. 1=T (in degree Kelvin) is given in Fig. Table 5 gives the thermodynamic parameters for the formation of UO 2 2þ complexes with DHDA from NO 3 À and SCN À media at 25 C along with the literature data for UO 2 2þ -HNO 3 -DHDA, [18] TBP [27] and tri-n-amyl phosphate (TAP). From the slope of the straight lines, DH has been evaluated using the van't Hoff equation.…”

Redox behavior of gas phase Pu(IV)-monodentate ligand complexes: an investigation by electrospray ionization mass spectrometry

“…Numerous approaches have been used to characterize these complexes, for example, distribution ratio measurements [4,7,8,[12][13][14][15][16], spectroscopic characterization [4,[16][17][18], and thermodynamic data measurements [7,8,13,15,19]. While classical solution chemistry methods are informative and helpful in providing insight into the coordination behavior of Pu(IV) with these ligands, there are only a few publications on the use of electrospray ionization mass spectrometry (ESI-MS) to obtain information on Pu(IV) complexes in solution.…”