Extraction of Uranium(VI) and Plutonium(IV) with Unsymmetrical Monoamides

Abstract

Solvent extraction of uranium(VI) and plutonium(IV) has been investigated by three unsymmetrical monoamides, viz., N-methyl, N-butyl derivatives of hexanamide (MBHA), octanamide (MBOA) and decanamide (MBDA) in n-dodecane at 25, 30, 40 and 50 °C (±0.1). The extraction of the metal ions follows the order of the basicity of the amides (except for plutonium (IV)-MBDA system) as indicated by the equilibrium constant for the uptake of nitric acid by the amide (K H ). The order of the basicity was found to increase with the length of the carbon chain, viz., MBHA < MBOA < MBDA. Uranium(VI) and plutonium(IV) were found to be extracted as disolvates and trisolvates respectively, as was observed in the case of symmetrical monoamides. The thermodynamic parameters determined by the temperature coefficient method indicate the extraction reactions to be predominantly enthalpy stabilized.

Synthesis and evaluation of N,N-di-alkyl-2-methoxyacetamides for the separation of U(VI) and Pu(IV) from nitric acid medium

“…Several long chain monoamides such as N,N-di-hexyloctanamide (DHOA), N,N-di-hexyl hexanamide (DHHA), N,N-di-hexyldecanamide (DHDA) and N,N-di-(2-ethylhexyl) isobutyramide (D2EHIBA) have been proposed as substitutes to TBP in solvent extraction procedures [11][12][13][14]. The advantages of using amides over TBP rely on the total incinerability of amides and innocuous nature of degradation products.…”

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.…”

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

“…The actinide ions, such as Pu(IV) preferentially bind with oxygen donor ligands. They are well extracted by the ligand tri-n-butylphosphate (TBP) used in the industrial PUREX process [1,2] as well as by N,N-dialkylamides [3][4][5][6][7][8][9]. Indeed dialkylamides have been under study as potential candidates for plutonium extraction since the 1960's [10].…”

“…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.…”