The novel extractants, six diglycolamides synthesized in our laboratory, were investigated for actinide extraction from nitric acid into n-dodecane. The dependence of the distribution coefficients of Eu(III) and Am(III) on the length of alkyl chain in the extractants was examined. Among the diglycolamides studied, N,N,N′,N′-tetraoctyl-3-oxapentanediamide (TOOPDA) and N,N,N′,N′-tetradecyl-3-oxapentanediamide (TDOPDA) showed a sufficient solubility in n-dodecane, due to their appropriate lipophilicity modified by increasing the length of the alkyl chain attached to amidic N atoms. The distribution coefficients, D M, of actinides obtained by TOOPDA increased with an increase in HNO3 concentration. The number of diglycolamide molecules coordinated to the actinide ions was estimated to be three for Th(IV), U(VI), Pu(IV), and four for Am(III) and Cm(III) by slope analysis. The order of D M for the actinides at high nitric acid concentrations is An(III), An(IV) > An(VI) > An(V) and that for lanthanides, heavier ...

THE NOVEL EXTRACTANTS, DIGLYCOLAMIDES, FOR THE EXTRACTION OF LANTHANIDES AND ACTINIDES IN HNO3–n-DODECANE SYSTEM

Separation and preconcentration of uranium from acidic media by extraction chromatography

Chemistry of Diglycolamides: Promising Extractants for Actinide Partitioning

Reagents and methods that have been developed during the past 20 years for hydrometallurgical partitioning of actinides from different types of transuranium (TRU) wastes and dissolved fuels are reviewed. Emphasis is placed on the extraction performance of the fully-optimized reagents rather than on the structural iterations that were undertaken (and in some cases are still being conducted) to identify the optimum species. Particular attention is paid to separation processes that have been demonstrated in batch and counter-current solvent extraction, and batch and column mode extraction chromatography. The salient features of the various techniques and reagents for actinide recycle are compared. Sections of the review focus on neptunium behavior in hydrometallurgy and on characterization of those reagents best suited to the separation of trivalent actinides from fission product lanthanides. Selected flowsheets that have been reported for the separation and recovery of actinides from TRU wastes are presented.

Actinide partitioning—a review

N,N,N′,N′‐Tetraoctyl diglycolamide (TODGA) has been evaluated as an extractant for the partitioning of minor actinides from simulated high level nuclear waste solutions. Acid uptake studies suggested that TODGA is more basic (KH: 4.1) as compared to TRUEX and DIAMEX solvents viz. CMPO (KH: 2.0) and DMDBTDMA (KH: 0.32), respectively. TODGA molecules display a tendency toward aggregation in n‐dodecane at lower acidities. Effect of diluent on the distribution behavior of Am(III) was studied employing diluents of different dielectric constants. N,N‐dialkyl amides with different alkyl groups viz. dibutyl decanamide (DBDA), di(2‐ethylhexyl) acetamide (D2EHAA), di(2‐ethylhexyl) propionamide (D2EHPRA), di(2‐ethylhexyl) isobutyramide (D2EHIBA), dihexyl octanamide (DHOA) and dihexyl decanamide (DHDA) were evaluated as phase modifiers. Distribution behavior of various metal ions viz. Am(III), Pu(IV), U(VI), Eu(III), Fe(III), Sr(II) and Cs(I) was studied from pure nitric acid solution as well as from simulat...

N,N,N′,N′‐Tetraoctyl Diglycolamide (TODGA): A Promising Extractant for Actinide‐Partitioning from High‐Level Waste (HLW)

A number of neutral extractants containing the P(0)(CH2)nC(0)N raolety were evaluated for their ability to extract Am from nitric acid and their selectivity for Am over Fe and selected fission products. Extractants containing alkoxy, alkyl, and aryl substltuents were evaluated. Tetrachloroethylene was used as a diluent. Fission products selected for study were Y, Zr, Mo, Tc, Ru, Rh, Pd, La, Ce, Pr, Nd, Sra, and Eu. The conclusions drawn were that the most efficient and selective Am extractant contains a single carbon bridging group, one or two phenyl groups attached to the phosphorus atom and l9obutyl groups attached to the amide nitrogen.

EXTRACTION OF Am FROM NITRIC ACID BY CARBAMOYL-PHOSPHORYL EXTRACTANTS: THE INFLUENCE OF SUBSTITUENTS ON THE SELECTIVITY OF Am OVER Fe AND SELECTED FISSION PRODUCTS

The hydrolytic and radlolytic degradaton of octyl(phenyl)-N,N-dIIsobutylcarbamoylmethylphosphine oxide [0ϕD(lB)CMPO] has been investigated by measuring the distribution ratio of Am, D., between degraded organic solutions and aqueous solutions of selected HN03 concentrations and by measuring the concentration of OϕD(IB)CMPO In degraded solution using gas chromatographic analysis. Hydrolysis was performed by continuous stirring of decalin and CCH solutions of 0ϕD(lB)CMP0 with 5 M HNO3 at 50°C. Radiolysis was performed in a similar manner while irradiating the biphasic system with gamma rays from a 60Co source. From the experimental data, evidence was obtained for a degradation scheme of 0ϕD(iB)CMPO which Involves the formation of methyl(octyl)-(phenyl)-phosphine oxide (MOϕPO) and octyl(phenyl)phosphinic acid (H[0ϕP]). The proposed degradation scheme has been experimentally verified by measuring DAm from mixtures of MOϕPO and OϕD(iB)CMPO and of H[ϕP] and OϕD(iB)CMPO. Evidence was found that MOϕPO ca...

Hydrolytic and radiolytic degradation of octyl(phenyl)-n,n-diiso-butylcarbamoylmethylphosphine oxide and related compounds

The degree of Interaction or compatibility of the neutral bifunctional extractant 0фD(lB)CMP0 with a diluent was determined by measuring the distribution ratio of the extractant between two phases. The distribution ratio, DCMPO, was highest in chloro-carbon and aromatic diluents with small molar volumes and lowest in normal paraffinic hydrocarbon diluents with large molar volumes. An approximate correlation between DCMPO in a variety of diluents and the solubility parameter (&#x1d6c5;) of the diluent was obtained using equations for regular solutions and b.delta;H2o =34.8. A much better correlation was obtained between DCMP0 find an empirical solution parameter. It was found that the distribution ratio of diisobutylcarbamoylmethylphosphine oxides increased by 3 orders of magnitude as the basicity of the phosphoryl group on the extractant was increased by the replacement of two phenyl substi-tutents on the phosphorus atom with two octyl groups The influence of TBP as a phase modifier in 0фD (iB)CMPO -dilu...

E. Philip Horwltz

Papers

EXTRACTION OF Am FROM NITRIC ACID BY CARBAMOYL-PHOSPHORYL EXTRACTANTS: THE INFLUENCE OF SUBSTITUENTS ON THE SELECTIVITY OF Am OVER Fe AND SELECTED FISSION PRODUCTS

Hydrolytic and radiolytic degradation of octyl(phenyl)-n,n-diiso-butylcarbamoylmethylphosphine oxide and related compounds

The influence op the diluent on the distribution behavior of octyl(phenyl)-n,n-diisobutylcarbamoylmethylph0sphine oxide*