M. S. Nagar

Extraction behavior of uranium(VI), plutonium(IV) and some fission products with gamma pre-irradiatedn-dodecane solutions of N,N′-dihexyl substituted amides

The extraction behavior of uranium(VI), plutonium(IV) and some fission products like zirconium(IV), ruthenium(III) and europium(III) from 3.5M nitric acid with γ-irradiated organic phase pre-equilibratedn-dodecane solutions of dihexyl derivatives of hexanamide (DHHA), octanamide (DHOA) and decanamide (DHDA) has been investigated as a function of absorbed dose upto 184·104 Gy. The results indicate that the extraction of uranium(VI) decreases gradually with dose upto 72·104 Gy and becomes almost constant thereafter, while, the extraction of plutonium(IV) decreases upto a dose of 20·104 Gy and then increases rapidly up to a dose of 82·104 Gy indicating synergistic effects of radiolytic products formed at higher doses. Extraction of zirconium(IV) increases gradually upto a dose of 72·104 Gy. Europium(III) does not get extracted with any of these amides in the entire dose range (0–184·104 Gy) studied, however, ruthenium shows insignificant increase in extraction with dose. The decrease inD values noticed in the case of plutonium and zirconium after the dose of 72·104 Gy which was attributed to the third phase formation and emulsification. Infrared studies confirm the final products of radiolysis as the respective amines and carboxylic acids. The degraded amide contents have been estimated by quantitative IR spectrophotometric technique. Extraction data obtained for uranium(VI) and plutonium(IV) with TBP/n-dodecane system have also been compared under similar experimental conditions.

Degradation, cleanup, and reusability of octylphenyl-N,N{prime}-diisobutylcarbamoylmethyl phosphine oxide (CMPO) during partitioning of minor actinides from high level waste (HLW) solutions

The radiolytic degradation of the extractant mixture 0.2 M octylphenyl-N,N{prime}-diisobutylcarbamoylmethyl phosphine oxide (CMPO) + 1.2 M tributyl phosphate in n-dodecane [to be utilized for the partitioning of minor actinides from high level waste (HLW) solutions of PUREX origin] has been investigated in contact with 3 M HNO{sub 3} or synthetic pressurized heavy water reactors (PHWR)-HLW solution under dynamic conditions. The distribution ratios of Am, Zr, Fe and Ru with the irradiated extractant mixture at varying doses have been determined under various aqueous phase conditions and correlated with the formation of degradation products. Various cycles of loading the extractant mixture with Am from PHWR-HLW, irradiating at a fixed gamma dose, and then primary and secondary clean-up of the solvent has been carried out to illustrate its reusability during partitioning of minor actinides from actual HLW solutions. The degradation products of CMPO have been identified by employing GC and GC-MS techniques.

Synthesis and characterization of some new mono- and diamide complexes of plutonium(IV) and dioxouranium(VI) nitrates

Abstract Plutonium tetranitrato complexes with N,N′-dialkyl monoamides A[A = dibutyl derivatives of hexanamide (DBHA), octanamide (DBOA)] and tetraalkyl diamides B [B = tetrabutyl, tetraisobutyl and tetrahexyl malonamide (TBMA, TIBMA, THMA)] have been isolated and characterized as Pu(NO3)4 · 3A and Pu(NO)3)4 · 2B, respectively. Complexes with diamides such as Pu(NO3)4 · 2TBMA and Pu(NO3)4 · 2TIBMA were isolated as solids while all others were viscous liquids. Uranyl dinitrato-amide complexes with the above monoamides and diamides were synthesized and characterized as UO2(NO3)2 · 2A and UO2(NO3)2 · B. The IR and visible absorption spectra of the plutonium and uranium complexes indicate that they are O-bonded and the nitrate group acts as a bidentate group. The NMR spectra of the uranyl monoamide complexes indicate the existence of restricted rotation around the CN bond, while thermal investigations reveal that decomposition proceeds through three exothermic steps corresponding to the release of amide and nitrate groups and finally leading to U3O8.

Extraction of uranium(VI) and plutonium(IV) with some aliphatic amides

Extraction of uranium(VI) and plutonium(IV) has been studied with N,N′-dibutyl derivatives of hexanamide (DBHA), octanamide (DBOA) and decanamide (DBDA) at various fixed temperatures of 20, 30, 40 and (50±0.1)°C. The equilibrium constants for the uptake of nitric acid (Kh, a measure of their relative basicities) by these amides were evaluated by the usual method. The equilibrium constants for the extraction of uranium as well as plutonium with all the three amides follow their order of basicity (Kh) viz. DBHA (0.09)<DBOA (0.10)<DBDA (0.13) with log K values of 1.31, 1.43 and 1.73 for uranium and 3.55, 3.65 and 4.17 for plutonium, respectively. It has been observed that whereas uranium(VI) is extracted as a disolvate (similar to TBP and sulfoxides), plutonium(IV) has been found to be extracted as a trisolvate. The thermodynamic parameters evaluated by the usual temperature coefficient method indicate that the extraction reactions of uranium as well as plutonium are stabilized by negative enthalpy change only.

Extraction of uranium, plutonium and some fission products with γ-irradiated unsymmetrical and branched chain dialkylamides

The extraction behavior of uranium(VI), plutonium(IV) and some fission products like zirconium, ruthenium and europium from 3.5M nitric acid with γ-irradiated dibutyl (DBEHA), di-isobutyl (DIBEHA), methylbutyl (MBEHA) derivatives of ethylhexylamide and di-isobutyl octanamide (DIBOA) in n-dodecane has been investigated as a function of absorbed dose up to 184 Mrad. The results indicate that the Kd values for extraction of uranium(VI) decreases gradually up to 45 Mrad and becomes almost constant beyond this dose up to 184 Mrad, while extraction of plutonium(IV) increases rapidly beyond a dose of 45 Mrad due to synergistic effect of the radiolytic products formed at higher doses. The extraction of zirconium(IV) increases gradually up to 45 Mrad and attains a limiting value at higher doses. Ruthenium and europium are not extracted in the entire dose range studied. Infrared studies confirm the final products of radiolysis as the respective amines and carboxylic acids. Radiolytic degradation of the pure amides was determined by estimating the residual amide contents using quantitative IR spectrometry and were found to follow the order DIBEHA > DBEHA > MBEHA > DIBOA.

Extraction behavior of uranium(VI), plutonium(IV), zirconium(IV), ruthenium(III) and europium(III) with γ-pre-irradiated solutions of N,N′-methylbutyl substituted amides in n-dodecane

The extraction of plutonium(IV), uranium(VI), zirconium(IV), europium(III) and ruthenium(III) with γ-pre-irradiated n-dodecane solutions of methylbutyl substituted hexanamide (MBHA), octanamide (MBOA) and decanamide (MBDA) from 3.5M HNO3 has been studied as a function of absorbed dose up to 184×104 Gray. The distribution ratios (Kd) of uranium(VI) decreased gradually up to a dose of 50×104 Gray and became almost constant thereafter, while ruthenium(III) and europium(III) were not extracted in the entire dose range studied. The Kd values of Pu(IV) decreased gradually up to 10×104 Gray, for MBOA, and 30×104 Gray for MBHA and MBDA and then increased up to a dose of 72×104 Gray, indicating the synergistic effect of radiolytic products at higher doses. The extraction of zirconium(IV) was found to increase gradually up to 72×104 Gray. However, the steep fall in Kd values of plutonium(IV), zirconium(IV) beyond a dose of 72×104 Gray was atrributed to third phase formation. The radiolytic degradation of amides was monitored by quantitative IR spectroscopy and was found to follow the order MBOA>MBDA>MBHA at 184×104 Gray having the amines and carboxylic acids as the main radiolytic products.

Synergistic complexes of uranyl ion with 1-phenyl-3-methyl-4-acetyl-pyrazolone-5 and some oxo-donors

Abstract Complexes of uranyl ion with 1-phenyl-3-methyl-4-acetyl-pyrazolone-5(PMAP) and various oxo-donors such as aliphatic sulphoxides [R2SO, where R = i-C5H11(DISO), n-C6H13(DHSO), n-C7H15(DSSO), n-C8H17(DOSO), n-C9H19(DNSO), n-C1OH21(DDSO), n-C11H23(DUDSO) and n-C4H9(DBUSO)] tributylphosphate (TBP) and tri-n-octyl phosphine oxide (TOPO) have been synthesised and characterized. Analytical data establish that they have the stoichiometry UO2(PMAP)2X where X is the oxo-donor. The IR spectra of the sulphoxide complexes in the SO stretching region indicate that the ligands R2SO are O-bonded. The methyl protons of the pyrazole ring and acetyl group in the PMAP ligand are equivalent giving rise to a single sharp peak in the PMR spectra, whereas in the synergistic complexes with the oxo-donors, two deshielded peaks of equal intensity are observed which indicate the non-equivalence of the methyl groups. The peak which is more deshielded has been ascribed to the methyl of the acetyl group. The higher deshielding of these methyl protons arises due to the transfer of electron density to the metal atom on complexation.

Extraction behavior of uranium, plutonium and some fission products with gamma-irradiated N, N′-dialkylamides

The extraction behavior of uranium(VI), plutonium(IV) and fission products like zirconium, ruthenium and europium from 3.5M nitric acid medium with gamma-irradiated dibutyl derivatives of hexanamide (DBHA), octanamide (DBOA) and decanamide (DBDA) in dodecane has been investigated as a function of absorbed dose up to 184 MRads. The results indicate that the Kd value for extraction of uranium(VI) decreases gradually, while Kd for extraction of plutonium(IV) decreases rapidly with dose up to 35 MRads, increasing thereafter with dose, indicating synergistic effects of radiolytic products at higher doses. Ruthenium and europium are not extracted in the entire dose range up to 184 MRads, while extraction of zirconium(IV) increases steadily up to 50 MRads and increases radiply thereafter, indicating synergistic effect of radiolytic products similar to that of plutonium(IV) beyond a dose of 50 MRads. The extractability of uranium(VI) and plutonium(IV) with 1M dibutyl decanamide (DBDA) in dodecane was studied for uranium loading up to 75 mg/ml and plutonium loading up to 3 mg/ml. The percent extraction was found to vary from 91 to 71 for uranium and 95 to 89 for plutonium, respectively. Quantitative stripping of uranium can be achieved with 0.01M nitric acid and plutonium with 0.5M nitric acid and 0.05M hydroxylamine soluton in two steps from an organic phase loaded with 53.2 mg/ml of uranium.

Ternary complexes of uranyl beta-diketones with aliphatic amides

Abstract Ternary adducts of uranyl beta-diketone chelates [beta-diketones = 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (PMBP), 1-phenyl-3-methyl-4-acetyl-pyrazolone-5 (PMAP) and thenoyltrifluoroacetone (TTA)] and dibutyl derivatives of hexanamide (DBHA), octanamide (DBOA) and decanamide (DBDA) have been isolated and characterized as UO2(beta-diketone)2·amide. The 1H NMR spectra indicate the existence of restricted rotation of the CN bond in these complexes. Evidence for the existence of the amide adducts of PMBP as an isomeric mixture has been adduced from the presence of four phenyl protons in their 1H NMR spectra. Thermal investigations confirm the existence of two types of PMBP moieties as opposed to the TTA adducts.

EXTRACTION OF U(VI) FROM NITRATE AND THIOCYANATE MEDIA WITH MONOAMIDES

ABSTRACT The extraction of UO2 2+ from nitrate and thiocyanate media at pH 2.0 has been carried out using N,N-methylbutyldecanamide (MBDA), N,N-dibutyldecanamide (DBDA), and N,N-dihexyldecanamide (DHDA) in dodecane, chlorobenzene, o-dichlorobenzene, and xylene. Thermodynamic parameters for the extraction of UO2 2+ in the system NO3 −/SCN−–DHDA in dodecane have been calculated from the temperature dependence of the log K ex values. UO2 2+–SCN–amide complexes have been synthesized, characterized, and compared with the species extracted in the organic phase from such systems.