Search

The degradation behavior of gamma irradiated solution of 1.1 M tri-butyl phosphate (TBP) in n-dodecane (n-DD) and 1.1 M tri-iso-amyl phosphate (TiAP) in n-DD loaded with nitric acid and uranium were compared up to 5 cycles upon recycling of the degraded solvent after 80 kGy in each cycle. The solvent was recycled by stripping the loaded metal with dilute nitric acid followed by alkali wash using sodium carbonate after each cycle. Subsequently, the physico-chemical properties and the metal extraction – retention properties of the recycled solvent were measured. The recycled solvent was analyzed using gas chromatographic and FT-IR spectroscopic analysis. Among the physico-chemical properties the interfacial tension of the recycled solvent decreased drastically after three cycles of irradiation, but the variation in the measured phase separation time was not significant. But, the concentration of the extractant (TBP/TiAP) decreased significantly upon recycling. Though the formation of nitro compounds was obvious from FT-IR analysis, the metal retention by recycled organic phases were comparable after each cycle of irradiation. Cyclic irradiation behavior of TiAP/n-DD and TBP/n-DD was compared under acid loaded and uranium loaded condition. The number of cycles, the solvent can be reused upon recycling was evaluated. Cyclic irradiation under uranium loading condition leads to degradation of the extractant (TBP/TiAP) to a significant extent as evident from GC-analysis. Accumulation of unwashable degraded products takes place upon recycling based on FT-IR analysis. [ABSTRACT FROM AUTHOR]

The aggregation behavior of a tri-n-octylmethylammonium bis(2-ethylhexyl)phosphate ([N1888][D2EHP]) in n-dodecane (n-DD) was investigated in detail by dynamic light scattering studies. The aggregate size was measured as a function of various parameters such as concentration of [N1888][D2EHP] in organic phase, concentration of nitric acid and Nd(III) in aqueous phase, and temperature of the system. The aggregate size increased with increase in the concentration of nitric acid and [N1888][D2EHP] in organic phase. The aggregate formation of [N1888][D2EHP] phase was compared with [N1888][NO3] and bis(2-ethylhexyl)phosphoric acid (D2EHPA) formed in organic phase upon nitric acid extraction. The results are reported in this paper. [ABSTRACT FROM AUTHOR]

A new ammonium-based task-specific ionic liquid, N,N-dioctyl-(4-trihexylammonium)butyramide bis(trifluoromethanesulfonyl)imide ([AmDOA][NTf2]), was synthesized and characterized by elemental analysis, and Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) spectroscopies. The extraction behavior of Pu(IV), U(VI), and Am(III) from nitric acid medium was studied in a solution of [AmDOA][NTf2] in an ionic liquid diluent, methyltributylammonium bis(trifluoromethanesulfonyl)imide ([N1444][NTf2]). The distribution ratio of actinides obtained in [AmDOA][NTf2]/[N1444][NTf2] was compared with other task-specific ionic liquids. The extraction stoichiometry of Pu(IV) in ionic liquid phase was determined, and the conditions needed for the efficient recovery of Pu(IV) from the loaded organic phase were evaluated. The results of these studies are reported in this article. [ABSTRACT FROM AUTHOR]

Imidazolium bis(2-ethylhexyl)phosphate ionic liquid was anchored on a polystyrene-divinylbenzene (PS-DVB) copolymer and the product (R-Im-DEHP) was studied for the extraction of Am(III) and Eu(III) from dilute nitric acid medium to examine the feasibility using the anchored adsorbent for their mutual separation. The effect of various parameters such as the duration of equilibration, concentration of nitric acid, europium ion, and diethylenetriaminepentaacetic acid (DTPA) in aqueous phase on the distribution coefficient (Kd) of Am(III) and Eu(III) was studied. The distribution coefficient of Am(III) and Eu(III) decreased with increase in the concentration of nitric acid. Rapid extraction of metal ions in the initial stages of equilibration followed by the establishment of equilibrium occurred within 4 h. The data on the rate of uptake of Am(III) and Eu(III) were fitted into pseudo-first order and pseudo-second order rate equation. The extraction isotherm was fitted to Langmuir and Freundlich adsorption models and the apparent europium extraction capacity was determined. The mechanism of extraction was elucidated and the conditions needed for efficient separation of Am(III) from Eu(III) was optimized using DTPA. The study indicated the possibility of using R-Im-DEHP for the separation of Eu(III) from Am(III) with high separation factors. [ABSTRACT FROM AUTHOR]

The rate of ion exchange of Eu(III) from semi-infinite bath containing dilute nitric acid solution was studied on a macroporous bifunctional phosphinic acid resin. The influence of particle size, concentration of nitric acid and temperature on the uptake of Eu(III) was examined. The kinetic data were fitted into the Reichenberg approximate solution, based on the Nernst–Planck resin diffusion model, that relates the fractional attainment of equilibrium (Ut) and internal diffusion coefficient (DA). The measuredDAwas of the order of 10−13m2/s, and it was found to increase with the increase of temperature, and decrease with the increase of particle size of the resin and concentration of nitric acid. [ABSTRACT FROM PUBLISHER]

The alkyl derivatives of N, N,-dialkyl-2-hydroxyacetamide (DAHyA), namely, N, N,-dihexyl-2-hydroxyacetamide (DHHyA), N, N,-dioctyl-2-hydroxyacetamide (DOHyA), N, N,-didecyl-2-hydroxyacetamide (DDHyA), were synthesized and characterized by FT-IR, and NMR spectroscopy. The extraction behaviour of Am(III) in a solution of DAHyA in n-dodecane was studied as a function of various parameters to evaluate the feasibility of using DAHyA for partitioning of trivalent actinides from high-level liquid waste (HLLW). The distribution ratio of Am(III) ( DAm(III)) in 0.1 M DAHyA/ n-DD increased from 10−4 to > 200 with increase in nitric acid concentration from 1 M to 6 M. A DAm(III) value 10-70 was obtained in a nitric acid concentration range from 3-4 M. The extraction of Am(III) in 0.1 M DAHyA/ n-dodecane decreased in the order DHHyA > DOHyA > DDHyA. The third-phase formation behaviour of nitric acid and neodymium (III) in 0.2 M DAHyA/ n-dodecane was studied. Near stoichiometric amount of neodymium (III) can be loaded in octyl and decyl derivatives without any third-phase formation from 3-4 M nitric acid medium. Unlike other extractants, the loaded trivalent metal ion in DAHyA can be recovered even with 1 M nitric acid. Therefore, the study revealed that N, N,-dialkyl-2-hydroxyacetamides are promising candidates for partitioning the trivalent actinides from HLLW. [ABSTRACT FROM AUTHOR]

Piperidinium nitrate (Pip − NO3) and pyrrolidinium nitrate (Pyr − NO3) functional groups were anchored on a poly(styrene-divinylbenzene) matrix and evaluated the resultant anion exchange resin for the extraction of plutonium from nitric acid medium. The distribution coefficient ( Kd, mL/g) of Pu(IV) in these resins increased with the concentration of nitric acid, reaching a maximum Kd at 7 M nitric acid, followed by decrease. The extraction of Pu(IV) increased with the duration of equilibration followed by the establishment of equilibrium, occurred within four hours of equilibration. The kinetic data were fitted with pseudo-first order and pseudo-second order rate equations. The apparent plutonium exchange capacity was determined to be ∼256 mg/g for Pip − NO3 resin and 285 mg/g for Pyr − NO3 resin at 7 M nitric acid. The radiolytic degradation of Pip − NO3 and Pyr − NO3 in presence of nitric acid (7 M) was studied upto a dose of 200 KGy and the results are reported in this paper. [ABSTRACT FROM AUTHOR]

Liquid-liquid extraction of U(VI) from nitric acid medium was carried out using three different class of CHON based molecular extractants namely monoamide, malonamide, and diglycolamide present in 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide ([C4mpip][NTf2]) ionic liquid. The extractants investigated were di-n-hexyloctanamide (DHOA),N,N-dimethyl-N,N-di-octyl-2-(2-hexyloxylethyl)malonamide (DMDOHEMA) andN,N,N’,N’-tetra(ethylhexyl)diglycolamides (T2EHDGA). The extraction behavior of uranium(VI) in ionic liquid medium was investigated as a function of various parameters, such as the duration and temperature of equilibration, aqueous phase concentrations of feed acid, extractant, NaNO3, and ionic liquid cation, etc. The extraction of U(VI) observed in these systems were compared with each other and the distribution ratios of U(VI) decreased in the order T2EHDGA > DMDOHEMA > DHOA. The slope analysis of the extraction data was carried out to understand the mechanistic aspects of extraction. The extraction of U(VI) observed in [C4mpip][NTf2] ionic liquid was also compared with pyrrolidinium ([C4mpyr][NTf2]) and imidazolium ([C4mim][NTf2]) based ionic liquids under identical experimental condition. [ABSTRACT FROM PUBLISHER]

Diglycolamic acid was anchored on a polyamine matrix and the product (PA-DGAH) was characterized by ion-exchange capacity measurement, TG-DTA and FT-IR spectroscopy. The extraction behavior of Am(III) and Eu(III) in PA-DGAH was studied from dilute nitric acid medium to examine the feasibility using the anchored adsorbent for their mutual separation. The effect of various parameters such as the duration of equilibration, concentration of europium, nitric acid and diethylenetriaminepentaacetic acid (DTPA) in aqueous phase on the distribution coefficient ( Kd) of Am(III) and Eu(III) was studied. The distribution coefficient decreased with increase in the concentration of nitric acid. Rapid extraction of metal ions in the initial stages of equilibration followed by the establishment of equilibrium occurred within 4 h. The data on the rate of uptake of Am(III) and Eu(III) were fitted into pseudo-first order and pseudo-second order rate equation. The extraction isotherm was fitted to Langmuir and Freundlich adsorption models and the apparent europium extraction capacity was determined. The mechanism of extraction was elucidated and the conditions needed for efficient separation of Am(III) from Eu(III) was optimized using DTPA. The study indicated the possibility of using PA-DGAH for the separation of Eu(III) from Am(III) with high separation factors. [ABSTRACT FROM AUTHOR]

Extraction of Am(III) from nitric acid medium was carried out in a solution of benzoylpyrazolone (HPMBP) dissolved in 1-butyl-1-methylpyrrolidinium bis(trifluoro-methanesulfonyl)imide ([C4mpyr][NTf2]) ionic liquid. The extraction behavior of Am(III) in ionic liquid phase was investigated as a function of various parameters, such as pH of aqueous phase, duration of equilibration, and concentration of ionic liquid and nitrate in aqueous phase. Appreciable extraction was obtained at low pH medium (< pH 2) unlike other diketone based extractant. Extraction of Am(III) in ionic liquid was compared with that observed in a molecular diluent,n-dodecane (n-DD) under similar experimental condition. Remarkably high distribution ratio was observed in IL medium as compared ton-DD medium. The slope analysis of the extraction data was carried out to evaluate the mechanistic aspects of extraction. Extraction mechanism was different from conventional molecular diluent. Recovery of americium from the loaded ionic liquid phase was also studied using nitric acid. [ABSTRACT FROM AUTHOR]

Partitioning of trivalent americium from fast-reactor (FR) simulated high-level liquid waste (SHLLW) has been demonstrated, for the first time, using a modifier-free organic phase containing an unsymmetrical diglycolamide, N, N,-didodecyl- N′, N′-dioctyl-3-oxapentane-1,5-diamide (D3DODGA), in n-dodecane ( n-DD). The extraction behavior of various metal ions present in the FR-SHLLW that contained about 3.2 g/L of trivalent metal ions (Am(III) and Ln(III)) was studied using a solution of 0.1 M D3DODGA/ n-DD, by batch equilibration mode. The extraction of Am(III) was accompanied by the co-extraction of all lanthanides and unwanted metal ions such as Zr(IV), Y(III), and Pd(II) from FR-SHLLW. The co-extraction of unwanted metal ions was minimized by adding a suitable aqueous soluble complexing agents to FR-SHLLW, prior to extraction. As a result, trans-1,2-diaminocyclohexane- N,N,N′N′-tetraacetic acid (CyDTA) was identified as an appropriate reagent for preventing the extraction of zirconium and palladium, that posed problems during recovery of trivalent metal ions from the loaded organic phase. The stripping of behavior of Am(III) and Ln(III) from the loaded organic phase was studied using dilute nitric acid in batch equilibration mode. Based on those results, a counter-current mixer-settler run was performed in a 20-stage mixer-settler. About 99.9% of Am(III), Ln(III) and Y(III) from FR-SHLLW in 0.1 M D3DODGA/ n-DD was achieved in 20 contacts and the recovery of Am(III) and other trivalents from the loaded organic phase was achieved in 5 contacts using 0.01 M nitric acid. The study demonstrated the possibility of using the modifier-free reagent, D3DODGA, for the separation of trivalent actinides from FR-SHLLW. [ABSTRACT FROM AUTHOR]

The extraction and stripping behavior of various metal ions present in the fast reactor simulated high-level liquid waste (FR-SHLLW) was studied using a solvent phase composed of a neutral extractant, N, N,-didodecyl- N′, N′-dioctyl-3-oxapentane-1,5-diamide (D3DODGA) and an acidic extractant, di-2-ethylhexyl diglycolamic acid (HDEHDGA) in n-dodecane ( n-DD). The third phase formation behavior of the solvent formulation D3DODGA + HDEHDGA/ n-DD, was studied when it was contacted with FR-SHLLW, and the concentration of neutral and acidic extractant needed to avoid the third phase formation was optimized. The distribution ratio of various metal ions present in FR-SHLLW was measured in a solution of 0.1 M D3DODGA + 0.2 M HDEHDGA/ n-DD. The extraction of Am(III) was accompanied by the co-extraction of lanthanides and unwanted metal ions such as Zr(IV), Y(III), and Pd(II). A procedure was developed to minimize the extraction of unwanted metal ions by using aqueous soluble complexing agents in FR-SHLLW. Based on those results, the counter-current mixer-settler run was performed in a 20-stage mixer-settler. Quantitative extraction of Am(III), Ln(III), Y(III), and Sr(II) in 0.1 M D3DODGA + 0.2 M HDEHDGA/ n-DD was observed. The recovery of Am(III) from the loaded organic phase was carried out by the optimized aqueous formulation composed of 0.01 M diethylenetriaminepentaacetic acid (DTPA) + 0.5 M citric acid (CA) at pH 1.5. The stripping of Am(III) was accompanied by co-stripping of some early lanthanides. However the later lanthanides (Eu(III) and beyond) were not back extracted to Am(III) product. Therefore, the studies foresee the possibility of intra-lanthanides as well as lanthanide-actinide separation in a single-processing cycle. [ABSTRACT FROM AUTHOR]

The organic solvent phase composed ofN,N,N’,N’-tetra-2-ethylhexyl diglycolamide (TEHDGA) and bis(2-ethylhexyl)phosphoric acid (HDEHP) inn-dodecane (n-DD) is regarded as a promising candidate for single-cycle separation of americium (III) from high-level liquid waste. The radiochemical degradation of a solution of TEHDGA + HDEHP/n-DD was investigated by irradiating the solvent to various absorbed dose levels ofγ-radiation. The neat extractants or a solution of extractants inn-dodecane were irradiated in the presence and absence of nitric acid. The degree of degradation was assessed by measuring the variation in the extraction behavior of Am(III), Eu(III) and other metal ions in irradiated solvent systems. The distribution ratio of americium and europium decreased with increase of absorbed dose. The presence ofn-dodecane enhanced the radiolytic degradation of the solvent; however, the role of nitric acid during degradation was insignificant. The recovery of Am(III) and Eu(III) from the irradiated solvent system was studied. The recovery of Am(III) was quantitative in 3 contacts; however, the separation factor of Eu(III) over Am(III) during stripping decreased marginally with increase of absorbed dose. [ABSTRACT FROM PUBLISHER]

A novel 2-oxy-N,N-dioctylacetamide anchored on Merrifield resin was synthesized and characterized by elemental analysis, TG-DTA and IR spectroscopy, for the first time. The extraction behavior of Am(III) and Eu(III) from nitric acid medium in the dioctylacetamide anchored resin (R-DOA) was studied as a function of various parameters such as duration of equilibration, concentration of nitric acid and sodium nitrate etc. The distribution coefficient ( Kd) of Am(III) and Eu(III) in R-DOA increased with increase in concentration of nitric acid. The Kd values reached a maximum at 3-4 M nitric acid concentration in both cases, followed by decrease in Kd values. Rapid extraction of Am(III) and Eu(III) from nitric acid medium was observed in the initial stages of equilibration followed by the establishment of equilibrium occurred within 60 min. The extraction data was fitted in to the first order rate equation. The recovery of Am(III) and Eu(III) from the loaded organic phase was studied using dilute nitric acid. The results revealed that 2-oxyacetamide functionalized resin is the promising candidate for the separation of trivalent actinides and lanthanides from nitric acid medium. [ABSTRACT FROM AUTHOR]

The extraction behavior of U(VI) in the PUREX solvent namely 1.1 M tri- n-butyl phosphate (TBP) in n-dodecane ( n-DD) was studied in the presence and absence of the ionic liquid, tri- n-octylmethylammonium bis-(2-ethylhexyl)phosphate ([A336]+ [DEHP] -). The discrepancy in the extraction behavior observed in these systems was probed by measuring the distribution ratio of U(VI) as a function of various parameters. The distribution ratio of U(VI) in 0.03 M [A336]+ [DEHP] -/ n-DD decreased with increase in the concentration of nitric acid. The extraction of U(VI) was accompanied by the extraction of nitric acid leading to the formation of ionic liquid constituents namely tri- n-octylmethylammonium nitrate ([A336]+ [NO3] - and bis(2-ethylhexyl)phosphoric acid (HDEHP). Therefore, the distribution ratio of U(VI) in the PUREX solvent was measured in the presence of these constituents also. The study revealed that extraction of U(VI) was controlled essentially by the synergistic contribution of TBP and the constituents of ionic liquid. [ABSTRACT FROM AUTHOR]

The extraction behavior of Am(III) in a solution of tetra-(2-ethylhexyl)diglycolamide (TEHDGA) inn−dodecane (n−DD) or toluene was studied as a function of nitric acid concentration. The distribution ratio of Am(III) in 0.1 M TEHDGA/molecular diluent increased with increase in the concentration of nitric acid. Since the Aliquat-336 based ionic liquid namely, tri-n-octylmethylammonium di-(2-ethylhexyl)phosphate ([A336]+[DEHP]−) was miscible in molecular diluents such asn-DD and toluene, the extraction behavior of Am(III) in TEHDGA/molecular diluent was investigated in the presence of small concentrations of ionic liquid to understand the role of ionic liquid in extraction. The distribution ratio of Am(III) in 0.2 M [A336]+[DEHP]−/molecular diluent was negligible. Significant increase in distribution ratio of Am(III) was observed when [A336]+[DEHP]−was added to 0.1 M TEHDGA/molecular diluent. Since [A336]+[DEHP]−was converted into its components, namely tri-n-octylmethylammonium nitrate ([A336]+[NO3]−) and di-(2-ethylhexyl)phosphoric acid (HDEHP) when contacted with nitric acid, the extraction behavior of Am(III) in 0.1 M TEHDGA/molecular diluents was also studied in the presence of [A336]+[NO3]−and HDEHP to elucidate the mechanism of extraction. The study confirmed that the extraction of Am(III) in ionic liquid medium was controlled by constituents of ionic liquid and the distribution ratio of Am(III) obtained in organic phase was due to the resultant of contributions of ionic liquid constituents. [ABSTRACT FROM PUBLISHER]

The radiolytic degradation of N, N-di-dodecyl- N′, N′-di-2-ethylhexyl-3-oxapentane-1,5-diamide (DDEHDGA) was studied at various absorbed doses of γ-radiation. The degradation was assessed by measuring the variation in the extraction behavior of Am(III) in irradiated solvent systems composed of neat DDEHDGA or 0.1 M DDEHDGA/ n-dodecane in the presence and absence of nitric acid. The distribution ratio of americium ( D) decreased with increase of absorbed dose. The presence of n-dodecane and nitric acid enhanced the radiolytic degradation of the solvent. The third phase formation behavior of Nd(III) decreased with increase of absorbed dose and the third phase was not observed at absorbed doses above 100 kGy. The recovery of Am(III) from the irradiated system was near quantitative in five contacts. The study revealed that the extraction and stripping behavior of the irradiated solvent was quite satisfactory for partitioning of minor actinides from real wastes. [ABSTRACT FROM AUTHOR]

The radiation stability of an unsymmetrical diglycolamide, di-2-ethylhexyl-di-octyl diglycolamide (DEHDODGA) has been evaluated under various process conditions. The influence of diluent ( n-dodecane), phase modifier ( N, N-dihexyl octanamide, DHOA), and nitric acid on the radiolysis of DEHDODGA was investigated. The distribution ratio ( D) of Am(III), Eu(III), and Sr(II) in the irradiated solvent was determined as a function of absorbed dose of γ-radiation. The distribution ratios decreased with increase of absorbed dose, indicating the radiolytic degradation of DEHDODGA with increase of absorbed dose. The stripping behavior of Am(III) from the degraded organic phase was studied. Quantitative back extraction of trivalent metal ions from the irradiated organic phase was achieved in a single contact using the stripping formulation composed of dilute nitric acid and citric acid. Our studies indicated the robust nature of DEHDODGA with respect to radiolysis, and innocuous nature of degradation products. [ABSTRACT FROM AUTHOR]

The extraction behavior of Eu(III) and Am(III) in a solution of bis(2-ethylhexyl)diglycolamic acid (HDEHDGA) in n-dodecane (n-DD) from citric acid (CA) medium was studied as a function of various parameters. The extraction increased with increase of pH, reached a maximum at pH 2 followed by decrease. The stripping behavior of Eu(III) and Am(III) from the loaded organic phase was studied by using a solution of diethylenetriaminepentaacetic acid (DTPA) and CA. The conditions needed for the efficient separation of Am(III) from Eu(III) were optimized. Based on the optimized conditions, the feasibility of separating Am(III) from Eu(III) present in CA feed solution was investigated in a 20- stage mixer-settler. Quantitative extraction of Eu(III) and Am(III) in 0.1 M HDEHDGA/n-DD was achieved in 3–4 stages, whereas the selective back extraction of Am(III) was achieved in ∼20 stages upon contacting the loaded organic phase with a stripping formulation composed of DTPA-CA at pH 1.5. The results confirmed the possibility of using diglycolamic acid for the separation of trivalent actinides from the chemically similar lanthanides, which is indeed necessary for transmutation of minor actinides present in high-level liquid waste (HLLW). [ABSTRACT FROM AUTHOR]

Room temperature ionic liquids (RTILs) are receiving increased attention for possible applications in nuclear fuel cycle. RTILs are being investigated as possible substitutes to molecular diluents in solvent extraction, and as an alternative to high temperature molten salts in non-aqueous reprocessing applications. It is well recognized that ionic liquids often display unique extraction behavior. Unusual extraction of various metal ions has been reported in literature when RTILs are used as solvent medium. These aspects make the subject of RTILs fascinating and challenging. This review provides the current status of room temperature ionic liquid research related to the extraction of actinides and fission products (cesium and strontium) from nitric acid medium, with special emphasis on the studies carried out in our laboratory. [ABSTRACT FROM AUTHOR]

Room temperature ionic liquids (RTILs) containing β-diketonate anions have been prepared and studied for the extraction of 239Pu(IV), 233U(VI), and 241Am(III) from nitric acid medium. The ionic liquids such as alkylquaternaryammonium thenoyltrifluoroacetonate (R4NTTA), and 1-alkyl-3-methylimidazolium thenoyltrifluoroacetonate (amimTTA), with methyl, butyl, hexyl, heptyl, and octyl moieties have been prepared and characterized by 1H and 13C nmr and IR spectroscopy. The distribution ratio of plutonium(IV) (DPu(IV)) in a solution of tri-n-octylmethylammonium thenoyltrifluoroacetonate (TOMATTA) present in tri-n-octylmethylammonium bis(trifluoromethylsulfonyl)imide (TOMANTf2) and amimTTA in amimNTf2 was studied as a function of various parameters. The unique property of β-diketonate ionic liquids, namely, the miscibility in molecular diluents, was exploited to elucidate the mechanism of Pu(IV) extraction in these ionic liquids. [ABSTRACT FROM AUTHOR]

A new unsymmetrical diglycolamide, N,N-di-2-ethylhexyl-N',N'-di-octyl-3-oxapentane-1,5-diamide, trivially known as di-ethylhexyl-di-octyl-diglycolamide (DEHDODGA) has been synthesized, and characterized by 1H, and 13C nmr, mass, and IR spectroscopy. Extraction behavior of 241Am(III), (152+154)Eu(III), 239Pu(III), 239Pu(IV), 233U(VI), 137Cs(I), and (85+89)Sr(II) from nitric acid medium by a solution of DEHDODGA in n-dodecane was studied, at 298-333 K. The effect of concentrations of HNO3 and DEHDODGA and of temperature on the distribution ratio (DM) was studied. Extraction of Eu(III), Am(III), Pu(III), and Pu(IV) increased with increase in nitric acid concentration, and the distribution ratio of Cs(I) was insignificant. However, the distribution ratios of U(VI) and Sr(II), though not insignificant, but was quite less compared to trivalents, and Pu(IV). The DSr(II) increased with increase in the concentration of nitric acid, reaching a maximum at 4 M followed by decrease. The stoichiometry of Am(III) - DEHDODGA was determined by slope analysis of extraction data, and the enthalpy change accompanied by the extraction of Eu(III), Pu(III), and Am(III) was determined and reported in this article. [ABSTRACT FROM AUTHOR]

Hydrolytic and radiolytic degradation of tri‐n‐amylphosphate (TAP) diluted in normal paraffin hydrocarbon (NPH) in the presence of nitric acid has been investigated. Physicochemical properties such as density, viscosity, and phase disengagement time (PDT) were measured for undegraded and degraded solutions. The extent of damage caused by chemical and radiation induced reactions in TAP‐NPH‐HNO 3 system has been assessed by the measurement of plutonium retention in the organic phase. The results are compared with those obtained using undegraded TAP as well as tri‐n‐butylphosphate (TBP) in NPH. The effectiveness of sodium carbonate washing of the degraded organic phase for restoring the original quality of the solvent has been detailed. The study indicates that plutonium retention exhibited by TAP/NPH is insignificant at dose levels typically encountered in the first extraction cycle (&nvsim;0.2 kGy), and the marginal increase of plutonium retention at higher dose levels is not, however, undesirable for the employment of TAP in an actual process. [ABSTRACT FROM AUTHOR]