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The bulk extraction of Nd(III) from 4 M nitric acid medium was studied in a solution of N,N-di-octyl-2-hydroxyacetamide (DOHyA) in n-dodecane as a function of γ absorbed dose up to 750 kGy. The average size of reverse micellar aggregates in the irradiated and un-irradiated DOHyA samples after the extraction of Nd(III) was measured by dynamic light scattering (DLS) spectroscopy. The effect of absorbed dose of γ radiation and concentration of Nd(III) in the organic phase on the aggregation behavior of DOHyA was investigated by DLS measurements and ATR-FTIR spectroscopy. The data on irradiated and un-irradiated samples were compared. FT-IR analysis of the irradiated samples of DOHyA showed the formation of degradation products which were mainly identified as hydroxyacetic acid and primary or secondary amines.

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 (K d) 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.

The homologs of N,N-di-alkyl-2-methoxyacetamides (DAMeOA) having three different alkyl chains varying from hexyl to decyl (C6, C8 and C10) were synthesized and characterized by NMR and IR spectral analyses. Extraction behavior of U(VI) and Pu(IV) from nitric acid medium in a solution of 0.5 M of DAMeOA in n-dodecane (n-DD) was studied and the results were compared with those obtained using N,N-di-hexyloctanamide (DHOA) in n-dodecane. The effect of various parameters on the distribution ratio of U(VI) and Pu(IV) in DAMeOA was studied. The extraction of nitric acid increased with decrease in chain length of alkyl group attached to amidic nitrogen atom of DAMeOA and the conditional nitric acid extraction constant was determined. The extraction of nitric acid in DAMeOA/n-DD resulted in the formation of third phase in organic phase and the third phase occurred early with DAMeOA having smaller alkyl chain length. In contrast to this, the distribution ratio (D) of U(VI) and Pu(IV) in DAMeOA/n-DD increased with increase in the concentration of nitric acid and with increase in the chain length of alkyl group attached to amidic nitrogen atom of DAMeOA. The stoichiometry of the metal – solvate was determined from the slope of extraction data. Quantitative recovery of uranium and plutonium from the loaded organic phase was achieved using dilute nitric acid.

Diglycolic acid modified zirconium phosphate (ZrP-DGA) was prepared and studied for the extraction of Am(III) and Eu(III) from dilute nitric acid medium. The distribution coefficient (Kd, mL·g−1) of Am(III) and Eu(III) was measured as a function of time, pH and concentration of Eu(III) ion etc. The Kd of Am(III) and Eu(III) increased with increase of pH, reached a maximum value of distribution coefficient at pH 1.5 – 2, followed by decrease in Kd values. Rapid extraction of Am(III) and Eu(III) in ZrP-DGA was observed followed by the establishment of equilibrium occurred in 100 min. Kinetics of extraction was fitted in to pseudo second order rate equation. The amount of Eu(III) loaded in ZrP-DGA increased with increase in the concentration of Eu(III) ion in aqueous phase and the isotherm was fitted in to Langmuir and Freundlich adsorption models. The extraction of Am(III) in ZrP-DGA was higher as compared to Eu(III) and the interference of Eu(III) on the extraction of Am(III) was studied. The distribution coefficient of some lanthanides in ZrP-DGA was measured and the Kd of lanthanides increased across the lanthanide series. The extracted trivalent metal ions were recovered in three contacts of loaded ZrP-DGA with 0.5 M nitric acid.

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 (K d, mL/g) of Pu(IV) in these resins increased with the concentration of nitric acid, reaching a maximum K d 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.

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) (D Am(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 D Am(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.

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 (K d) of Am(III) and Eu(III) in R-DOA increased with increase in concentration of nitric acid. The K d values reached a maximum at 3–4 M nitric acid concentration in both cases, followed by decrease in K d 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.

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.

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.

The alkyl derivatives of diglycolamide (DGA) such as N,N,N´,N´-tetraoctyldiglycolamide (TODGA), N,N,N´,N´-tetraethylhexyldiglycolamide (TEHDGA) and N,N-diethylhexyl- N´,N´-dioctyldiglycolamide (DEHDODGA) are chain isomers differing only in the arrangement of carbon chain of the alkyl group. The extraction behavior of Am(III) in the solution of these diglycolamides in ionic liquid medium was studied as a function of concentration of nitric acid and diglycolamide. The results were compared with those obtained in a molecular diluent, n-dodecane. The extraction of Am(III) in ionic liquid medium increased in the order TEHDGAn-DD. The anomaly observed in ionic liquid medium was probed by IR spectroscopy and measurement of stoichiometry. The stoichiometry of Am : DGA in each case was different and that exhibited a strong influence on the observed extraction trend. The unprotonated fraction of DGA, assessed from FTIR measurements, increased in the order TEHDGA