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A significant reduction in the aggregate size of TODGA/n-DD suggests that gamma irradiation is favourable for minimizing third phase formation.

The radiolytic stability of aqueous solutions containing two different bis-1,2,4-triazines was studied under static gamma irradiation. Sulphophenyl derivatives of bis-1,2,4- triazinyl pyridine (SO3-Ph-BTP) and bis-1,2,4-triazinylbipyridine (SO3-Ph-BTBP) were dissolved in 0.1 M and 1 M HNO3 solutions and the impact of gamma irradiation was assessed by the measurement of distribution ratios of Am(III) and Eu(III) using irradiated samples. The results were compared for two different organic solvents containing N,N,N’,N’-tetraoctyldiglycolamide (TODGA) or N,N-didodecyl-N’,N’-dioctyldiglycolamide (D3DODGA). The separation efficiency of all the systems remained unchanged when the absorbed dose was 100 kGy, and gradually decreased at 200 kGy and 500 kGy. The radiolytic degradation was more apparent for SO3-Ph-BTBP in comparison to SO3-Ph-BTP at higher acidity. The degradation of sulphonate groups in the molecules was evidenced in ATR-FTIR spectral studies.

The selective partitioning of trivalent actinides (An(III)) from high-level liquid waste (HLLW) is considered as an essential step in the management of spent nuclear fuel. The i-SANEX process for the separation of An(III) from the co-existing lanthanides (Ln(III)) in 4 M nitric acid solution and simulated HLLW was studied using a couple of symmetrical diglycolamides (TODGA and TDDGA) and an unsymmetrical diglycolamide (D3DODGA) in n-dodecane as the extraction phase. The selective stripping of Am(III) from the loaded organic phase containing trivalent Ln(III) was investigated using aqueous soluble bis-1,2,4-triazine derivatives such as SO3-Ph-BTP, SO3-Ph-BTBP and SO3-Ph-BTPhen in dilute nitric acid solution. The results revealed that the SF of Eu(III) over Am(III) decreased with increase in the concentration of nitric acid in all cases and SF decreased in the order SO3-Ph-BTP > SO3-Ph-BTBP > SO3-Ph-BTPhen. The co-stripping of lighter lanthanides (La, Ce, Pr, Nd) was also observed during the recovery of Am(III).

A metallic alloy of uranium–zirconium and uranium–plutonium–zirconium has been proposed as a fuel for fast reactors, owing to the possibility of achieving high breeding ratio in a short span of time. About 6–10 wt.% of zirconium has been added to these actinide fuels to increase the melting temperature and thermal-mechanical stability. Aqueous reprocessing of the spent metallic fuel generates the high-level liquid waste (HLLW) that contains about 60 % of the total zirconium from the fuel. In view of this, the extraction behavior of a trivalent representative ion, Nd(III) in the presence of Zr(IV) was studied from nitric acid medium using the candidate ligands proposed for trivalent actinide separation from HLLW, such as N,N,N′N′-tetraoctyldiglycolamide (TODGA), and N,N-di-octyl-2-hydroxyacetamide (DOHyA). The extraction was studied as a function of nitric acid concentration, zirconium and neodymium concentration and Nd(III) to Zr(IV) ratio. The findings of dynamic light scattering (DLS) and ATR-FTIR spectral techniques were used for understanding the complex chemistry of Zr(IV) extraction under different conditions. Poor extraction of nitric acid, smaller aggregate size, no third phase formation during the extraction of Zr(IV) and Nd(III) and other unique solvent properties favor the DOHyA molecule in n-dodecane as a solvent for partitioning of trivalent actinides from HLLW generated from metallic fuel reprocessing.

Long chain monoamide extractants, N,N-di-decyloctanamide(DDOA), N,N-di-hexyldecanamide(DHDA), N,N-di-2-ethylhexyloctanamide(D2EHOA) and N,N-dihexyl-2-ethylhexanamide(DH2EHA) were synthesized and studied for the recovery of U(VI), Pu(IV) and Zr(IV) from a simulated dissolver solution of un-irradiated U–Zr metallic fuel. The results were compared with the results of N,N-dihexyloctanamide(DHOA) and tri-n-butylphosphate(TBP) under similar conditions. Solvent extraction studies were carried out for comparing the extraction behavior of U(VI), Pu(IV) and Zr(IV) in monoamide extractants with TBP system. The influence of length and branching of alkyl chains on either side of the amidic group on the extraction efficiency, third phase behaviour and metal ion selectivity in long chain monoamides has been discussed based on the results of above studies.

The extraction behavior of Am(III) and Eu(III) from nitric acid medium (0.001 M to 3 M) was studied in a binary solution of N,N-dioctylhydroxy acetamide (DOHyA) and bis(2-ethyhexyl)diglycolamic acid (HDEHDGA) in n-dodecane to evaluate the feasibility of separating Am(III) from Eu(III) present in 3–4 M nitric acid medium. The extraction of Am(III) and Eu(III) was studied as a function of various parameters. The results were compared with the individual extractants in n-dodecane. Synergic extraction of Am(III) and Eu(III) was observed at nitric acid concentrations above 0.5 M and antagonism at lower nitric acid region. The dependence of distribution ratio of Am(III) and Eu(III) on binary extractants was probed by the slope analysis of the extraction data, and the mechanism of Am(III) and Eu(III) extraction was determined at various acidities. The results revealed the possibility of single-cycle separation of Am(III) from Eu(III) with a separation factor ~13.

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.

The aggregation behavior of N,N,N’,N’-tetraoctyldiglycolamide (TODGA) in n-dodecane was studied in the presence of two different phase modifiers, N,N-di-hexyloctanamide (DHOA) and 1-octanol using dynamic light scattering (DLS) spectroscopy. The results were compared with the aggregation behavior of a modifier free extractant system N,N-di-octyl-2-hydroxyacetamide (DOHyA) in n-dodecane. Aggregation studies were done as a function of concentration of nitric acid and Nd (III) ions in the aqueous phase. The size distribution of reverse micellar aggregates revealed different aggregation mechanisms in the presence and absence of phase modifiers. For TODGA-modifier systems, the sizes of reverse micellar aggregates were bigger than DOHyA and among the two phase modifiers studied, use of 1-octanol resulted in the formation of bigger aggregates compared to DHOA. The observations from DLS measurements were co-related with the results from ATR-FTIR spectroscopy for all the three extractant systems. The sizes of reverse micellar aggregates increased with increase in extraction of nitric acid and/or Nd (III) ions and no third phase was visible in all the three systems even under very high loading conditions. The aggregation studies under co-current extraction conditions from fast reactor simulated high level waste solution (FR-SHLLW) showed the formation of smaller reverse micellar aggregates and third phase or crud formation after 3–4 successive contacts for all the three systems.

A liquid-liquid extraction method for the separation of Zr(IV) from simulated high-level liquid waste (SHLLW) solutions using N,N-di-octyl-2-hydroxyacetamide (DOHyA) was studied. The method was found to be applicable for the recovery of Zr(IV) from conventional SHLLW solutions as well as the SHLLW solutions from metallic fuel reprocessing streams containing Zr(IV) up to 8 g/L. DOHyA showed quantitative extraction of Zr(IV) from all the simulated waste solutions, along with co-extraction of other fission products and Am(III). Excluding Zr(IV) and Mo(VI), all the other co-extracted metal ions were efficiently scrubbed from the loaded DOHyA solvent using 0.5 M or 1 M nitric acid. The selective stripping of Zr(IV) that remained in the solvent phase was subsequently accomplished using 0.2 M oxalic acid solution. The complexation behaviour of Zr(IV) with DOHyA was investigated using Density Functional Theory (DFT) calculations, which divulged the geometry and stability of Zr-DOHyA-HNO3 and Zr(C2O4)2 complexes formed under the extraction and stripping conditions. With the aid of quantum theory of atoms in molecules, natural bond orbital and non-covalent interaction analyses, the rationale behind the selective removal of Zr(IV) from SHLLW using DOHyA extractant was clearly unravelled.

Zirconium was identified as a troublesome fission product interfering with the separation of trivalent actinides from high-level liquid waste (HLLW) solution. Since zirconium was used as a fuel component in metallic fuels, the amount of Zr(IV) present in HLLW arising from reprocessing of metallic fuel was nearly ten times higher than the conventional HLLW solutions. In the present study, the diglycolamide extractants proposed for the separation of trivalent actinides from HLLW were employed for the extraction of metal ions from nitric acid medium and fast reactor simulated high level liquid waste (FR-SHLLW) having the Zr(IV) concentrations varied from 0.006 M to 0.09 M. Dynamic light scattering study was performed on the organic phase obtained after extraction of zirconium to analyze the aggregation of extractants. The solvent system consisting of 0.1 M TODGA (N,N,N’,N’-tetraoctyldiglycolamide) along with 0.25 M HDEHP (bis(-2-ethylhexyl)phosphoric acid) in n-dodecane showed minimal aggregation tendency and higher loading capacity of Zr(IV) and was selected for further extraction of trivalent metal ions from FR-SHLLW. To minimize the extraction of Zr(IV) in organic phase, the effect of aqueous soluble complexing agent namely trans-1,2-diaminocyclo-hexane-N,N,N’N’-tetraaceticacid (CyDTA) was also studied during the extraction of trivalent lanthanides.

The extraction behaviour of Am(III) and other metal ions present in the fast reactor simulated high- level liquid waste (FR-SHLLW) was studied using a modifier-free solvent phase composed of N,N-di-octyl-2-hydroxyacetamide (DOHyA) in n-dodecane. Quantitative extraction of Am(III) was achieved with the co-extraction of all lanthanides, Y(III) and Mo(VI) in the first five stages of a 20-stage mixer-settler. During the stripping run with 0.5 M HNO3, Am(III), Ln(III) and Y(III) were quantitatively transferred to the aqueous product in three stages. The other extracted metal ions were retained in organic phase. The results showed that the extraction performance of DOHyA was superior to other amide extractant systems reported in the literature.

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.

The radiation stability of N,N-di-alkyl-2-hydroxyacetamide derivatives having alkyl side chain varying from hexyl to decyl was studied as a function of absorbed dose of gamma irradiation up to 700 kGy. The samples were irradiated as neat, and as 0.2 M solutions in n-dodecane in the presence and absence of 4 M nitric acid. The radiolytic degradation of the compounds were assessed by the measurement of distribution ratio of Am(III) (DAm(III)) and also by the measurement of hydrodynamic properties such as density, viscosity and phase disengagement time.

The solvent phase composed of tetraoctyl diglycolamide (TODGA) in n-dodecane (n-DD) undergoes the undesirable organic phase splitting during the solvent extraction of trivalent actinides and lanthanides from nitric acid medium. To overcome this limitation a neutral extractant namely the N,N-dioctyl hydroxyacetamide (DOHyA), which was half the molecule of TODGA, has been added to the solvent phase and evaluated for the extraction of Nd(III) from nitric acid medium. Since the reverse micellar aggregates of the extracted species in the organic phase was responsible for organic phase splitting, the aggregation behaviour of the organic phase was probed by dynamic light scattering (DLS) technique. The results have been compared with the individual solvent systems, namely DOHyA/n-DD and TODGA/n-DD. The investigations revealed that the extraction of nitric acid and loading of Nd(III) in organic phase increased upon adding DOHyA, but the size of aggregates formed in the organic phase decreased remarkably with DOHyA addition, which was in contrast to the expected behaviour of increase in aggregate size with increase of extraction in the organic phase. To understand the unexpected behaviour of aggregation, the extracted organic phase was further probed by UV–visible and luminescence spectroscopy. The results further revealed that DOHyA in the binary solution served as a reactive organic phase modifier and induced antagonistic effect on aggregation when mixed with TODGA, which was, in fact an advantage for the extraction of trivalent actinides from high-level nuclear waste.

Fourier Transform Infra Red (FTIR) spectroscopy is an excellent tool for probing the co-ordination chemistry of the solvent extracted metal complexes in organic phase. The organic phase containing tetraoctyldiglycolamide (TODGA) and N,N-dioctylhydroxyacetamide (DOHyA) ligands dissolved n-dodecane was employed for the extraction of Nd(III) from nitric acid medium. The extracted organic phase was probed by FTIR spectroscopy to understand the coordination chemistry and aggregation behaviour of Nd(III)-ligand complex in the binary solution. The results were compared with those obtained in the individual solvent system. The extraction of Nd(III) and nitric acid in organic phase was accompanied by shifting and broadening of amidic carbonyl stretching bands of TODGA and DOHyA, and the degree of shift or broadening was dependent on the amount of Nd(III) or nitric acid loaded in organic phase. Near complete shift of amidic carbonyl transmittance bands from 1660 cm−1 to 1610 cm−1 was observed prior to the undesirable event known as organic phase splitting. The results showed the possibility of employing the FTIR spectroscopic technique for understanding the extraction and for the prevention of organic phase splitting during the course of solvent extraction.

The process methods developed for partitioning of trivalent actinides from high-level liquid waste (HLLW) are being focussed on single-cycle processing approaches. This method involves the separation of trivalent actinides and chemically similar lanthanides, as a group, from HLLW followed by the mutual separation of lanthanides and actinides from the loaded organic phase using aqueous soluble complexing agents. The potential solvents identified for the group separation of trivalents from HLLW are 1) 0.2 M TODGA (N,N,N’N′-tetraoctyldiglycolamide) + 5% octanol / n-DD, 2) 0.2 M TODGA + 0.5 M TBP (tri-n-butylphosphate) / n-DD, 3) 0.1 M TODGA + 0.25 M HDEHP (di-(2-ethylhexyl)phosphoric acid) / n-DD, 4) 0.2 M TDDGA (N,N,N’N′-tetradecyldiglycolamide) / n-DD, 5) 0.2 M D3DODGA (N,N-didodecyl-N’N′-dioctyldiglycolamide) / n-DD, 6) 0.4 M DOHyA (N,N-dioctyl-2-hydroxyacetamide) / n-DD. The extraction behaviour of Am(III) and Eu(III) from dilute nitric acid solution (0.1 M to 1 M) containing aqueous soluble nitrogen-donor derivative, SO3-Ph-BTP, was studied in the above solvents. The separation factor (SF) of Eu(III) over Am(III) was determined. Among the different solvents investigated, the SF achieved in TDDGA and D3DODGA was quite higher than other solvents, and recommended for the single-cycle separation of trivalent actinides from HLLW.

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 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

The third phase formation of neodymium (III) and nitric acid in N,N-di-2-ethylhexyl-N′,N′-di-octyl-3-oxapentane-1,5-diamide (DEHDODGA) was studied. The limiting organic concentration (LOC) and critical aqueous concentration (CAC) of nitric acid and neodymium (III) were determined as a function of various parameters such as aqueous phase acidity, extractant concentration, temperature and the nature of diluent. The influence of phase modifier, N,N-di-hexyloctanamide (DHOA) on the third phase formation behaviour was studied at different temperatures. The LOC of Nd (III) in a solution of DEHDODGA in n-dodecane (n-DD) increased with increasing temperature, concentrations of extractant and phase modifier, and decreased with increase of aqueous phase acidity and alkyl chain length of the diluent. The concentration of DHOA needed to prevent the third phase formation during minor actinide partitioning from high-level liquid waste was optimised.

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 (D M) 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 D Sr(II) increased with increase in the concentration of nitric acid, reaching a maximum at 4 M followed by decrease. The stoichiometry of Am(...

Background: People with chronic diseases are more likely to have depression than those without any physical illness. Lack of adherence to treatment, poor compliance to life style modification therapy and lost to follow up are major concerns raised in the management of hypertension among subjects with co-morbid depression. Hence it is very important to explore the epidemiology of depression among hypertensives. Methods: The study was conducted in Medical College health unit area of urban Trivandrum as a cross sectional survey among adults >18 years who were diagnosed to have hypertension. The subjects were interviewed using a semi structured questionnaire to collect the socio-demographic variables and the 9 item Patient Health Questionnaire (PHQ 9) to capture depression. Data from a sample of 432 hypertensive individuals collected were analyzed and Chi square, t test, was done to find the associated factors. Results: Mean age of the study subjects was 62.47 years. Among the study subjects the blood pressure was under control among only 33.8% of the study population. The prevalence of depression was found to be 33.3% (144) with 95% C.I (27.98-39.14). Gender, Socio economic status, marital status, low educational status, regular physical activity, duration of hypertension, uncontrolled BP, were found to be significantly associated with depression. Conclusions: The prevalence of depression among hypertensive individuals is high in this study population. Adequate control of BP along with awareness among primary care physicians in identifying those with hypertension and co-morbid depression is essential.