The complexation thermodynamics of 2-thenoyltrifluoroacetone (HTTA) with lanthanide cations was investigated in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (Bumim·Tf
2
N) medium by ...liquid-liquid extraction and microcalorimetry. The Eu
3+
ion distribution ratio measurement from aqueous pH 3.5 to 5.2 confirmed the extraction of anionic species of the type Ln(TTA)
4
−
, and this species did not change with pH. Measurement of direct heat of complexation between Nd
3+
and HTTA confirmed endothermic complexation reactions with Δ
H
° values of 4.81, 17.4, 23.3 and 37.9 kJ mol
−1
for Nd(TTA)
2+
, Nd(TTA)
2
+
, Nd(TTA)
3
and Nd(TTA)
4
−
species, respectively. The complexation was favoured by positive stepwise entropy changes of 128, 134, 94 and 112 J mol
−1
K
−1
for ML
1
, ML
2
ML
3
and ML
4
species, respectively. The overall extraction enthalpy of the Ln(TTA)
4
−
complex into Bumim·Tf
2
N was also endothermic with a Δ
H
° value of 42.5 kJ mol
−1
. The enthalpy change for mass transfer of the Ln(TTA)
4
−
complex into Bumim·Tf
2
N was estimated to be 4.6 kJ mol
−1
, indicating that the overall extraction process was governed by the complexation enthalpy with the phase transfer enthalpy playing only a minor role. Efforts were devoted to investigate the structural features of the Ln(TTA)
4
−
complex with the support of molecular dynamics simulations.
HTTA forms Ln(TTA)
2+
, Ln(TTA)
2
+
, Ln(TTA)
3
and Ln(TTA)
4
−
endothermic complexes with lanthanides in an ionic liquid which are independent of aqueous pH.
•Extraction chromatographic resins were prepared using T-DGA and C4DGA.•The resin had Chromosorb W as the solid support and ionic liquid as solvent.•Uptake of actinide ions such as Am3+ was ...investigated.•Kinetic modeling of the uptake data was done.•Column studies were carried out for Am3+ separation.
Extraction chromatography resins, prepared by impregnating two multi-podant diglycolamide ligands, viz. diglycolamide-functionalized calix4arene (C4DGA) and tripodal diglycolamide (T-DGA) dissolved in the room temperature ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide (RTIL: C4mimTf2N) on Chromosorb-W (an inert solid support), gave excellent results for the removal of trivalent actinides from acidic waste solutions. Distribution coefficient measurements on several metal ions showed selective sorption of Am(III) over hexavalent uranyl ions and other fission product elements such as strontium and cesium. The sorbed metal ions could be efficiently desorbed with a complexing solution containing guanidine carbonate and EDTA buffer. The sorption of Am(III) on both resins followed pseudo-second order rate kinetics with rate constants of 1.37×10−6 and 6.88×10−7g/cpmmin for T-DGA and C4DGA resins, respectively. The metal sorption on both resins indicated the Langmuir monolayer chemisorption phenomenon with Eu(III) sorption capacities of 4.83±0.21 and 0.52±0.05mg per g of T-DGA and C4DGA resins, respectively. The results of column studies show that these resins are of interest for a possible application for the recovery of hazardous trivalent actinides from dilute aqueous solutions.
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Diglycolamide (DGA)-functionalized poly(propyleneimine) diaminobutane dendrimers of the first (DGA-Den-I) or second (DGA-Den-II) generation and a room temperature ionic liquid (RTIL), viz., ...1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide, based extraction chromatography resins were prepared for minor actinide separations from high level radioactive waste. The weight distribution coefficients (K d) of actinides on the two resins gave excellent and selective sorption of Am(III) and Pu(IV) over hexavalent uranyl ions, Sr(II) and Cs(I), over a wide range of acidity (0.01–6 M HNO3). The sorbed Am(III) and Pu(IV) could be efficiently desorbed with a buffered complexing solution of 1 M guanidine carbonate + 0.05 M EDTA. The sorption of metal ions on both the resins followed pseudo-second order rate kinetics and proceeded via a chemisorption phenomenon with a sorption energy of 13.4 ± 0.2 kJ/mol. The resin capacities were estimated to be 4.64 ± 0.18 and 4.19 ± 0.21 mg of Eu per g of DGA-Den-I and DGA-Den-II resins, respectively. The column loading of Eu(III) was about 85% of the theoretical value with a narrow elution profile using a buffered complexing solution. The resin affinity toward U(VI), Sr(II), and Cs(I) cations over Am(III) and Pu(IV) was poor, indicating the possible use of the resins for selective separation of Am(III) and Pu(IV) from other metal ions over a wide range of feed acidity.
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•Extraction chromatographic resins containing TODGA in a RTIL were made.•The coated resin beads were used for actinide ion extraction from acidic feeds.•Spectacular enhancements in metal ion uptake ...were seen.•Adsorption isotherm studies were carried out.•Column mode operations were also tested for possible applications.
Several novel extraction chromatographic (XC) resins were prepared with varying compositions of N,N,N′,N′-tetraoctyl diglycolamide (TODGA) and C4mimNTF2 (a room temperature ionic liquid) impregnated onto Chromosorb-W. The first set of XC resins had varying fractions of TODGA (10–30% (w/w)) with a fixed amount (10% (w/w)) of the room temperature ionic liquid (RTIL), while the RTIL composition was varied (10–30% (w/w)) for the second set of resins while keeping a fixed (10% (w/w)) amount of TODGA. In the third set of resins, both TODGA as well as RTIL contents were varied in the range10–30% (w/w). The loading of Eu(III) on the resin increased linearly from 8.74±0.40mg/g to 23.66±0.17mg/g with increasing TODGA concentration from 10% TODGA to 30%. However, increase in the RTIL concentration did not affect the Eu loading. The loading of Eu(III) deviated from the stoichiometric value of 1:3 (metal:ligand) with increased TODGA concentration.
Sorption isotherms were obtained for Eu(III) and the data were fitted with models such as Langmuir, Freundlich and Dubinin–Radushkevich (D–R). The results suggested that the sorption of Eu(III) on TODGA-RTIL resin followed the Langmuir mono layer chemisorptions model with sorption energy (obtained from the D–R model fitting) of 21.28±1.27kJ/mol. The results of the column studies revealed that 6.67mg Eu could be loaded per gm of resin on the column without any breakthrough. The loaded Eu from the column was efficiently eluted in about 5mL of 0.01M EDTA solution. Distribution coefficient measurements of various metal ions suggested selective sorption of trivalent f-elements over hexavalent uranyl ions and other fission product elements over a wide range of acidity (0.01–6M HNO3).
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Extraction behaviour of actinides, lanthanides, fission products and structural elements has been studied with the two diglycolamide extractants, namely N,N,N′,N′-tetra-2-ethylhexyl diglycolamide ...(T2EHDGA) and N,N,N′,N′-tetraoctyl diglycolamide (TODGA). The acid extraction studies suggested that T2EHDGA (K
H
: 1.8) is less basic as compared to its linear homologue, TODGA (K
H
: 4.1). The distribution ratio of Am(III) by 0.1 M diglycolamides followed the order: TODGA > T2EHDGA. The number of ligand molecules present in the stoichiometry of the extracted species of Am(III) was found to be three and four for T2EHDGA and TODGA, respectively. Thermodynamics studies suggested that the extraction of Am(III) by both the extractants is exothermic in nature. The radiolytic stability of TODGA and T2EHDGA solutions in
n
-dodecane has been investigated. Due to lower distribution ratio of Am by T2EHDGA, 0.2 M of its solution has been used as compared to 0.1 M solution of TODGA. The distribution behaviour of various metal ions, viz. Am, Nd, Fe, Mo, Cr, Sr and Cs has been studied from nitric acid as well as from simulated high level waste solution.
A mixture of N,N,N′,N′-tetraoctyl diglycolamide (TODGA) and N,N-dihexyl octanamide (DHOA) dissolved in NPH has been evaluated for actinide partitioning from simulated high-level waste by cold tests ...in mixer–settler runs. The feed solution was a synthetic purex raffinate of pressurized heavy water reactor (PHWR) origin where lanthanides were taken as stand-in for trivalent actinides. Quantitative extraction (forward and backward) of trivalent lanthanides was observed in four stages each. Elements such as Fe, Mn, Ni, Ba and Cs were practically un-extracted. However, Cr and Mo were partially co-extracted. Reusability of the organic phase in five successive cycles suggested excellent hydrolytic stability of the reagent. Though the solvent system was susceptible to radiolytic degradation, negligible effects on the extraction as well as on the stripping of lanthanides were observed with solvent irradiated to 100
KGy radiation dose.
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•Blended polymer beads containing PEEK WC and Cyanex 923 were made.•The beads were used for actinide ion extraction from acidic feeds.•Adsorption isotherm studies were carried out.•Column mode ...operations were also tested.
Conventional phase inversion technique has been successfully applied for the preparation of the solid phase extractant (SPE), Cyanex 923 loaded polymer beads. Two types of polymer beads prepared by blending Polyetherether ketone with card (PEEKWC)/DMF with 5% Cyanex 923 (SPE-I, av bead size: 900μm) and 10% Cyanex 923(SPE-II, av. bead size: 1100μm) were evaluated for the uptake of actinide ions. The polymer beads were characterized by various physical methods such as thermal analysis, surface morphology analysis by SEM, EDAX techniques, etc. The polymer beads were used for the experiments involving the uptake of both U(VI) and Pu(IV) at tracer scale and U(VI) at milli molar concentrations from nitric acid feeds. The actinide ion uptake studies involved kinetics of metal ion sorption, adsorption isotherms, and column studies. The metal sorption capacities for U(VI) at 3M HNO3 were found to be 38.8±1.9mg and 54.5±1.7mg per g of SPE-I and SPE-II, respectively. The sorption isotherm analysis with Langmuir, D–R and Freundlisch isotherms indicated chemisorption monolayer mechanism. Column studies were also carried out using 4.5mL bed volume columns containing about 0.4 and 0.45g of SPE-I and SPE-II, respectively. The breakthrough profiles were obtained for U(VI) and the elution profiles were obtained using 1M Na2CO3 as the eluent.
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•A novel extraction chromatography resin containing a calix4arene-mono-crown-6 has been prepared.•The resin was found to be far superior to the only similar resin reported before.•The extraction of ...radio-cesium could be done from 3 M HNO3 and the stripping of the loaded activity was done by water.•The resin has good radiation stability and recyclability for about 5 cycles of loading and stripping.•The resin hold great potential for application in actual acidic radioactive feeds.
An extraction chromatography resin, prepared by the impregnation of bis-octyloxy-calix4arene-mono-crown-6 (BOCMC)onto an acrylic ester based polymeric support material, gave excellent uptake data for the removal of radio-cesium (Cs-137) from nitric acid feed solutions. The weight distribution coefficient (Kd) value of >300 obtained during the present study at 3 M HNO3 was the highest reported so far while using a calix-crown-6 based extraction chromatographic resin material. Analogous resin reported previously has yielded a Kd value <100 at comparable feed conditions. The sorbed metal ions could be efficiently desorbed with de-ionized water. Kinetic modeling of the uptake data indicated that both the film and the intra-particle diffusion mechanism are simultaneously operating in the sorption of Cs+ion onto the BOCMC resin. The metal ion sorption data were fitted to the sorption isotherm models and did not conform to the chemisorptions of physisorption models and indicated a pi-pi interaction between the benzene rings of the calix-crown-6 ligand and the Cs+ ion. The reusability of the resins was quite satisfactory after 5 cycles and the radiation stability of the resin material was very good upto an absorbed dose of 500 kGy. The results of column studies were quite encouraging with 15 mL (9 bed volumes) as the breakthrough volume while the elution was complete in about 12 bed volumes of de-ionized water.
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•TODGA containing PS beads were prepared by phase inversion.•Uptake of actinide ions such as Am3+ was investigated.•Kinetic modelling of the uptake data was done.•Column studies were carried out for ...Am3+ separation.
Polyethersulphone (PES) based composite polymeric beads (CPB) containing TODGA (N,N,N′,N′-tetraoctyldiglycolamide) as the extractant were prepared by conventional phase inversion technique and were tested for the uptake of actinide ions such as Am3+, UO22+, Pu4+, Np4+ and fission product ions such as Eu3+ and Sr2+. The CPBs containing 2.5–10wt.% TODGA were characterized by various physical methods and their porosity, size, surface morphology, surface area and the degradation profile by thermogravimetry were analyzed. The batch uptake studies involved kinetics of metal ion sorption, uptake as a function of nitric acid concentration, kinetic modelling and adsorption isotherms and most of the studies involved the Am3+ ions. The batch saturation sorption capacities for Eu3+ loading at 3M HNO3 were determined to be 6.6±0.02, 9.1±0.02 and 22.3±0.04mgg−1 of CRBs with 2.5wt.%, 5wt.% and 10wt.% TODGA, respectively. The sorption isotherm analysis with Langmuir, D–R and Freundlisch isotherms indicated chemisorption monolayer mechanism. Chromatographic studies indicated breakthrough of Eu3+ (using a solution containing Eu carrier) after about 0.75 bed volume (3.5–4mL). Elution of the loaded Eu was carried out using 0.01M EDTA as the eluent.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The behavior of three symmetrical sulphoxides, R
2
SO, where R = Di-(2-ethylhexyl) (DEHSO), R = dihexyl (DHSO) or R = diisoamyl (DIASO) in ionic liquid diluent, 1-methyl-3-octylimidazolium ...hexafluorophosphate (C
8
mimPF
6
) were examined for the extraction of uranyl ion from nitric acid medium. The extraction efficiency is found to be higher for sulphoxides with branched-chain alkyl substituents (DEHSO and DIASO) as compared to the one with linear chain (DHSO). Between branched chain analogues, the one with longer alkyl chain showed better extraction. The stoichiometry of the uranyl species extracted and its redox characteristics were probed by slope analysis, and cyclic voltammetry respectively. The aggregation behavior of the extractant, DEHSO in ionic liquid was examined by small-angle X-ray scattering and is compared with that of DEHSO in dodecane. The extractant remains as aggregates in ionic liquid while in non-polar diluent like dodecane, no aggregates were formed.
