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Tri-n-butylphosphate (TBP) in an ionic liquid (IL) has been proposed as a suitable alternative for the solvent extraction of actinides from nitric acid solutions. This paper reports the detailed investigations on the physicochemical and hydrodynamic properties of the solvent system containing TBP in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide ([C4mim][NTf2]) IL. The properties such as density, viscosity, phase separation time (PST), etc., were measured for irradiated and unirradiated solvent phases composed of TBP, [C4mim][NTf2] and 1.1 mol.L-1 TBP in [C4mim][NTf2]. The results are compared with the values obtained in acid-equilibrated IL phases. ATR- FTIR spectroscopy and dynamic light scattering measurement of the IL phase were employed to characterize the interactions among the IL, TBP and nitric acid medium, and the aggregate size of the adduct formed in the IL phase. [ABSTRACT FROM AUTHOR]

High-level liquid waste from fast reactor fuel reprocessing stream contains significant quantities of lanthanides and trivalent minor actinides. The lanthanides and minor actinides (MA) have been separated from the fast reactor high-level liquid waste (FR-HLLW) using TRUEX solvent, which is a mixture of 0.2 M octyl(phenyl)- N, N-diisobutylcarbamoylmethylphosphine oxide (CMPO)-1.2 M tri- n-butylphosphate (TBP) in n-dodecane. A new stripping composition, 0.1 M HNO and 0.1 M citric acid (CA), has been employed for back extraction of them from the TRUEX solvent. In order to separate lanthanides from actinides present in the strip solution, the extraction behavior of Am(III) and Eu(III) from CA–HNO medium by a solution of bis-2-ethylhexylphosphoric acid (HDEHP) in n-dodecane has been studied. Separation factors (SF = D/ D) has been reported as a function of various parameters such as pH, concentrations of HDEHP, diethylenetriamine- N, N, N′, N′′, N′′′-pentaaceticacid (DTPA), 1-octanol and TBP in this paper. [ABSTRACT FROM AUTHOR]

Dysprosium hafnate is a candidate material for as control rods in nuclear reactor because dysprosium (Dy) and hafnium (Hf) have very high absorption cross-sections for neutrons. Dysprosium hafnate (Dy2O3·2HfO2-fluorite phase solid solution) was prepared by solid-state as well as wet chemical routes. The fluorite phase of the compound was characterized by using X-ray diffraction (XRD). Thermal expansion characteristics were studied using high temperature X-ray diffraction (HTXRD) in the temperature range 298–1973 K. Heat capacity measurements of dysprosium hafnate were carried out using differential scanning calorimetry (DSC) in the temperature range 298–800 K. The room temperature lattice parameter and the coefficient of thermal expansion are 0.5194 nm and 7.69 × 10−6 K−1, respectively. The heat capacity value at 298 K is 232 J mol−1 K−1. [ABSTRACT FROM AUTHOR]

Imidazolium nitrate anchored on poly(styrene-divinylbenzene) co-polymer, Im-NO3, has been synthesized and evaluated for plutonium purification. The results are compared with those obtained using Dowex 1 × 4 anion exchange resin. The distribution coefficient (Kd) of Pu(IV) increased with increase in concentration of nitric acid, reached a maximum at 8 M, followed by decrease in Kd values. Rapid ion exchange of Pu(IV) followed by the establishment of equilibrium occurred within 100 min of equilibration and the data was fitted in to first order rate equation. Variation of distribution coefficient of Pu(IV) as a function of exchange capacity and nitrate ion concentration suggest the involvement of anion exchange mechanism is responsible for extraction. The apparent ion exchange capacity was 310 mg/g at 8 M nitric acid. The performance of the Im-NO3 under dynamic condition was assessed by column breakthrough experiments. Radiolytic degradation of Im-NO3 resin in presence and absence of nitric acid (8 M) was studied and the results are reported in this paper. [ABSTRACT FROM AUTHOR]

The commercially available crystalline silicotitanate inorganic ion exchanger, IONSIV IE-911, and its parent precursor, TAM-5, have been evaluated for the removal of 137Cs from nitric acid medium and simulated high-level liquid waste. The distribution coefficient ( K d) of cesium decreased with increasing nitric acid concentration and at 3.0 M nitric acid, a distribution coefficient of 1150 mL/g and 2600 mL/g were obtained for IONSIV IE-911 and TAM-5, respectively. Rapid uptake of cesium followed by the establishment of equilibrium occurring within three hours. Loading of cesium in ion exchangers increased with the increase in the concentration of cesium in aqueous phase and from Langmuir adsorption model the apparent capacity of cesium was 69 mg/g and 82 mg/g for IONSIV IE-911 and TAM-5, respectively. The performance of the sorbent under dynamic conditions was assessed by following a breakthrough (BT) curve up to C/ C o = 1, where C and C o are the concentrations of cesium in the effluent and feed, respectively. [ABSTRACT FROM AUTHOR]

Batch and dynamic extractions of uranium(VI) in 10−3–10−2M concentrations in 3–4M nitric acid medium have been investigated using a commercially available phosphinic acid resin (Tulsion CH-96). The extraction of uranium(VI) has been studied as a function of time, batch factor ( V/m), concentrations of nitric acid and uranium(VI) ion. Dual extraction mechanism unique to phosphinic acid resin has been established for the extraction of uranium(VI). Distribution coefficient ( K d ) of uranium(VI) initially decreases with increasing concentration of nitric acid, reaches a minimum value at 1.3M, followed by increases in K d . A maximum K d value of ∼2000 ml/g was obtained at 5.0M nitric acid. Batch extraction data has been fitted into the linearized Langmuir adsorption isotherm. The performance of the resin under dynamic extraction conditions was assessed by following the breakthrough behavior of the system. Effect of flow rate, concentrations of nitric acid and uranium ion in the feed on the breakthrough behavior of the system was studied and the data was fitted using Thomas model. [ABSTRACT FROM AUTHOR]

Commercially available polystyrene-divinylbenzene (PS-DVB) resins functionalized with isothiouronium (Tulsion CH-95), phosphinic acid (Tulsion CH-96) and methylene thiol (Tulsion CH-97) moieties have been used for separating palladium from nitric acid medium. Extraction of palladium has been studied as a function of time, concentration of nitric acid and palladium. The distribution coefficients ( K d, ml/g) of palladium on sulfur based resins (Tulsion CH-95 and Tulsion CH-97) are higher (5000-104ml/g in 0.1M nitric acid) than on Tulsion CH-96 resin and decrease with increasing concentration of nitric acid. The initial rate of extraction of palladium by Tulsion CH-95 and Tulsion CH-97 resins was very rapid and the time required for the establishment of equilibrium was a function of palladium concentration in the aqueous phase. The rate data could be fitted by a second order rate equation and the magnitude of rate constant for the extraction of palladium by these resins (~102M-1. min-1) decreased in the order of: Tulsion CH-95 > Tulsion CH-97 > Tulsion CH-96. The extraction isotherms of Tulsion CH-95 were fitted by Langmuir adsorption model and the coefficients were obtained by regression. The extraction capacity of palladium on Tulsion CH-95 was found to be ~20 mg/g at 3M nitric acid. Column experiments have been conducted and the data were fitted using Thomas model. A column utilization of 75% was achieved for the extraction of palladium by Tulsion CH-95 resin. [ABSTRACT FROM AUTHOR]

Organic complexing moieties such as amine, 2°-amide and benzamide functional groups were covalently linked to silica gel by performing organomodification on commercially available silica gel. The extraction of uranium as a function of pH, time, concentration of uranium and the effect of ions such as Fe2+, Co2+, Ni2+ and CO32- on the distribution coefficient of uranium by sorbent was studied. The data was fitted into Langmuir adsorption isotherm. The selectivity of the sorbents towards uranium were found to decrease in the order gel-amine >> gel-benzamide @ gel-2°-amide at all pHs. The presence of metal ions such as Fe2+, Co2+, Ni2+ and CO32- were found to decrease the distribution coefficients (Kd, ml/g) of uranium and the decrease was very high when Fe2+ was present. The performance of the sorbent, gel-amine, under a given column condition was tested by following the breakthrough curve of uranium up to C/C0 = 0.025. The sorbent was found to be good for the quantitative pre-concentration of uranium from a large amount of sodium. [ABSTRACT FROM AUTHOR]