Radiochemical separation of110mAg,210Pb,127Te and131I from aqueous nitric acid solution by bis-2-(butoxyethyl ether)

A bis-2-(butoxyethyl ether) (DBC) solvent extraction method has been developed for the radiochemical separation of^110mAg,²¹⁰Pb,¹²⁷Te and¹³¹I in varying concentrations of aqueous HNO₃. Various factors were examined to determine the optimum conditions of extraction. The effect of various masking agents has been studied. The extraction of¹³¹I is enhanced to 99% at 2.4M HNO₃ in the presence of KSCN.¹³¹I was stripped into aqueous sodium hydroxide from the oxygenated organic extractant. The method was then applied for the recovery of¹³¹I from neutron irradiated tellurium metal. The mechanism and reactivity of DBC with metal ions is described.     

Extraction of uranium(VI) and thorium(IV) from nitric acid solution by N-alkylcaprolactam

Extraction of uranium(VI), thorium(IV) from nitric acid has been studied with N-octylcaprolactam and N-(2-ethyl)hexylcaprolactam. Distribution coefficients of U(VI), Th(IV) and HNO₃ as a function of aqueous NHO₃ concentration, extractant concentration and temperature have been studied. The compositions of extracted species, thermodynamic parameters of extraction have been evaluated. Third phase formation in extraction of U(VI) has been studied. Back extraction behavior of U(VI) and Th(IV) from the organic phase has also been tested. The results obtained are compared with those obtained by using TBP under the same experimental conditions.     

Extraction of neodymium and europium by bis-(2-ethylhexyl) phosphoric acid from aqueous diamine solutions

The extraction of Nd³⁺ and Eu³⁺ from aqueous media containing selected diamine ligands by HDEHP solution in benzene has been investigated. It is found that the presence of the diamine in the aqueous phase enhances the extraction of both Nd³⁺ and Eu³ in the organic phase. The possible explanation for this behaviour is presented and a mechanism based on extraction of an adduct of the type MH₃(DEHP)₆. B is found to be the most probable.     

Extraction of uranium(VI) from nitric acid solution by N,N-dibutyldodecanamide

The partition of uranium(VI) between nitric acid solutions and solutions of N,N-dibutyldodecanamide (DBDA) in kerosene has been investigated at varying concentrations of nitric acid, extractant, salting-out agent LiNO₃ and at different temperatures. The mechanism of extraction is discussed in the light of the results obtained.     

Extraction of uranium(VI) from nitric acid solution with hexyloctylsulfoxide (HxOSO)

The thermodynamic extraction of uranium(VI) with hexyloctylsulfoxide (HxOSO) has been studied. It was found that the distribution ratio increases with increasing nitric acid concentration up to 2.3 mol/l and then decreases. The distribution ratio also increases with increasing extractant concentration. The extracted species appears to be UO₂(NO₃)₂ ^.2HxOSO. The influences of temperature, sodium nitrate and oxalate concentrations on the extraction were also investigated, and the thermodynamic functions of the extraction reaction were obtained.     

Solvent extraction of thorium from mixed organic — aqueous nitric acid media by try-n-octylphosphine oxide

The extraction equilibria of Th in tri-n-octylphosphine oxide (TOPO)–HNO₃–H₂O systems have been investigated in the absence and presence of water-miscible alcohols and acetone. The influence of TOPO concentration in an inert diluent (toluene) and the concentration of nitric acid and the water-miscible additives have been systematically examined. The slopes of the log-log plots of D_Th vs. the TOPO concentration (up to 0.02M) are found to be close to 3 over a wide range of polar phase compositions leading to a coordination number of 11 for Th. The D_Th values were determined as a function of the concentration of uranyl nitrate in the aqueous phase, while the effect of additives was also examined in the absence and presence of uranyl nitrate in the polar phase. The results show that at TOPO concentrations above about 2.5 · 10^–3 M (about 1%) in toluene, polymerization of the solvent occurs.     

Extraction of uranyl(VI) ion with N,N-diethyloctadecanamide from nitric acid solution

The extraction of U(VI) with newly synthesized alkylamide, N,N-diethyloctadecanamide (DEODA), has been studied. The dependence of the extraction on nitric acid concentration, DEODA concentration and temperature from nitric acid solution has been considered. The extracted species has also been investigated using FT-IR spectrometry. The related themodynamic functions were calculated.     

Structural effect of N,N-dialkylamide on the extraction of thorium(IV) ion from nitric acid solution

N,N-dialkylamides, (octan-, decan- and dodecanamides) having ethyl and butyl groups as alkyl substituents, were synthesized in order to investigate their selectivity and capability in the extraction of Th(IV) from acidic nitrate media (3 and 6M HNO₃) in nuclear reprocessing. The distribution ratios of Th (IV) with the amides in kerosene decrease with the increase of the alkyl chain length (C₈, C₁₀, C₁₂), probably due to steric hindrance.     

Kinetic studies on the stripping of thorium (IV) and uranium (IV) from tributylphosphate-kerosene with dilute nitric acid solution

The cold solution of a pyrophosphate kit was prepared and dispensed into 2-ml fractions which were stored at −20°C for one week. The solution was prepared by using two protection methods. The first was nitrogen purging to exclude air and the second one the addition of the well known antioxydant ascorbic acid. The aim was to determine the stability of^99mTc(Sn)-PyP obtained by labeling these fractions prepared under the given experimental conditions. The content of^99mTc-pertechnetate in the unprotected samples raises with time. Nitrogen purging provides some protection but already after a few days the content of pertechnetate exceeds 5%. The addition of ascorbic acid gave good results. The content of pertechnetate was 1–2% after seven days in the presence of 50 μg of acid per ml of the cold kit.     

Extraction of neptunium(VI) from nitric acid solution with di(1-methyl-heptyl) methyl phosphonate

Journal of Radioanalytical and Nuclear Chemistry - The extraction behaviors of Np(VI) from nitric acid medium by di(1-methyl-heptyl) methyl phosphonate (DMHMP) diluted in kerosene has been...     

Adsorption of thorium from aqueous solution by HDTMA+-pillared bentonite

The ability of hexadecyltrimethylammonium cation pillared bentonite (HDTMA⁺-bentonite) has been explored for the removal and recovery of thorium from aqueous solutions. The adsorbent was characterized using small-angle X-ray diffraction, high resolution transmission electron microscopy and Fourier transform infrared spectroscopy. The influences of different experimental parameters such as solution pH, initial thorium concentration, contact time and temperature on adsorption were investigated. The HDTMA⁺-bentonite showed the highest thorium sorption capacity at initial pH of 3.5 and contact time of 60?min. Adsorption kinetics was better described by the pseudo-second-order model and adsorption process could be well defined by the Langmuir isotherm. The thermodynamic parameters, ?G° (298?K), ?H° and ?S° were determined to be ?31.78, ?23.71?kJ/mol and 27.10?J/mol?K, respectively, which demonstrated the sorption process of HDTMA⁺-bentonite towards Th(VI) was feasible, spontaneous and exothermic in nature. The adsorption on HDTMA⁺-bentonite was more favor than Na-bentonite, in addition the saturated monolayer sorption capacity increased from 17.88 to 31.20?mg/g at 298?K after HDTMA⁺ pillaring. The adsorbed HDTMA⁺-bentonite could be effectively regenerated by 0.1?mol/L HCl solution for the removal and recovery of Th(VI). Complete removal (99.9?%) of Th(VI) from 1.0?L industry wastewater containing 16.8?mg Th(VI) ions was possible with 7.0?g HDTMA⁺-bentonite.     

Highly efficient elimination of thorium(IV) from aqueous solution using poly(cyclotriphosphazene-co-melamine) microspheres

Highly crosslinked organic–inorganic hybrid polymer poly(cyclotriphosphazene-co-melamine) microspheres (PZM) were synthesized by a simple method. The microspheres was characterized by FTIR, SEM and EDX. It was applied to eliminate thorium(IV) from aqueous solution under various conditions, i.e., pH, initial concentration, dosage and contact time. The experimental data were well-imitated via the pseudo-second-order kinetic model and its adsorption processes comply with the Langmuir isotherm model. Adsorption thermodynamic studies demonstrated that the adsorption process, in essence, was spontaneous and endothermic. Furthermore, the maximum experimental adsorption capacity was 98.6 mg g^?1 for initial thorium(IV) concentration 50 mg L^?1. When pH?=?0.0, the thorium(IV) removal efficiency reached at 76.9%, which indicates that the adsorbent can also was used in a peracid environment. Adsorption behavior of thorium(IV) onto the microspheres were weakly affected via temperature, implying that adsorption would be done at room temperature.

     

Extraction of bismuth(III) with 2-bromoalkanoic acid in nondonating solvent from highly acidic aqueous solution.

The extraction behaviors of bismuth(III) with carboxylic acid (HL), which have not yet been clearly elucidated, because of the precipitation of hydroxide, were studied using the 2-bromoalkanoic acid in benzene and in hexane systems under aqueous conditions of high acidity at I = 1.0 M ((H,Li)NO3). The extraction equilibria were analyzed based on the-initial concentration of nitric acid and the concentration of bismuth(III) extracted in the organic phase. The extracted species and the logarithmic values of the extraction constant (log Kex) were found to be a single species of BiL3(HL)3 for the systems of 2-bromooctanoic acid/benzene (log Kex = -1.66) and 2-bromohexadecanoic acid/benzene (-1.58), and to be two species of BiL3(HL)4 (-1.01) and Bi3L9HL (-1.62) for the system of 2-bromooctanoic acid/hexane, where the monomer was dominant at a higher reagent concentration.     

Extraction of uranium(VI) and thorium(IV) ions from nitric acid solutions by N,N,N′,N′-tetrabutyladipicamide

A new symmetrical diamide, the straight-chain alakyl substituted neutral tetrabutyladipicamide (TBAA) has been synthesized, characterized and used for the extraction of U(V) and Th(IV) from nitric acid solutions in a diluent composed of 50% 1,2,4-trimethylbenzene (TMB) and 50% kerosene (OK). Extraction distribution coefficients of U(VI) and Th(IV) as a function of aqueous nitric acid concentration, extractant concentration and temperature have been studied. Back-extraction of U(VI) and Th(IV) from organic phases by dilute nitric acid has been undertaken. From the data, the compositions of extracted species, equilibrium constants and enthalpies of extraction reactions have also been calculated.     

Extraction behavior of yttriuí with diisodecylphosphoric acid from nitric acid solution

Extraction of yttrium and some of the lanthanoids by diisodecylphosphoric acid (DIDPA) has been studied as a function of nitric acid concentration in the aqueous phase and concentration of the DIDPA in n-dodecane. The distribution ratio of yttrium was found to increase with the second power of concentration of the extractant and decrease with the third power of concentration of nitric acid. As the concentration of yttrium in the organic phase increased, an amorphous solid was found to precipitate and the composition of the solid was determined to be Y(DIDP)₃. To dissolve Y(DIDP)₃ into n-dodecane, a 14-fold molar excess of DIDPA was required over Y(DIDP)₃. The distribution ratio of yttrium was found to be too high to back-extract this element by nitric acid of medium concentration.     

Extraction of metals by bis-(2-ethylhexyl) phosphoric acid in 2-ethylhexanoic acid as monomerizing diluent from an aqueous chloride phase: Am(III), Eu(III), Tm(III) and Y(III)

The extraction of Am³⁺, Eu³⁺, Tm³⁺ and Y³⁺ from an aqueous chloride phase into a solution of bis 2-ethylhexyl phosphoric acid, (2-C₂H₅·C₆H₁₂O)₂PO(OH), HDEHP, in the monomerizing diluent 2-ethylhexanoic acid has been studied in terms of the concentration of hydrogen ion in the equilibrated aqueous phase and of HDEHP in the opposing equilibrated organic phase. The extraction stoichiometries, with the corresponding expression for K in terms of F (the formality of HDEHP in the organic phase), [H⁺](the concentration of hydrogen ion in the aqueous phase), and K_S, for a 1.00 F(NaCl + HCl) aqueous phase are

where HY represents the monomer of HDEHP and the formulations of extracted species are non-committal with respect to structure. With HZ representing the monomer of 2-ethylhexanoic acid, suggested formulations of the extracted species in terms of homogeneousand heterogeneous dimers are: for Am³⁺, and Eu³⁺, M(HYZ)₃; and for Tm³⁺, Y³⁺, M(HY₂)₂(HYZ). The K_S values are: Am³⁺(5 × 10⁻³), Eu³⁺(1 × 10⁻²), (1 × 10⁻²), Tm³⁺(7) and Y³⁺(2).