Coordination compounds of uranium and thorium with a novel double β-diketone

A novel double -diketone 1,6-bis(1-phenyl-3-methyl-5-oxo-pyrazol-4-yl) hexanedione-[1,6] (BPMOPH) was further studied on its coordination compounds with uranium and thorium, respectively. The IR, UV, and¹H-NMR spectra were examined, and the proposed structure is discussed.     

Anion-exchange separation and determination of thorium and uranium in Eskişehir-Beylikahir ore in Turkey

Eskişehir-Beylikahir ore contains rare earth elements (REE) and thorium as bastnaesite mixed with barite, calcite and fluorite and small amounts of uranium. The mineralogical composition and Th, U, REE contents of the ore samples taken from different sectors of the same region show important variations. For the spectrophotometric determination of Th and U in the ore, successive anion-exchange and solvent extraction procedures are carried out to separate U and Th from each other and from accompanying interfering elements. The accuracy and precision of the method is demonstrated by intercomparison of the thorium standard reference samples S-14, S-15 and S-16 of IAEA. In all cases very good agreement was obtained.     

Thermodynamic functions of thorium–cerium mixed oxides

Journal of Thermal Analysis and Calorimetry - Thorium–cerium mixed oxides (Th1?xCex)O2 (x?=?0.25, 0.5, 0.75) were prepared by the citrate gel combustion technique. X-ray...     

Thermophysical properties of thorium–praseodymium mixed oxides

Thorium–Praseodymium mixed oxide solid solutions (Th_1?yPr_y)O_2?x (y = 0.15, 0.25, 0.4, 0.55) were prepared by co-precipitation method. These mixed oxides form single-phase fluorite solid solutions (fm3m). Heat capacity (C _p) measurements and lattice thermal expansion characteristics of these solid solutions were determined with differential scanning calorimeter in the temperature range of 298–800 K and high temperature X-ray diffractometer in the temperature range of 298–2,000 K, respectively. The C _p,₂₉₈ of (Th _1?yPr_y)O_2?x pertaining to the solid solutions with the compositions, y = 0.15, 0.25, 0.4, and 0.55, were found to be 65.2, 62.4, 60.1, and 57.1 J K^?1 mol^?1, respectively. The coefficients of lattice thermal expansion in the temperature range of 298–2,000 K of (Th_1?yPr_y)O_2?x for these solid solutions with the compositions y = 0.15, 0.25, 0.4, and 0.55 were found to be 16.97, 20.43, 25.63 and 30.82 × 10^?6 K^?1, respectively.     

Determination of thorium with DBF-arsenaz by flow-injection analysis

A sensitive,selective,rapid,simple,and convenient method for the determination of thoriumwas developed.The method was based on the color reaction of thorium with DBF-arsenazo in astrong acidic medium (4 mol/L HCI).The flow-injection technique was used with an automated flow-injection analyzer.Beer's law was obeyed in the range of 0—1.4 μg/mL.The relative standarddeviations were less than 1%.     

Preparation of thorium oxalate–silica sorbent and its application for the sorption of americium from aqueous solutions

A new sorbent, thorium oxalate incorporated in silica gel matrix was prepared. This material was characterized by X-ray, Thermo-gravimetric Analysis, surface area and porosity analysis. The material was obtained in the form of granular particles in the mesh size range of 80–150 American Standard of Testing Materials, yielding good liquid flow, when packed in ion exchange column. This sorbent was investigated for the sorption of americium from various aqueous media such as nitric acid, oxalic acid and sulphuric acid by distribution coefficient studies. Column experiments were carried out to study the practical application of this sorbent for removal of americium from oxalic acid-nitric acid solutions. Elution studies were also carried out for the recovery of americium.     

Determination of uranium and thorium in Eskişehir-Beylikahir ore samples by delayed neutron counting technique

The Eskiehir-Beylikahir district has the largest and richest thorium and rare earth elements deposits in Turkey. The uranium and thorium concentrations of samples taken from four different parts of this area have been determined by the delayed neutron counting technique. The results are compared with those of previous analyses by other techniques and found to be in good agreement.     

The structure effect of N,N,N′,N′-alkylamide in the extraction of uranium and thorium

In this paper, nine N,N,N,N-tetraalkyldiamides have been synthesized and the extracting ability for uranium and thorium under different conditions has been studied. All results were compared with those obtained by using tributyl phosphate (TBP) under exactly the same conditions. The extracting ability of thorium and uranium for different N,N,N,N-tetraalkyldiamides is discussed.     

Extraction of uranium into a third phase of thorium nitrate—tributyl phosphate

Extraction of 0.05–0.25M uranyl nitrate into 30% tributyl phosphate (TBP) in dodecane from nitric acid solutions of thorium nitrate at equilibrium with its salt has been studied. Under investigated conditions a third (second organic) phase is formed. As the heavy organic phase extracts uranium, the calculated ratio of TBP to thorium and uranium sum decreases from 2.7 to less than 7. Electronic spectra show that in heavy organic phase approximately 80% of uranium is found as trinitrate complex, while in the light organic phase this complex is not detected. The measurements of dielectric constant () of the heavy phase reveal a frequency dependence of . The data obtained point to the existence of an ordered structure in the heavy organic phase.     

Preparation of lanthanide,thorium and uranium oxide films by chemical vapor deposition using β-diketone chelates

Preparation of thin film deposits of lanthanide, thorium and uranium oxides has been studied by chemical vapor deposition (CVD) method using -diketonate metal chelates with 2,2,6,6-tetramethyl-3,5-heptanedione and some reactant gases as starting materials. The deposition process was carried out using a special apparatus designed for the CVD method at atmospheric pressure and temperatures as low as 400–600°C.As a result, it was demonstrated that each chelate used was well suited for the above purpose by its high volatility and reactivity with the reactant, especially with water vapor.     

Sol–gel synthesis of a humic acid-silica gel composite material as low-cost adsorbent for thorium and uranium removal

In the present work, three neutral ^99mTc(CO)₃ complexes of nitroimidazole were synthesized and their potential to detect tumor hypoxia is evaluated in vivo. Triazole derivatives of 2-, 4- and 5-nitroimidazole were synthesized via ‘click chemistry’ route. The ligands synthesized were characterized and subsequently radiolabeled using [^99mTc(CO)₃(H₂O)₃]⁺ precursor complex to obtain corresponding neutral ^99mTc(CO)₃ complexes in >90 % radio chemical purity. The complexes were subsequently evaluated in Swiss mice bearing fibrosarcoma tumor and in vivo distribution observed was thoroughly analyzed. All complexes showed uptake in tumor, however, contrary to general expectations, the 5-nitroimidazole complex showed significantly higher tumor uptake (p < 0.05) at 30 min and 60 min p.i., compared to the 2-nitroimidazole counterpart. Though a conclusive explanation for this observation could not be obtained, present study underlined the significance of evaluating nitroimidazole radiotracers other than 2-nitroimidazole for detecting tissue hypoxia.     

Surface’s weights of electrodeposited thorium samples determined by alpha spectrometry

The aim of this work was the preparation of samples with thorium on the steel discs by electrodeposition for determination of natural thorium by alpha spectrometry and for following analysis by secondary ion mass spectrometry. The samples with ²³²Th isotope were prepared by electrodeposition from solution Th(NO₃)₄·12H₂O on steel discs in electrodeposition cell with use of solutions of Na₂SO₄, NaHSO₄, KOH and ammonia oxalate by electric current of 0.75 A. Weights of electrodeposited thorium samples were calculated on the basis of intensities of peak of ²³²Th isotope in the alpha spectra. The layer thickness was calculated for following analysis of surface layers of thorium using secondary ion mass spectrometry.     

Biosorption of uranium (VI) and thorium (IV) onto Ulva gigantea (K��tzing) bliding: discussion of adsorption isotherms, kinetics and thermodynamic

Ulva gigantea (Kützing) bliding (UGB) obtained from sea inlet of Izmir-Turkey has been studied as a biosorbent for removal of radioactive metals from water. In this study, unmodified UGB and modified UGB with glutaraldehyde (GUGB) characterized by FTIR spectroscopy were used as biosorbents for removal of U(VI) and Th(IV) ions from aqueous solution. Adsorption experiments performed under batch process with initial pH, contact time, adsorbent mass and temperature as variables. In order to determine the adsorption characteristics, Langmuir, Freundlich and Dubinin-Raduschkevich adsorption isotherms were applied to the adsorption data. Adsorption experiments showed that the adsorption isotherms correlated well with the Freundlich model. The sorption followed pseudo-second-order kinetics. The thermodynamic parameters such as variations of ??H°, ??G° and ??S° were estimated as a function of temperature. The thermodynamics of the adsorption of U(VI) and Th(IV) onto UGB and GUGB indicates that the spontaneous and exothermic nature of the process. The results showed that UGB and GUGB were potential for application in removal of U(VI) and Th(IV) from aqueous solution.     

Understanding the extraction mechanism,radiolytic stability and stripping behavior of thorium by ionic liquid based solvent systems: evidence of ‘ion-exchange’ and ‘solvation’ mechanism

The extraction efficiency for thorium followed the trend: Cyanex-923 > Cyanex-272 > DHOA > TBP. In case of TBP and DHOA the extraction proceeded via ‘solvation mechanism’ through Th(NO₃)₄·2L, while for Cyanex-923 and Cyanex-272 it proceeded via ‘ion exchange’ mechanism through (Th(NO₃)₂·2L)²⁺. The extraction process followed slower kinetics while change in Gibb’s energy revealed the spontaneity of the process. These ionic liquid based systems were found to be radiolytically stable, highly efficient and selective for Th. Oxalic acid was found to be suitable for almost quantitative stripping of Th from extracted ionic liquid phase.     

Liquid–liquid extraction of thorium(IV) with N-n-heptylaniline from acid media

The extraction behavior of thorium(IV) from sulphuric acid medium with N-n-heptylaniline in xylene. Various parameters like reagent concentration, acid concentration, equilibration time, diverse ions and effect of diluents were studied. Thorium(IV) was selectively extracted and separated from many metal ions. The nature of the extracted species was determined. Thorium(IV) was analyzed from monazite ore and gas mantle.

     

Selective determination of thorium in water using dual-wavelength β-correction spectrophotometry and the reagent 4-(2-pyridylazo)-resorcinol

A simple, fast, low cost, and precise direct β-correction spectrophotometric method was developed for thorium determination in water. The method is based on the reaction of Th(IV) with 4-(2-pyridylazo)-resorcinol (PAR) in aqueous solution of pH 5–6 and measuring the absorbance of the resulting red-colored complex at λ_max 497 nm. The effective molar absorptivity of the Th(IV)-PAR complex was 2.52 × 10⁴ L mol⁻¹ cm⁻¹. Beer’s law and Ringbom plots were obeyed in the concentration range 0.04–2.0 and 0.07–1.2 μg mL⁻¹ of thorium ions using β-correction spectrophotometry, respectively. The limits of detection and quantification of Th(IV) were 0.02 and 0.066 μg mL⁻¹, respectively. The developed method was applied for the analysis of thorium in certified reference material (IAEA-soil-7), tap-, underground- and Red-sea water samples. The validation of the method was also tested by comparison with data obtained by ICP-MS. The method is convenient, less sensitive to common interfering species and less laborious than most of published methods. The statistical treatment of data in terms of Student t-tests and variance ratio f-tests has revealed no significance differences. The structure of the Th(IV)-PAR complex was determined with the aid of spectroscopic measurements (UV–Visible and Fourier Transform Infrared Spectroscopy).     

The electronic structure of thorium monoxide: Ligand field assignment of states in the range 0–5 eV

Configuration interaction ligand field theory (CI LFT) calculations of the electronic energy levels of ThO were performed by treating the molecular electronic states as Th ^{2 +} free-ion levels perturbed by the ligand field of O²⁻. Twenty nine experimentally characterized ThO v = 0 energy levels, together with the energy difference between the v = 0 levels of the Y and W states were fitted using a CI LFT model that included Th ^{2 +} 7s ² , 6d7s, 6d², 7s7p, 6d7p, 5f7s, and 7p² configurations. Predictions from these calculations were used to provide tentative assignments for 171 out of 250 ThO band heads listed by Gatterer et al. [“Molecular Spectra of Metallic Oxides”, Specola Vaticana (1957)]. Term energies for 30 electronic states have been determined based on these assignments. Subsequently, the CI LFT model was refined by fitting to a set of 59 electronic term energies. The inclusion of CI effects together with integer valence, atomic-in-molecule, ionic bonding ideas reveals atomic energy level patterns that are multiply replicated in the molecular energy level patterns of six Th ^{2 +} O²⁻ atomic ion configurations (6d7s, 6d², 7s7p, 6d7p, 5f7s, and 7p²) revealing the underlying atomic ion structure that gives rise to the complex and seemingly erratic unassigned bands reported in the Vatican Atlas. © 2018 Wiley Periodicals, Inc.