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.     

Electrochemical separation of uranium and cerium in molten LiCl–KCl

The electrochemical separation of uranium from cerium in LiCl–KCl eutectic and the electrochemical behavior of Ce(III) were studied. According to the cyclic voltammogram of Ce(III) and the former result of U(III), electrodeposition potential was determined at ?1.65 V (vs Ag/AgCl). The uranium metal was successfully deposited and separated from cerium. The morphology of deposit and cross section of electrode were investigated by SEM, firstly uranium deposit alloys with stainless steel and forms a thin transition layer, and secondly the uranium metal layer grows from the transition layer. The separation factors of uranium/cerium on different recovery ratios were determined through a series of steps. It was found that the content of cerium in the deposit and separation factors declined with increasing the initial concentration of U³⁺ in molten salts; the separation factors remained stable at around 20 in different uranium recovery ratios.     

Geological and thermal characterization of Eskişehir region oil shales

In this study, geological consideration and thermal characterization of oil shale samples were studied. Geological considerations of oil shale samples were studied using Rock–Eval analysis and it was observed that the kerogen type of all oil shale samples were in the majority of Type-I and II. Thermal characteristics and kinetics analysis of oil shale samples were studied by non isothermal differential scanning calorimeter (DSC) and thermogravimetry (TG/DTG). In air atmosphere, two different mechanisms causing loss of mass were observed known as loss of moisture, and decomposition of kerogen and bitumen. Kinetic parameters of the samples are determined using ASTM-I and II (DSC), Kissinger, and KAS (TG–DTG) kinetic models and the results are discussed.     

α-Picolinic acid and quinaldinic acid in the separation and volumetric determination of palladium

Analytical and Bioanalytical Chemistry - Palladium can be determined volumetrically after separation with α-picolinic or quinaldinic acid by dissolving the complex in an excess of standard...     

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.     

Spectrophotometric determination of thorium in standard samples and monazite sands based on the floated complex of thorium with N-hydroxy-N,N′-diphenylbenzamidine and thorin

A selective and sensitive spectrophotometric method for the determination of Th(IV) has been based on the reaction with thorin and subsequent extraction of the red-orange coloured complex with N-hydroxy-N,N'-diphenylbenzamidine (HDPBA) in benzene as floated complex at pH 2.2. The complex in ethanol exhibits a maximum absorbance at 495 nm, with a molar absorptivity of 6.0x10(4) l mol(-1) cm(-1), with a Sandell's sensitivity of 3.9x10(-3) microg cm(-2). The method follows Beer's law up to 3.0 microg Th(IV) ml(-1). None of the common cations and anions tested interfere. The detection limit of the method is 0.04 microg Th(IV) ml(-1), the RSD (n=10) is 1.4%. The method has been successfully employed for the determination of thorium in various standard and monazite samples.     

Selective extraction of uranium from uranium–beryllium ore by acid leaching

Journal of Radioanalytical and Nuclear Chemistry - Both uranium and beryllium are very important strategic metals and have been applied to many fields, such as nuclear industries, atomic energy,...     

Application of β-cyclodextrin in polymeric solid phase for separation and determination of lead in different environmental matrices

Immobilization of β-cyclodextrin on Dowex resin as an insoluble polymeric matrix by covalent bond presents a new solid-phase medium for preconcentration of Pb (II) at trace level in environmental samples prior to its flame atomic absorption spectrometric determination. The method is based on the sorption of lead after passing on modified Dowex sorbent in a column. The effect of several parameters such as pH, flow rate of sample, eluent kind and volume was investigated. The sorption capacity of the matrix has been found to be 0.4996?mg?g^?1 of adsorbent with the preconcentration factor of 250 for Pb (II). Nitric acid (3 M) as an eluent was sufficient to obtain quantitative recovery (>95%) for Pb (II). The optimum flow rate was 10?ml?min ^?1. The calibration curve was linear in the range of (3–250?ng?mL^?1) with a correlation coefficient of 0.9995. The limit of detection (LOD) based on three times the standard deviation of the blank was 1.37?ng?mL^?1. The relative standard deviation (RSD) for determination of 10?ng?mL^?1 and 100?ngmL^?1 of Pb (II) was 3.00 % and 0.58 % (n?=?10), respectively. The method was successfully applied to determination of lead in some environmental samples such as tap water, river water, soil and rice.     

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.     

Simultaneous determination of uranium and thorium using 4-(2′-thiazolylazo)resacetophenone oxime as analytical reagent. A derivative spectrophotometric method

A first derivative spectrophotometric method has been developed for the simultaneous determination of uranium(VI) and thorium(IV) when present in the same solution using 4-(2-tiazolylazo)resacetophenone oxime (TARPO) as analytical reagent without prior separation of any of the metals or using masking agents, etc. The method allows the determination of uranium and thorium in their mixtures in the range of 0–10 ppm each. Many common anions and cations even in large quantities do not interfere.     

Solid-phase extraction–spectrophotometric determination of uranium(VI) in natural waters

A method for the extraction and determination of uranyl ion in natural waters using octadecyl bonded silica membrane disks modified with piroxicam and spectrophotometry with arsenazo(III) is proposed. The perconcentration step was studied with regard to experimental parameters such as amount of extractant, type and amount of eluent, pH, flow rates and tolerance limit of diverse ions on the recovery of uranyl ion. The limit of detection of the proposed method is 0.4 micro g L(-1) of uranyl. The method was applied to the recovery of uranyl from different water samples.     

Feasibility study of <Superscript>233</Superscript>Pa and <Superscript>233</Superscript>U determination in neutron irradiated thorium for future applications in thorium–uranium nuclear fuel cycle

With regard to the use of thorium fuel for future nuclear energy production, two methods of ²³³U assay were studied in neutron irradiated thorium and in a mixture of thorium and uranium. The former was based on gamma-spectrometry determination of the ²³³Pa radionuclide, a precursor of ²³³U. The latter was direct determination of ²³³U by neutron activation analysis with counting of delayed neutrons. The mass of ²³³U determined by both methods is compared with that calculated using Maple9.5 software package.     

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.     

A novel method of synthesizing solid phase adsorbent silica modified with xylenol orange: application for separation, pre-concentration and determination of uranium in calcium rich hydro-geochemical samples and sea water—Part 1

A novel, single-step route has been developed for the synthesis of solid phase adsorbent silica modified with xylenol orange. The addition of cationic surfactant cetyl tri-methylammonium bromide during the synthesis of the adsorbent supports the formation of a stable coating of xylenol orange on silica. The adsorbent showed no signs of degradation in contact with organic solvents and with solutions of varying pH between 1 and 9. This adsorbent has been used for separation and pre-concentration of uranium from hydro-geochemical samples with high calcium content and from sea water. Quantitative sorption of uranium was observed above pH 3 and complete desorption can be achieved using 0.2 M sodium pyrophosphate solution. The uranium content in the extract was determined by laser fluorimetric technique. The equilibration time is 30 min. The sorption capacity of the adsorbent for uranium is 10 mg g^?1. An enrichment factor of 50 was obtained by this procedure taking 500 mL of sample solution. Uranium concentrations down to 0.05 ng mL^?1 can be determined after pre-concentration using this method. The relative standard deviation at an 0.1 ng mL^?1 level is ±15%.     

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).     

Enantioselective separation and simultaneous determination of fenarimol and nuarimol in fruits, vegetables, and soil by liquid chromatography–tandem mass spectrometry

A method for simultaneous enantioselective determination of fenarimol and nuarimol in apple, grape, cucumber, tomato, and soil was developed using liquid chromatography–tandem mass spectrometry. The enantioseparation results of the two fungicides through three different cellulose-based chiral columns are discussed. The influence of column temperature on the resolution of the enantiomers of the two fungicides was examined. Complete enantioseparation of the two fungicides’ enantiomers was obtained on a cellulose tris(4-methylbenzoate) column (Lux Cellulose-3) at 25?°C using methanol and 0.1?% formic acid solution (80:20, v/v) as mobile phase. The linearity, matrix effect, recovery, and precision were evaluated. Good linearity was obtained over the concentration range of 1–500?μg?L^?1 for each enantiomer in the standard solution and sample matrix calibration solution. There was no significant matrix effect in apple, grape, cucumber, or tomato samples, but signal suppression was typically observed with the soil extracts. The mean recoveries, repeatability, and reproducibility were 76.5–103?%, 2.1–9.0?%, and 4.2–11.8?%, respectively. The limit of quantification for enantiomers of the two fungicides in fruits, vegetables and soil was 5?μg?kg^?1. Moreover, the absolute configuration of the enantiomers of fenarimol and nuarimol was determined from a combination of experimentally determined and predicted electronic circular dichroism spectra.

Accurate purification age determination of individual uranium–plutonium mixed particles

Age of individual uranium–plutonium (U/Pu) mixed particles with various U/Pu atomic ratios (1–70) were determined by inductively coupled plasma mass spectrometry. Micron-sized particles were prepared from U and Pu certified reference materials. The Pu reference was stored for 4–6 years since the last purification (July 14, 2008). The Pu purification age was obtained from the ²⁴¹Am/²⁴¹Pu ratio which was calculated from the product of three measured ratios of Pu and Am isotopes in the eluted fractions. These ratios were measured by a high-resolution inductively coupled plasma mass spectrometer equipped with a desolvation system. Femto-gram to pico-gram quantities of Am, U, and Pu in a sample solution were sequentially separated on a small anion-exchange column. The ²⁴¹Am/²⁴¹Pu ratio was accurately determined by spiking pure ²⁴³Am into the sample solution. The average determined age for the particles for the five independent U/Pu ratios was in good agreement with the expected age with high accuracy (difference age 0.27 years) and high precision (standard deviation 0.44 years). The described analytical technique can serve as an effective tool for nuclear safeguards and environmental radiochemistry.

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Figure Young (4?6 y) Pu purification age of individual U/Pu mixed micron-sized reference particles for the five independent U/Pu ratios (1?70) were determined with 0.27±0.44 y difference from the expected age. Sub pico-gram quantities of Am, U and Pu were sequentially separated a small column, and their isotope ratios were accurately measured using an ICP-MS by applying the ²⁴³Am spiking technique to the analysis and correcting the impurity and the contaminations.