Traces Of Thorium Research Articles

Determination of Trace Thorium and Uranium Impurities in Scandium with High Matrix by ICP-OES.

High-purity scandium oxide is the principal raw material of high-purity scandium metal and aluminum scandium alloy targets for electronic materials. The performance of electronic materials will be significantly impacted by the presence of trace amounts of radionuclides due to the increase in free electrons. However, about 10 ppm of Th and 0.5-20 ppm of U are typically present in commercially available high-purity scandium oxide, which it is highly necessary to remove. It is currently challenging to detect trace impurities in high-purity scandium oxide, and the detection range of trace thorium and uranium is relatively high. Therefore, it is crucial to develop a technique that can accurately detect trace Th and U in high concentrations of scandium solution in the research on high-purity scandium oxide quality detection and the removal of trace impurities. This paper adopted some advantageous initiatives to develop a method for the inductively coupled plasma optical emission spectrometry (ICP-OES) determination of Th and U in high-concentration scandium solutions, such as spectral line selection, matrix influence analysis, and spiked recovery. The reliability of the method was verified. The relative standard deviations (RSD) of Th is less than 0.4%, and the RSD of U is less than 3%, indicating that this method has good stability and high precision. This method can be used for the accurate determination of trace Th and U in high Sc matrix samples, which provides an effective technical support for the preparation of high purity scandium oxide, and supports the production of high-purity scandium oxide.

Role of nuclear energy in carbon mitigation to achieve United Nations net zero carbon emission: evidence from Fourier bootstrap Toda-Yamamoto.

In this communication, the time series data of three major countries USA, France, and Japan from 1965 to 2020 for CO2 emission, GDP, and nuclear energy (NE) are evaluated. It also analyzed and validated the EKC hypothesis while using nuclear energy for electricity generation. Fourier ARDL is used to investigate the hypothesis criteria, and the Fourier bootstrap Toda-Yamamoto (FBTY) causality test is used for causal linkage between the variables as well as the wavelet coherence; it is also presented the time and frequency dependency of the variables. The CO2 mitigation by using the NE is also assessed for all three countries and assessed that the France, Japan, and USA mitigated the CO2 per year is 0.0463 million metric ton (MMT), 0.0239 and 0.0728 MMT per year respectively. Similar to that the SO2 is reduced by using the NE is 24.322, 43.527, and 132.592 MMT/year, and NOx is reduced by approximately 0.2847, 0.147, and 0.4478 MMT/year by France, Japan, and USA respectively by applying the NE for power generation. The evidence of the EKC, Fourier bootstrap and Toda-Yamamoto clarifies the important role of nuclear energy in terms of carbon mitigation to achieve UN net zero carbon emission by 2050. Hence, in order to meet the UN target of net zero carbon emission by 2050, the USA and Japan should increase the production of nuclear energy as France meets its 74.1% energy demand through NE by validating the EKC hypothesis; on the other hand, all the three countries should increase the production of tidal energy due to their geographical location as tides are much more predictable than wind and sun keeping in consideration to the expenses incurred and a full proof plan for disposing NE residuals in a safe place as NE residuals are highly radioactive and contains traces of thorium and uranium.

Comment on “Limitation of uranium and thorium traces in charnockite matrix‐PIXE analyses at 3 MeV with Si (Li) detector”

Comment on “Limitation of uranium and thorium traces in charnockite matrix‐PIXE analyses at 3 MeV with Si (Li) detector”

Reply to comment on “Limitation of uranium and thorium traces in charnockite matrix‐PIXE analyses at 3 MeV with Si (Li) detector”

Reply to comment on “Limitation of uranium and thorium traces in charnockite matrix‐PIXE analyses at 3 MeV with Si (Li) detector”

Limitation of uranium and thorium traces in charnockite matrix-PIXE analyses at 3 MeV with Si (Li) detector

In the geochemical analysis of charnockite matrix, PIXE results do not show either the minor or traces of thorium and uranium even though they are present in that charnockite composition. Because of a continuous range of elements in charnockite composition and characteristic X-rays of some elements present at similar to characteristic X-rays of thorium and uranium. Therefore, Th and U traces quantification are limited due to the interferences in the PIXE spectrum at similar characteristic X-ray energies of the elements. Otherwise, it is possible for quantification, if the composition does not contain the elements at similar characteristic X-rays of Th and U or using complementary techniques.

Batch and column studies of radium, actinium, thorium and protactinium on CL resin in nitric acid, hydrochloric acid and hydrofluoric acid

CL resin (TrisKem International) was characterized for separations of radium, actinium, thorium and protactinium. Batch studies are presented for radium, actinium and thorium in HCl and HNO3 as well as for radium, thorium and protactinium in HF. The uptake of thorium from dilute HNO3 (≤ 10−4 M) and dilute HCl (≤ 10−4 M) was found to be very high (Dw > 100 in HNO3 and > 1000 in HCl). Kinetics studies on thorium were performed in HCl and HNO3 to determine suitably for column separations. Six column separation studies are presented including the separation of trace thorium from radium and actinium in dilute HCl and HNO3, the separation of radium from 1 mg 232Th in dilute HCl, the separation of thorium and radium in the presence of HCl and excess Cl−, the separation of radium, protactinium and thorium by retention of protactinium and the separation of protactinium and thorium by retention of thorium.

“Super moiety”-phosphoramidate in task-specific ionic liquids for effcient thorium separation through hybrid interaction

Replacing conventional solvents by ionic liquids is a promising route to greener nuclear fuel cycles. Here, we report a unique multi-functional task-specific ionic liquid (TSIL) for the extraction and separation of trace thorium (Th). The phosphoramidate substituted butyl groups to imidazolium ionic liquid (PN-TSIL) shows superior extraction ability and selectivity (distribution rations of Th ~ 8302 and separation factor of Th to uranium (U) ~ 793 at 2 mol/L HNO3). For industial application purpose, an extraction chromatographic resin perpared by PN-TSIL (called PN-TSIL Resin) was made to develop a rapid, highly specific separation technique for simulative 229Th/233U separation process. Moreover, combination of spectroscopic investigations, quantum-mechanical calculations and thermodynamic parameters mearsurment, an unprecedented resolution picture of extraction process was delineated. The extraction ability and selectivity of thorium could be explained by the multiple binding sites though hybrid interactions (coordination and hydrogen bond) between thorium and PN-TSIL, leading to an entropy-driven extraction process. The understanding of solvent extraction mechanism in molecular scale will inspire new ways for TSIL design for nuclear fuel cycles.

Removal of trace thorium(IV) from aqueous solutions using a pseudo-polyrotaxane

Abstract The adsorption of thorium(IV) was studied using a pseudo-polyrotaxane, which was obtained by the reaction of poly(propyleneglycol) (PPG) and 6-OTs-β-CD. The adsorption of thorium(IV) was examined as a function of the contact time, pH of the solution, adsorbent dose, concentration of thorium(IV) and temperature using batch adsorption experiments. The experimental results suggested that the optimum conditions were found to be at pH 3.5, contact time 40 min, 10 mg adsorbent doses, 20 mg L−1 thorium(IV) concentration and 298 K. The maximum adsorption capacity was found to be 15.366 mg g−1. The thermodynamic parameters (ΔG 0<0, ΔH 0<0) were calculated, the result showed that the adsorption of thorium(IV) was exothermic and spontaneous process.

Adsorption of trace thorium(IV) from aqueous solution by mono-modified β-cyclodextrin polyrotaxane using response surface methodology (RSM)

The adsorption of thorium(IV) was studied using a novel supramolecular polyrotaxane based on β-cyclodextrin derivatives. The effects of pH, contact time, Th(IV) initial concentration and adsorbents dosage on the adsorption of thorium(IV) by polyrotaxane were optimized using Box–Behnken design of response surface methodology. Analysis of variance and correlation coefficients showed that the predicted model was consistent with the experimental data well. The adsorption best fitted to the Langmuir model indicated that the adsorption process happened on homogeneous surface. The thermodynamic parameters (∆G 0 < 0, ∆H 0 > 0, ∆S 0 > 0) demonstrated that the adsorption of Th(IV) ions onto polyrotaxane was spontaneous and endothermic.

Separation and determination of trace thorium in uranium matrix using chelation ion chromatography

ABSTRACTA simple chromatographic method for the determination of trace thorium in uranium matrix has been reported after studying the retention behavior of U(VI) and Th(IV) as their 2,6-pyridine dicarboxylic acid (PDCA) complexes on a reversed phase column. The method does not require pre-separation of uranium matrix. A mobile phase consisting of PDCA, KNO3, and HNO3 in 5% methanol was used. A calibration plot was constructed in the presence of uranium matrix (r2 = 0.9978). The precision of the method is 5% at 1 ppm of Th and LOD was obtained at 0.1 ppm (S/N =3). The accuracy of the method was checked by comparing the results with neutron activation analysis.

Study on adsorption of trace thorium(IV) using 6-o-monotosyl-deoxy-β-cyclodextrin inclusion complex of dibenzoyl

The adsorption of thorium(IV) [Th(IV)] was studied using a novel 6-o-monotosyl-deoxy-β-cyclodextrin inclusion complex of dibenzoyl (inclusion complex), which was acquired by the reaction of dibenzoyl and 6-OTs-β-CD with the mole ratio of 1:2. The adsorption of Th(IV) onto inclusion complex were investigated as a function of pH value, contact time, temperature, interfering ions and Th(IV) concentration using batch adsorption technique. The maximum adsorption of Th(IV) and the equilibrium adsorption capacity were found to be 89 ± 1 % and 17.83 mg g−1 respectively at pH 3.0, equilibrium time 20 min and initial Th(IV) concentration 20 mg L−1. Adsorption kinetics, adsorption isotherm and thermodynamics were carried out.

Separation of thorium ions from wolframite and scandium concentrates using graphene oxide.

The separation of rare metals from the ores and commercially available compounds is an important issue due to the need of their high purity in advanced materials and devices. Important examples of two highly important elements that co-exist in the ores are scandium and thorium. Scandium containing ores and consequently also commercially available scandium compounds often contain traces of thorium which is very difficult to separate. We used graphene oxide for the selective sorption of thorium ions from scandium and thorium mixtures originating from the mined ores as well as from commercially available scandium salts. Our results showed that graphene oxide has an extreme affinity towards thorium ions. After the sorption process the graphene oxide contained over 20 wt% of thorium while the amount of scandium sorbed on GO was very low. This phenomenon of high sorption selectivity of graphene oxide can be applied in industry for the purification of various chemicals containing scandium and for separation of thorium containing mixtures. Alternatively, this methodology can be used for preconcentration of thorium from low-grade ores and its further use in the new generation of nuclear reactors.

Mass spectrometric determination of uranium and thorium traces in aerosols, collected over Russian territory after “Fukushima-1” accident

Secondary Ion Mass-Spectrometry was used to detect the isotopes 238U and 232Th in aerosols, sampled after damage of the “Fukusima-1” atomic station. The isotopes present only on the surface of the particles, so, fuel assemblages were melted, and they penetrated into environment through the gaseous phase without leakage of a solid substance in the form of primary aerosols. The presence of 232Th is treated as a sign of 233U production.

Flow-Injection Potentiometry by Poly(vinyl chloride)-Membrane Electrodes with Diphosphoryl-dicarboxylicacid-p-tert-butylcalix[4] arene Ionophore for the Determination of Th(IV) Ions

A new coated ion-selective electrode for the determination of trace thorium ions by flow-injection potentiometry (FIP) has been developed. A poly(vinyl chloride) (PVC)-based membrane was coated on a graphite electrode. The optimum membrane contained 5 wt% diphosphoryl-dicarboxylicacid-p-tert-butylcalix[4]arene (L) as the ionophore, 59 wt% dioctyl phthalate (DOP), 33 wt% PVC and 3 wt% additive sodium tetraphenylborate. The response was linear from 2.0 × 10(-7) to 1.0 × 10(-2) M with a slope of 13.9 mV decade(-1) and a limit of detection of 9.0 × 10(-8) M. The pH-independent region ranged from 3.15 to 6.5, and the lifetime was longer than 8 weeks when used in the flow injection analysis (FIA) system. Selectivity coefficients for several ions were obtained by the separate solutions method. Results showed that, for all cations used, the selectivity coefficients were in the order of 10(-3), or smaller. The flow cell is simple to construct and free from memory effect problems over long periods of use. The proposed sensor was successfully applied to the direct determination of thorium in both real and synthetic samples.

Solvent Extraction Separation of U (VI), Th (IV) and Cd (II) from Chloride Media by Trioctylmethylammonium Chloride and Bis (2-ethylhexyl) Phosphate

Solvent Extraction Separation of U (VI), Th (IV) and Cd (II) from Chloride Media by Trioctylmethylammonium Chloride and Bis (2-ethylhexyl) Phosphate Solvent extraction of U (VI), Th (IV) and Cd (II) from chloride solutions with trioctylmethylammonium chloride (TOMACl), bis (2-ethylhexyl) phosphate (D2EHPA) and dimethylformamide in cyclohexane was investigated. The effect of the extractant, organic diluents, as well as HCl concentration on the extraction process was carried out. The influence of various stripping agents has also been investigated. The optimum conditions for separation of U (VI), Th (IV) and Cd (II) was found to be using 0.2 M trioctylmethyl ammonium chloride in cyclohexane in which uranium, cadmium and traces of thorium were extracted, and then uranium was stripping with H2O. The analysis was done using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The complete process of separation was carried out and the yield of U (VI) and Th (IV) was evaluated with percentage of recovery of 83 ± 2.5% and 75 ± 3% respectively.

Selective preconcentration of trace thorium from aqueous solutions with Th(IV)-imprinted polymers prepared by a surface-grafted technique

A novel ion-imprinted adsorbent for selective solid phase extraction of thorium(IV) based on the surface of silica gel was prepared by a surface-grafted technique with methacrylic acid (MAA) as a functional monomer. After removal of Th(IV) ions with 3 mol L−1 HCl solution, the obtained imprinted particles for Th(IV) exhibited specific recognition and relatively rapid kinetic process. The maximum static and total dynamic adsorption capacity of the ion-imprinted polymers (IIPs) for Th(IV) was 33.2 and 17.3 mg g−1, respectively. A comparison of the selectivity coefficient of the imprinted polymers with that of non-imprinted polymers showed that the imprinted matrix for Th(IV)/U(VI), Th(IV)/Ce(III), Th(IV)/La(III) and Th(IV)/Zr(IV) was 58.8, 107, 106.4 and 151.7 times greater than non-imprinted matrix, respectively. With a series of samples loading flow rate of 3 mL min−1 for preconcentration, an enrichment factor of 14.6 and the detection limit of 0.59 µg L−1 were obtained. The relative standard deviation of the method under optimum conditions was 2.1% (n = 7). The developed method was successfully applied to the determination of trace Th(IV) in real water samples with satisfactory results.

Purification of lanthanides for large neutrino detectors: Thorium removal from gadolinium chloride

Metal-loaded liquid scintillators are the detectors of choice for various neutrino experiments. Procedures have been developed to transfer metals into organic liquids by solvent extraction or direct dissolution of a metallic compound. Traces of natural radioactivity introduced into the scintillator with the metal may produce undesirable backgrounds. Measurements using a 229Th tracer indicate that the inclusion of a pH-controlled partial hydrolysis and filtration prior to the preparation of a gadolinium-loading compound can reduce thorium by a factor of ∼100. This “self-scavenging” procedure has the advantage that it uses only reagents encountered in the production process. Addition of non-elemental scavengers such as iron, or the use of solvent extraction or ion exchange procedures can be avoided. It also improves the optical transmission in the blue region by removing traces of iron. This purification method has potential applications to the large-scale production of other metal-loaded liquid scintillators and for the removal of traces of thorium in the industrial production of lanthanides.

Selective solid-phase extraction of trace thorium(IV) using surface-grafted Th(IV)-imprinted polymers with pyrazole derivative

A new pyrazole derivative 1-phenyl-3-methylthio-4-cyano-5-acrylicacidcarbamoyl-pyrazole (PMTCAACP) was synthesized and chosen as a complexing monomer for the preparation of surface-grafted ion-imprinted polymers for selective solid-phase extraction of thorium(IV). The silica gel, modified with maleic anhydride, was prepared as a carrier material. In the ion-imprinting process, Th(IV) was complexed with PMTCAACP, and then imprinted in the polymers grafted to the surface of modified silica gel. Subsequently, the template Th(IV) ions were removed with 6 mol/L HCl solution. The obtained ion-imprinted particles for Th(IV) showed specific recognition, and rapid adsorption and desorption kinetics process. The maximum static and total dynamic adsorption capacity of the ion-imprinted polymers (IIPs) for Th(IV) was 64.8 and 37.4 mg/g, respectively. The relative selectivity coefficient values of the imprinted adsorbent for Th(IV)/U(VI), Th(IV)/Ce(III), Th(IV)/La(III), and Th(IV)/Zr(IV) were 72.9, 89.6, 93.8, and 137.2 times greater than non-imprinted matrix, respectively. The interference effect of common cations tested did not interfere with the recovery of Th(IV). The enhancement factor of 20.2, the detection limit of 0.43 microg/L, and the precision of 2.47% (n=7) of the method under the optimized conditions were obtained. Additionally, the calibration curve (r=0.9993) was linear in the range of 1.43-103 microg/L of thorium(IV). The prepared IIPs were shown to be promising for solid-phase extraction coupled with UV-vis spectrophotometry for determination of trace Th(IV) in real samples.

The Recovery of Trace Thorium from Large Quantities of Uranium

This work describes the chromatographic separation of trace amounts of Thorium (mg or less) from large quantities of Uranium (g or kg). The separation method employs extraction chromatographic materials containing tetra(n‐octyl)diglycolamide (TODGA) and quaternary amine extractants. Applications of this separation include isolation of 234Th from 238U and 229Th from 233U. 234Th could be a useful radiotracer, providing a continuous supply of radiothorium from natural or depleted uranium, while 229Th is the source material for 225Ac and 213Bi, radionuclides with promising applications in nuclear medicine.

Estudo de metais e de substâncias tóxicas em brinquedos

The main goal of the present study is the analysis of toxic elements in plastic toys commercialized in Brazil. Metals like cadmium, lead, chromium, zinc, and aluminum, along with organic substances, such as phthalates, were identified in different toys by quantitative analytical techniques. Traces of thorium were detected in one of the studied samples. Although the measured radioactive dose was rather low, the presence of such a radioactive contaminant is against to the International Agency of Atomic Energy regulations. Similar toys manufactured in Brazil were analyzed and found to observe the standards defined by the National Institute of Metrology (Inmetro).