• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1564-1568
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• 2011

A solvent extraction separation, preconcentration and determination of thorium with a new crown, 2-ethyl-N-benzyl-4,7,10,13,16-pentaoxa-1-azacyclooctadecane (MACE), is described in the study. The amount of thorium in the aqueous phase and organic phase was determined by Inductively Coupled Plasma-Optical Emission Spectroscopy and Ultraviolet-Visible, respectively. Thorium loaded organic phase was quantitatively stripped in a stage by using 1.0 M $HNO_3$. Thorium was effectively extracted with MACE in the pH range of 6-7 to produce a 3:2 complex ratio in the chloroform. A highly sensitive and rapid spectrophotometric method was described for determination of trace amounts of thorium with MACE. The effective molar absorption coefficient at 281 nm is $1.98{\times}10^3\;mol^{-1}cm^{-1}$, and the system complies with Beer's law in the range from 0.464 to 2.32 ${\mu}gm\;L^{-1}$ of thorium. Thorium was also determined in standard and environmental samples.

• Analytical Science and Technology
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• v.10 no.5
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• pp.307-314
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• 1997

Inductively coupled plasma atomic emission spectrometry(ICP/AES) was used for the determination of uranium and thorium in geological materials. Samples were predecomposed by mixed acid digestion technique. The separation of the uranium and thorium was achieved by systematic solvent extraction with TTA(thenoyltrifluoroacetone) and TOA (tri-n-octylamine) and back extraction into HCl. The results for standard rock sample, NIST SRM 278, showed a good agreement with those certified from NIST as well as found values by other non-destructive techniques. Additional purification for extracted portions was carried out by anion exchange chromatography for measurement of several natural radioisotopes of uranium and thorium by alpha spectrometry.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.631-640
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• 2019

Thorium ($^{232}Th$) is four times more abundant than uranium in nature and has become a new important source of energy in the future. This is due to the ability of thorium to undergo the bombardment of neutron to produce uranium-233 ($^{233}U$). The aim of this study is to investigate the production cost of thorium oxide ($ThO_2$) resulted from the thorium extraction process. Four main parameters were studied which include raw material and chemical cost, total capital investment, direct cost and indirect cost. These parameters were justified to obtain the final production cost for the thorium extraction process. The result showed that the raw material costs were $63,126.00 - $104,120.77 (0.5 ton), $126,252.00 - $178,241.53 (1.0 ton), and $1,262,520.00 - $1,782,415.33 (10.0 tons). The total installed equipment and total cost investment were estimated to be approximately $11,542,984.10 and $13,274,431.715 respectively. Hence, the total costs for producing 1 kg $ThO_2$ were $6829.79 - $6911.78, $3540.95 - $3592.94, and $501.18 - $553.17 for 0.5, 1.0, and 10.0 tons respectively. The result concluded that with higher mass production, the cost of 1 kg $ThO_2$ would be reduced which in this scenario, the lowest production cost was $$501.18kg^{-1}$-$$553.17kg^{-1}$ for 10.0 tons of $ThO_2$ production.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1560-1569
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• 2022

Liquid fueled molten salt reactors (MSRs) have seen renewed interest because of their inherent safety features, higher thermal efficiency and potential for efficient thorium utilisation for power generation. Thorium fluoride is one of the salts used in liquid fueled MSRs employing Th-U cycle. In the present study, ThF₄ was prepared by hydro-fluorination of ThO₂ using anhydrous HF gas. Process parameters viz. bed depth, hydrofluorination time and hydrofluorination temperature, were optimized for the preparation of ThF₄ in a static bed reactor setup. The products were characterized with X-Ray diffraction and experimental conditions for complete conversion to ThF₄ were established which also corroborated with the yield values. Hydrofluorination of ThO₂ at 450 ℃ for half an hour at a bed depth of 6 mm gave the best result, with a yield of about 99.36% ThF₄. No unconverted oxide or any other impurity was observed. Rietveld refinement was performed on the XRD data of this ThF₄, and Chi2 value of 3.54 indicated good agreement between observed and calculated profiles.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.94-98
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• 2008

A fundamental study was developed concerning the novel solvent extraction of the tetravalent metal ions; zirconium(IV), hafnium(IV) and thorium(IV). Their extraction behavior in toluene was investigated with a recently synthesized naphthol-derivative Schiff base, 1-({[4-(4-{[(E)-1-(2-hydroxy-1-naphthyl)methyliden]amino}phenoxy) phenyl]imino}methyl)-2-naphthol (HAPMN). The spectrophotometrical examination of the complex formation between HAPMN and the Zr(IV), Hf(IV) and Th(IV) ions in acetonitrile revealed the formation of stable 1:1 complexes in the solution. After the thorium extraction in toluene, it was found that [Th(OH)3HA] was the respective deriving substance. While, in the case of zirconium and hafnium extraction, the extracted adduct was found to be [M4(OH)8(H2O)16Cl62HA]. The stoichiometric coefficients of these extracted species were determined by the slope analysis method. The extraction reaction followed a cation exchange mechanism.

• Resources Recycling
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• v.30 no.5
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• pp.32-37
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• 2021

Thorium extraction and possible separation from monazite leaching solution was studied. Primary amine Primene JM-T was select ed for t horium ext ract ion processing. Various experiment s were t est ed and est ablished for t he t horium liquid -liquid extraction process. The screening of extractant, lower pH conditions, extractant variation and extraction isotherms construction, and finally, stripping studies were established.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.2926-2936
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• 2021

Rare-earth (RE) industries generate a massive amount of radioactive residue containing high thorium concentrations. Due to the fact that thorium is considered a non-economic element, large volume of these RE processed residues are commonly disposed of without treatment. It is essential to study an appropriate treatment that could reduce the volume of waste for final disposition. To this end, this research investigates the applicability of carbon-based adsorbent in separating thorium from aqueous phase sulphate is obtained from the cracking and leaching process of solid rare-earth by-product residue. Adsorption of thorium from the aqueous phase sulphate by carbon-based electrodes was investigated through electrosorption experiments conducted at a duration of 180 minutes with a positive potential variable range of +0.2V to +0.6V (vs. Ag/AgCl). Through this research, the specific capacity obtained was equivalent to 1.0 to 5.14 mg-Th/g-Carbon. Furthermore, electrosorption of thorium ions from aqueous phase sulphate is found to be most favorable at a higher positive potential of +0.6V (vs. Ag/AgCl). This study's findings elucidate the removal of thorium from the rare-earth residue by carbon-based electrodes and simultaneously its potential to reduce disposal waste of untreated residue.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2418-2425
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• 2021

Monazite is a phosphate mineral that contains thorium (Th) and rare earth elements. The Th concentration in monazite can be as high as 500 ppm, and it has the potential to be used as fuel in the nuclear power system. Therefore, this study aimed to conduct the techno-economic analysis (TEA) of Th extraction in the form of thorium oxide (ThO₂) from monazite. Th can be extracted from monazite through an alkaline fusion method. The TEA of ThO₂ production studied parameters, including raw materials, equipment costs, total plant direct and indirect costs, and direct fixed capital cost. These parameters were calculated for the production of 0.5, 1, and 10 ton ThO₂ per batch. The TEA study revealed that the highest production cost was ascribed to installed equipment. Furthermore, the highest return on investment (ROI) of 21.92% was achieved for extraction of 1 ton/batch of ThO₂, with a payback time of 4.56 years. With further increase in ThO₂ production to 10 ton/batch, the ROI was decreased to 5.37%. This is mainly due to a significant increase in the total capital investment with increasing ThO₂ production scale. The minimum unit production cost was achieved for 1 ton ThO₂/batch equal to 335.79 $/Kg ThO₂.

• Analytical Science and Technology
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• v.17 no.4
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• pp.302-307
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• 2004

Determination of actinides in the environmental sample requires separation of each element. This procedure is tedious and time consuming. And also, the detection limits of some nuclides using alpha spectrometry are rather higher. To overcome the lower detection limit and complicated separation procedure, a simple analytical technique for the determination of actinide isotopes in the environmental samples was developed and applied to IAEA and NIST reference sediment samples. For the separation of actinides from matrix, anion exchange resin and TRU-spec extraction chromatography resin were used and chemical yields were obtained using natural uranium, thorium, $^{242}Pu$ and $^{243}Am$ tracers. For overcoming the higher detection limits of U and Th in alpha spectrometry, neutron activation analysis was applied. Using combined method, the detection limit was increased about 10 times. The activity values of each isotope were consistent with the reference values reported by IAEA and NIST.