• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4664-4670
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• 2023

Radiation is the main safety issue for almost all nuclear applications, which must be controlled to protect living organisms and the surrounding materials. In this context, radiation shielding materials have been investigated and used in nuclear technologies. The choice of materials depends on the radiation usage area, type, and energy. Polymer materials are preferred in radiation shielding applications due to their superior characteristics such as chemical inertness, resistivity, low weight, flexibility, strength, and low cost. In the presented work, ABS polymer material, which is possibly the most commonly used material in 3D printers, is mixed with Gd₂O₃ and Er₂O₃ nanoparticles. ABS filaments containing these rare-earth elements are then produced using a filament extruder. These produced filaments are used in a 3D printer to create shielding samples. Following the production of shielding samples, SEM, EDS, and gamma-ray shielding analyses (including experiments, WinXCOM, GEANT4, and FLUKA) are performed. The results show that 3D printing technology offers significant enhancements in creating homogeneous and well-structured materials that can be effectively used in gamma-ray shielding applications.

• Analytical Science and Technology
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• v.16 no.3
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• pp.206-211
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• 2003

The DC polarograms of some rare earth elements have been investigated in various pH solution and electrolytes. Samarium ion has two well-defined reduction waves at -1.75 V and -1.95 V in 0.1 M NaCl solution and those are a diffusion controlled in nature. Europium and ytterbium ions give also two step reduction waves at -0.75 V and -1.95 V for europium and -1.45 V and -2.00 V for ytterium in $(C_2H_5)_4NCl$ solution. On the other hand, lantanium and neodium ions show a single reduction wave at -1.75 V. The differences of half wave potentials between europium, ytterium and samarium ions make it possible to determine each ions in the mixed solution sponteniously. In case of europium ion, the stability constants for the complexs of $Eu^{3+}$-EDTA and $Eu^{3+}$-DTPA are evaluated.

• Journal of the Korean Chemical Society
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• v.33 no.3
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• pp.304-308
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• 1989

The spectrophotometric determination of $Lu^{3+},\;Eu^{3+}$ and some other rare earths have been investigated using Methyl Thymol Blue(MTB) as spectrophotometric reagent. Rare earth elements form a stable complex with MTB abount pH 6.5 and the ratio of its complex is 1 to 1. MTB has a absorption maxima at 440nm and rare earth MTB complex has absorption maxima 610nm at pH 6.5, respectively. The absorbance of the rare earth MTB complex is stable in 7 hours after color developing and obey the Beer law in the range of $0{\sim}110{\mu}g/50ml$. The ligand such as phosphate, citrate and EDTA decrease the absorbance of its complex considerably, and this method has a poor selectivity of each rare earth element and the molar absorptivity is $1.2{\sim}2.0{\times}10^4mol^{-1}{\cdot}l{\cdot}cm^{-1}$. In methyl alcohol, ethyl alcohol and acetone medium we did not find out any absorption change of the rare earth MTB complex.

• Analytical Science and Technology
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• v.18 no.5
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• pp.369-375
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• 2005

The differential pulse anode stripping voltammograms of some rare earth elements and their complexes with catechol have been investigated in various pH and electrolytes. In a 0.1 M LiCl and pH 5.3 solution, $Euv^{3+}$ and $Pr^{3+}$ showed a single oxidation peak at -0.2 V and the oxidation currents were linearly increased with the concentration of those ions. $Tm^{3+}$, $Tb^{3+}$, $Yb^{3+}$ and $Sm^{3+}$ showed two oxidation peaks at -0.5 V and -0.2 V and the oxidation currents at -0.5 V were increased with the concentration increase of those ions. The linear range of those calibration curves was in 1 ppm-10 ppm. In the case of voltammograms of catechol complexes of rare earth elements, $Tb^{3+}$-catechol and $Eu^{3+}$-catechol complex showed a single oxidation peak at -0.95 V and -0.65V, respectively and $Sm^{3+}$-catechol, $Pr^{3+}$-catechol, $Tm^{3+}$-catechol and $Yb^{3+}$-catechol complexes showed two oxidation peaks. The linear range of the calibration curves of those complex was 0.1 ppm~1.0 ppm.

• Economic and Environmental Geology
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• v.31 no.4
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• pp.297-310
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• 1998

Geochemical characteristics of environmental toxic elements at the Narim mine area were investigated on the basis of major, minor, rare earth element geochemistry and mineralogy. Ratios of $Al_2O_3/Na_2O$ and $K_2O/Na_2O$ in soils and sediments range from 11.57 to 22.21 and from 1.86 to 3.93, and are partly negative and positive correlation against $SiO_2/Al_2O_3$ (3.41 to 4.78), respectively. These suggested that sediment source of host granitic gneiss could be due to rocks of high grade metamorphism originated by sedimentary rocks. Characteristics of some trace and rare earth elements of V/Ni (0.33 to 1.95), Ni/Co (2.00 to 6.50), Zr/Hf (11.27 to 53.10), La/Ce (0.44 to 0.55), Th/Yb (4.07 to 7.14), La/Th (2.35 to 3.93), $La_N/Yb_N$ (6.58 to 13.67), Co/Th (0.63 to 2.68), La/Sc (3.29 to 5.94) and Sc/Th (0.49 to 1.00) are revealed a narrow range and homogeneous compositions may be explained by simple source lithology. Major elements in all samples are enriched $Al_2O_3$, MgO, $TiO_2$ and LOI, especially $Fe_2O_3$ (mean=7.36 wt.%) in sediments than the composition of host granitic gneiss. The average enrichment indices of major and rare earth elements from the mining drainage are 2.05 and 2.91 of the sediments and are 2.02 and 2.60 of the soils, normalizing by composition of host granitic gneiss, respectively. Average composition (ppm) of minor and/or environmental toxic elements in sediments and soils are Ag=14 and 1, As=199 and 14, Cd=22 and 1, Cu=215 and 42, Pb=1770 and 65, Sb=18 and 3, Zn=3333 and 170, respectively, and extremely high concentrations are found in the subsurface sediments near the ore dump. Environmental toxic elements were strongly enriched in all samples, especially As, Cd, Cu, Pb, Sb and Zn. The level of enrichment was very severe in mining drainage sediments, while it was not so great in the soils. Based on the EPA value, enrichment index of toxic elements is 8.63 of mining drainage sediments and 0.54 of soils on the mining drainage. Mineral composition of soils and sediments near the mining area were partly variable being composed of quartz, mica, feldspar, amphibole, chlorite and clay minerals. From the gravity separated mineralogy, soils and sediments are composed of some pyrite, arsenopyrite, chalcopyrite, sphalerite, galena, goethite and various hydroxide minerals.

• Ocean and Polar Research
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• v.43 no.3
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• pp.165-178
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• 2021

Gadolinium (Gd), one of a rare earth element (REE), has been widely used worldwide since the 1980s, as a resource material for contrast agents injected into examiners of magnetic resonance imaging (MRI) test. The organic complexed form of Gd shows an extremely stable behavior in natural environment (water), so is known that the artificial Gd from medical uses is not removed from the waste water treatment plant (WWTP) and eventually introduced into the ocean through the estuary. Since the 1990s, some previous studies have often been conducted on Gd anomalies in natural water and their effects an artificial origin from land or metropolitan areas, but little research has been potential impacts on the ocean water. In this paper, we review and introduce recent studies related to Gd anomaly in natural water and related marine effects, and also propose the future research directions.

• Resources Recycling
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• v.24 no.4
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• pp.67-75
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• 2015

The content distributions of some rare metals and rare earthe metals in coal ash (fly ash, bottom ash and pond ash) and leachate from coal-fired power plants were investigated. In case of Yttrium (Y) and Neodymium (Nd) which were strategic critical elements, their contents were ranged from about 23 ~ 75 mg/kg and it is shown they are worth to be developed for the recovery and separation method. Considering the annual amount of fly ash and bottom ash and pond ash, coal-fired power plants have great value of about 1,670 billion KRW and it is regards they are worthy as urban mines.

• Korean Journal of Metals and Materials
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• v.56 no.12
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• pp.870-877
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• 2018

Cyanex 272 shows the highest separation factor for the rare earth elements from hydrochloric acid solution among the organophosporus acidic extractants, D2EHPA and PC 88A. Solvent extraction of Tb(III) from weak hydrochloric acid solution with an initial pH 3 to 6 was compared with Cyanex 272, its mixture with Alamine 336, and ionic liquid with Aliquat 336. The solvent extraction reaction of Tb(III) using Cyanex 272 was the same as that of light rare earth elements. Synergism was observed for the extraction of Tb(III) by the mixture with Alamine 336 when the initial concentration ratio of Cyanex 272 to Alamine 336 was higher than 5. Use of the ionic liquid led to a great increase in the extraction percentage of Tb(III) from the same initial extraction conditions. While the equilibrium pH of the mixture was always lower than the initial pH, under some conditions extraction with the ionic liquid resulted in a higher equilibrium pH than the initial pH. The loading capacity of the mixture and the ionic liquid was the same and 2.6 times larger than that using Cyanex 272 alone. Ionic liquid was recommended as a suitable extractant for the extraction of Tb(III) from hydrochloric acid solution based on the ease of handling and higher extraction percentage.

• Economic and Environmental Geology
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• v.56 no.3
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• pp.259-275
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• 2023

Pan African granitoids of Kaiama is comprised of K-feldspar rich granites, porphyritic granites, and granitic gneiss that are intruded by quartz veins and aplitic veins and dykes which trend NE-SW. In order to establish the geochemical signatures, petrogenesis, and tectonic settings of the lithological units, petrological, petrographical, and geochemical studies was carried out. Petrographic analysis reveals that the granitoids are dominantly composed of quartz, plagioclase feldspar, biotite, and k-feldspar with occasional muscovites, sericite, and opaque minerals that constitute very low proportion. Major, trace, and rare earth elements geochemical data reveal that the rocks have moderate to high silica (SiO₂=63-79.7%) and alumina (Al₂O₃=11.85-16.15) contents that correlate with the abundance of quartz, feldspars, and biotite. The rocks are calc-alkaline, peraluminous (ASI=1.0-<1.2), and S-type granitoids sourced by melting of pre-existing metasedimentary or sedimentary rocks containing Al, Na, and K oxides. They plot dominantly in the WPG and VAG fields suggesting emplacement in a post-collisional tectonic setting. On a multi-element variation diagram, the granitoids show depletion in Ba, K, P, Rb, and Ti while enrichment was observed for Th, U, Nd, Pb and Sm. Their rare-earth elements pattern is characterized by moderate fractionation ((La/Yb)_N=0.52-38.24) and pronounced negative Eu-anomaly (Eu/Eu^*=0.02-1.22) that points to the preservation of plagioclase from the source magma. Generally, the geochemical features of the granitoids show that they were derived by the partial melting of crustal rocks with some input from greywacke and pelitic materials in a typical post-collisional tectonic setting.

• Journal of the Korean Chemical Society
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• v.14 no.3
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• pp.257-261
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• 1970

Some factors such as the weight ratio, reaction time and temperature for the separation of rare earth elements from monazite are studied. The influence of the inorganic phosphate for the leaching is also studied.