• Resources Recycling
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• v.24 no.3
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• pp.44-50
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• 2015

Recycling technologies would be required in consideration of increasing demand in lithium ion batteries (LIBs). In this study, the leaching behavior of Ni, Co and Mn is investigated with ammoniacal medium for spent cathode active materials, which are separated from a commercial LIB pack in hybrid electric vehicles. The leaching behavior of each metal is analyzed in the presence of reducing agent and pH buffering agent. The existence of reducing agent is necessary to increase the leaching efficiency of Ni and Co. The leaching of Mn is insignificant even with the existence of reducing agent in contrast to Ni and Co. The most conspicuous difference between acid and ammoniacal leaching would be the selective leaching behavior between Ni/Co and Mn. The ammoniacal leaching can reduce the cost of basic reagent that makes the pH of leachate higher for the precipitation of leached metals in the acid leaching.

• Journal of Radiation Protection and Research
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• v.27 no.1
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• pp.27-35
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• 2002

Characteristics of Amberlite IRN 77, a cation exchange resin, and the mechanisms of its adsorption equilibria with Co(II), Ni(II), Cr(III) and Fe(III) ions were investigated for the application of the demineralizing process in the primary coolant system of a pressurized water reactor (PWR). The optimum dosage of the resin for removal of the dissolved metal ions at $200mgL^{-1}$ was 0.6 g for 100 mL solution. Most of each metal ion was adsorbed onto the resin in an hour from the start of the reaction. Each metal adsorption onto the resin could be well represented by Langmuir isotherms. However, in the case of Fe(III) adsorption, continuous formation of Fe-oxide or -hydroxide and its subsequent precipitation inhibited the completion of the equilibrium between the metal and the adsorbent Cobalt(II) and Ni(II), which have an equivalent electrovalence, were adsorbed to the resin with a similar adsorption amount when they coexisted in the solution. However, Cr(III) added to the solution competitively replaced Co(II) and Ni(II) which were already adsorbed onto the resin, resulting in desorption of these metals into the solution. The result was likely due to a higher adsorption affinity of Cr(III) than Co(II) and Ni(II). This implies that the interactively competitive adsorption of multi-cations onto the resin should be fully considered for an efficient operation of the demineralizing ion exchange process in the primary coolant system.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.6
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• pp.717-729
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• 1999

Although many studies on the cytotoxicity of the dental cast base metal alloys and their components have been carried out, the results are rather conflicting because of the different type of cells used and the various experimental procedures taken. Recently a number of scientists have claimed that it would be preferable to focus on the use of cells from relevant specific location of the human bodies. Consequently, the primary cultured oral keratinocyte derived from oral mucous along with nickel chloride and several of widely used dental cast base metal alloys(two Ni-Cr alloys and one Co-Cr alloy)in domestic were selected for this study, from which 1) The amounts of released metal ions were determined using atomic absorption spectrometry, 2) The cytotoxicity of nickel chloride and dental cast base metal alloys was evaluated via MTT assay, and finally, 3) The amounts of released metal ions and the cytotoxicity of nickel chloride were correlated with the cytotoxicity of dental cast base metal alloys And, the results were summarized as follows; 1. Nickel ion from Ni-Cr alloys and Cobalt ion from Co-Cr alloys resulted in maximum releasing rate during first 2h hours, followed by a decrease in releasing rate with time. Chromium ion were found to be minimal in all alloys. 2. In cytotoxic test. with $40{\mu}M,\;80{\mu}M$ of nickel chloride, there were observed an increase in the relative cell number compared to control samples after 24 hours. With $160{\mu}M$, there was found to be no difference in the relative cell number with control, except that 48 hour showed a increase in relative cell number. With $320{\mu}M$, the relative cell number remained constant and decreased after 48 hours, and with $640{\mu}M$, a continuing decrease in relative cell number was observed throughout test period. 3 The sensitivity of primary cultured oral epithelium to nickel was lower compared to the cells used in other studies. 4. CB-80 Soft and Regalloy showed no cytotoxicity to primary cultured oral epithelium and New crown resulted in a slight cytotoxicity. In conclusion, it was shown that the primary cultured oral keratinocytes could be applied successfully as testing cells in cytotoxicity test. Futhermore, the dental cast base metal alloys used in this study were found to be biocompatible.

• Clean Technology
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• v.27 no.1
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• pp.33-38
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• 2021

Demand for lithium-based secondary batteries is greatly increasing with the explosive growth of related industries, such as mobile devices and electric vehicles. In Korea, there are several top-rated global lithium-ion battery manufacturers accounting for 40% of the global secondary battery business. Most discarded lithium secondary batteries are recycled as scrap to recover valuable metals, such as Nickel and Cobalt, but residual wastes are disposed of according to the residual lithium-ion concentration. Furthermore, there has not been an attempt on the possibility of water discharge system contamination due to the concentration of lithium ions, and the effluent water quality standards of public sewage treatment facilities are becoming stricter year after year. In this study, the as-received waste water generated from the cathode electrode coating process in the manufacturing of high-nickel-based NCM cathode material used for high-performance and long-term purposes was analyzed. We suggested a facile recycling process chart for waste water treatment. We revealed a correlation between lithium-ion concentration and pH effect according to the proposed waste water of each recycling process through analyzing standard water quality tests and daphnia ecological toxicity. We proposed a realistic waste water treatment plan for lithium electrode manufacturing plants via comparison with other industries' ecotoxicology.

• Journal of the Korean Chemical Society
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• v.25 no.5
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• pp.306-310
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• 1981

Induced circular dichroism spectra of racemic cobalt(III) complexes for $[Co(en)_3]^{3+},\;[Co(tn_)3]^{3+},\;cis-[Co(NH_3)(en)_2]^{3+},\;[Co({\beta}-ala)(en)2_]^{2+},\;[Co(gly)(en)_2]^{2+}\;and\;[Co(acac)(en)_2]^{2+}$ were measured when they were dissolved in aqueous d-tartrate2- solution at room temperature. Only a single negative CD spectrum was observed for all the complexes above in visible region(400∼500nm). It was interpreted that these CD bands were attributed to the difference in interaction between ${\Lambda}$-and ${\Delta}$-enantiomers with d-tartrate$^{2-}$. Namely, when d-tartrate$^{2-}$ was added to ${\Lambda}$-enantiomer and ${\Delta}$-enantiomer, it caused ${\Lambda}$-enantiomer to change greatly and ${\Delta}$-enantiomer to change only slightly; combined the results proved induced circular dichroism. The enantiomer for which the eluent has a stronger affinity should be eluted faster in ion-exchange column chromatography. It is possible to predict the elution order of chromatography from the sign of the induced CD if stronger interaction of chiral anion with the complex leads to greater change in the natural CD spectrum of the complex. The elution order was in complete agreement with the prediction from the sign of the induced CD spectrum for all the measured complexes.

• Applied Biological Chemistry
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• v.11
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• pp.55-61
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• 1969

This K-17 strain was not absolutely requiring xylose as an inducer for enzyme formations. The most activity of this enzyme was lost when treated at $75^{\circ}C$. for 30 hours but was not influenced at $70^{\circ}C$. for 70 hours of treatment. The activity of this enzyme was increased by the addition of magnesium ions or cobalt ions in the reaction system. In the studies, we found that the magnesium ions simply activate the enzyme reaction and the cobalt ions do not but protect the enzyme from heat inactvation. And it was also found the phosphate buffer solution was very suitable as glucose dissolving solvent on the enzyme reaction. The mixed carbon source medium containing glucose, fructose, sorbitol, xylose and sucrose was more favorable for enzyme production then a sole carbon source containing medium on the shaking culture method.

• Progress in Medical Physics
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• v.25 no.1
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• pp.46-52
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• 2014

Liquid ionization chamber is filled with liquid equivalent material unlike air filled ionization chamber. The high density material allow very small-volume chamber to be constructed that still have a sufficiently high sensitivity. However liquid ionization chamber should be considered for both initial recombination and general recombination. We, therefore, studied using the Co-60 beam as the continuous beam and the microLion chamber (PTW) for comparing the ion collection efficiency by Greening theory, two-dose rate method and our experiment method. The measurements were carried out using Theratron 780 as the cobalt machine and water phantom and 0.6 cc Farmer type ionization chamber was used with microLion chamber in same condition for measuring the charge of microLion chamber according to the dose rates. Dose rate was in 0.125~0.746 Gy/min and voltages applied to the microLion chamber were +400, +600 and +800 V. As the result, the collection efficiency by three method was generally less than 1%. In particular, our experimental collection efficiency was in good agreement within 0.3% with Greening theory except the lowest two dose rates. The collection efficiency by two-dose rate method also agreed with Greening theory generally less than 1%, but the difference was about 4% when the difference of two dose rates were lower. The ion recombination correction factors by Greening theory, two-dose rate method and our experiment were 1.0233, 1.0239 and 1.0316, respectively, in SSD 80 cm, depth 5 cm recommended by TRS-398 protocol. Therefore we confirmed that the loss by ion recombination was about 3% in this condition. We think that our experiment method for ion recombination correction will be useful tool for radiation dosimetry in continuous beam.

• Journal of the Korean Chemical Society
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• v.17 no.1
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• pp.15-19
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• 1973

A method was developed for the separation of titanium, niobium and zirconium together in a group from the coexisting ions of various metals such as iron, cobalt, nickel, yttrium and rare earths by means of the cation exchange column using ${\alpha}$-hydroxyisobutyric acid as the eluent. In the course of the present investigation, it was found that the tailing phenomena of zirconium were attributable to the hydroxide precipitation which was made prior to the elution. For example, if zirconium was precipitated by sodium hydroxide, the tailing of zirconium became very serious in contrast to the results reported by others. This paper describes how these tailing phenomena of zirconium were prevented and how a practical procedure for the separation of these ions was, achieved using ion-exchange method. Using the present method the nuclides of $^{90m}Y$ and $^{90}Y$ were separated with radiochemical purity from the irradiated zirconium.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.287-293
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• 2015

This paper discusses quantitative analyses of patents published for cathode active materials for lithium secondary batteries based on layer structure. Numbers of the patents analyzed were 356, 1628, 2915, 439, and 611 for Korea, USA, Japan, Europe, and PCT (WO), respectively. Trends of improved technologies and alternative technologies concerning lithium cobalt, from 1991 to 2012 were examined and the patent shares distribution of each principal countries about lithium secondary battery technologies were also scrutinized. The number of patents for the mixed structure technology and next-generation lithium secondary battery technology increased numerously in 2000. Particularly in 2005, lots of patents were also published and SANYO (34.5%), SONY (17.5%), LG (7%), and SAMSUNG (5.5%) possessed leading patent applicants. Finally, the research focus on cathode active materials for lithium secondary batteries was confirmed by bubble chart distributions for component-by-step process.

• Journal of the Korean Chemical Society
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• v.29 no.5
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• pp.516-521
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• 1985

Ethylenediamine-triacetatocobalt (III) complexes with an ammine, an ethylene-diamine, and a trimethylenediamine as the unidentate ligand were prepared, and were isolated as only one isomer for each case by the Dowex 50W-X8, cation exchange resin in $H^+$ form. The geometrical isomer of these complexes have been assigned cis-equatorial form in the three possible geometrical isomers from the elemental analysis, pH titration, IR, NMR, and electronic absorption spectrum. It was found that $[CoN_3O_3]$ system of the meridional form with multidentate ligand have the first absorption band of the largely splitting pattern, and that the diamines (ethylenediamine, trimethylenediamine) have coordinated to the central cobalt (III) ion as a unidentate ligand.