• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.269.1-269
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• 2001

• Journal of Radiation Protection and Research
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• v.24 no.1
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• pp.1-7
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• 1999

Using the TBP slovent extraction method, a simple and precise method for determining uranium isotopes in the environment samples was developed. The soil sample was decomposed with $HNO_3$ and HF. Uranium isotopes were extracted with 15% TBP in $CCl_4$ from aqueous phase to organic phase, and Th fraction was removed with 8M HCl. Uranium fraction was purified in back extraction step with 1M HCl. Optimized electrode position conditions of uranium Isotopes were set using a new electrode position solution including a DTPA chelating agent. The new method of uranium isotopes determination was validated with a result of application to IAEA Reference Soils.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2109-2113
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• 2014

Solvent extraction of Fe(III) from chloride solution by using a mixture of D2EHPA (Di-(2-ethylhexyl)-phosphoric acid) and TBP (Tri-butyl phosphate) and the reductive stripping of Fe(III) from the loaded organic were investigated. Quantitative extraction of Fe(III) from the solution (Fe concentration = 90 g/L) was accomplished in two cross-current extraction stages by using the mixture of D2EHPA and TBP. In order to facilitate the stripping efficiency, a reductive stripping method was employed by using $H_2SO_3$ or $Na_2SO_3$ as a reducing agent. The addition of $H_2SO_4$ into reducing agents led to improvement in the stripping efficiency while high concentration acid would suppress it. Both of the mixtures of $H_2SO_4+H_2SO_3$ and $H_2SO_4+Na_2SO_3$ showed good efficiency for the stripping of Fe(III), while the latter was recommended as the stripping solution based on the economics and experimental condition.

• Resources Recycling
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• v.25 no.2
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• pp.3-9
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• 2016

Separation of Zr(IV) and Hf(IV) from sulfuric acid solutions was investigated by extraction with several acidic extractants such as Versatic acid, LIX 63, and Cyanex 301. From strong sulfuric acid solutions, the separation of Zr(IV) and Hf(IV) by Versatic acid and LIX 63 was not possible, while selective extraction of Hf(IV) over Zr(IV) was obtained with Cyanex 301. However, the extraction percentage of the two metals was much lower compared to that by D2EHPA. Mixing of TBP with Cyanex 301 and D2EHPA led to negative effect on the extraction and separation of the two metal ions. The difference in the extraction reaction and separation selectivity between HCl, $HNO_3$ and $H_2SO_4$ media with each extractant was discussed.

• Nuclear Engineering and Technology
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• v.32 no.4
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• pp.309-315
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• 2000

The changes of Np oxidation state in nitric acid and the effect of nitrous acid on the oxidation state were analyzed by spectrophotometry, solvent extraction, and electrochemical methods. An enhancement of Np extraction to 30 vol.% TBP was carried out through adjustment of Np oxidation state by using a glassy carbon fiber column electrode system. The information of electrolytic behavior of nitric acid was important because the nitrous acid affecting the Np redox reaction was generated during the electrolytic adjustment of the Np oxidation state. The Np solution used in this work consisted of Np（V) and Np（Ⅵ）without （IV）. The composition of Np（V) in the range of 0.5M -5.5 M nitric acid was 32% ~ 19%. The electrolytic oxidation of Np（V) to Np（Ⅵ）in the solution enhanced Np extraction efficiency about five times higher than the case without the electrolytic oxidation. It was confirmed that the nitrous acid of less than about 10-5 M acted as a catalyst to accelerate the chemical oxidation reaction of Np（V) to Np（Ⅵ）.

• Applied Chemistry for Engineering
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• v.5 no.1
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• pp.121-126
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• 1994

To elucidate the effect on the reactive extraction of acetic acid, various carriers and modifiers were investigated. Carriers used were secondary and tertiary amines and solvation extractant. Diluent was n-butylacetate. Modifiers were 4-nonylphenol, TBP(Tti-n-butyl phospate) and isodecanol. Besides the effect of temperature and pH in aqueous phase were studied. The mixture of 50% tri-n-octyl/n-decylamine tertiary amine, gave higher degree of extraction and selectivity than other extractants in the extraction of acetic acid. It was found that 4-nonylphenol as modifier fairly good. The degree of extraction was higher with decreasing the pH in aquous phase and the temperature of extraction system.

• Resources Recycling
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• v.26 no.1
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• pp.51-58
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• 2017

The present study to develop a process for extracting nitric acid and gold from aqua regia leach solution using TBP(tributyl phosphate) was conducted. The pure aqua regia was used to investigate the extractive behavior of nitric acid depending on the concentration of extractant, concentration ratio of nitric and hydrochloric acid. The extraction rate of nitric acid and gold from the gold bearing aqua regia was also examined. The theoretical extraction number was verified by counter current using the number of operations and the phase ratio obtained from McCabe-Thiele diagram. Stripping experiments were carried out for continuous recovery of nitric acid and gold in loaded organic. Considering the effect of extraction acid and gold, the simulation showed that greater than 99.9% extraction of $103.0mg{\cdot}L^{-1}$ gold and 98.0% of $151.2g{\cdot}L^{-1}$ nitric acid could be attained in a two and three-stage counter-current extraction at an O/A phase ratio of 1:0.85. Distilled water and sodium thiosulfate were used as the nitric acid and gold stripping solution. The stripping rates were 99.5% and 92.0%, respectively. The study revealed that the recovery of nitric acid and gold from gold bearing aqua regia was a plausible approach through simultaneous extraction and continuous stripping of nitric acid and gold.

• Resources Recycling
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• v.22 no.5
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• pp.29-34
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• 2013

Solvent extraction experiments were performed to separate platinum and rhodium from mixed chloride solution by using tri 2-ethylhexyl amine (TEHA) and its mixture with TBP and LIX 63. Effects of extraction conditions on the separation of the two metals were investigated as a function of extractant concentration in the HCl concentration range from 1 to 9 M. The concentration of Pt (IV) and Rh(III) was controlled to $1{\times}10^{-3}M$ and $2{\times}10^{-4}M$, respectively. In the extraction with TEHA and its mixture, Pt was quantitatively extracted irrespective of HCl concentration, while the extraction percentage of Rh depended on the extraction condition. When the concentration of HCl in the mixed solution was low, the extraction of Rh was nil and separation of Pt and Rh was possible. Adding TBP to TEHA had little effect on the extraction of both metals, while adding LIX63 to TEHA favored the extraction of Rh.

• Resources Recycling
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• v.32 no.1
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• pp.21-32
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• 2023

Because the application of lithium has gradually increased for the production of lithium ion batteries (LIBs), more research studies about recycling using solvent extraction (SX) should focus on Li⁺ recovery from the waste solution obtained after the removal of the valuable metals nickel, cobalt and manganese (NCM). The raffinate obtained after the removal of NCM metal contains lithium ions and other impurities such as Na ions. In this study, we optimized a selective SX system using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as the extractant and tri-n-butyl phosphate (TBP) as a modifier in kerosene for the recovery of lithium from a waste solution containing lithium and a high concentration of sodium (Li⁺ = 0.5 ~ 1 wt%, Na⁺ = 3 ~6.5 wt%). The extraction of lithium was tested in different solvent compositions and the most effective extraction occurred in the solution composed of 20% D2EHPA + 20% TBP + and 60% kerosene. In this SX system with added NaOH for saponification, more than 95% lithium was selectively extracted in four extraction steps using an organic to aqueous ratio of 5:1 and an equilibrium pH of 4 ~ 4.5. Additionally, most of the Na⁺ (92% by weight) remained in the raffinate. The extracted lithium is stripped using 8 wt% HCl to yield pure lithium chloride with negligible Na content. The lithium chloride is subsequently treated with high purity ammonium bicarbonate to afford lithium carbonate powder. Finally the lithium carbonate is washed with an adequate amount of water to remove trace amounts of sodium resulting in highly pure lithium carbonate powder (purity > 99.2%).

• Proceedings of the Korean Nuclear Society Conference
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• 2003.05a
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• pp.306-306
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• 2003