• Resources Recycling
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• v.31 no.1
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• pp.21-28
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• 2022

The smelting reduction of spent lithium-ion batteries results in metallic alloys of cobalt, nickel, and copper. To develop a process to separate the metallic alloys, leaching of the metallic mixtures of these three metals with H₂SO₄ solution containing 3% H₂O₂ dissolved all the cobalt and nickel, together with 9.6% of the copper. Cyanex 301 selectively extracted Cu(II) from the leaching solution, and copper ions were completely stripped with 30% aqua regia. Selective extraction of Co(II) from a Cu(II)-free raffinate was possible using the ionic liquid ALi-SCN. Three-stage cross-current stripping of the loaded ALi-SCN by a 15% NH₃ solution resulted in the complete stripping of Co(II). A process was proposed to separate the three metal ions from the sulfuric acid leaching solutions of metallic mixtures by employing solvent extraction.

• Resources Recycling
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• v.29 no.4
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• pp.67-72
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• 2020

Recycling processes of spent copper wires cosisnt of several steps of cutting and chopping processes for peeling covering materials followed by gravity separation processes, where copper is recovered. Because copper thin wires could be lost during further recycling processes, the wire may need to be further treated. In the present study, the copper thin wire was treated with ball milling to prevent the loss. Since the aggregation of the copper wire could be formed by bending and entangling the copper wire each other, the degree of flexion of the copper wire was measured after ball milling. When the 0.5 cm and 3 cm copper wires were used, the 0.5 cm copper wire was not bent and the 3 cm copper wires were aggregated regardless of the ball addition. When the 1 cm and 2 cm copper wires were used, the degree of flexion was remarkable when the balls were added. In the tests using 2 cm copper wires, the aggregation ratio of the copper wire gradually increased with the amount of the 20 mm alumina ball, and when 200 ml of 30 mm alumina ball was used, the aggregation ratio increased to 89.29 %, but after increasing the ball amount further, the aggregation ratio decreased. Thus, it is expected that the loss of the copper wire could be reducedif when the copper thin wire is treated with ball milling by the aggregation of copper thin wires.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.122-125
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• 2004

본 연구는 친환경적 유기흡착제로서 휴믹물질의 활용성을 평가하기 위한 기초 연구로서 Peat moss에서 추출된 불용성 휴믹성분인 피트휴민(p-Humin)을 충진한 컬럼을 이용하여 카드뮴과 구리이온에 대한 파과곡선을 얻었고, 각 금속이온에 대한 제거능을 비교해 보았다. 카드뮴의 경우, 파과시간은 7.5 hr, 77 BV로 나타났으며, 구리의 경우, 7.3 hr, 76 BV으로 나타났다. Thomas model로부터 구한 최대 흡착량은 구리가 44.66 mg/g로 카드뮴의 41.61 mg/g보다 높게 나타났다. 0.05 N HNO$_3$를 이용한 탈질실험 결과, 각 중금속에 대한 회수율은 95% 이상으로 높았다.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.8
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• pp.844-851
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• 2005

The purpose of this study was to determine feasibility of application of regenerated or recycled $TiO_2$ on the successive treatment of Cu(II)-EDTA. The recovery of copper, the reuse of $TiO_2$ and the assessment of acute toxicity was studied in the total eight successive photocatalytic reactions. Aqueous solution of $10^{-4}\;M$ Cu(II)-EDTA was treated using an illuminated $TiO_2$ at pH 6 in a circulating reactor. Two different procedures were applied in the reuse of $TiO_2$: i) recycle of $TiO_2$ without acid wash ii) regeneration of $TiO_2$ with acid wash to remove adsorbed copper in a previous experiment. The averaged decomplexation rate constant($k'_{obs}$) of Cu(II)-EDTA in recycle of $TiO_2$ without acid wash was approximately 45% less than that in regeneration of $TiO_2$ with acid wash. Removal of Cu(II) was near complete after 180 minutes in the total eight successive photocatalytic reactions using the regenerated $TiO_2$ after acid wash. In contrast, removal of Cu(II) was minimum at total fifth successive photocatalytic oxidation using the recycled $TiO_2$ without arid wash. The recovered $TiO_2$ was approximately 86% in average in each procedure. The recovered Cu(II) was 67.9% in average. The acute relative toxicity of the treated water rapidly declined at an initial reaction time up to 60 minutes but little declination was observed after 60 minutes due to little degradation of DOC. Relative toxicity of treated water using the recycled $TiO_2$ without acid wash we some what well correlated with the concentration of dissolved Cu(II). From this work, it is suggested that Cu(II)-EDTA can be effectively treated using an integrated cyclic photocatalytic oxidation with recovery of $TiO_2$ and Cu(II).

• Resources Recycling
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• v.21 no.5
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• pp.3-17
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• 2012

Selective leaching processes for copper, gold, nickel, and cobalt have been investigated because there is an advantage of ammoniacal hydrometallurgy that metal such as copper could be selectively extracted restricting the dissolution of iron or calcium. In the present article, the studies for selective ammoniacal leaching of copper from motor scraps and waste printed circuit boards (PCBs), for ammoniacal leaching of gold to decrease the amount of cyanide used or to substitute cyanide by thiosulfate, and for ammoniacal leaching to recover nickel and cobalt from nickel oxide ore and intermidiate obtained from manganese nodule treatment process were summarized and further studies were proposed for domestic technology development for ammoniacal hydrometallurgy processes.

• Resources Recycling
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• v.12 no.2
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• pp.3-10
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• 2003

Copper oxychloride used as an agricultural fungicide has been recovered from copper-containing waste etchant by the neutralization with alkali hydroxides. Large amount of copper-containing waste etchant is generated from Printed Circuit Board industry. In an environmental and economic point of view, retrieve of the valuable natural resource from the waste is important. Recycling process of copper oxychloride from the waste etchant is discovered through the our study. In the range of reaction temp. 2$0^{\circ}C$-4$0^{\circ}C$, pH 5-7, pure copper oxychloride was able to prepare and the yield of copper oxychloride was higher than 95%. Physical properties of the sample have been characterized using SEM, XRD, TGA, ICP and Atomic absorption spectroscopy.

• Korean Journal of Environmental Agriculture
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• v.16 no.1
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• pp.48-54
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• 1997

This study was performed to develop the biological treatment technology of wastewater polluted with heavy metals. The copper-tolerant bacteria, Pseudomonas stutzeri which possessed the ability to accumulate copper, was isolated from mine wastewaters polluted with various heavy metals. The characteristics of copper accumulation in the cells and the recovery of the copper from the cells accumulating zinc, were investigated. Removal rate of copper from the solution containing 100mg/l of copper by copper-tolerant bacteria was more than 78% at 2 days after inoculation with the cells. A large number of the electron-dense granules were found mainly on the cell wall and cell membrane fractions, when determined by transmission electron microscopy. Energy dispersive X-ray spectroscopy revealed that the electron-dense granules were copper complex with the substances binding copper. The copper accumulated into the cells was not desorbed by deistilled water, but more than 80% of the copper accumulated was desorbed by 0.1M-EDTA solution. The residues of the cells after combustion at $550^{\circ}C$ amounted to about 23.2% of the dry weight of the cells. EDS analysis showed that residues were relatively pure copper compound containing more than 78.4% of copper.

• Journal of Food Hygiene and Safety
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• v.34 no.2
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• pp.191-198
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• 2019

This study investigated the residual characteristics of bifenthrin and chlorothalonil in crown daisy and suggested pre-harvest residue limits (PHRLs) based on their dissipation patterns and biological half-lives. The samples for residue analysis were harvested at 0 (3 hr), 1, 3, 5, 7, 9, 11, 13, 15, 18, 22 and 26 days after treatment, and analyzed by $GC/{\mu}-ECD$ and TOF/MS. The limit of quantitation (LOQs) of bifenthrin and chlorothalonil were 0.0046 mg/kg and 0.0007 mg/kg, respectively. Recoveries ranged from $88.67{\pm}7.97%$ and $99.90{\pm}16.03%$, showing that this method is appropriate for the analysis of the pesticide residues in crown daisy. Being well within first order kinetics, the biological half-lives of the pesticide residues in crown daisy were 9.63 days for bifenthrin and 6.54 days for chlorothalonil. The PHRLs of bifenthrin and chlorothalonil were recommended as 11.70 mg/kg and 24.10 mg/kg for 26 days before harvest, respectively.

• Resources Recycling
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• v.24 no.1
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• pp.66-72
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• 2015

Various waste PCBs arose during disassembly of LCD TVs and monitors in which they originally functioned for transmission of imaging signal, power supply, and imaging control. In those functional PCBs, gold and copper are contained at far more acceptable level, exceeding mining grade ores. Those valuable metals and their contents widely vary with functionality and end use of PCBs. Therefore, compositional analysis of individual waste PCBs from disassembled LCD TVs and monitors were performed in the present study to classify them into three categories: high gold yield and low gold yield PCBs and those without gold contents. Besides, additional chemical analysis was made to reveal gold and copper contents in the waste PCBs arising from actual disassembly/separation of end-of-life LCD TVs and monitors.

• Resources Recycling
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• v.23 no.1
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• pp.64-69
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• 2014

For the recovery of Co and Cu, bioleaching behavior of Co, Cu, Fe, Mg, Al by Aspergillus niger culture from the molasses growth medium was investigated. Series of leaching tests have been conducted by varying Aspergillus niger's type, molasses concentration in the growth medium, pulp density and reaction time. The results showed that increase of the molasses concentration in the growth medium from 1% to 4% increased the leaching percentage of Co and Cu and the optimal molesses concentration was found to be 4% in the growth medium. Maxinum 90% of Co and 70% of Cu were dissolved from the leaching test at the 10 g/L pulp density, 4 % of molasses concentration in the growth medium after 21 days by Aspergillus niger KCTC 6985. But in case of using Aspergillus niger KCTC 6144, the maxium leaching percentage of Co and Cu was reached 90% respectively at a pulp density 5 g/L and 4% of molasses concentration.