• 한국재료학회지
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• 제30권8호
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• pp.393-398
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• 2020

We propose a novel stripping solution containing acids (HCl and HNO₃), an oxidant [(NH₄)₂S₂O₈], and complexing agents (NaCl and citric acid) to remove surface passivation layers from 14K gold alloys fabricated using an investment casting process. The optimized solution employing only HCl acid is determined by varying molar fractions of HCl and HNO₃ on 14K yellow gold samples. Stripping properties are also identified for red and white gold alloy samples under the optimized stripping conditions. The removal of passivation layers, weight loss, and microstructure evolution are characterized using Raman spectroscopy, a precision scale, and optical microscopy. The proposed stripping solution effectively removes passivation layers more rapidly than conventional cyanide stripping. Weight loss increases linearly for up to 5 min for all 14K gold alloys. Red gold exhibits the greatest weight loss, followed by yellow gold and white gold. The results of microstructural analysis reveal that the conformal stripping occurs according to time. These results imply that the proposed oxidative chloride stripping might replace conventional cyanide stripping.

• 자원리싸이클링
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• 제17권5호
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• pp.37-43
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• 2008

Alamine336에 추출된 염화 제 2철의 탈거실험을 위해 아황산과 염산 및 황산용액의 농도와 탈거조건을 변화시키며 탈거실험을 수행했다. 염산과 황산용액의 농도가 증가함에 따라 철의 탈거율은 감소했으나, 아황산용액의 경우에는 3M의 농도범위에서 산의 농도에 따라 탈거율이 증가하였다. 탈거온도가 증가하면 아황산용액에 의한 철의 탈거율은 감소하나, 염산용액의 경우에는 탈거율이 증가하였다. 0.5M의 철이 함유된 유기상으로부터 O/A=1/10의 조건에서 0.1 M의 염산의 경우에는 3단에 의해, 0.1M의 황산용액으로는 4단에 의해 0.05M농도의 철이 탈거된 용액을 얻을 수 있는 것을 등온탈거곡선으로부터 알 수 있었다.

• Membrane and Water Treatment
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• 제3권2호
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• pp.123-131
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• 2012

This study investigated the extraction and stripping performance of PIMs consisting of PVC and Aliquat 336. Extraction and stripping of three representative heavy metals - namely $Cd^{2+}$, $Cu^{2+}$, and $Zn^{2+}$ - by the synthesized membranes were evaluated as a function of sodium chloride concentration and under different stripping solutions (0.01 M $HNO_3$, Milli-Q water, 0.01 M HCl and 0.01 M NaOH), respectively. Results reported here indicate that the formation of negatively charged metal chloride complex species was responsible for the extraction of the target metal to PIMs. Experimental results and thermodynamic modeling of the speciation of chloro metal complexes further confirm that the extraction selectivity between $Cd^{2+}$, $Cu^{2+}$ and $Zn^{2+}$ can be controlled by regulating the chloride concentration of the feed solution. An acidic solution without any chloride was the most effective stripping solution, followed by Milli-Q water, and a diluted hydrochloric acid solution. On the other hand, the stripping of metals from PIMs did not occur when a basic stripping solution was used.

• Bulletin of the Korean Chemical Society
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• 제35권7호
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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.

• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2004년도 춘계임시총회 및 제23회 학술대회
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• pp.218-226
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• 2004

Solvent extraction and stripping experiments were conducted to separate iron from a spent $FeCl_3$ etching solution containing nickel. In the extraction, PC88A, MIBK and Alamine336 were tested as an extractant in various diluents. Alamine336 salt in toluene led to the highest extraction percentage of iron. Stripping percentage of iron from the loaded organic by Alamine336 increased with decreasing HCl conentration of stripping solution and with increasing volume ratio of aqueous to organic. In the operation of bench scale mixer-settler, 7 extraction stage with 1.0M Alamine336 salt in toluene and 10 stripping stage with 0.01M HCl solution resulted in a stripped solution with 133g/L of iron and in a raffinate with most of nickel together with a small amount of iron when the flow rate ratio of organic to aqueous was 7.

• 분석과학
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• 제5권4호
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• pp.417-423
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• 1992

음극 벗김 전압전류법을 이용하여 비소(III)의 벗김 봉우리에 대한 금속 이온의 영향에 대하여 조사하였다. 비소(III)의 환원 벗김 봉우리 이론적인 전위값이 -0.84V(vs. Ag/AgCl)인데 비하여, 0.1N- 염산을 사용하였을 때 전위값은 -0.79V(vs. Ag/AgCl)이고, 여기에 구리(II)를 10배 첨가하였을 때 -0.84V로써 이론적인 전위값과 일치하였으며 전류값은 $0.86{\mu}A$로 가장 높게 나타났다. 비소(III)의 벗김 봉우리를 증가시키는 금속이온으로 납(II), 구리(II) 등이 있었고, 특히 구리(II)이온이 비소(III)의 벗김 봉우리를 가장 많이 증가시켰다.

• 대한금속재료학회지
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• 제48권10호
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• pp.929-935
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• 2010

The solvent extraction behavior of Sn(IV) from hydrochloric acid was investigated using Alamine336 (Tri-n-cotylamine) as an extractant. The experimental parameters of the concentration of the HCl solution, chloride ions, extractant, and Sn(IV) were assessed. The results showed that the extraction percentage of Sn(IV) was more than 95% in our experimental range and was only slightly affected by the HCl concentration. The extraction reaction of Sn(IV) by Alamine 336 from the chloride solution was identified as follows: $SnCl_6{^{2-}}+2R_3NHCl_{(org)}=(R_3NH)_2SnCl_{6(org)}+2Cl^-$ and $K=6.3{\times}10^4$. Stripping experiments of Sn(IV) from the loaded organic phase were done by using several stripping agents. A stripping percentage of 90% was obtained with a 2.0 M NaOH solution.

• Journal of Electrochemical Science and Technology
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• 제10권1호
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• pp.14-21
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• 2019

Supported liquid membrane process usually is used for recovering or enrichment of valuable metals in the industrial wastewater. But, even if the metals in the wastewater was separated with high chemical selectivity, it cannot be enough concentrated since separation performance of supported liquid membrane (SLM) process is limited by concentration gradient between feed solution and stripping solution. If metal concentration in the stripping solution to be enough low, transport of metal through membrane can be accomplishment constantly. Therefore, Electrodialysis (ED) has been placed after SLM process and the stripping solution of SLM was used as the feed solution for the ED process. Transport of ions in the solutions is successfully performed by ED process. Thus, the metal concentration in the stripping solution does not rise as to stop ion transport. Besides, valuable metals easily are concentrated by ED process for re-use. In this study, effects of operation parameters like initial Cd(II) concentration, HCl concentration in the feed solution of SLM and applied voltage are investigated on separation efficiency, flux and permeability of the both processes. As the feed solution concentration increased, all performance values has increased. When initial concentration of 100 mg/L is used, separation performances (SP) are 55% and 70%, for SLM and consecutive process, respectively. The best HCl concentration in the feed solution of SLM has determined as 2 M, in this conditions SP are 64% and 72%, for SLM and consecutive process, respectively. With increased of applied voltage on ED process, SP of the consecutive process has been raised from 72% to 83%. According to the obtained experimental data, consecutive process has better separation performance than SLM. When the separation performances of both processes were compared for the same operating conditions, it was determined higher the separation efficiency, permeability and flux values of the consecutive process, 8%, 9% and %10.6, respectively. Consequently, the use of the consecutive process increases the performance efficiency of both processes. The consecutive process studied has quite a good chemical separation efficiency, and enrichment capability. Moreover, this process requires few water and energy.

• 약학회지
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• 제27권1호
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• pp.1-10
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• 1983

Voltammetric deposition and differential pulse anodic stripping (DPASV) of Ge(IV)at a gold electrode was investigated. Germanium (IV) exhibits two stripping peaks by DPASV in sodium borate solution, the first peak at about -1.1v. vs SCE and the second one, in the range of -0.6 to -0.2v. vs SCE. Factors affecting the sensitivity and precision included the nature of working electrode, supporting electrolytes, deposition potential, deposition time, pH, pulse height, voltage scan rate. The relative standard deviation of the measurements of the peak currents, for 100ng/ml Ge(IV), was less than ${\pm}3%$. The detection limit of Ge(IV) was 0.01ng/ml. Percent recovery in the extraction procedure of Ge(IV) from matrices by benzene in c-HCl, followed by back extraction with saturated borax solution, ranged from 96 to 104%.

• 한국생산제조학회지
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• 제25권1호
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• pp.14-20
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• 2016

This paper describes a green stripping process to effectively strip the remaining DFR layer on a non-alkali-based ITO glass surface after an etching process. A stripper, water-soluble amine compound, is used to investigate the characteristics of stripping ability and to suggest a valid method for the green process. Increasing the composition (5-30% concentration) of the ethanol amine-based stripper was found to greatly reduce the stripping time applied in the dipping method. The composition (30%) achieved an excellent stripping effect and free-residue impurities. Additionally, it was possible to obtain the effect of stripping in a way to sustain the release before generating DFR sludge from the ITO glass surface by using dipping condition (stripping time) in the composition. An Additional stripping process (buffering) out of dipping can realize productivity improvement and cost reduction because of the higher proportion of re-use of the stripping solution used in the DFR removal step.