• Bulletin of the Korean Chemical Society
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• 제15권12호
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• pp.1035-1037
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• 1994

An ultrasensitive and selective stripping voltammetric scheme for the determination of rhodium is described. By the use of combined accumulation and catalytic effects in formaldehyde-hydrochloric acid medium, substantial improvement in the limit of detection can be obtained. Optimal experimental conditions were found to be 0.42 M hydrochloric acid solution containing 0.008${\%}$ formaldehyde, an accumulation potential of -0.70 V (vs. Ag/AgCl) and an accumulation time of 20 s. The stripping mode was differential pulse voltammetry. In these conditions the limit of detection lies at 2 ${\times}$ l0$^{-12}$ M (0.21 ppt). The relative standard deviation at 5 ${\times}$ l0$^{-11}$ M was 4.9${\%}$ (n=5). There were no serious interferences from other platinum group metal ions being the tolerable amounts more than 500 times that of rhodium.

• 대한금속재료학회지
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• 제46권4호
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• pp.227-232
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• 2008

Solvent extraction reaction of cobalt by Alamine336 from strong hydrochloric acid solution was identified by analyzing the solvent extraction data reported in the literature. Analysis of the data by graphical method revealed that Alamine336 took part in the solvent extraction reaction as a monomer in the concentration ranges, [Co(II)] : 0.0169 - 0.102 M, [Alamine336] ; 0.02- 1.75 M, and [HCl ] : 5 - 10 M. The following solvent extraction reaction and equilibrium constant was obtained from the experimental data by considering the activity coefficients of chemical species present in the aqueous phase. $Co^{2+}+2Cl^{-}+R_3NHCl_{org}=CoCl_3\;R_3NH_{org}$, $K_{ex}=2.21$ The distribution coefficients of cobalt predicted in this study agreed well with those reported in the literature.

• Corrosion Science and Technology
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• 제14권6호
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• pp.273-279
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• 2015

Effects of passive film quality by chemical passivation and solution flow on the corrosion behavior of 304 stainless steel in HCl solution were investigated using a coloration indicator, and by corrosion weight loss, electrochemical polarization and element dissolution measurements. A high redness degree suggests a low passive-film integrity for 304 stainless steel following air exposure, while the minimum redness degree for the samples after chemical passivation suggests a high passive-film integrity. In the static condition, samples subjected to air exposure exhibited a high corrosion rate and preferential dissolution of Fe. Chemical passivation inhibited the corrosion rate due to the intrinsically high structural integrity of the passive film and high concentrations of Cr-rich oxides and hydroxide. Solution flow accelerated corrosion by promoting both the anodic dissolution reaction and the cathodic reaction. Solution flow also altered the preferential dissolution to fast uniform dissolution of metal elements.

• 자원리싸이클링
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• 제19권5호
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• pp.25-30
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• 2010

CMSX-4 초내열합금의 순환활용을 위한 습식제련기술 개발의 일환으로 영신에서의 니켈, 코벨트, 크롬, 알루미늄 등 주요 구성 금속성분들의 침출 특성을 조사하였다. 염산농도에 따른 합금시료 내 주요 금속성분들의 침출율은 염산농도가 높아짐에 따라 증가하였으나, 3 M 이상에서는 둔화되었다 염산농도 4 M, 고액비 10 g/L, 침출시간 60 분 조건에서 침출온도가 높아짐에 따라 침출율은 급격히 증가하였으며, $90^{\circ}C$에서 니켈 93.2%, 알루미늄 89.9%, 코발트 80.4%, 크롬 79.1%의 침출율을 나타내었다. 한편 침출 초기에는 니켈과 알루미늄의 침출속도가 빠르고 60 분 이후 급격히 둔화되는 형태를 보인 반면 코발트와 크롬은 침출이 느리고 60 분 이후의 감소율만 상대적으로 적었다. 120 분 경과 시 주요 금속원소들의 침출율은 모두 99% 수준에 도달하였다. 고액비가 높아지면 침출율은 서서히 감소하였으며, 니켈과 알루미늄이 코발트와 크롬에 비하여 침출율 감소가 적었다. 염산농도 4 M, 침출온도 $90^{\circ}C$, 침출시간 120 분의 조건에서 고액비 125 g/L 이하의 조건이 주요 금속 성분의 침출에 효과적임을 확인하였으며, 이는 CMSX-4 합금의 금속학적 조직구조와 관련이 있는 것으로 생각된다.

• 공업화학
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• 제29권2호
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• pp.215-224
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• 2018

염산 5, 10, 15 wt% 용액(1.5, 3.0, 4.5 M; 석유정 산성화에 사용되는 범위)에 대하여 여러 가지 조건에서 자기장이 미치는 영향을 연구하였다. 자화된 염산의 pH 변화를 정상적인 염산과 비교하였다. Taguchi 실험 설계법을 사용하여 자장강도, 농도, 유속, 온도 및 시간의 영향을 모델링하였다. 실험 결과 자화에 따라 염산의 $H^+$ 농도가 42%까지 감소하였다. 자장 강도(기여도 28%), 염산의 농도(기여도 42%), 유속이 커지면 자기장 적용의 효과가 증가하였다. 염산에 대한 자기장의 영향은 용액의 유속과 가열에 의하여 영향받지 않았으며 시간에 따른 자기장 메모리가 유지되는 것으로 나타났다. 최대 $H^+$ 농도 변화에 대한 최적의 조합은 10% 염산 용액 및 4,300 Gauss일 때로 얻어졌다. 자화 과정 중 염산의 반응 속도가 감소하므로 자화된 염산은 탄화수소(원유 및 천연가스)정의 매질 산성화에 대한 대체 지연제로 비용면에서 경제적이고 신뢰성 있는 방법이 될 것으로 제안한다.

• 한국세라믹학회지
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• 제22권1호
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• pp.35-39
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• 1985

Synthetic mica $NaMg_{2.5}(Si_4O_{10})F_2 (Na-TSM)$ was treated with HCl solution and H-type exchange resin to investigate the chemical stability and the ion exchange by measuring the dissolution of chemical components and the exchanged $H^+$ ion. The replacement of $Na^+$ ion occurred in contact with HCl solution and H-type ion exchange resin at the surface of Na-TSM particles reached $Na^+$ ions at maximum value of 70~80%. $Mg^{2+}$ ion of octahedral layer became to dissolve from the pH2 solution and th amount of it dissolved in-creased almost proportional to $H^+$ ion concentration from around 0.02N $H^+$ ion equilibrium concentration. The crystalline structure of Na-TSM was destructed by dissolution of Mg2+ ion in cncentrated hydrochloric acid solution and resulted silica gel precipitation.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.113-116
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• 2011

Slope analysis method was applied to determine the stoichiometry of the solvent extraction reaction of Ni(II) by Alamine336 from strong HCl solution range from 1 to 10 M. Solvent extraction data was obtained from the literature. The effective equilibrium constant for the solvent extraction reaction was estimated by considering the ionic equilibria of $NiCl_2$ in the HCl solution. The measured distribution coefficients of Ni(II) agreed well with those calculated in this study. Our results suggest that further study on the measurement of the activities of nickel complexes at high HCl solution need to be done.

• 한국표면공학회지
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• 제19권1호
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• pp.13-19
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• 1986

Manganese in the Anode slime and the paste-positive material of waste-dry cell was recovered by leaching with the hydrochloric acid solution. The impurities (Zn, Fe, Pb), co-leached with manganese were removed from the leached solution prior to electrolysis by hydrometallurgical techniques such as the neutralization with ammonium hydroxide and cementation on manganese powder. The electrodeposition of manganese from the purified chloride solution with sodium selenate was performed. Cathode current efficiency was found to be affected significantly by the concentration of sodium selenate and ammonium chloride salt, bath temperate, current density and PH. The current efficiency of about 88.7% was obtained by electrolysis manganese chloride solution with sodium selenate (0.1/g) at 10$^{\circ}C$.

• 자원리싸이클링
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• 제14권1호
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• pp.55-63
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• 2005

This study investigated the electrochemical recovery of palladium in a HCl solution that is used for palladium leaching. The high acidity of HCl solution and the low concentration of Pd ions increased the cathodic overpotential and reduced the limiting current density. Lowering the current density produced dense deposits; however, they were under high tensile stress. Raising the temperature affected both the densification and the stress, which enabled the attainment of dense Pd deposits under low stress. Lowering the current density and raising the temperature up to 70$^{\circ}C$ was recommended for the recovery of palladium as sound bulk Pd deposits. Current efficiency was over 85% at the initial stage of recovery may decrease the current efficiency, since a low Pd ion concentration results in a low limiting current density.

• 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.