• 유기물자원화
• /
• 제9권1호
• /
• pp.127-133
• /
• 2001

미분해 유기물이 다량 존재하는 매립초기에 발생되는 침출수는 미생물에 의한 혐기성 소화가 진행됨에 따라 침출수중의 유황성분이 유황환원세균 등에 의해 황화물이온으로 환원되고, 이것이 금속이온의 양보다 과잉으로 많을 경우 sol화된 금속황화물이 되어 침출수를 검은색으로 변색시킴을 알 수 있었으며, 이들은 검은색의 입자상 물질을 형성하여 침전물을 생성함을 알 수 있었다. 따라서 이와 같은 침출수 처리를 위해 과잉의 황화물이온을 당량이상의 금속이온과 반응시킨다면 부동태화시킬 수 있다는 향후의 경제적 효율적인 처리를 위한 중요한 가능성을 확인할 수 있었다.

• 분석과학
• /
• 제6권1호
• /
• pp.47-55
• /
• 1993

구리 착물을 수은 방울 전극에 흡착시키는 방법을 이용하여 음극 벗김 전압전류법으로 황화이온 존재하에서 미량의 시안화물을 효과적으로 정량할 수 있는 방법을 연구하였다. 염화칼륨과 인산염의 완충 용액(pH=7.0) 중에서 구리 이온 농도를 $1.0*10^{-3}M$로 유지하고서 석출 전위 -0.30V, 석출 시간 3.0분에서 약 500배의 황화이온이 있을 때 시안화이온의 검출 한계는 $2.0*10^{-7}M$이었다.

• 방사성폐기물학회지
• /
• 제21권1호
• /
• pp.43-53
• /
• 2023

Sulfide concentrations critically affect worker safety and the integrities of underground facilities, such as deep geological repositories for spent nuclear fuel. Sulfide is highly sensitive to oxygen, which can oxidize sulfide to sulfate. This can hinder precise measurement of the sulfide concentration. Hence, a literature review was conducted, which revealed that two methods are commonly used: the methylene blue and sulfide ion-selective electrode (ISE) methods. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used for comparison with the two methods. The sulfide ISE method was found to be superior as it yielded results with a higher degree of accuracy and involved fewer procedures for quantification of the sulfide concentration in solution. ICP-OES results can be distorted significantly when sulfide is present in solution owing to the formation of H₂S gas in the ICP-OES nebulizer. Therefore, the ICP-OES must be used with caution when quantifying underground water to prevent any distortion in the measured results. The results also suggest important measures to avoid problems when using ICP-OES for site selection. Furthermore, the sulfide ISE method is useful in determining sulfide concentrations in the field to predict the lifetime of disposal canisters of spent nuclear fuel in deep geological repositories and other industries.

• Bulletin of the Korean Chemical Society
• /
• 제22권1호
• /
• pp.53-58
• /
• 2001

Sulfonated poly(phenylene sulfide) (SPPS) polymers were prepared by sulfonation of poly[methyl[4-(phenylthio) phenyl]sulfonium trifluoromethanesulfonate] (PPST) with fumic sulfonic acid (10% $SO_3-H_2SO_4$) and demethylation with aqueous NaOH solution. The equilibrium constants of ion exchange reactions between alkali metal cations ($Li^+,\;Na^+,\;and\;K^+$) and SPPS ion exchanger in organic solvents such as tetrahydrofuran (THF) and dioxane were measured. The equilibrium constants of ion exchange reactions increased as the polarity of the solvent increased, and the reaction temperature decreased. The equilibrium constants of the ion exchange reaction ($K_{eq}$) also increased in the order of $Li^+,\;Na^+,\;and\;K^+$. To elucidate the spontaneity of the exchange reaction in organic solvents, the enthalpy, entropy, and Gibbs free energy were calculated. The enthalpy of reaction ranged from -0.88 to -1.33 kcal/mol, entropy ranged from 1.42 to 4.41 cal/Kmol, and Gibbs free energy ranged from -1.03 to -2.55 kcal/mol. Therefore, the exchange reactions were spontaneous because the Gibbs free energies were negative. The SPPS ion exchanger and alkali metal ion bounding each other produced good ion exchange capability in organic solvents.

• 한국재료학회지
• /
• 제32권12호
• /
• pp.545-552
• /
• 2022

Tin-antimony sulfide nanocomposites were prepared via hydrothermal synthesis and a N₂ reduction process for use as a negative electrode in a sodium ion battery. The electrochemical energy storage performance of the battery was analyzed according to the tin-antimony composition. The optimized sulfides exhibited superior charge/discharge capacity (770 mAh g^-1 at a current density of 100 mA g^-1) and stable lifespan characteristics (71.2 % after 200 cycles at a current density of 500 mA g^-1). It exhibited a reversible characteristic, continuously participating in the charge-discharge process. The improved electrochemical energy storage performance and cycle stability was attributed to the small particle size, by controlling the composition of the tin-antimony sulfide. By optimizing the tin-antimony ratio during the synthesis process, it did not deviate from the solubility limit. Graphene oxide also acts to suppress volume expansion during reversible electrochemical reaction. Based on these results, tin-antimony sulfide is considered a promising anode material for a sodium ion battery used as a medium-to-large energy storage source.

• 대한화학회지
• /
• 제36권5호
• /
• pp.638-643
• /
• 1992

황화이온검출기로서 2가지 형태의 연속 flow-through 전극계의 분석적 감응성질을 조사하고, 최적조건에서 그들의 감응특성을 직접 비교하였다. 두 검출계에 있어서 측정한 봉우리전위를 황화이온농도의 대수값과 관련지웠으며, 적어도 시간당 20개의 시료를 정량할 수 있었다. pH전극법에서는 투석기를 지나 흘러가는 recipient stream의 pH를 측정하였다. 장치는 연속흐름형의 기체투석기가 관형 polymer 막전극과 연결되도록 설계되어 있다. 이 방법의 최적실험조건은 recipient $5.0 {\times} 10^{-5} M NaOH ＋ 5.0 {\times} 10^{-3} M$ NaCl과 diluent 0.10M $H_2SO_4$이며, recipient stream, diluent stream 및 시료의 유속은 모두 1.0ml/min이다. 황화이온 전극법에서는 시판하는 황화이온선택성 전극을 flow-through cell 속의 황화이온을 검출하는 데에 썼다. 이 방법의 최적실험조건인 황화이온 산화방지 완충제(1.0M NaOH 용액에 3.5g 아스코르브산과 7.6g $Na_2EDTA$를 용해)와 시료의 유속은 각각 1.4 ml/min와 1.0 ml/min이다.

• 대한화학회지
• /
• 제11권1호
• /
• pp.38-43
• /
• 1967

In order to explain the positive catalytic action of copper compound for the rate of leaching of zinc sulfide minerals, the electrode and redox potentials of both synthetic and natural sulfides were measured at various conditions of temperatures and pressures. The potentials of Chalcopyrite and copper sulfide were considerably higher than that of zinc sulfide, whereas lead sulfide and Galena had slightly lower potentials than that of zinc sulfide. At elevated temperatures and pressures, the same tendency was obtained. By means of comparing the calculated and measured values of potentials for sulfides, it was suggested that the electrode potentials in acid solution were generated by oxidation of sulfur ion. As a result, it was concluded that the catalytic action of copper compound in the leaching of synthetic zinc sulfide should be arised from the galvanic action between sulfides keeping intimate contact one another in which copper sulfide worked as cathodic and zinc sulfide as anodic part analogous to the metal corrosion under galvanic action.

• Applied Biological Chemistry
• /
• 제2권
• /
• pp.9-14
• /
• 1961

The formation of sulfide from sulfate has been discussed from the thermodynamic principles. No mechanism of the reaction has been presented. From the stoichiometric and Nernst equations for the conversion of sulfate into sulfide, it was concluded that the formation of sulfide from sulfate can take place more readily if pH of a medium is low. The difficulty of this conversion increases with increasing pH. As pH of a medium increases, the degree of dissociation of H₂S into S= increases and this, in turn, renders the chance of precipitation of sulfide as FeS easier. Higher the pH of a soil or medium, greater is the S= concentration. The concentration of ferrous ion required to remove dissolved sulfide in a medium by forming insoluble FeS decreases with increasing pH. From the theory it was pointed out that an application of lime and iron rich foreign substances to a soil may be effective in causing the removal of dissolved sulfide from solution.

• 한국결정성장학회지
• /
• 제33권6호
• /
• pp.203-209
• /
• 2023

차세대 나트륨이온전지용 음극 소재로 유망한 코발트 황화물 나노복합체를 간단한 수열법을 통해 합성하였다. 본 연구에서는 배터리의 전기화학적 에너지 저장 성능 향상을 위해 코발트 황화물 나노입자와 환원된 산화그래핀과 복합화 된 코발트 황화물 나노복합체를 제조하여 비교해주었다. 제조된 나노복합체 전극은 가역적이고 안정적인 사이클 성능(전류밀도 200 mA g^-1에서 30 사이클 후 62 %)을 보였다. 개선된 전기화학적 특성은 수열합성 과정에서 코발트 황화물의 입자 크기가 작고 균일하게 분포되어 나트륨 이온의 확산 경로를 극대화함에서 기인하였다. 뿐만 아니라 전환 반응 중 음극재의 박리 및 부피 팽창을 효과적으로 억제함으로써 차세대 나트륨이온전지용 유망한 음극 소재로써의 가능성을 보여주었다.

• 한국환경과학회지
• /
• 제9권5호
• /
• pp.437-441
• /
• 2000

A study on the removal of Pb ion from Pb-contaminated soil was carried out using ex-site extraction process. Tartaric acid (TA) and iminodiacetic acid sodium salt(IDA) as a washing agent were evaluated as a function of concentration reaction time mixing ratio of washing agent and recycling of washing agent. TA showed a better extraction performance than IDA. The optimum washing condition of TA and IDA were in the ratio of 1:15 and 1:20 between soil and acid solution during 1 hr reaction. The total concentrations of Pb ion by TA and IDA at three repeated extraction were 368.8 ppm and 267.5 ppm respectively. The recovery of Pb ion from washing solution was achieved by adding calcium hydroxide and sodium sulfide form the precipitation of lead hydroxide and lead sulfide and optimum amounts of sodium sulfide and calcium hydroxide were 7 g/$\ell$ for the TA washing solution and 4 g/$\ell$, 5g/$\ell$ for the IDA washing solution respectively. The efficiency of recycle for TA and IDA washing solution were 78.8% , 95.1%, and 89.2%, 96.6% at third extractions under $Na_2S$ and $Ca(OH)_2$, respectively.