• Economic and Environmental Geology
• /
• v.39 no.6 s.181
• /
• pp.653-662
• /
• 2006

Quartz veins from the Jukwangri area of Hwawon-myeon are epithermal quartz veins that are filling the NW or NE-trending faults within Precambrian metasedimentary rocks. Based on their prolongation and ore grades, No. 1 quartz vein can be traced for about 200 m and varies 0.1 to 3 m in thickness. Mineralization of No. 1 quartz vein can be divided into hypogene and supergene stages. Hypogene stage is associated with hydrothermal alteration minerals(phyllic and argillic zones) such as illite, sericite and sulfides such as pyrite, arsenopyrite, sphalerite. chalcopyrite, galena, argentian tetrahedrite. Supergene stage is composed of Fe-Mn oxide, Zn-Fe oxide and Pb oxide. Fluid inclusion data indicate that homogenization temperature and salinity of hypogene stage range from 187 to $306^{\circ}C$ and ken 0.0 to 6.2 wt.% eq. NaCl, respectively. They suggest that ore forming fluids were progressively cooled and diluted from mixing with meteoric water. Oxygen($-4.1{\sim}4.1%o$) and hydrogen($-107{\sim}-88%o$) isotope com-positions indicated that hydrothermal fluids were derived from meteoric and evolved by progressive mixing with meteoric water during mineralization.

• Korean Journal of Materials Research
• /
• v.8 no.4
• /
• pp.323-327
• /
• 1998

All solid state lithium based rechargeable batteries were fabricated in a cell structure of Li/PEO-$LiCIO_4$-PC /$LIMn_2O_4$$LIMn_2O_4$ thin films were prepared by RF magnetron sputtering and the spinel structure could be obtained by Rapid Thermal Annealing (RT A) process at the temperature of around 750$750^{\circ}C$ . Room temperature cycling of this cell showed a nearly constant cell potential of 4 V( us. Li) and good reversibility.

• Journal of Soil and Groundwater Environment
• /
• v.14 no.1
• /
• pp.44-50
• /
• 2009

The occurrence of endocrine disrupting compounds (EDCs), chemicals that interfere with human hormone system, are increasing in the freshwater, waste water and subsurface as well. In this study, we determined the reactivity of three EDCs in the presence of birnessite. In aqueous phase, bisphenol A, 2,4-dichlorophenol and 17${\beta}$-estradiol, which possesses phenoxy-OH, were very rapidly transformed by birnessite: up to 99% of initial concentrations (50 mg/L for bisphenol A, 100mg/L for 2,4-dichlorophenol, and 1.5mg/L for 17${\beta}$-estradiol) were destroyed within 60 minutes. Especially, bisphenol A was the most reactive chemical, disappearing by 99% in a few minutes. The reaction occurred on the surface of birnessite, showing a linear increase of first-order kinetic constants with the increase of the surface area of birnessite. In soil slurry phase, the reactivity of birnessiteto EDCs was faster than in aqueous phase probably due to the cross coupling reaction of phenoxy radicals with soil organic matter. Considering the rapid transformation of the EDCs in the both phases, this oxidative cross coupling reaction mediated by birnessite would be an effective solution for the remediation of EDCs in environmental media, especially in soil.

• Economic and Environmental Geology
• /
• v.36 no.4
• /
• pp.285-293
• /
• 2003

Tailings of Dukum mine in the vadose and saturated zone were investigated to reveal the mobility of metal elements and the condition of mineralogical solubility according to redox environments throughout the geochemical analysis, thermodynamic modelling, and mineralogical study for solid-samples and water samples(vadose zone; distilled water: tailings=5 : 1 reacted, saturated zone; pore-water extracted). In the vadose zone, sulfide oxidation has generated low-pH(2.72∼6.91) condition and high concentration levels of S $O_4$$^{2-}$(561∼1430mg/L) and other metals(Zn : 0.12∼l57 mg/L, Pb : 0.06∼0.83 mg/L, Cd : 0.06∼l.35 mg/L). Jarosite$(KFe_3(SO_4)_2(OH)_6)$ and gypsum$(CaSO_4{\cdot}2H_2O$) were identified on XRD patterns and thermodynamics modelling. In the saturated zone, concentration of metal ions decreased because pH values were neutral(7.25∼8.10). But Fe and Mn susceptible to redox potential increased by low-pe values(7.40∼3.40) as the depth increased. Rhodochrosite$(MnCO_3)$ identified by XRD and thermodynamics modelling suggested that $Mn^{4+}$ or $Mn^{3+}$ was reduced to $Mn^{2+}$. Along pH conditions, concentrations of dissolved metal ions has been most abundant in vadose zone throughout borehole samples. It was observed that pH had more effect on metal solubilities than redox potential. How-ever, the release of co-precipitated heavy metals following the dissolution of Fe-Mn oxyhydroxides could be the mechanism by which reduced condition affected heavy metal solubility considering the decrease of pe as depth increased in tile saturated zone.

• Applied Chemistry for Engineering
• /
• v.28 no.2
• /
• pp.193-197
• /
• 2017

In this study, we report on the catalyst process installed in conjunction with a wet plasma electrostatic precipitator to remove the oil mist and fine dust emitted from large-size grill restaurants. The multi-stage catalyst module reduced odor through catalytic reaction of acetaldehyde on catalysts even at an ambient temperature with ozone as an oxidant readily produced in a wet plasma electrostatic precipitator. Two types of manganese-based catalysts, $Mn_2O_3$ and $CuMnO_x$ were fabricated by extrusion molding for structured catalysts in practical applications, and the optimum conditions for high removal efficiencies of acetaldehyde and ozone were determined. When two optimized catalysts were applied in a two-stage catalyst module, the removal efficiency of acetaldehyde and ozone were ${\geq}85%$ and 100% respectively at the space velocity of $10,000h^{-1}$ and the reaction temperature of $100^{\circ}C$.

• Resources Recycling
• /
• v.30 no.5
• /
• pp.57-66
• /
• 2021

In this study, we attempted to separate and recover Cu from low-grade copper ore by a hydrometallurgical process. The leaching sample obtained after crushing and sieving by 0.355 mm of low-grade copper ore contained 1.5% Cu, 4.7% Fe, 1.0% Mn, and 0.3% Zn. The Cu in the oxide ore was very well leached into sulfuric acid and 97% Cu leaching efficiency was achieved at 80℃ and 3 M sulfuric acid (H₂SO₄). From the leaching solution, Cu was separated by solvent extraction from Fe, Mn, and Zn using LIX984N. The separation tendency between Cu and other metals was confirmed through the distribution ratio and separation factor. By plotting the McCabe-Thiele Diagram, the optimum condition for recovering Cu is 5 vol.% LIX984N, 2-stage counter-current solvent extraction, and an O/A ratio of 0.5. Using this method, 99% of the Cu was extracted and a CuSO₄ solution was finally obtained that contained 1.6 g/L Cu after the stripping process using 2 M H₂SO₄.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.28 no.1
• /
• pp.15-30
• /
• 2002

최근 화장품 사용인구의 증가와 안전성에 대한 관심 증대에 따라 화장품 중 유해성분 함유에 대한 논란이 종종 있어왔다. 화장품에 대한 전문적 지식이 없는 사람들에 의하여 진행된 잘못된 정보로 인하여 화장품 중에 포함된 모든 중금속이 인체에 심각한 영향을 초래한다는 등의 오해를 불러와 관련 업계에 적지 않은 피해를 주기도 하였다. 이에 본 자료에서는 구체적 근거자료와 연구 논문들을 기반으로 유해한 중금속, 안전하여 사용이 공인된 중금속 등을 조사하여 화장품에서의 중금속의 개념을 정립하고자 하였다. 국내에서는 식품의약품안전청 고시 제2000-27호에 화장품에 포함되었을 때 유해한 중금속으로 납, 비소 및 수은을 명시하고 그 규제농도를 규정하고 있다. 규제 중금속은 아니지만 피부에 알러지를 일으키는 중금속으로는 니켈이 있는데 화장품 중 몇몇 제품군에서 소량(수∼수십ppm) 이 검출되기도 한다. 그러나 이는 일상으로 사용하는 각종 귀금속, 시계, 안경테, 클립, 지퍼 등의 금속 용품에 포함된 니켈의 양(수∼수십%)에 비하여 매우 적은 양이며 정상적인 사람에게는 무해하다. 실제 대다수의 니켈 알러지는 화장품이 아닌 귀금속이나 시계 등의 금속류 제품 등에 의하여 유발된다. 또한 많은 종류의 중금속 화합물이 화장품 원료로 사용되고 있다. 전세계적으로 널리 사용되는 것으로 크롬, 망간, 비스머스, 구리, 철, 코발트, 티타늄, 아연 등의 화합물이 있으며 이들은 각종 화장품 공정서 및 원료집 등에 수재되어 사용되고 있다. 이들 중 코발트와 크롬이 피부에 유해하다는 몇몇 보고가 있지만, 이는 이들 원소의 수용성염형태의 특정 화합물인 cobalt chloride와 chromate 및 dichromate의 염에 관한 것으로 화장품에서 사용되는 불용성 산화물인 cobalt aluminum oxide, cobalt titanium oxide, cobalt blue, chromium oxde greens 및 chromium hydroide green 등, 국제적으로 널리 사용되는 안전한 중금속 화합물과는 그 특성 및 독성이 판이하게 다르다. 따라서 화장품에서는 매우 안전한 중금속 화합물만이 사용된다. 업계는 유해 중금속에 관해서는 규제에 입각한 엄격한 품질관리에 힘쓰고 중금속의 화학적 분자구조(수용성염 vs 불용성산화물)를 구별할 수 있는 분석방법 개발에 주력하여야 한다. 그리고 안전한 화장품을 사용하고자 하는 소비자의 욕구를 충족시키고 잘못된 인식과 보도로 인하여 안전한 화장품이 유해한 것으로 오도되는 것을 막아야 할 것이다.

• Journal of the Korean Chemical Society
• /
• v.42 no.1
• /
• pp.122-134
• /
• 1998

In this review, we describe the electrochemical properties of spinel-type lithium manganese oxides $(Li_xMn_2O_4)$ and their failure modes encountered in 4 V lithium rechargable cells. The long-term cyclability (reversibility) of spinel electrodes is determined partly by the purity, size and distribution of spinel particles, and also by the microstructure of electrode plates. A proper selection of electrolytes is another important task in cyclability enhancements. In the spinel preparation, impurity formation and cation mixing should be minimized. The carbon content in composite cathodes should also be minimized to the extent where the cell polarization does not bring about adverse effects on cell performances. The binder content should be optimized on the basis of dispersion of component materials and mechanical strength of the plates. Cathodic capacity losses arising from solvent oxidation and spinel dissolution can be mitigated by using electrolytes composed of carbonates and/or fluorine-containing lithium salts. The carbon additives may be selected after a trade-off between the cell polarization in composite cathodes and the solvent oxidation on carbon surface.

• Journal of the Mineralogical Society of Korea
• /
• v.17 no.3
• /
• pp.189-199
• /
• 2004

Cretaceous sedimentary rocks bearing dinosaur tracks in the Goseong interchange area were studied for their conservation and public display in the aspect of applied mineralogy. Black clay layers alternate with silt layers in the sedimentary rocks. The verical and horizontal fissures are commonly filled with calcite veinlets, supergenetic iron and manganese oxides. The rocks are composed of quartz, albite, K-feldspar, calcite, chlorite, illite, muscovite, and biotite, with minor apatite and rutile. Silt layers are relatively rich in calcite and albite, whereas clay layers are abundant in quartz, illite, and chlorite. Al, Fe, Mg, K, Ti, and P are enriched in the clay layers, while Ca, Na, and Mn in silt. Most of trace elements including V, Cr, Co, Ni, Cs, Zr, REE, Th, and U are enriched in clay layers. Inorganic carbon are present in silt layers as calcite, while organic carbon in black clay layers. The black clay layers were partly altered to yellow clay layers along the fissures, simultaneously with the decrease of organic carbon. Selective exfoliation of clay-rich black and yellow clay layers, calcite matrix of silt layers and calcite infillings of fissures are estimated as the major weakness potentially promoting chemical and physical degradation of the track-bearing rock specimens.

• Applied Chemistry for Engineering
• /
• v.9 no.1
• /
• pp.121-128
• /
• 1998

In fields of operating or handling a hydrogen isotope facility, and of the technology for nuclear fusion source management, gas chromatography has been used as one of the practical techniques lot separation and enrichment of hydrogen isotopic gases including tritium. Chromatographic separation experiments of the hydrogen isotope mixture (hydrogen, deuterium and tritium) were carried out by use of a commercially available gas chromatograph. An aliquot of gas sample was injected by a specially designed vacuum sampler into the stream of inert carrier gas which went through the separation column under liquid nitrogen temperature. The complete separation of hydrogen isotopic molecules was observed with an alumina adsorbent partially deactivated by coating with 10% manganese chlorine. In addition, fairly good separation conditions were obtained without any appearance of nuclear spin isomers with shorter retention time, which would be available for the practical applications of the hydrogen isotope separation and enrichment.