• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.313-322
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• 2012

몽골 우기누르 지역 철-망간 광상과 타미르골 지역 철 광상의 광체는 먼곤체지 층 내에 렌즈상으로 협재되는 특성을 갖는다. 이러한 광상은 캠브리아 기에서 실루리아기에 이르는 화산 기원의 퇴적형 광상인 타미르골-요루골 광상구에 해당된다. 우기누르 지역의 철-망간 광체와 타미르골 지역의 철광체는 주로 규암과 편암을 모암으로 하여 먼곤체지 층 내에 렌즈상으로 협재되어 있다. 우기누르지역의 편암이 주로 세리사이트 편암인 데 비해 타미르골 지역은 주로 백운모 편암이 나타나는 차이를 갖는다. 또한 우기누르 지역의 광석은 망간이10에서 12% 함유되나 타미르골 지역의 광석은 망간이 1% 이하로 함량이 낮은 특성을 갖는다. 우기누르 철 망간 광상의 철 광물은 주로 자철석, 적철석이 우세하게 나타나고 기타 철 산화물과 황철석이 미량으로 수반되어 나타나며, 망간 광물은 주로스페사틴, 버네사이트가 우세하게 나타나고 기타망간 산화물이 수반되어 나타난다. 타미르골 지역의 철 광석은 자철석이 우세하게 나타나고 적철석이 수반되며 황철석, 철 산화물, 탄산질 철 등이 미량으로 수반되어 나타난다. 우기누르 철-망간 광상에 대한 육상 자력탐사 결과 높은 자기 이상값을보이는 영역이 지표에서 확인된 광체의 방향과 같은 약 $N30^{\circ}W$ 방향으로 나타나며 지표에서 확인된 광체 이외에 지표에 드러나지 않은 부분에서도 연장되는 것이 확인되었다.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.11
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• pp.603-610
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• 2016

This work studies the synthesis of birnessite (${\delta}-MnO_2$), a catalyst of oxidative-coupling reactions, from the powder of spent alkaline manganese batteries (SABP, <8 mesh) and evaluate its reactivity for 1-naphthol (1-NP) removals. Manganese oxides using commercial reagents ($MnSO_4$, $MnCl_2$) and the acid birnessite (A-Bir) by McKenzie method were also synthesized, and their crystallinity and reactivity for 1-NP were compared with one another. 96% Mn and 98% Zn were extracted from SABP by acid leaching at the condition of solid/liquid (S/L) ratio 1:10 in $1.0M\;H_2SO_4+10.5%\;H_2O_2$ at $60^{\circ}C$. From the acid leaching solution, 69% (at pH 8) and 94.3% (pH>13) of Mn were separated by hydroxide precipitation. Optimal OH/Mn mixing ratio (mol/mol) for the manganese oxide (MO) synthesis by alkaline (NaOH) hydrothermal techniques was 6.0. Under this condition, the best 1-NP removal efficiency was observed and XRD analysis confirmed that the MOs are corresponding to birnessite. Kinetic constants (k, at pH 6) for the 1-NP removals of the birnessites obtained from Mn recovered at pH 8 (${Mn^{2+}}_{(aq)}$) and pH>13 ($Mn(OH)_{2(s)}$) are 0.112 and $0.106min^{-1}$, respectively, which are similar to that from $MnSO_4$ reagent ($0.117min^{-1}$). The results indicated that the birnessite prepared from the SABP as a raw material could be used as an oxidative-coupling catalyst for removals of trace phenolic compounds in soil and water, and propose the recycle scheme of SAB for the birnessite synthesis.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.473-482
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• 2009

In this study, iron and manganese coated sand (IMCS) was prepared by mixing Joomoonjin sand with solutions having different molar ratio of manganese ($Mn^{2+}$) and iron ($Fe^{3+}$). Mineral type of IMCS was analyzed by X-ray diffraction spectroscopy. Removal efficiency of arsenic through As(III) oxidation and As(V) adsorption by IMCS having different ratio of Mn/Fe was evaluated. The coated amount of total Mn and Fe on all IMCS samples was less than that on sand coated with iron-oxide alone (ICS) or manganese-oxide alone (MCS). The mineral type of the manganese oxide on MCS and iron oxides on ICS were identified as ${\gamma}-MnO_2$ and mixture of goethite and magnetite, respectively. The same mineral type was appeared on IMCS. Removed amount As(V) by IMCS was greatly affected by the content of Fe rather than by the content of Mn. Adsorption of As(V) by IMCS was little affected by the presence of monovalent and divalent electrolytes. However a greatly reduced As(V) adsorption as observed in the presence of trivalent electrolyte such as $PO_4\;^{3-}$. As(III) oxidation efficiency by MCS in the presence of NaCl or $NaNO_3$ was two times greater than that in the presence of $PO_4\;^{3-}$. Meanwhile a greater As(III) oxidation efficiency was observed by IMCS in the presence of $PO_4\;^{3-}$. This was explained by the competitive adsorption between phosphate and arsenate on the surface of IMCS.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.1233-1236
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• 2010

본 연구에서는 메탄을 물질로 산화실험을 수행하였다. 메탄의 발화온도가 탄화수소 중에 가장 높으며, 대부분의 전이금속촉매 활성온도가 가장 높게 나타나는 물질이므로 메탄의 연소가 일어날 경우 대부분의 탄화수소류는 연소가 일어날 수 있으므로 메탄의 산화반응을 연구하였다. 메탄의 산화를 위한 전이금속 촉매중 망간을 산화물형태로 $Al_2O_3$, $TiO_2$에 담지하여 메탄에 대한 활성능을 측정하였으며, 조촉매로 금속산화물을 이용하여 활성능의 변화를 연구하였다. 또한 자연에 존재하는 천연망간광석과 금속산화물을 담지하여 최적의 메탄에 대한 활성능을 지닌 촉매를 선별하였다. 조촉매로는 Ce, Sn, Ni, Co, Mo 등을 이용하였다. 또한 본 연구에서는 촉매 제조는 과잉용액함침법을 사용하여 담지체에 촉매물질을 분산하였으며, 온도와 유량에 대한 각 조성 촉매의 활성능을 측정하여 활성화에너지 및 $T_{50}$, $T_{90}$을 도출하였다.

• Journal of the Korean Electrochemical Society
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• v.13 no.2
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• pp.132-137
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• 2010

This study is concerned the electrocatalytic generation of oxygen gas at electrochemically deposited manganese oxide electrode in KOH solution. Manganese oxide nanoparticles electrodeposited onto relatively substrate, e.g glassy carbon, Au, Ti electrode. MnOx is electrodeposited in nanorod structure which cover the overall surface of the substrate. The $\gamma$-MnOOH that is kind of manganese oxide species plays a significant role as a catalytic mediator, which promote 4-electron reduction process. Modified electrodes with electrodeposited manganese oxide structures resulted in significant decrease in the anodic polarization compared with the unmodified electrodes in alkaline media.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.485-488
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• 2004

1M, 2M 황산망간 수용액에서 25회 dipping하여 대기중 $450^{\circ}C$에서 1시간동안 열분해법으로 Mn 산화물을 형성시켜 Mn $oxide/IrO_2/Ti$ 전극을 제조하였다. 제조된 Mn $oxide/IrO_2/Ti$ 전극은 XRD를 통하여 MnO의 결정구조를 가지는 것을 확인하였다. 또한 전극 표면은 열분해법으로 발생하는 가스에 의해 미소 균열이 형성되어 있었다. dipping 횟수가 증가할수록 피복되는 Mn 산화물의 무게는 감소하였고, 이것은 $450^{\circ}C$에서의 계속적인 열처리에 의해 열분해되어 제거되는 가스로 인해 무게가 감소됨을 알 수 있었다. 황산망간 수용액의 농도가 높으면 형성되는 Mn 산화물의 무게도 증가하였다. 황산망간 수용액에서 25회까지 dipping을 한 후 전기비저항의 변화는 초기 Mn 산화물이 형성되는 경우에는 비저항이 증가하다가, 일정 횟수 이상에서는 감소함을 알 수 있었다. 또한 황산망간 수용액의 농도가 클수록 비저항이 증가하는 것으로 나타났다.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.54-60
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• 2006

[ $MnO_2$ ]-Coated Sand(MCS) was prepared with variation of coating temperature, coating time, and dosage of initial Fe(III) with two kinds of sands such as Joomoonjin and quartz sand. An optimum condition for the preparation MCS was determined from the coating efficiency as well as the oxidation efficiency of As(III). Coating efficiency of Mn was strongly dependent on the coating temperature but quite similar over the investigated coating time, showing an increased coating efficiency at higher coating temperature. In contrast to coating efficiency, the oxidation efficiency of As(III) by MCS was severely reduced as increase of coaling temperature. By considering these results, an optimum coating temperature and time for the preparation of MCS was selected as $150^{\circ}C$ and 1-hr, respectively. Coating efficiency increased as the dosage of initial Mn(II) increased, while As(III) oxidation was maximum at 0.8 Mn(II) mol/kg sand. The solution pH was identified as an important parameter affecting stability of MCS, and dissolution of Mn from MCS increased as pH decreased. Oxidation rate of As(III) increased as the dosage of MCS increased as well as solution pH decreased.

• Journal of Life Science
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• v.15 no.1 s.68
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• pp.94-99
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• 2005

Sixty four bacterial colonies which were able to oxidize the manganese were isolated from soil samples in Mokcheon and Ochang area. Among them, one bacterial strain was selected for this study based on its higher manganese oxidation, and this selected bacterial strain was identified as Aeromonas sp. MN44 through physiological-biochemical test and analysis of its 16s rRNA sequence. Aeromonas sp. MN44 was able to utilize lactose but did not utilize various carbohydrates as a sole carbon source. Aeromonas sp. MN44 showed a very sensitive to antibiotics such as kanamycin, chloramphenicol, ampicillin, tetracycline and spectinomycin, and heavy metal such as cadmium. But this strain showed a high resistance up to mg/ml unit to heavy metals such as lithium and manganese. Optimal manganese oxidation condition of Aeromonas sp. MN44 was pH 7.4 and manganese oxidation activity was inhibited by proteinase K and boiling treatment. So, we concluded that this factor was protein. The manganese oxidizing factor produced by Aeromonas sp. MN44 was partial purified by ammonium sulfate precipitation, DEAE-Toyopearl 650M ion exchange chromatography and Sephadex gel filtration chromatography. Its molecular mass was about 113 kDa.

• Clean Technology
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• v.2 no.1
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• pp.60-68
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• 1996

The oxidation of carbon monoxide of low concentration on the natural manganese dioxide (NMD) has been investigated in a fixed bed reactor. The experimental variables were concentration of oxygen (500ppm~99.8%) and carbon monoxide (500ppm~10000ppm) and catalyst temperature ($50{\sim}750^{\circ}C$). The NMD(Natural Manganese Dioxide) has been characterized by temperature - program reduction(TPR) using 2.4% $CO/H_2$ as a reducing agent, thermogravimetric analysis (TGA), and reduction of NMD by 2.4% $CO/H_2$. It was found that the NMD catalyst activity on the unit area was greater than the $MnO_2$ catalyst for oxidation of CO at the same temperature. The thermal stability of oxidation activity was considered to be maintained when the NMD was heated to $750^{\circ}C$. The TGA, reduction by CO, and TPR of the NMD showed that the NMD had active lattice oxygen which was easily liberated on heating in the absence and low concentration of oxygen. The reaction order in CO is 0.701 between 500~3500ppm and almost zero between 3500~10000ppm of CO.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.4
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• pp.327-332
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• 1999

Manganese (Mn) oxides in soils have been a research subject since they react with nutrients and contaminants and Mn itself is an essential element for plant growth. Birnessite was synthesized in the presence of iron (Fe) in the precipitating solution. Influence of Fe, one of common elements in soils, on crytallinity, morphology, and chemical reactivity of birnessite was examined using X-ray diffraction (XRD), electron microscope, canon exchange capacity (CEC), and chromium (Cr) oxidation capacity. With increasing Fe concentration in the precipitating solution, crystallinity and crystal size decreased. Hexagonal plates of the birnessites formed at low Fe concentration were dominant and replaced more and more by aggregate of small particles with increasing the Fe concentration. There is no significant change in CEC with changing the Fe concentration. Chromium oxidation capacity of the birnessite increased with increasing the Fe concentration. Iron in the precipitating solution poisoned crystal growth by adsorption on the surface and increased nucleation. Since Fe is a common constituent under pedogenic environment and Fe and Mn oxides often coexist in Mn oxide nodules, the birnessite with small particle, low crystallinity, and high chemical reactivity is the form which is more likely to be formed in soils. The high CEC ($140cmol_ckg^{-1}$) and oxidation capacity of birnessite indicate that birnessite can be used in environment and agriculture.