• Title, Summary, Keyword: 망간산화물

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Estimate of Manganese and Iron Oxide Reduction Rates in Slope and Basin Sediments of Ulleung Basin, East Sea (동해 울릉분지 퇴적물에서 망간산화물과 철산화물 환원율 추정)

  • Choi, Yu-Jeong;Kim, Dong-Seon;Lee, Tae-Hee;Lee, Chang-Bok
    • The Sea
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    • v.14 no.3
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    • pp.127-133
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    • 2009
  • In order to determine organic carbon oxidation by manganese and iron oxides, six core sediments were obtained in slope and basin sediments of Ulleung Basin in East Sea. The basin sediments show high organic carbon contents (>2%) at the water depths deeper than 2,000 m; this is rare for deep-sea sediments, except for those of the Black Sea and Chilean upwelling regions. In the Ullleung Basin, the surface sediments were extremely enriched by Manganese oxides with more than 2%. Maximum contents of Fe oxides were found at the depth of $1{\sim}4cm$ in basin sediments. However, the high level of Mn and Fe oxides was not observed in slope sediment. Surface manganese enrichments (>2%) in Ulleung Basin may be explained by two possible mechanisms: high organic carbon contents and optimum sedimentation rates and sufficient supply of dissolved Manganese from slope to the deep basin. Reduction rates of iron and manganese oxides ranged from 0.10 to $0.24\;mmol\;m^{-2}day^{-1}$ and from 0.30 to $0.57\;mmol\;m^{-2}day^{-1}$, respectively. In Ulleung Basin sediments, $13{\sim}26%$ of organic carbon oxidation may be linked to the reduction of iron and manganese oxides. Reduction rates of metal oxides were comparable to those of Chilean upwelling regions, and lower than those of Danish coastal sediments.

Enhancement of Phenanthrene Sorption Rate on Natural Manganese Oxide Using the Oxidative Coupling Reaction of Phenanthrene (천연망간산화물에 의한 클로로페놀의 산화결합생성물을 매개로 한 다환방향족화합물(PAH) 오염물의 고정화 효과)

  • Jeon Sun-Young;Park Jae-Woo;Shin Won-Sik;Ko Seok-Oh
    • Journal of Soil and Groundwater Environment
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    • v.10 no.5
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    • pp.45-51
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    • 2005
  • The sorption/desorption characteristics of phenanthrene on the natural manganese oxide (NMD) were investigated in the presence of phenolic compounds. 4-chlorophenol (4-CP) was effectively oxidized by NMD catalyzed reaction and transformed into humic-like macromolecular compound through inter-or cross-coupling reaction between byproducts. As 4-CP was degraded with time, sorbed amount of phenanthrene on NMD was significantly increased, resulting from the formation of oxidative coupling products. These results imply that NMD can be used for simultaneous treatment of phenolic contaminants and polycyclic aromatic hydrocarbons (PAHs) in soils, sediments, or water. Also, sorbed phenanthrene on NMD in the presence of 4-CP showed high degree of desorption resistance, indicating that sequestration process of phenanthrene was ongoing with time.

Relationship between Structural Stability and Crystallinity in Layered Manganese Oxide (층상구조 망간산화물에서의 구조적 안정도와 결정성과의 관계)

  • Hwang, Seong-Ju
    • Journal of the Korean Chemical Society
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    • v.48 no.1
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    • pp.46-52
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    • 2004
  • The effect of crystallinity on the structural stability of layered manganese oxide has been systematically investigated. While well-crystalline manganate was prepared by solid-state reaction-ion exchange method, nanocrystalline one was obtained by Chimie-Douce reaction at room temperature. According to micro-Raman and Mn K-edge X-ray absorption spectroscopic results, manganese ions in both the manganese oxides are stabilized in the octahedral sites of the layered lattice consisting of edge-shared MnO6 octahedra. The differential potential plot clarifies that the layered structure of nanocrystalline material is well maintained during electrochemical cycling, in contrast to the well-crystalline homologue. From the micro-Raman results, it was found that delithiation-relithiation process for well-crystalline material gives rise to the structural transition from layered to spinel-type structure. On the basis of the present experimental findings, it can be concluded that nanocrystalline nature plays an important role in enhancing the structural stability of layered manganese oxides.

Oxidative Transformation of Tetracycline in Aqueous Solution by Birnessite (망간산화물(birnessite)에 의한 수용액 중 Tetracycline의 산화-변환반응에 대한 연구)

  • Eom, Won-Suk;Kim, So-Hui;Shin, Hyun-Sang
    • Journal of Korean Society of Environmental Engineers
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    • v.37 no.2
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    • pp.73-80
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    • 2015
  • An investigation on the removals of tetracycline (TTC), which is a family of antibiotics widely founded in the environment, from the aqueous solution by birnessite(${\delta}-MnO_2$)-mediated oxidative transformation was described. This study also examined the potential effect of the naturally occurring substances, humic acid (HA) on the oxidative transformation. The experiment was carried out in various conditions (reaction time, Mn oxide loadings, pH) and in the presence of HA as a batch test. The removals of TTC followed pseudo-first order reactions, and rate constants (k, $hr^{-1}$) for the removals of TTC were constantly increased with decreasing pH from 0.98 (pH 9) to 2.97 (pH 3). The rate constants also increased about 1.3 times when the birnessite loading increased from 1 to 2 g/L. Presence of HA (5 mg-C/L, at $pH{\geq}6$) caused some enhancement in the removals of TTC as compared to the control, and also showed the removal efficiencies of TTC in the birnessite mediated systems (TTC=0.25 mM, ${\delta}-MnO_2=2.0g/L$, pH 6) increased with increasing HA concentrations (1~10 mg-C/L). The results obtained from the oxidative transformation of TTC and the effect of HA were discussed in terms of reaction characteristics and mechanism.

A Review of Geochemical Factors Governing the Phase Transformation of Birnessite (버네사이트 상변화 반응의 지화학적 반응 조절인자 연구)

  • Namgung, Seonyi;Chon, Chul-Min;Lee, Giehyeon
    • Economic and Environmental Geology
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    • v.50 no.6
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    • pp.545-554
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    • 2017
  • Birnessite is one of the dominant Mn (oxyhydr)oxide phases commonly found in soil and deep ocean environments. It typically occurs as nano-sized and poorly crystalline aggregates in the natural environment. It is well known that birnessite participates in a wide variety of bio/geochemical reactions as a reactive mineral phase with structural defects, cation vacancies, and mixed valences of structural Mn. These various bio/geochemical reactions control not only the fate and transport of inorganic and organic substances in the environment, but also the formation of diverse Mn (oxyhydr)oxides through birnessite transformation. This review assessed and discussed about the phase transformation of birnessite under a wide range of environmental conditions and about the potential geochemical factors controlling the corresponding reactions in the literature. Birnessite transformation to other types of Mn (oxyhydr)oxides were affected by dissolved Mn(II), dissolved oxygen, solution pH, and co-existing cation (i.e., $Mg^{2+}$). However, there still have been many issues to be unraveled on the complex bio/geochemical processes involved in the phase transformation of birnessite. Future work on the detail mechanisms of birnessite transformation should be further investigated.

Adsorption Characteristics of Pb(II) by Manganese Oxide Coated Activated Carbon in Fixed Bed Column Study (망간산화물이 코팅된 활성탄의 납 흡착특성에 관한 칼럼 실험)

  • Lee, Myoungeun;Lee, Chaeyoung;Chung, Jaewoo
    • Journal of the Korean Geoenvironmental Society
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    • v.15 no.8
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    • pp.39-44
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    • 2014
  • Effects of operating parameters on the breakthrough properties of Pb(II) by $Mn_3O_4$ coated activated carbon prepared by supercritical technique were investigated through fixed-bed column experiments. The mass transfer zone and equilibrium adsorption capacity were enhanced about 2.8 times for Pb(II) by $Mn_3O_4$ coating onto activated carbon. Increase of bed height enhanced the residence time of Pb(II) in adsorption zone, giving the higher breakthrough time, mass transfer zone and equilibrium adsorption capacity. Increase of flow rate reduced the residence time and diffusion of Pb(II) in adsorption zone, therefore decreased the equilibrium adsorption capacity. The higher inlet concentration of Pb(II) decreased the breakthrough time and mass transfer zone through the promotion of Pb(II) transfer onto adsorbent.

Oxidative Coupling Reaction of Chlorophenols by Natural Manganese Dioxides (천연망간산화물을 이용한 클로로페놀류의 산화중합반응)

  • Jeon Sun-Young;Ko Seok-Oh
    • Journal of Soil and Groundwater Environment
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    • v.10 no.4
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    • pp.62-69
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    • 2005
  • Removal of 4-chlorophenol (4CP) by natural manganese dioxide (NMD) catalyzed reaction was investigated in this study. Tests were also carried out to evaluate the effects of pH and natural organic matter (NOM) on the degradative oxidation of 4CP. Experimental results proved that NMD was effective for the removal of 4CP. Extensive kinetic analysis suggests that overall oxidation of 4CP by NMD is second-order reaction, the first-order with respect to 4CP, and the first-order with respect to NMD, respectively. Also, 4CP oxidation rates on the Mn-oxide surfaces were highly dependent upon experimental conditions such as pH, initial concentration of 4CP or NMD, and existence of humic acid. As pH increased above PZC of NMD, the reaction rate of 4CP was decreased, due to the low affinity of 4CP on NMD at high pH. At pH lower than PZC of NMD, reaction rate of 4CP was also decreased. It was considered that humic acid was involved in the oxidative coupling reaction of 4CP by NMD, resulting in the enhanced degradation rate of 4CP. This study proved that natural manganese oxide can be effectively applied for the removal of chlorophenols in aqueous phase.

A Study on the Oxidative Transformation of Quinone Compound using Nanostructured Black-birnessite (나노구조의 블랙-버네사이트를 이용한 퀴논계 화합물의 산화-변환 연구)

  • Harn, Yoon-I;Choi, Chan-Kyu;Shin, Hyun-Sang
    • Journal of Korean Society of Environmental Engineers
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    • v.32 no.6
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    • pp.547-554
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    • 2010
  • In this study, new manganese oxide (i.e., black-birnessite) particles with nanostructures were prepared and its physico-chemical properties and oxidative-transformation efficiency on 1,4-naphthoquinine(1,4-NPQ) in the presence of reactive mediator was investigated. The results were also compared with that of the manganese oxide (i.e., brown-birnessite) particles synthesized by classical McKenzie method. Analysis of XRD and SEM data show that the particles are a single phase corresponding to a birnessite-based manganese oxide with cotton ball-like shapes containing nanofibers. In batch experiments, removals of 1,4-NPQ by the black-birnessite follows pseudo-first-order kinetics and the rate constant values obtained are greater about 2.3 times than that of the brown-birnessite in spite of its lower surface area (41.0 vs 19.80 $m^2/g$). The results can be explained by the higher crystallinity and nano structured features of the back-birnessite particles, which give higher reactivity for the removals of the quinone compound. HPLC analysis of the reaction products confirmed that the balck-birnessites removed 1,4-NPQ through cross-coupling reaction in the presence of catechol as a reactive mediator.

Oxidative-Coupling Reaction of Aromatic Compounds by Mn Oxide and Its Application for Contaminated Soil Remediation (망간산화물에 의한 방향족 유기화합물의 산화-공유결합반응 및 이를 이용한 오염토양 정화기법)

  • Kang, Ki-Hoon;Shin, Hyun-Sang;Nam, Kyoung-Phile
    • Journal of Soil and Groundwater Environment
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    • v.12 no.5
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    • pp.115-123
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    • 2007
  • Immobilization of contaminants in subsurface environment is one of the major processes that determine their fate. Especially, immobilization by oxidative-coupling reactions, which is irreversible in the bio-chemical reactions and results in a significant reduction of toxicity, can be successfully applied for the remediation of contaminated soil and groundwater more effectively than conventional degradation. As a catalyst of this oxidative-coupling reaction, manganese oxide has many advantages in practical aspects as compared to microorganisms or oxidoreductive enzymes extracted from microorganisms, fungi, or plants. This paper is to present recent research achievements on the treatment mechanisms of various organic contaminants by manganese oxide. Especially, treatment methods of non-reactive organic compounds to Mn oxide are the main focus; i.e., application of reaction mediator, PAHs treatment method, combination with an appropriate pretreatment such as reduction using $Fe^0$, which suggests the potential of a wide range of engineering application. Concerning the natural carbon cycle processes, immobilization and stabilization by oxidative coupling reaction can be effectively applied as a environmentally-friend remediation method especially for aromatic contaminants which possess a high resistance to degradation.