• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.71-77
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• 2013

Aluminium powder as reductant in aluminothermy process needs a fine particle size under 200 mesh, but it is not easy economically to make that because of its high ductility and powder production cost. In order to reduce the production cost of fine aluminum powder as reductant of $Mn_3O_4$ waste dust, therefore, the properties of aluminium alloy powder were investigated. Aluminium alloy ingot containing large amount of manganese can be crushed easily because of its intermetallic compounds having brittle properties. The manganese is also main element in ferro-manganese. We can obtain economically Al-15%Mn alloy powder by mechanical comminution process. And the result of thermite reaction using Al-15% Mn alloy powder instead of pure Al powder showed the fact that can be obtained the ferro-manganese which have a high purity in case of using pure aluminium powder as reductant. The recovery of manganese from $Mn_3O_4$ waste dust with Al-15%Mn alloy powder was higher level of about 70% than about 65% in case of using aluminium powder, that is due to lower spatter loss.

• Journal of Electrochemical Science and Technology
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• v.3 no.4
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• pp.178-184
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• 2012

A porous nickel (P-Ni) substrate was prepared by selective leaching of zinc from pressed pellets containing powders of Ni & Zn in 4 M NaOH solution. Anodic deposition of manganese oxide onto the porous Ni substrate ($MnO_x$/P-Ni) formed nano-flakes of manganese oxide layers as revealed in SEM studies. Pseudocapacitance of this oxide electrode was evaluated by cyclic voltammetry (CV) and chronopotentiometry (CHP) in 2 M NaOH solution. The specific capacitance of the Mn oxide electrode was as high as 1515 F $g^{-1}$, which was ten times higher than Mn oxide deposited on a flat Ni-ribbon. 80% of capacity was retained after 200 charge/discharge cycles. The system showed no loss of activity in dry form over period of days. The impedance studies indicated highly conducting $MnO_x$/P-Ni substance and the obtained specific capacitance from impedance data showed good agreement with the charge/discharge measurements.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.323-324
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• 2023

The properties of cement mortar mixed with manganese-doped titanium dioxide nanowires (TiO₂(Mn)-NWs) were investigated in this study. The TiO₂(Mn)-NWs were synthesized using solvo-thermal synthesis and electro-spinning techniques. The TiO₂(Mn)-NWs at weights of 1%, ₂%, and 3% of the cement were respectively mixed into the cement mortar. The results showed that as the amount of TiO₂(Mn)-NWs increased, the flow value of the cement mortar was decreased and the setting time of cement mortar was accelerated. Moreover, as the amount of TiO₂(Mn)-NWs increased, the compressive strength of cement mortar was increased and the efficiency of acetaldehyde removal was improved.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.5
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• pp.571-576
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• 2007

Manganese-Coated Sand(MCS) prepared with three different methods were applied in the treatment of soluble $Mn^{2+}$ in batch and column experiments. In the bench-scale MCS preparation, the coating efficiency of manganese on the surface of sand increased as the dosage of initial Mn(II) increased. The removed amount of the soluble $Mn^{2+}$ by MCS increased as the solution pH increased, following a typical anionic-type adsorption. The removed amounts of the soluble $Mn^{2+}$ through adsorption was quite similar over the entire pH range, without depending on the contents of Mn on the surface of sand as well as coating methods. When NaClO was used an oxidant, the removed amount of the soluble $Mn^{2+}$ by MCS increased as the concentration of NaClO increased, This trend might be explained by the increased removal efficiency through coating of manganese oxides produced from oxidation of the soluble $Mn^{2+}$ by NaClO on the surface of MCS. From the bench-scale column experiments, the breakthrough of $Mn^{2+}$ occurred after 4,100 bed volume without presence of NaClO while 1.6-times delayed breakthrough of $Mn^{2+}$ was observed in the presence of NaClO. This result also supports that the removal efficiency of the soluble $Mn^{2+}$ could be enhanced by using NaClO.

• Resources Recycling
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• v.17 no.1
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• pp.66-72
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• 2008

Fundamental studies for the synthesis of Mn-Zn ferrite powder were investigated using a series of leaching and coprecipitation processes from spent alkaline manganese batteries. Zinc and Manganese dissolution rates obtained at the reaction conditions of 100g/L pulp density, 3.0M $H_2SO_4$, $60^{\circ}C$ and 200 rpm with 30 ml $H_2O_2$ as a reducing agent were more than 97.9% and 93.9% and coprecipitation of Mn-Zn ferrite powder was performed according to various reaction conditions such as temperature, time and amount of $O_2$ gas injection using the leaching solution. As a result of coprecipitation, Mn-Zn ferrite could be synthesized directly at low temperature in the reaction condition pH 12, $80^{\circ}C$, $O_2$ 1.3 L/min. and 400 rpm. The synthesized Mn-Zn ferrite powder was spherical powder of $0.143{\mu}m$ particle size and had a saturation magnetization about 80 emu/g.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2343-2347
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• 2013

In this work, manganese dioxide ($Mn_3O_4$)/carbon black (CB) composites (Mn-CBs) were prepared by an in situ coating method as electrical fillers and the effect of the Mn-CBs on the electrical performance of activated carbon (AC)-based electrodes was investigated. Structural features of Mn-CBs produced via in situ coating using a $KMnO_4$ solution were confirmed by XRD and TEM images. The electrical performances, including cv curves, charge-discharge behaviors, and specific capacitance of the ACs/Mn-CBs, were determined by cyclic voltammograms. It was found that the composites of $Mn_3O_4$ and CBs were successfully formed by in situ coating method. ACs/Mn-CBs showed higher electrical performance than that of AC electrodes fabricated with conventional CBs due to the pesudocapacitance reaction of manganese oxides in the aqueous electrolyte. Consequently, it is anticipated that the incorporation of $Mn_3O_4$ into CBs could facilitate the utilization of CBs as electrical filler, leading to enhanced electrochemical performance of AC electrodes for supercapacitors.

• Journal of the Mineralogical Society of Korea
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• v.23 no.2
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• pp.161-170
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• 2010

Many microbes, including both bacteria and fungi, produce manganese (Mn) oxides by oxidizing soluble Mn(II) to form insoluble Mn(IV) oxide minerals, a kinetically much faster process than abiotic oxidation. These biogenic Mn oxides drive the Mn cycle, coupling it with diverse biogeochemical cycles and determining the bioavailability of environmental contaminants, mainly through strong adsorption and redox reactions. This mini review introduces recent findings based on quantum mechanical density functional theory that reveal the detailed mechanisms of toxic metal adsorption at Mn oxide surfaces and the remarkable role of Mn vacancies in the photochemistry of these minerals.

• Ocean and Polar Research
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• v.44 no.2
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• pp.139-145
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• 2022

Manganese nodules were recovered within the deep subseafloor sediments (118.22 mbsf) at Site U1371 during International Ocean Discovery Program (IODP) expedition 329 from the South Pacific Gyre (SPG). Because most manganese nodules exist on the seabed surface, nodules present in deep sediments are uncommon. Therefore, the growth origin of manganese nodules was identified through mineralogical and geochemical analyses. The manganese nodule was divided into the concentric layer outside the manganese region and the inner part of the phosphatized region consisting of manganese oxide minerals and carbonate fluorapatite (CFA) minerals, respectively. The two-dimensional element distribution analysis of Mn, Co, Ni, Sr and Cu, Zn with low Mn/Fe ratio confirmed that manganese nodules were formed predominantly by a hydrogenetic process and a biogenic process in certain manganese layers. As a result, the manganese nodule was continuously precipitated in SPG environments of oligotrophic open paleoocean conditions and rapidly buried with siliceous ooze sediments when the SPG changed to a eutrophic environment. It has been confirmed that manganese nodules found within deep subseafloor sediments could be used as a new proxy for the reconstruction of paleooceanographic conditions.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.483-486
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• 2021

Catalytic ozonation of methyl ethyl ketone (MEK) has been examined over mesoporous MnO_x/Al₂O₃ (MA) catalysts developed by a solvent deficient method using two different manganese precursors including manganese chloride (C) and manganese sulfate (S) at room temperature. The maximum catalytic activities of MA with C (MEK removal efficiency and ozone decomposition of 98.4 and 93.7%, respectively) were higher than those of MA with S (MEK removal efficiency and ozone decomposition of 96 and 68%, respectively). Also the catalytic stability of MA with C was much higher than that of MA with S. The physico-chemical properties of catalysts are well correlated with the activity results, which confirmed that fine dispersion of MnO_x species with high ratios of Mn³⁺/Mn⁴⁺ and more acid sites are attributed to the higher catalyst stability for the MA-C catalyst.

• Journal of the Korean Magnetic Resonance Society
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• v.6 no.1
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• pp.20-37
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• 2002

MnAPSO-34 and Mn-impregnated SAPO-34(Mn-SAPO-34) sample were prepared with various manganese contents and studied by electron spin resonance(ESR) and electron spin echo modulation(ESEM). Electron spin echo modulation analysis of 0.07mo1 ％ Mn(relative to p) in MnAPSO-34 with adsorbed D$_{2}$O shows two deuteriums at 0.26 nm and two at 0.36 nm from Mn. This suggests that two waters hydrate an MnO$_{4}$ configuration with a D-O bond orientation for the waters as expect for a negatively charged site at low manganese content (0.1 mol％), the ESR spectra of MnAPSO-34 and MnH-SAPO-34 exhibit the same parameters(g 2.01 and A 89 G), but the spectra obtained from MnAPSO-34 samples are better resolved. The decomposition temperature of as-synthesized MnAPSO-34 were in the range of 200-600 $^{\circ}C$ of the morpholine which is 12 $^{\circ}C$ higher than that in as-synthesized MnH-SAPO-34. Infrared spectra showed that the position of a band at 3450 $cm^{-1}$ / shifted about 15 $cm^{-1}$ / toward higher energy in MnAPSO-34 versus MnH-SAPO-34. The modulation depth of the two-pulse ESE of MnAPSO-34 with adsorbed D$_{2}$O is deeper than that of MnH-SAPO-34 with adsorbed D$_{2}$O. Three-pulse ESEM of MnAPSO-34 and MnH-SAPO-34 with adsorbed deuterium oxide shows that the local environments of manganese in the hydrated samples are different, suggesting that Mn(II) is framework substituted in MnAPSO-34 since it obviously occupies an extraframework position in MnH-SAPO-34.