Manganese Dioxide Powder Research Articles

Corrosion and adsorption properties of electrochemical manganese dioxide in the acidic and weakly alkaline sulfate solutions

Corrosion and adsorption properties of manganese dioxide, which was anodically deposited on platinum, its powder, and compacted tablets of manganese dioxide in the solutions with various pH values are studied using various experimental methods. It is shown that the corrosion rate of manganese dioxide decreases with increasing pH of solution, and the process proceeds by the electrochemical mechanism with conjugate chemical reactions of the formation and decomposition of the product of transition stage. The adsorption properties of manganese dioxide powder with respect to copper ions increase with increasing pH of solution, whereas the amount of manganese ions passing to the solution almost vanishes at pH 9.

In situ TiC-reinforced austenitic steel composite by self-propagating high temperature synthesis

TiC-reinforced austenitic steel composites have been prepared by self-propagating high temperature synthesis (SHS). The in situ reinforcement of a Fe-Mn-based austenitic steel matrix with TiC was achieved upon aluminothermic reduction of iron oxide (Fe2O3), manganese dioxide (MnO2) and titanium dioxide (TiO2) powders in the presence of carbon (C). This highly exothermic thermite reaction was found to produce in situ the Fe-Mn-TiC austenitic steel composites. The reaction kinetics, recovery of Mn and TiC, yield of metal, and composite microstructure were found to strongly depend on the process parameters, such as green composition, blending sequence, and average particle size of Al powder used as a reducing agent.

The importance of aeration in passive treatment schemes for manganese removal

A major breakthrough has been achieved in passive manganese treatment, since manganese can now be removed at the same time as iron, and efficient manganese removal is feasible even where land availability is limited. The active ingredients of this novel sub-surface flow gravel bed are dolomite and manganese dioxide powder. The catalytic action of these substrates combined with aeration provides the conditions required to overcome the usually slow kinetics of manganese oxidation in the presence of dissolved iron. Three small-scale (5 L containers) continuous flow systems were operated for seven months and successfully removed >95% of manganese in this period (raw water Mn concentration ~20 mg/L). The importance of aeration was successfully demonstrated, particularly when the systems were subjected to environmental stresses such as low (or non-existent) light, low temperatures (down to 4oC) and the presence of dissolved iron in the influent water. Spiking with additional iron (to an initial concentration of 5 mg/L) not only failed to significantly lessen manganese removal rates, but complete removal of the added iron itself was also observed. Since current manganese removal systems fail with iron present at such concentrations in the influent water, these results represent a significant advance in manganese removal options.

Manganese Dioxide (MnO2) by XPS

XPS spectra of manganese dioxide (MnO2) powder are presented. The spectra were collected using monochromated Al Kα x-rays. Spectra include survey scan, the Mn 2p, 3p, and 3s regions, the O 1s region, and the Mn LMM Auger transitions.

Kinetics of Heavy Metal Ion Adsorption on to, and Proton Release from, Electrolytic Manganese Dioxide

The kinetics of adsorption of lead(II), as well as of copper (II), zinc(II) and thallium(I), on commercial electrolytic manganese dioxide (EMD) powder of different size fractions has been followed by a pH-stat method involving the computer-controlled neutralisation of released protons from the EMD at a fixed pH with hydroxide ion. Base uptake versus time profiles in all cases indicated a rapid initial change followed by a slower process. These can be interpreted in terms of either a solution kinetic model or an adsorption kinetic model. In the former analysis, the adsorption-time profile can be interpreted in terms of two, or at most three, exponentials. The contribution of the first fast step increases with decreasing average particle size (or increasing surface area), consistent with its interpretation as being associated with the replacement of accessible protons on the exposed surface of the EMD by metal ions. The slower rate processes can be considered to be associated with adsorption in less accessible clefts or pores in the structure. In the diffusion model, the experimental data were fitted to the equation of diffusion in a sphere, fitting again requiring a first initial step followed by a slower step, with one diffusion coefficient having typically an upper limit of 10-9 and the other a lower limit of 10-11 cm2/s. For the complete reaction, the moles of protons released per mole of metal ion adsorbed were also measured and found to be relatively insensitive with respect to pH, metal ion concentration, electrolyte concentration and EMD size fraction. At pH 4, the H+: Mn+ ratio ranged from 1.4 to 2.1 (±0.1) for divalent transition metal ions, consistent with dominant chelation of the divalent metal ion to two adjacent oxygen sites on the surface; for thallium(I), a low ratio (0.5) indicated a different mode of surface attachment.

γ-Ray radiation preparation and characterization of nanocrystalline manganese dioxide

Nanocrystalline manganese dioxide (MnO 2) powders have been prepared by radiating potassium permanganate (KMnO 4) aqueous solution with γ-ray at ambient pressure and temperature. The influence of the experimental conditions on the results has been studied in detail. TEM and XRD show that the smallest mean particle size of the product is about 6 nm and the particle size distribution is very narrow.

電池材料の開発とその事業化

Since Leclanche invented the dry battery with manganese dioxide and zinc as active materials, batteries have yielded revolutionary improvement with the growth of industry. Today, the production of the chemical batteries in Japan has reached 6 billion units, corresponding to 656 billion in sale. Most recent remarkable development of electronic devices has made appliances cordless and small-sized so that high performance batteries have attracted growing interest as small size and high energy density. Nowaday, batteries have been recognized as one of three key devices in electronic industry. We, Mitsui Mining & Smelting Co., Ltd. started the commercial production of electrolytic manganese dioxide in 1949 and has produced variety of key materials for batteries, i. e., zinc alloy powders, lead alloys, cadmium oxide, lithium foils and hydrogen storage alloys. In this paper, high quality of electrolytic manganese dioxide and mercury-free zinc alloy powders will be introduced and Research Development activities for battery materials in Mitsui Mining & Smelting Co., Ltd. will be outlined as well.

Chemical Preparation of Manganese Dioxide/Polypyrrole Composites and Their Use as Cathode Active Materials for Rechargeable Lithium Batteries

Chemical preparation of composite powders of polypyrrole and either , , or spinel has been successfully achieved by injecting liquid pyrrole into an acidic medium containing suspended manganese dioxide powder as an oxidizing agent. The content of manganese dioxide in the composites increased with increasing amount of suspended manganese dioxide in the polymerization bath. The maximum content of manganese dioxide was 85, 87, and 83.3 weight percent for , , and , respectively. Charge‐discharge tests of and composites conducted in a mixed solvent of propylene carbonate and 1,2‐dimethoxyethane (1:1) containing 1 mol dm−3 have revealed that the polypyrrole worked well both as an active material and as a conducting network for manganese dioxide. The composite gave one potential plateau in both charge and discharge curves, whereas the composite exhibited two distinct potential regions. The utilization of manganese dioxide was higher when polypyrrole was used as the conducting matrix than when carbon powder was used. Elemental analyses of the composites have revealed that both electrolyte anions and cations were involved in the charge‐discharge reaction of the composite, but electrolyte cations alone were involved in that of the /polypyrrole composite. The mechanisms of the charge‐discharge reaction of these two kinds of composites are in good conformity with the mechanism of composite formation.

Thermoelectric e.m.f. of battery grade manganese dioxide

Measured Seebeck coefficients of 5 battery grade manganese dioxide powder samples against solid graphite are reported. Temperature: 10 and 50 °C, respectively. Pressure: 7.5 megapascal (1 MPa ≙ 10 bar). All samples exhibit n-type semiconductivity with very high carrier concentration and very low mobility. Apparently, close correlations exist between thermoelectric behaviour, powder conductivity, water content, and electrode potential.

The particle shape influence on the apparent density and electric conductivity of pressed powder materials

Depending on the particle shape the apparent density of different manganese dioxide and copper powders (particle-size < 40 μm) have been investigated. In the range of pressure between 10 MPa and 100 MPa the different gradients of the graphs in the double-logarithmic density-pressure-diagram will be compared. In relation to the particle shape of the manganese dioxide powders a series with rising interdependency of apparent density and compacting pressure can be demonstrated: spherical, angular (crystalline), spheroidal, dendritic (agglomerate), and for the copper powders: spherical, irregular, plate-like, dendritic. The influence on the electric conductivity of pressed powder materials will be discussed.

Thermoelectric e.m.f. of battery grade manganese dioxide

Measured Seebeck coefficients of 5 battery grade manganese dioxide powder samples against solid graphite are reported. Temperature: 10 and 50 °C, respectively. Pressure: 7.5 megapascal (1 MPa ≙ 10 bar). All samples exhibit n-type semiconductivity with very high carrier concentration and very low mobility. Apparently, close correlations exist between thermoelectric behaviour, powder conductivity, water content, and electrode potential.

Der einfluss des feinmaterials auf dichte und leitfähigkeit von Braunsteinpulver unter Druck — eine technische bemerkung

The dependence of the apparent density and electrical conductivity of two manganese dioxide powders on the amount of admixed very fine (< 5 μm) material have been investigated. In general, even a small amount of fine particles results in considerable changes. At low pressure (10 MPa ⋍ 100 bar), the powder density shows a maximum; at high pressure (1250 MPa) a monotonic increase is observed. The specific powder resistivity rises monotonically at low pressure with increasing amount of fine particles. At high pressure, it rises (NMD) or shows a minimum (CMD).

Electrical characteristics of a highly hydrated battery grade manganese dioxide powder

The manganese dioxide powder under study, called Permanox is a byproduct of saccharin manufacture. It contains about 10% by weight of water and 7.5% KOH. The electric conductivity is highly dependent on pressure, water content, temperature and not least, the measuring procedure. Conductivity rises considerably in transverse electric fields. From Argand diagrams, the apparent powder resistivity can be split into two parts. To a first approximation, the first part belongs to the grain cores, the second to intergranular contacts.

The effect of high energy milling on the catalytic behaviour of manganese dioxide

A technique of dry high energy milling has been used to increase the catalytic activity of naturally occurring manganese dioxide powder. The effect of the basic milling parameters (ball charge, milling time and milling atmosphere) has been examined. The subsequent catalytic activity of the manganese dioxide powder has been assessed by quantitative measurement of the oxidation of carbon monoxide over a range of temperatures. A surface area increase alone did not explain the results, and hence a change in defect structure is suspected. The activity of a high purity synthetic manganese dioxide powder was reduced by the milling treatment.

Tumorigenic effect of an organomanganese compound on F344 rats and Swiss albino mice.

Trioctanoin suspensions of manganese dioxide and manganese powder were injected im into inbred F344 rats and Swiss albino mice. The manganese powder was also administered orally to the rats. No difference in tumor incidence was noted between treated and control animals. In contrast, manganese (manganous) acetylacetonate administered im to rats produced a statistically significant number of fibrosarcomas at the sites of injection.

Die herstellung von braunstein-schicht-elektroden und deren anwendung bei untersuchungen uber die depolarisationsreaktion des braunsteins

The preparation of a new kind of manganese dioxide electrode for discharge experiments is described. These electrodes can be prepared from various types and modifications of manganese dioxide utilizing definite particle sizes. They give relatively good reproducibility of discharge curves and, therefore, appear to be suitable for systematic investigation of the depolarization process. For this preparation, the manganese dioxide powder is placed as uniformly as possible on a non-depolarizable conducting foil and is firmly secured. This layer can be produced by sprinkling, or spreading a slurry of manganese dioxide in water. Discharge curves of β- and γ-manganese dioxide were taken in ammonium chloride solutions at various current densities in the unstirred and stirred electrolyte. Their shape is in agreement with previous results and concepts.

Some Effects observed by Electron Spin Resonnce of the Diffusion of Manganese into the Calcium and Strontium Fluoride Lattices

The x-band electron spin resonance spectra of calcium or strontium fluoride powder mechanically mixed with manganese fluoride, manganese ammonium fluoride, or manganese dioxide powder were observed immediately after nofixing, after periods of time, and after heating at various temperatures in an argon stream or in air. The proportion of manganese to calcium or strontium was 0.5%. The spectrum immediately after mixing is that of the manganese compound alone. Subsequent spectra depended on the grain size of the alkaline earth fluoride powder. (L.N.N.)