Reduction Of KMnO4 Research Articles

Direct synthesis of nanocrystalline, spherical α-Mn2O3 particles by mechanochemical reduction

The preparation of nanocrystalline α-Mn2O3 by using the mechanochemical reduction of KMnO4 with NH4Cl in stoichiometric ratio 1:1 was investigated in this work. High-energy milling with ball to powder mass ratio 20:1 and centrifugal forces 60 g lead to the completion of the reaction between the reactants after 10 min. Further 15–60 min milling transforms the amorphous and hydrated Mn2O3 to the nanocrystalline α-Mn2O3 phase. This synthesis involves a direct preparing of α-Mn2O3 with spherical geometry and average XRD crystallite size above 50 nm.

New Synthetic Route, Characterization, and Electrocatalytic Activity of Nanosized Manganite

Nanosized γ-MnOOH (manganite) has been synthesized by a new route via the reduction of KMnO4 with sucrose and MnSO4 in acidic medium under refluxing conditions for 4 and 6 h. Characterization of these manganite materials using XRD, FESEM, TEM, TGA, and IR were carried out. The obtained manganite samples using the new route were compared against a conventionally prepared one where synthesis involved the oxidation of MnSO4 with a H2O2 solution in a basic medium. Two new synthetic methods were developed, one involving addition of KMnO4 into a solution of both sucrose and MnSO4 while the other involved addition of KMnO4 solution into sucrose only followed by addition of MnSO4 (s). The latter method yielded smaller particles (up to 30 nm) than the former method (up to 80 nm) and the conventionally prepared manganite (up to 50 nm). The synthesized manganite materials exhibited promising characteristics when tested as electrocatalysts in the reduction of O2. The larger particles gave higher peak currents in CV. When incorporated in Yardney's medium-sized lithium-air battery, the larger particles gave higher specific capacity (up to 2.2 A·h/g), which corresponds to about a 38% increase in specific energy of the battery when compared to a battery where no manganite was incorporated.

Synthesis of electrode materials by reduction of KMnO 4 with NiCl 2·6H 2O in aqueous solutions

The nickel–manganese compounds were synthesized by redox reactions in aqueous solutions using potassium permanganate as an oxidizing agent at ambient temperature. Also, a layered Li–Ni–Mn–O system was synthesized by using a nickel–manganese compound as precursor for electrode materials. X-ray diffraction patterns of the lithiated Li 1.296Ni 0.056Mn 0.648O 2 sample were indexed to a layered structure based on hexagonal α-NaFeO 2 (space group: R-3 m, 166) with signs of monoclinic-related peaks indicating the existence of monoclinic Li 2MnO 3 phase. The lithiated Li 1.296Ni 0.056Mn 0.648O 2 electrode provides the initial discharge capacity of 108 mAh g −1 and the maximum discharge capacity of 192 mAh g −1 between 2.0 and 4.8 V versus Li/Li + at 0.2 mA cm −2.

Synthesis of Nanoporous Materials by Reduction of KMnO4 with NiCl2 6H2O in Aqueous Solutions

not Available.

Carbon Nanotubes as Catalyst Supports for Oxygen Electrodes

Carbon nanotubes modified with manganese dioxide were prepared. Manganese dioxide was deposited by reduction of KMnO4 in solution using formic acid or nanotube carbon. The electrochemical properties of oxygen electrodes containing nanotubes modified with manganese dioxide were studied.

Particle Size Control of Cryptomelane Nanomaterials by Use of H2O2 in Acidic Conditions

A new soft-step chemistry method has been developed to prepare pure cryptomelane-type manganese oxide materials (OMS-2) with the smallest particle sizes ever reported. The synthetic procedure is based on the reduction of KMnO4 by H2O2 under acidic conditions followed by reflux. An acetate-containing buffer solution and HNO3 are used to control the pH of the reaction mixture. The formation process, particle size, crystallite size, crystal structure, and properties of these nanomaterials have been investigated by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), potentiometric titration, thermogravimetric analysis, and N2 sorption analyses. Both the concentration of H2O2 and the nature of the acid used affect the crystalline phase formation, microstructure, thermal stability, and the composition of the final product. HRTEM images reveal that the OMS-2 nanofibers are not oriented preferentially and present significant twinning, along with discontinuity...

Sol–gel synthesis and characterization of mesoporous manganese oxide

Mesoporous manganese oxide (MPMO) from reduction of KMnO 4 with maleic acid, was obtained and characterized in detail. The characterization of the material was confirmed by high-resolution transmission electron microscopy (HRTEM), X-ray powder diffractometry (XRD) and N 2 sorptometry. The results showed that MPMO is a pseudo-crystalline material with complex network pore structure, of which BET specific surface area is 297 m 2/g and pore size distribution is approximately in the range of 0.7–6.0 nm. The MPMO material turns to cryptomelane when the calcinating temperature rises to 400 °C. The optimum sol–gel reaction conditions are KMnO 4/C 4H 4O 4 molar ratio=3, pH=7 and gelation time>6 h.

MnO x/C composites as electrode materials II. Reduction of oxygen on bifunctional catalysts based on manganese oxides

MnO x /C composites prepared by the reduction of KMnO 4 by active carbon black and doped with Ca(II), Mg(II), Ni(II), Bi(III), and Cr(III) ions were tested as catalysts of oxygen reduction in alkaline electrolyte. The polarisation curves were analysed by logarithmic wave analysis. MnO x doped with the transition metal salts are slightly more active than those with Ca(II) and Mg(II).

Synthesis and Characterization of Mesoporous Manganese Oxides

Mesoporous manganese oxide (MPMO) K0.216MnO2 ⋅ 1.26H2O was synthesized by reduction of KMnO4 with maleic acid. Its composition and structure were analyzed and characterized by inductive coupled plasma atomic emission spectrometry (ICP-AES), titration, X-ray powder diffractometry (XRD), thermogravimetry (TG)-differential thermoanalysis (DTA). The morphology and pore structure of the MPMO material were accomplished by means of high-resolution transmission electron microscopy (HRTEM) and N2 sorptometry and transmission electron microscopy (TEM). The results show that MPMO is a pseudocrystalline material with complex network pore structure; its BET surface area is 261.6 m2/g and pore diameter distribution is approximately in the range of 2–10 nm. The MPMO material turns into α-MnO2 when the calcinating temperature rises to 400°C.

Standard Nitrogen Adsorption Data for Manganese Oxide and like (CBET = 40–60) Surfaces

Calcination to 1170 K of materials obtained by mild and intensive reduction of KMnO4 and HMnO4 solutions was found to produce manganese oxides assuming the crystalline bulk structure of α-Mn2O3 Nitrogen adsorption isotherms at 77 K revealed that they also assume non-porous surfaces of low specific area (4 ± 1 m2/g) with CBET equal to 40–60; t- and αs-curves derived therefrom were found to coincide with those determined reportedly on non-porous surfaces of 11 < CBET < ∞, irrespective of the surface chemical similarity. The experimental and reported standard adsorption data were used to analyze a type-IV nitrogen adsorption isotherm determined at 77 K on a porous manganese oxide (δ-MnO2) which was obtained by sol–gel processing of a KMnO4 solution, and found to similarly reveal a mesoporous surface of SBET = 73 m2/g and CBET = 125. The close agreement between the surface area values (St and Sα) derived for the test material (δ-MnO2) from the t- and αs-plots thus obtained and its CBET value (73 m2/g) was the basis on which reference materials with 11 < CBET < ∞ were found to be appropriate. Since most of the appropriate reference materials were dissimilar chemically to the test material, the results of the present investigation may imply that the surface chemical similarity demanded by the αs-method is better manifested in terms of the surface activity (heat of adsorption monitored by the CBET value) than the chemical composition.

The 2D Rancieite-type manganic acid and its Li-exchanged derivative: A new synthetic route for a better cycling behavior

The usual preparation route of lithiated Rancieite-type Manganese Oxide (Li-RMO) includes three steps: reduction of KMnO4 in acidic medium (1), followed by a further acidic treatment which ensures a complete K+/H+ exchange (2) and subsequent Li+/H+ ion-exchange reaction (3). The surface area of the as prepared Li-RMO is always several tens of m2g−1. Its initial capacity with respect to electrochemical Li intercalation is 220 mAh/g with an average voltage of 2.85V (vs Li). However, a rapid capacity fading is observed upon cycling, due to a dissolution of the material likely related to its large surface area. A new synthetic route is proposed leading to a material with a surface area less than 10 m2g−1. As expected, the cycling behavior of this new material is greatly improved.

The 2D Rancieite-type manganic acid and its alkali-exchanged derivatives: Part I — Chemical characterization and thermal behavior

The 2D Rancieite type manganic acid was prepared by reduction of KMnO 4 in acidic medium. Its ion exchange behavior allows to prepare alkali derivatives. All compounds were characterized with use of a combination of X-ray diffraction, chemical analyses, TGA, magnetic measurements and spectroscopic techniques. The evolution of their chemical composition versus temperature was studied between 180 and 400 °C. It shows that the dehydration process is partly reversible in these compounds whereas the weak reduction is irreversible. The 2D Rancieite-type manganic acid is readily different from a Birnessite-type phyllomanganate, as shown by several features: the interlayer distance, the ion exchange capacity, the thermal behavior, the interlayer cation content, the manganese average oxidation state, the magnetic behavior and the IR spectrum.

ChemInform Abstract: Reinvestigation of the Electrochemical Reduction of KMnO4.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Reinvestigation of the Electrochemical Reduction of KMnO4

Abstract Investigating the electrochemical reduction behavior of MnO4−, we determined the consecutive reduction/oxidation potentials of MnO4− by the cyclic voltammetric method. We have also confirmed that MnO42− is reduced into MnO43−. We then investigated the cause of the generation of MnO2 on the electrode surface with the rotating ring-disk electrode method. The reversibility of the reduction of MnO4− depends on the concentration of KMnO4 and KOH. Reversibility increases when the concentration of KOH increases, but the reversibility decreases when the concentration of KMnO4 increases. The reaction rate of MnO4−/MnO42− follows the law:

ChemInform Abstract: Photochemistry of Aqueous Permanganate Ion.

AbstractThe mechanism of the photolytic reduction of KMnO4 has been studied under neutral, basic, and acidic conditions in both the presence and absence of organic substrates.

ChemInform Abstract: Chemistry of Colloidal Manganese Dioxide. Part 1. Mechanism of Reduction by an Organic Radical (A Radiation Chemical Study).

AbstractThe preparation of colloidal MnOz by radiation Chemical reduction of KMnO4 in alkaline solution is described.

Síntese de criptomelana

Cryptomelane was synthetised from several runs by methods whose reproductibility was proved. The best conditions of temperature and pH for the synthesis, the influence of the digestion time on the degree of crystallinity, and the role of the presence of Zn and K ions in the cryptomelane structure as a function of aging of the mineral in contact with the mother solution, were studied. By reduction of KMnO4 with HC1 or Zn/H2 SO4 , the highest degree of crystallinity was found at temperatures above 60ºC in an extended digestion time. The behavior of constituent ions as a function of digestion time indicates that the crystallinity of the cryptomelane is improved by increasing incorporation of K and Mn (IV) ions and decreasing of Mn (II) content, H2O and Zn ions. The probable mechanism of cryptomelane formation is thought to occur under conditions of low pH with K+ present, nucleation being induced mainly by H3O+.

A Kinetic and Mechanistic Study of Reduction of KMnO4 by L-Ascorbic Acid in Sulphuric Acid Medium

A Kinetic and Mechanistic Study of Reduction of KMnO4 by L-Ascorbic Acid in Sulphuric Acid Medium

A Kinetic and Mechanistic Study of Reduction of KMnO4 by L-Ascorbic Acid in Sulphuric Acid Medium

Article A Kinetic and Mechanistic Study of Reduction of KMnO4 by L-Ascorbic Acid in Sulphuric Acid Medium was published on January 1, 1982 in the journal Zeitschrift für Physikalische Chemie (volume 263O, issue 1).

ChemInform Abstract: THE FORMATION AND SOME PROPERTIES OF HYDROUS MANGANESE(IV) OXIDE

AbstractEigenschaften und Reaktivität von "wasserhaltigem MnO2", das durch Reduktion von KMnO4 ( ;z.B. nach Reaktion A) und durch Disproportionierung von K2MnO4 gemäß B in alkalischen Lösungen dargestellt wurde, hängen in erster Linie vom pH der Suspensionen ab.