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Showing 1 to 20 of 35 for “"Manganese oxides"”.
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Understanding Heterogenous Catalysis on Zeolites and Manganese Oxides
… their ability to be shape selective. Octahedral manganese oxides are another type of heterogenous catalyst that have emerged in significance and have been identified recently to be highly active and selective in the hydrogenation of α, β unsaturated aldehydes. In this thesis, using density …
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Investigating the controlled oxidation of manganese oxides with the Brownmillerite structure
… an initial investigation into the potential of manganese containing Brownmillerite phases, with the stoichiometry (Sr2-xCax)MnGaO5+δ, to display significant mixed conductivity and interesting magnetic properties by forming mixed manganese valence. Significant mixed valency in manganese has not …
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Electronic structures of iron and manganese oxides with applications to their mineralogy
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1984.
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The contribution of manganese oxides to redox buffering in selected soils of the South African Highveld
… The major difference between these soils was the manganese content, with manganiferous soils lacking the expression of mottles. Results from XRF abd chemical extractions indicated that the dolomites had the highest Mn content while the quartzites and granites had negligible Mn contents. It was not …
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Development of manganese oxide based nanostructures by wet chemical methods for enhanced energy storage and photocatalytic applications
… chemistry, morphology, porosity and textures, manganese oxides exhibit a variety of distinct electrochemical and dye degradation applications. This work mainly comprised of development of manganese oxide nanostructures via wet chemical approaches such as electrochemical deposition and …
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Stability of lithium aluminum manganese oxide cathodes for rechargeable lithium batteries
Lithium manganese oxides have attracted wide attention as low-cost, nontoxic intercalation cathode materials for rechargeable lithium batteries. In this work, the stability of these compounds during synthesis and in use has been studied in several respects. (1) Phase stability of LiMnO2 polymorphs …
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Carbon deposition on transition metal- and uranium-oxides
… on a range of transition metal spinels, manganese oxides, uranium oxides and single crystal magnetite samples with a view to furthering knowledge of catalytic reactions that may occur within an AGR. In particular, the effect of mixed valency on deposition rates was studied. The spinels …
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MANGANESE OXIDE AS A NEW CATHODE CATALYST IN MICROBIAL FUEL CELLS (MFCs)
This study focused on manganese oxides with a cryptomelane-type octahedral molecular sieve (OMS-2) structure to replace platinum as a cathode catalyst in microbial fuel cells (MFCs). Undoped (ud-OSM-2) and three catalysts doped with cobalt (Co-OMS-2), copper (Cu-OMS-2), and cerium (Ce-OMS-2) to …
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Phosphate and thermal stabilization of heavy metals in dredged sediments
… (ZnCO_3) (67%) and adsorbed to hydrous iron oxides (15%) and hydrous manganese oxides (18%). Phosphate addition and calcination resulted in sparingly soluble phases, hopeite (Zn_3(PO_4)_2.4H_2O) (22%), and spinels, gahnite (ZnAl_2O_4) (44%) and franklinite (ZnFe_2O_4) (34%). Sequential …
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Mechanistic understanding of biogenic Mn-oxide mediated bisphenol A degradation
… studies showed that BPA is degraded by synthetic manganese oxides (MnO[subscript 2-syn]) without the requirement of oxygen. Manganese oxides (MnO₂) is a naturally occurring, strong oxidant, and its formation is mainly attributed to microbial Mn(II) oxidation in the environment. However, the …
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Interaction of Na, O₂, CO₂ and water on MnO(100): Modeling a complex mixed oxide system for thermochemical water splitting
… water splitting based on sodium and manganese oxides (Xu, Bhawe and Davis, PNAS, 2012). The key steps are thought to be hydrogen evolution from a Na₂CO₃/MnO mixture, and oxygen evolution by thermal reduction of solids formed by Na⁺ extraction from NaMnO₂. Our work is aimed at …
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Direct Lithium-ion Battery Recycling to Yield Battery Grade Cathode Materials
… LIBs becomes urgent needs. Lithium nickel cobalt manganese oxides (NCM) are one of the most essential cathode materials for EV applications due to their long cycle life, high capacity, and low cost. In 2008, 18.9% of Lithium-ion batteries used NCM cathode material worldwide while this number …
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Bacterial influence on uranium oxidation reduction reactions : implications for environmental remediation and isotopic composition
… of 235U in the reaction product, UO2. The manganese oxidizing bacterium Leptothrix discophora produces manganese oxides with can both adsorb uranyl and partially oxidize UO2. Determination of if and how bacteria can influence the oxidation of uranium is important because oxidation will …
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Manganese oxide deposits in water treatment facilities, North East Scotland.
… investigation was to examine the deposition of manganese oxides in water treatment facilities. To facilitate this work, suitable sources of manganese oxide were located in water treatment plants throughout the Grampian region of Scotland. These oxides provided an ideal and abundant media on …
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Hydrologic and environmental drivers of metals (Al, Ba, Cu, Sr) in two drinking water reservoirs in southwestern Virginia
… due to sorption of these metals onto iron and manganese oxides, which are released to the water column under reducing conditions. Strontium displayed intermediate behavior, showing signatures of oxidation-reduction and pH-driven desorption processes, in addition to dilution during high …
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Hazardous waste treatment and disposal: alternative technologies and groundwater impacts
… clay is augmented by adsorption onto iron and manganese oxides and complexing with organic matter such as humic acids. Many field studies with landfarmed metal-bearing wastes show that these mechanisms are usually sufficient to retain metals to within several inches of their zone of application.
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Hydrogeochemical and radiometric investigation of the uranium tailings Schneckenstein
… fraction is in association with the iron and manganese oxides. Hence, the decrease of the oxygen contents in the environment will increase their solubility. Assuming an equilibrium between most of the radionuclides in the uranium chain before the ore processing and assuming that radium has not …
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Deriving a rate equation for the removal of manganese from solution using a gas mixture of sulphur dioxide and oxygen
… - oxygen gas mixture to selectively remove manganese from other metals, such as cobalt and nickel, from leach solutions is kinetically favourable and inexpensive. However, this technology for precipitating manganese has not been used commercially, mainly due to a lack of understanding of the …
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Ion Current Rectification in Nano/Micro-Fluidic Interfaces and Pulsed Glow Discharge Time-of-Flight Mass Spectrometric Chemical Speciation
… ratios can be used for speciation of chromium oxides, manganese oxides, and iron oxides.;Chapters 3 and 4 focus on extending the application of pulsed glow discharge time-of-flight mass spectrometry for chemical speciation. Chapter 3 is the analysis of cysteine using pulsed glow discharge …
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Manganese deposits of the Cape Peninsula, South Africa
The outcrops, petrography and geochemistry of manganese deposits were studied at several sites on the Cape Peninsula (Skeleton Gorge, Kasteelpoort Path, Kommetjie and Hout Bay) as well as at Rooi Els on the opposite side of False Bay. The purpose of this study was to understand the origin and …
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