Manganese oxide presentations

The nearly colorless glass fragment (object 1) has essentially the matrix composition. The slight green tint probably comes from the very small amounts of iron, copper, and manganese oxides present. 

Water samples from the Main Stem and the South Fork of the Coeur d Alene River, Idaho, USA, which were contaminated with Sb and As, and the other heavy metals from the local mining operation, showed high levels of Sb (0.23-8.25 ppb) and As (0.11 -1.64 ppb). The major inorganic Sb species was Sb(V) in all three branches of the river. Leaching of Sb and As species from the contaminated Main Stem sediments depended on the pH values of the water as well as on the free iron oxides and manganese oxides present in the sediments ... 

CIS of potassium permanganate in 2000 c.c. of water is placed in a, and an emulsion of 100 grams of the hydrocarbon in 600 c.c. of water is gradually added in small portions. The mixture is kept cool by means of a current of cold water, and shaken continuously. The oxidation products are then treated as follows The liquid is filtered from manganese oxide, and evaporated to about 1000 c.c., saturated with carbon dioxide, and the neutral and unaltered compounds removed ly extract jn with ether in the usual manner. The crude pinonic acid is separated from its potassium salt by sulphuric acid and is then extracted with ether. If /S-pinene be present, nopinic acid will be present... 

Where present in boiler MU water, both iron and manganese may present fouling and deposition problems in the pre-boiler section. These problems may extend to the boiler section, and therefore these metals must be removed at source. Typically, this is achieved by oxidation followed by filtering off the flocculated iron. (Process examples are aeration towers, contact with chlorine, pressure filters with BIRM media, manganese greensand filters, etc.)... 

Other metal oxide catalysts studied for the SCR-NH3 reaction include iron, copper, chromium and manganese oxides supported on various oxides, introduced into zeolite cavities or added to pillared-type clays. Copper catalysts and copper-nickel catalysts, in particular, show some advantages when NO—N02 mixtures are present in the feed and S02 is absent [31b], such as in the case of nitric acid plant tail emissions. The mechanism of NO reduction over copper- and manganese-based catalysts is different from that over vanadia—titania based catalysts. Scheme 1.1 reports the proposed mechanism of SCR-NH3 over Cu-alumina catalysts [31b],... 

As presented by this paper, our aim was to describe some preliminary results demonstrating that amorphous manganese-oxide-based materials synthesised by means of precipitation technique from aqueous solutions could serve as effective cathodes in lithium batteries. 

In Limnodrilus sp., an oligochaete worm, copper bioavailability from surhcial freshwater sediments is associated with the amount of copper present in the manganese oxide fraction of the sediment. The redox potential and pH in the gut of Limnodrilus allows the dissolution of the manganese oxide coating, making copper and other metals available for uptake (Diks and Allen 1983). 

Most of the zinc introduced into aquatic environments is sorbed onto hydrous iron and manganese oxides, clay minerals, and organic materials, and eventually is partitioned into the sediments (USEPA 1987). Zinc is present in sediments as precipitated zinc hydroxide, ferric and manganic... 

Several reactions between constituents in As-contaminated groundwater and oxic sediments controlled As mobility in the laboratory experiments. Adsorption was the primary mechanism for removing As from solution. The adsorption capacity of the oxic sediments was a function of the concentration and oxidation state of As, and the concentration of other solutes that competed for adsorption sites. Although As(lll) was the dominant oxidation state in contaminated groundwater, data from the laboratory experiments showed that As(lll) was oxidized to As(V) by manganese oxide minerals that are present in the oxic sediment. Phosphate in contaminated groundwater caused a substantial decrease in As(V) adsorption. Silica, bicarbonate and pH caused only a small decrease in As adsorption. 

Hydrous Manganese oxides, widely distributed in natural systems, are stronger oxidants than iron(III)(hydr)oxide. These oxides readily oxidize many natural and xenobiotic organic compounds. Various substituted phenols, naturally present in... 

With XPS it is possible to obtain good analytical information on the amount of metal adsorbed and, in favourable cases, to identify the chemical form of that metal. Oxidation states are readily determined and it can be shown, for example, that adsorption of Co(II) on manganese oxides results in oxidation to Co(III) (38,39), whereas adsorption of Co(II) on zirconia and alumina leads to the formation of cobalt(II) hydroxide (40). With Y-type zeolites hexaaquacobalt(II) is adsorbed as Co(II), and cobalt(III) hexaammlne is adsorbed as Co(III). The XPS spectrum of Co(II) adsorbed on chlorite was consistent with the presence of the hexaaquacobalt(II) ion for pH 3-7 and indicated that no cobalt(II) hydroxide was present (41). With kaollnlte and llllte, Co is adsorbed as Co(II) over the pH range 3-10 (39,42), it being bound as the aqua ion below pH 6 and as the hydroxide above pH 8. Measurements involving Pb have... 

Occurrence. In order of abundance in the earth s crustal rocks, it is the third within the transition elements (after Fe and Ti) and the 12th in the general order of all the elements. It occurs in several minerals such as primary deposits of silicates and as secondary deposits (commercially more important) of oxides and carbonates as pyrolusite, Mn02, hausmannite, Mn304, rhodochrosite, MnC03, etc. Large amounts of manganese are present in the deep sea nodules located over certain areas of the ocean floor. 

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