Manganese sulfide oxidant

The principal ores of zinc are sphalerite (sulfide), smithsonite (carbonate), calamine (silicate), and franklinite (zine, manganese, iron oxide). One method of zinc extraction involves roasting its ores to form the oxide and reducing the oxide with coal or carbon, with subsequent distillation of the metal. 

Manganese dioxide Aluminum, hydrogen sulfide, oxidants, potassium azide, hydrogen peroxide, peroxosulfuric acid, sodium peroxide... 

Seif-Test D.4B Write the formulas for (a) cesium sulfide tetrahydrate (b) manganese(VII) oxide (c) hydrogen cyanide (a poisonous gas) (d) disulfur dichloride. 

A few examples of chemoautolithotrophic processes have been mentioned in this chapter, namely anaerobic methane oxidation coupled to sulfate reduction and the ones listed in Table 12.2 involving manganese, iron, and nitrogen. Another example are the microbial metabolisms that rely on sulfide oxidation. Since sulfide oxidation is a source of electrons, it is a likely source of energy that could be driving denitrification, and manganese and iron reduction where organic matter is scarce. 

All measured profiles of sulfate reduction in sediments indicate that much sulfide production and, by inference, oxidation occurs in permanently anaerobic sediments (78, 73, 90,101). The two most likely electron acceptors for anaerobic sulfide oxidation are manganese and iron oxides. Burdige and Nealson (151) demonstrated rapid chemical as well as microbially catalyzed oxidation of sulfide by crystalline manganese oxide (8-Mn02), although elemental S was the inferred end product. Aller and Rude (146) documented microbial oxidation of sulfide to sulfate accompanied by reductive dissolution... 

Measured rates of sulfate reduction can be sustained only if rapid reoxidation of reduced S to sulfate occurs. A variety of mechanisms for oxidation of reduced S under aerobic and anaerobic conditions are known. Existing measurements of sulfide oxidation under aerobic conditions suggest that each known pathway is rapid enough to resupply the sulfate required for sulfate reduction if sulfate is the major end product of the oxidation (Table IV). Clearly, different pathways will be important in different lakes, depending on the depth of the anoxic zone and the availability of light. All measurements of sulfate reduction in intact cores point to the importance of anaerobic reoxidation of sulfide. Little is known about anaerobic oxidation of sulfide in fresh waters. There are no measurements of rates of different pathways, and it is not yet clear whether iron or manganese oxides are the primary electron acceptors. 

Among the interesting results of such endeavors for 304 stainless steel is a stress upon inclusions involving manganese sulfide and manganese oxide. Surprisingly, traces ofCu in the steel are detected and form flowerlike deposits prior to the initiation of a pit. Metallic inclusions tend to dissolve anodically in 0.1 MNaCl at 400 mV SCE. There is some evidence for their readsorption. However, to be the cause ofpit initiation, the inclusions have to be at least 0.7 jum in size. It may be that the local current density for dissolution at smaller inclusions is too high to sustain CF adsorption there. 

From Table 2, the organic matter in the sediments has a of about —27.3. Combining equal amounts of this carbon with 0 per mil HCO from seawater would produce a carbonate mineral with of about —14 per mil, very close to the observed value. At the same time that the manganese is oxidizing the organic matter, it also attacks any iron sulfide in the sediment (Aller and Rude, 1988 Schippers and J0rgensen, 2001) ... 

In cases where neutral or alkaline mine drainage predominates, problems may arise because of elevated concentrations of SO4, iron, manganese, and other solutes that are derived from sulfide oxidation or from reactions with carbonate or aluminosilicate minerals. Dissolved iron and aluminum may precipitate as the pH increases, and these precipitates can act as substrates for adsorption and co-precipitation (Stumm and Sulzberger, 1992 Foos, 1997 Brake et al., 2001). The dissolution of siderite,... 

Removal of interfering cations from the manganese(ll) sulfate solution is necessary before the subsequent electrochemical production of manganese IV) oxide (HMD) or manganese metal. Transition metal ions such as cobalt, nickel or copper and traces of arsenic are precipitated as their sulfides. 

Because UV radiation disinfection provides no disinfecting residual, a secondary disinfectant is needed. Very little oxidation of organic materials occurs with typical UV radiation systems used for drinking water disinfection consequently, if oxidation is required (for iron, manganese, sulfide, nitrate, etc.), a strong oxidizing agent may be... 

Sulfide Oxidation by Metal Oxides. Millero (47) proposed that sulfide is oxidized by settling particulate Mn02 (s) and possibly FeOOH(s) formed by bacteria in shallower oxic waters. Luther et al. (20) proposed that dissolved Mn(III) was responsible. Lewis and Landing (40) did not observe a significant particulate Fe oxide maximum above the sulfide interface. They did observe, however, two maxima in particulate manganese in the central basin. A shallow maximum, located at 76 m, may not contain oxidized Mn (48). The deeper maximum, at 105 m, does contain oxidized Mn. Both maxima have similarly... 

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