Oxidation iron and manganese

Ability to oxidize iron and manganese Excellent Less effective... 

When oxidizing iron and manganese using dissolved oxygen, the process is usually carried out under catalytic reaction on some contact surfaces. To accomplish... 

Like ozone, chlorine dioxide is also beneficial for controlling taste and odor problems, for oxidizing iron and manganese, for oxidizing pollutants in raw water, and for bleaching color in water. From a practical perspective, chlorine dioxide is also five times more soluble in water than chlorine and is effective over a wide pH range. Chlorite dioxide also produces fewer chlorinated by-products than chlorine, as evidenced by lower organic chlorite levels produced. 

Noticeable amoxmts of are expended for oxidizing iron and manganese. Bacteria capable of oxidizing or accumulating iron are called... 

Here oxidizing iron and manganese plays the role not of a source of energy but of detoxifier of a harmful released product. Thereby iron-depositing bacteria prevent the accumulation of iron and manganese in water. 

In further contributions, the kinetics of the reaction of [Cu(S2CNR2)2] (R = Me, Et R2 = MePh) with periodate have been studied. Oxidation is shown to be first order with respect to the complex and periodate (1729), while copper(III) complexes, [Cu(S2CNR2)2][BF4] (R =Me, Et), have been found to oxidize iron and manganese(III) tris(dithiocarbamate) complexes to give [M(S2 CNR2)3][BF4] (M = Fe, Mn) (1124). 

Iron and Manganese Removal. Soluble ferrous and manganous ions are oxidized by ozone (typicaUy 2.5 ppm) to less soluble higher... 

Oxidation of sulfur dioxide in aqueous solution, as in clouds, can be catalyzed synergistically by iron and manganese (225). Ammonia can be used to scmb sulfur dioxide from gas streams in the presence of air. The product is largely ammonium sulfate formed by oxidation in the absence of any catalyst (226). The oxidation of SO2 catalyzed by nitrogen oxides was important in the eady processes for manufacture of sulfuric acid (qv). Sulfur dioxide reacts with chlorine or bromine forming sulfuryl chloride or bromide [507-16 ]. 

Anhydrous zinc chloride can be made from the reaction of the metal with chlorine or hydrogen chloride. It is usually made commercially by the reaction of aqueous hydrochloric acid with scrap zinc materials or roasted ore, ie, cmde zinc oxide. The solution is purified in various ways depending upon the impurities present. For example, iron and manganese precipitate after partial neutralization with zinc oxide or other alkah and oxidation with chlorine or sodium hypochlorite. Heavy metals are removed with zinc powder. The solution is concentrated by boiling, and hydrochloric acid is added to prevent the formation of basic chlorides. Zinc chloride is usually sold as a 47.4 wt % (sp gr 1.53) solution, but is also produced in soHd form by further evaporation until, upon cooling, an almost anhydrous salt crystallizes. The soHd is sometimes sold in fused form. 

Oxides of manganese and iron are often found deposited together. Similar conditions cause oxidation of both iron and manganese ions. Exposure to oxygenated water, chlorination, and some microbiological processes causes such oxidation. Often, a few percent chlorine is found in deposits, possibly because of associated chlorination. 

It is during oxidation that iron and manganese in suspension are removed from the water. Oxidizing agents (chlorine, ozone, hydrogen peroxide, potassium permanganate, etc.) or direct aeration is used the metals in... 

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.)... 

The principal reactions for the aeration/oxidation of dissolved iron and manganese are ... 

Aeration towers are often simply constructed wooden towers with or without the benefit of a forced-air draft, over which the well water is distributed. Typically, the tower holds 8 to 10 trays, each with a 3- to 4-inch (7.6-10.2 cm) bed depth of volcanic lava or coke media to provide the total 30 to 36" (76-91 cm) depth required. The lava or coke acts as a catalyst for the further precipitation of iron and manganese salts. These salts can be readily oxidized provided there is sufficient alkalinity present. If in doubt, ensure a minimum of 120 to 150 ppm total alkalinity (T Aik or M Aik) as CaC03. 

Metal cycles Iron and manganese oxidation and reduction Iron bacteria and manganese bacteria... 

In addition to effects on the concentration of anions, the redox potential can affect the oxidation state and solubility of the metal ion directly. The most important examples of this are the dissolution of iron and manganese under reducing conditions. The oxidized forms of these elements (Fe(III) and Mn(IV)) form very insoluble oxides and hydroxides, while the reduced forms (Fe(II) and Mn(II)) are orders of magnitude more soluble (in the absence of S( — II)). The oxidation or reduction of the metals, which can occur fairly rapidly at oxic-anoxic interfaces, has an important "domino" effect on the distribution of many other metals in the system due to the importance of iron and manganese oxides in adsorption reactions. In an interesting example of this, it has been suggested that arsenate accumulates in the upper, oxidized layers of some sediments by diffusion of As(III), Fe(II), and Mn(II) from the deeper, reduced zones. In the aerobic zone, the cations are oxidized by oxygen, and precipitate. The solids can then oxidize, as As(III) to As(V), which is subsequently immobilized by sorption onto other Fe or Mn oxyhydroxide particles (Takamatsu et al, 1985). 

Microbiologically influenced corrosion is defined by the National Association of Corrosion Engineers as any form of corrosion that is influenced by the presence and/or activities of microorganisms. Although MIC appears to many humans to be a new phenomenon, it is not new to the microbes themselves. Microbial transformation of metals in their elemental and various mineral forms has been an essential part of material cycling on earth for billions of years. Some forms of metals such as reduced iron and manganese serve as energy sources for microbes, while oxidized forms of some metals can substitute for... 

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