Manganese coprecipitation

Laboratory Tests of the Lead—Manganese Coprecipitation Model... 

Laboratory Tests of Cobalt Manganese Coprecipitation Models... 

Mechanisms for coprecipitation of lead and cobalt with manganese oxide can be derived based on thermodynamic calculations. They can explain the increased oxidation state of manganese reached in the mixed oxide precipitates, and they provide a potential control of the solubility of the accessory metals. The effectiveness of the control has been evaluated in a preliminary way by laboratory experiments described here, and by some fleld observations. Cobalt activity seems to be controlled by manganese coprecipitation in many natural systems. Although more testing by both laboratory experiments and fleld studies is needed, the proposed mechanisms appear to be applicable to many coupled oxidation-reduction processes. 

Stripping voltammetry procedure has been developed for determination of thallium(I) traces in aqueous medium on a mercury film electrode with application of thallium preconcentration by coprecipitation with manganese (IV) hydroxide. More than 90% of thallium present in water sample is uptaken by a deposit depending on conditions of prepai ation of precipitant. Direct determination of thallium was carried out by stripping voltammetry in AC mode with anodic polarization of potential in 0,06 M ascorbic acid in presence of 5T0 M of mercury(II) on PU-1 polarograph. 

Adsorption and coprecipitation by hydrous iron and manganese oxides... 

The mobility of arsenic compounds in soils is affected by sorp-tion/desorption on/from soil components or co-precipitation with metal ions. The importance of oxides (mainly Fe-oxides) in controlling the mobility and concentration of arsenic in natural environments has been studied for a long time (Livesey and Huang 1981 Frankenberger 2002 and references there in Smedley and Kinniburgh 2002). Because the elements which correlate best with arsenic in soils and sediments are iron, aluminum and manganese, the use of Fe salts (as well as Al and Mn salts) is a common practice in water treatment for the removal of arsenic. The coprecipitation of arsenic with ferric or aluminum hydroxide has been a practical and effective technique to remove this toxic element from polluted waters... 

Hiraide et al. [737] developed a multielement preconcentration technique for chromium (III), manganese (II), cobalt, nickel, copper (II), cadmium, and lead in artificial seawater using coprecipitation and flotation with indium hydroxide followed by ICP-AES. The metals are simultaneously coprecipitated with indium hydroxide adjusted to pH 9.5, with sodium hydroxide, ethano-lic solutions of sodium oleate and dodecyl sulfate added, and then floated to... 

Holzbecker and Ryan [825] determined these elements in seawater by neutron activation analysis after coprecipitation with lead phosphate. Lead phosphate gives no intense activities on irradiation, so it is a suitable matrix for trace metal determinations by neutron activation analysis. Precipitation of lead phosphate also brings down quantitatively the insoluble phosphates of silver (I), cadmium (II), chromium (III), copper (II), manganese (II), thorium (IV), uranium (VI), and zirconium (IV). Detection limits for each of these are given, and thorium and uranium determinations are described in detail. Gamma activity from 204Pb makes a useful internal standard to correct for geometry differences between samples, which for the lowest detection limits are counted close to the detector. 

Early work was based on concentrating the radium from the seawater sample by adding barium and coprecipitating with barium sulfate. This concentration procedure has been replaced by one involving the extraction of radium from seawater on acrylic fibre coated with manganese dioxide [19,20] (Mn fibres). By use of this technique, volumes of 200-2000 litres may be sampled routinely. 

Bodine, M. W., H. D. Holland, and M. Borcsik (1965), "Coprecipitation of Manganese and Strontium with Calcite. Symposium Problems of Postmagmatic Ore Deposition", Prague2, 401-406. 

Copper high Miller index, 26 12 Copper oxide, 27 184-187, 199 as adsorbent, 21 44 on alumina, 27 80-85 -manganese oxide, 27 91, 92 oxidation of CO over, 24 86 -platinum catalyst, 27 86-88 propylene oxidation, 30 141 Coprecipitation, perovskite preparation, 36 247-250... 

Some metals are irreversibly adsorbed, probably via incorporation into the mineral phases, such as amorphous iron oxyhydroxides, as shown in Figure 11.6d. Some of these amorphous phases form by direct precipitation from seawater. As noted earlier, hydrothermal fluids are an important source of iron and manganese, both of which subsequently precipitate from seawater to form colloidal and particulate oxyhydroxides. Other metals tend to coprecipitate with the iron and manganese, creating a polymetallic oxyhydroxide. It is not clear the degree to which biological processes mediate the formation of such precipitates. Since the metals are incorporated into a mineral phase, this type of scavenging is better referred to as an absorption process. 

Precipitation can remove soluble nickel Ifom water. In aerobic waters, nickel ferrite is the most stable compound (Rai and Zachara 1984). Nickel may also be removed by coprecipitation with hydrous iron and manganese oxides. Nickel removed by precipitation and coprecipitation settles into the sediment. 

Adequacy of Thermodynamic Data. Data on several important aluminosilicates appear to be insufficient for a detailed discussion of all equilibria. Information on the influence of solid solutions or coprecipitated phases on thermodynamic properties appears to be rather limited, as is that for metastable non-stoichiometric oxides (e.g., of manganese) and surface complexes. 

Manganese (oxy)(hydr)oxide sorbents and manganese-oxidizing bacteria Permeable reactive barriers with lime, iron oxides, and limestone Siderite (coprecipitation and possibly sorption)... 

Precipitation Refers to dissolved species (such as arsenate oxyanions) in water or other liquids reacting with other dissolved species (such as Ca2+, Fe3+, or manganese cations) to form solid insoluble reaction products. Precipitation may result from evaporation, oxidation, reduction, changes in pH, or the mixing of chemicals into an aqueous solution. Also a water treatment technology that primarily uses precipitation to remove contaminants (compare with coprecipitation). 

Tech. Data Sheet No. 7 , New York, Comml. Solvents Corp., 1968 The heat of adsorption of 2-nitropropane is very high, so carbon-containing respirators should not be used in high vapour concentrations. Also, if Hopcalite catalyst (coprecipitated copper(II) oxide and manganese (IV) oxide) is present in the respirator cartridge, ignition may occur. 

Coprecipitation of Polonium, Radiolead, Uranium, and Plutonium with Manganese Dioxide in... 

Wong, K.M., G.S. Brown, and V.E. Noshkin. 1978. A rapid procedure for plutonium separation in large volume of fresh and saline water by manganese dioxide coprecipitation. J. Radioanal. Chem. 42 7-15. 

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