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Hematite contamination

Contaminants such as oil, magnesium phosphate, and hematite have a natural binding action that exacerbates the fouling problem and may result in the rapid agglomeration of tube deposits in WT boilers and fire-tube bridging in FT boilers. [Pg.154]

M) or chloride ions (o) vs. pH. o chloride contamination, chloride-free hematite (Matijevic, 1980, with permission). [Pg.238]

As argued earlier, by coupling redox and dissolution reactions, it should be possible to form phosphate ceramics of certain insoluble oxides by reducing them to a lower oxidation state that is more soluble, or to convert contaminants of lower oxidation states and stabilize them as phosphates. For example, a mixture of insoluble hematite and elemental... [Pg.77]

Raman chemical imaging can be employed to access the homogeneity and the structural stability in terms of oxidation rates, onset of hematite, and organic contamination of as-precipitate and oxidized iron oxide samples. Oxidation-related Raman features have been established by comparative study of bulk oxides and nanoparticles attained in two different oxidation states, suggesting that the solid nanophase synthesized had a mixed magnetite-maghemite composition [52]. [Pg.402]

Hematites with a particular crystal shape (plates, needles, spindles, pseudocubes, peanuts) and a narrow size distribution (monodisperse) can be obtained by adding various chemicals (shape controllers) to the system. The mechanism behind the control of shape is most likely to be the adsorption of impurities on certain crystal faces thereby reducing their growth rate in favor of that of the other faces. Internally these crystals may be either mono- or polydomainic, depending on the type and concentration of the additive. It must be kept in mind that higher additive concentrations may lead to product contamination. Some examples are summarized in the following section. [Pg.130]

Figure 4. Effect of acidic and basic contamination, u, on the results of mass titration with a hematite suspension [47]. u/mol g- ( ) - 10- , ( ) 0, (a) lO" , ( ) lo-. ... Figure 4. Effect of acidic and basic contamination, u, on the results of mass titration with a hematite suspension [47]. u/mol g- ( ) - 10- , ( ) 0, (a) lO" , ( ) lo-. ...
All glassware used was cleaned with concentrated HCl (36%) to avoid nucleation at the glass surface. It is essential to use clean vials and wash bottles to avoid contamination of the hematite surface and thus variation of the surface characteristics. [Pg.342]

Alternatively, iron-rich sacrificial electrodes, which dissolve under acidic conditions generated at the anode by the application of electric field, may be used. The dissolved iron, in cationic form, migrates toward the cathode and then precipitates as iron-rich mineral phases (ferric iron oxyhydroxides, hematite, goethite, magnetite, and ZVl) near the cathode due to high-pH conditions. Contaminants such as Cr(Vl) can react with this iron and reduce into Cr(III). Cr(VI) transport may be limited by high sorption under low-pH conditions therefore, alkaline solution may be injected from the anode to increase the soil pH, and thereby reduce sorption and increase transport of Cr(Vl) to react with iron. [Pg.22]


See other pages where Hematite contamination is mentioned: [Pg.146]    [Pg.289]    [Pg.67]    [Pg.289]    [Pg.236]    [Pg.239]    [Pg.408]    [Pg.439]    [Pg.465]    [Pg.523]    [Pg.530]    [Pg.589]    [Pg.554]    [Pg.464]    [Pg.219]    [Pg.507]    [Pg.471]    [Pg.160]    [Pg.127]    [Pg.559]    [Pg.338]    [Pg.340]    [Pg.128]    [Pg.1961]    [Pg.5128]    [Pg.308]    [Pg.465]    [Pg.64]    [Pg.85]    [Pg.122]    [Pg.869]    [Pg.869]    [Pg.341]    [Pg.46]    [Pg.47]    [Pg.83]    [Pg.349]    [Pg.1960]    [Pg.645]    [Pg.305]    [Pg.395]   
See also in sourсe #XX -- [ Pg.85 , Pg.122 , Pg.127 ]




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Hematite

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