Manganese adsorption

Fig. 4.18 Plot of log (.x/(mg g" )) against log (p°/p) for the adsorption of nitrogen at 77 K on the samples of manganese dioxide referred to in Fig. 4.16. Outgassing temperature (A) room (B) 393 K (C)443 K (D) 493 K. For the points denoted by V in Curve A, a sample was outgassed at 493 K and charged with nonane before the final outgassing at room temperature. (Courtesy Lee and Newnham.)...

R. Patel and D. Clifford, Radium Removalfrom Water by Manganese Dioxide Adsorption and Diatomaceous Earth Filtration, NTIS PB92-115260/AS, Springfield, Va., 1992. 

Pretreatment of aqueous streams may be required prior to using ion exchange. Suspended soHds that can plug an ion-exchange unit should be reduced to the 10 p.m level. Organics that can foul resins can be removed by carbon adsorption. Iron [7439-89-6] and manganese [7439-96-5], commonly present in ground waters, should be removed because they precipitate on the resin. 

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). 

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

Luo, J., Zhang, Q., Garcia-Martinez, J. and Suib, S.L. (2008) Adsorptive and acidic properties, reversible lattice oxygen evolution, and catalytic mechanism of cryptomelane-type manganese oxides as oxidation catalysts. Journal of the American Chemical Society, 130, 3198-3207. 

Hu, B., Chen, C., Frueh, S.J., Jin, L., Joesten, R. and Suib, S.L. (2010) Removal of aqueous phenol by adsorption and oxidation with doped hydrophobic cryptomelane-type manganese oxide (K-OMS-2) nanofibers. Journal of Physical Chemistry C, 114, 9835-9844. 

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 (co-precipitated copper(II) oxide and manganese (IV) oxide) is present in the respirator cartridge, ignition may occur. 

McKenzie R.M. The adsorption of lead and other heavy metals on oxides of manganese and iron. Austral J Soil Res 1980 18 61-73. 

Shuman L.M. Effect of removal of organic matter and iron or manganese-oxides on zinc adsorption by soil. Soil Sci 1988 146 248-254. 

The shift of the amide I mode (FTIR spectra) from 1657 to 1646 cm-1 was attributed to a change in the a-helix native structure to fl-sheets, secondary structure conformations. Atomic Force Microscopy (AFM) images display the coating of the manganese oxide surface as well as the unfolding in a ellipsoidal chain of the protein molecules after adsorption and immobilization on the surface. 

Y. Lvov, B. Munge, O. Giraldo, I. Ichinose, S.L. Suib, and J.F. Rusling, Films of manganese oxide nanoparticles with polycations or myoglobin from alternate-layer adsorption. Langmuir 16, 8850-8857 (2000). 

Morales F., de Smit E., de Groot F.M.F., Visser T., and Weckhuysen B.M. 2007. Effects of manganese oxide promoter on the CO and H2 adsorption properties of titania-supported cobalt Fischer-Tropsch catalysts. J. Catal. 246 91-99. 

Ming, J., Koizumi, N., Ozaki, T., and Yamada, M. 2001. Adsorption properties of cobalt and cobalt-manganese catalysts studied by in-situ diffuse reflectance FTIR using CO and CO+H2 as probes. Appl. Catal. A Gen. 209 59-70. 

Yoshimura et al. [193] carried out microdeterminations of phosphate by gel-phase colorimetry with molybdenum blue. In this method phosphate reacted with molybdate in acidic conditions to produce 12-phosphomolybdate. The blue species of phosphomolybdate were reduced by ascorbic acid in the presence of antimonyl ions and adsorbed on to Sephadex G-25 gel beads. Attenuation at 836 and 416 nm (adsorption maximum and minimum wavelengths) was measured, and the difference was used to determine trace levels of phosphate. The effect of nitrate, sulfate, silicic acid, arsenate, aluminium, titanium, iron, manganese, copper, and humic acid on the determination were examined. 

Brewer and Spencer [428] have described a method for the determination of manganese in anoxic seawaters based on the formulation of a chromophor with formaldoxine to produce a complex with an adsorption maximum at 450 nm. Sulfide (50 xg/l), iron, phosphate (8 ig/l), and silicate (100pg/l) do not interfere in this procedure. The detection limit is 10 pg/1 manganese. 

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