Manganese immobilization

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). 

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. 

Susla M, Svobodova K (2008) Effect of various synthetic dyes on the production of manganese-dependent peroxidase isoenzymes by immobilized Irpex lacteus. World J Microbiol Biotechnol 24 225-230... 

Moreira MH, Feijoo G, Palma C, Lema JM (1997) Continuous production of manganese peroxidase by Phanerochaete chrysosporium immobilized on polyurethane foam in pulsed packed bed bioreactor. Biotechnol Bioeng 56 130-137... 

Rogalski J, Szczodrak J, Janusz G (2006) Manganese peroxidases production in submerged cultures by free and immobilized mycelia of Nematoloma frowardii. Bioresour Technol 97 469-476... 

Emissions of silver from coal-fired power plants may lead to accumulations in nearby soils (Fowler and Nordberg 1986). Silver in soils is largely immobilized by precipitation to insoluble salts and by complexation or adsorption by organic matter, clays, and manganese and iron oxides (Smith and Carson 1972). 

Most pubhcations regarding this field are based on immobilized chiral salen U-gands [62] which are coordinated with manganese [45 a, 78-82] or chromium [83]... 

Polyaza macrocycle derivatives have been employed in a number of analytical applications." " For example, polymer-immobilized cyclam has been employed for the preconcentration of manganese in seawater prior to analysis." ... 

Thermistor basedflow-through calorimetric sensors. Enzyme thermistors make the most widely developed type of heat measurement-based sensors. The thermistors are normally used as temperature transducers in these devices. Thermistors are resistors with a very high negative temperature coefficient of resistance. They are ceramic semiconductors made by sintering mixtures of metal (manganese, nickel, cobalt, copper, iron) oxides. Like the two previous groups, thermistor sensors do not comply strictly with the definition of "sensor" as they do not consist of transducers surrounded by an immobilized enzyme rather, they use a thermistor at the end of a small... 

To immobilize a protein the biologic activity of which depends on a cofactor, this cofactor has to be present in sufficient concentration during the immobilization step. Thus, for example, the lectin Concanavalin A is immobilized in the presence of a buffer containing 0.1 M glucose or a-methylmannoside, 1 mM calcium chloride and 1 mM manganese chloride. 

Figure 1. PhIO oxidation of cyclooctene catalyzed by various sulfonated manganese porphyrin immobilized on methylated PVP, [Mn-porphyrin-S-PVPMe+][TsO-]. [MnTMPS-PVPMe+][TsO-] (O), [MnBrgTMPS-PVPMe+][TsO-] ( ), [MnTDCPPS-PVPMe+][TsO-] (1) and [MnCli2TMPS-PVPMe ][TsO ] (O). Conditions cyclooctene (150 imol), PhIO (750 jimol), Mn-porphyrin-S (2 jimol) immobilized on [PVPMe+][TsO-] (200 mg of PVP treated by TsOMe) in 3 mL of dichloromethane at room temperature. (Reproduced from ref. 12a. Copyright 1992 American Chemical Society.)...

In Fig. 2.1.6.6, the FTIR spectra of the Jacobsen ligand (a), the Jacobsen catalyst (bj, and the immobilized manganese salen complex in the cages of dealuminated faujasite zeolite (c) are compared. While spectra a and b have been measured using the standard KBr technique, the spectrum c of the ship in a bottle catalyst has been recorded using a self-supported wafer. The bands at wavenumbers 1466 cm, 1434 cm" , 1399 cm" and 1365 cm" in spectrum c can be assigned to the... 

Dramatic shape selectivities in competitive olefin epoxidation was observed with picnic basket metalloporphyrins312 313 designed to exclude bulky axial ligands on one sterically protected porphyrin face. When oxidized with PhIO in acetonitrile in the presence of the rigid p-xylyl-strapped porphyrin, cis-2-octene reacted selectively versus ds-cyclooctene or 2-methyl-2-pentene, giving >1000 reactivity ratios.313,314 Some immobilized manganese(III) porphyrins proved to be as efficient as their homogeneous equivalents in epoxidation with PhIO.151,315... 

Literally hundreds of complex equilibria like this can be combined to model what happens to metals in aqueous systems. Numerous speciation models exist for this application that include all of the necessary equilibrium constants. Several of these models include surface complexation reactions that take place at the particle-water interface. Unlike the partitioning of hydrophobic organic contaminants into organic carbon, metals actually form ionic and covalent bonds with surface ligands such as sulfhydryl groups on metal sulfides and oxide groups on the hydrous oxides of manganese and iron. Metals also can be biotransformed to more toxic species (e.g., conversion of elemental mercury to methyl-mercury by anaerobic bacteria), less toxic species (oxidation of tributyl tin to elemental tin), or temporarily immobilized (e.g., via microbial reduction of sulfate to sulfide, which then precipitates as an insoluble metal sulfide mineral). 

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