Amorphous iron

M. W. Grinstafif, M. B. Salmon, and K.S. Suslick, Magnetic properties of amorphous iron,... 

The corrosion behaviour of amorphous alloys has received particular attention since the extraordinarily high corrosion resistance of amorphous iron-chromium-metalloid alloys was reported. The majority of amorphous ferrous alloys contain large amounts of metalloids. The corrosion rate of amorphous iron-metalloid alloys decreases with the addition of most second metallic elements such as titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, copper, ruthenium, rhodium, palladium, iridium and platinum . The addition of chromium is particularly effective. For instance amorphous Fe-8Cr-13P-7C alloy passivates spontaneously even in 2 N HCl at ambient temperature ". (The number denoting the concentration of an alloy element in the amorphous alloy formulae is the atomic percent unless otherwise stated.)... 

It has been observed that, in some older power plants designed with precoat filters installed ahead of deep-bed polishers, the deep-bed units were not needed because of effective filtration by the precoats. Where precoat filters are installed, it is sometimes the practice to make use of hydrazine (or hydrazine substitute) to convert amorphous iron oxides to crystalline iron oxides, which enhances filtration. 

Fig. 15-5 Comparative adsorption of several metals onto amorphous iron oxyhydroxide systems containing 10 M Fej and 0.1 m NaNOs. (a) Effect of solution pH on sorption of uncomplexed metals, (b) Comparison of binding constants for formation of soluble Me-OH complexes and formation of surface Me-O-Si complexes i.e. sorption onto Si02 particles, (c) Effect of solution pH on sorption of oxyanionic metals. (Figures (a), (c) reprinted with permission from Manzione, M. A. and Merrill, D. T. (1989). "Trace Metal Removal by Iron Coprecipitation Field Evaluation," EPRI report GS-6438, Electric Power Research Institute, California. Figure (b) reprinted with permission from Balistrieri, L. et al. (1981). Scavenging residence times of trace metals and surface chemistry of sinking particles in the deep ocean, Deep-Sea Res. 28A 101-121, Pergamon Press.)...

Davis, J.A. and Leckie, J.O., Surface ionization and complexation at the oxide/water interface, II surface properties of amorphous iron oxyhydroxide and adsorption of metal ions, J. Colloid Interface Sci. 67, 90-107, 1978. 

Suslick KS, Choe SB, Cichowlas AA, Grinstaff MW (1991) Sonochemical synthesis of amorphous iron. Nature 353 414-416... 

Chao T.T., Zhou L Extraction techniques for selective dissolution of amorphous iron oxides from soils and sediments. Soil Sci Soc Am J 1983 47 225-232. 

Pierce, M.L. Moore, C.B. 1982. Adsorption of arsenite and arsenate on amorphous iron hydroxide. Water Research, 16, 1247-1253. 

Belzile, N., Chen, Y.W., Wang, Z.J., 2001. Oxidation of antimony (III) by amorphous iron and manganese oxy hydroxides. Chemical Geology, 174, 379-389. 

With the emplacement of the cover, the atmospheric oxygen that fuelled the precipitation of secondary As phases was essentially eliminated. Secondary phases such as jarosite, scorodite and amorphous iron sulfo-arsenates became unstable in the present conditions in the ARS (Salzsauler et at. 2005). Reductive dissolution of the secondary phases and residual arsenopyrite gives rise to 100 mg/L As in pore water at the base of the residue pile (Salzsauler et al. 2005). 

Benjamin, M. M. and Leckie, J. O. (1981). Multiple-site adsorption of cadmium, copper, zinc, and lead on amorphous iron oxyhydroxide, J. Coll. Inter/. Sci., 79, 209-221. 

The immobilized arsenic in the precipitate is bound only by sorption onto the amorphous iron hydroxides. A sustainable immobilization would need additional action. 

Cornell, R. M., R. Giovanoli, and W. Schneider (1989), "Review of the Hydrology of Iron(III) and the Crystallization of Amorphous Iron(III) Hydroxide Hydrate", J. Chem. Techn. Biology 46, 115-134. 

Davis, J. A., and J. O. Leckie (1978a), "Surface Ionization and Complexation at the Oxide/Water Interface. II. Surface Properties of Amorphous Iron Oxyhydroxide and Adsorption of Metal Ions," J. Colloid Interface Sci. 67, 90-107. 

Figure 12. Comparison of the observed Cd(II) fractional removal f = [Cd(II). g/Cd(II)T] with model results incorporating different characteristics of x- Open circles Kurbatov coefficients for end-members (Tltania Xr = 0.99, pKj, = 1.77 Amorphous Iron ...

Effects of Pentavalent Sb Ions on the Adsorption of Divalent Co-57 on Hematite. Benjamin and Bloom reported that arsenate ions enhance the adsorption of cobaltous ions on amorphous iron oxyhydroxide (J 6). Similarly, when divalent Co-57 ions were adsorbed on hematite together with pentavalent Sb ions, an increase of adsorption in the weakly acidic region was observed. For example, when 30 mg of hematite was shaken with 10 cm3 of 0.1 mol/dm3 KC1 solution at pH 5.5 containing carrier-free Co-57 and about 1 mg of pentavalent Sb ions, 95 % of Co-57 and about 30 % of Sb ions were adsorbed. The emission spectra of the divalent Co-57.ions adsorbed under these conditions are shown in Figure 8 together with the results obtained under different conditions. As seen in Figure 8, the spectra of divalent Co-57 co-adsorbed with pentavalent Sb ions are much different from those of Co-57 adsorbed alone (Figure 3). These observations show a marked effect of the.co-adsorbed pentavalent Sb ions on the chemical structure of adsorbed Co-57. 

The amorphous iron oxide is observed to be considerably more photoactive than the crystalline oxide - presumably as a result of the greater number of surface-located ferric hydroxy chromophores (the BET surface area of the synthesized Y-FeOOH is only 34 m2/g... 

Poulson RL, Beard BL, Johnson CM (2003) Investigating isotope exchange between dissolved aqueous and precipitated amorphous iron species in natural and synthetic systems. IS Arm Goldschmidt Meeting, abstract A3 82... 

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