Iron oxyhydroxide

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.)...

Leckie, J. O., Appleton, A. R., Ball, N. B., Hayes, K. F. and Honeyman, B. D. (1986). Adsorptive removal of trace elements from fly-ash pond effluents onto iron oxyhydroxide. Final Report EPRI-RP-910-1, Electric Power Research Institute, Palo Alto, CA. 

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. 

Shannon R.D., White J.R. The selectivity of a sequential extraction procedure for the determination of iron oxyhydroxides and iron sulfides in lake sediments. Biogeochem 1991 14 193-208. 

Addition of sufficient base to give a > 3 to a ferric solution immediately leads to precipitation of a poorly ordered, amorphous, red-brown ferric hydroxide precipitate. This synthetic precipitate resembles the mineral ferrihydrite, and also shows some similarity to the iron oxyhydroxide core of ferritin (see Chapter 6). Ferrihydrite can be considered as the least stable but most reactive form of iron(III), the group name for amorphous phases with large specific surface areas (>340 m2 /g). We will discuss the transformation of ferrihydrite into other more-crystalline products such as goethite and haematite shortly, but we begin with some remarks concerning the biological distribution and structure of ferrihydrite (Jambor and Dutrizac, 1998). 

Jones, F., Colfen, H. and Antonietti, M. (2000) Iron oxyhydroxide colloids stabilized with polysaccharides. Colloid and Polymer Science, 278, 491—501. 

In the oxidized tailings, pyrrhotite and sphalerite (Fig. 2) show the most alteration with both minerals being surrounded by iron oxyhydroxides. Pyrite is relatively unaltered. 

In summary, the results of this investigation indicated that the formal oxidation of the nickel sites in a composite nickel-iron oxyhydroxide modifies the electronic and structural properties of the ferric sites yielding a more d-electron deficient iron species. Although it may be reasonable to suggest that the elec-trocatalytic activity of this composite oxide for oxygen evolution may be related to the presence of such highly oxidized iron sites,... 

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. 

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. 

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. 

Direct Photolysis of Surface-Located Inner Coordination Sphere Complexes. In the presence of a strong metal binding ligand, the underlying central metal ion in the surface layer of a metal oxide can exchange its structural OH" ions for the ligand. Thus, the association of citrate with an iron oxyhydroxide surface may be represented ... 

At low pH, where resorption reactions are minimal, the photodissolution process may be represented as a two-step process involving adsorption of ligand L to metal oxide surface sites followed by detachment of reduced metal ions that is, for an iron oxyhydroxide ... 

Solids Organic Particulate Matter Inorganic Particulate Matter ng/L to mg/L ng/L to mg/L Plankton biomass, fecal pellets, molts, feeding nets Atmospheric dust, riverborne clay minerals, iron oxyhydroxides, micrometeorites... 

Colloids Organic Colloids Inorganic Colloids iron oxyhydroxides... 

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. 

During this zone refining, the primary (igneous) rocks are transformed into secondary minerals. These include (1) clay minerals, such as phillipsite, chlorite, montmo-rillonite (smectite), saponite, celadonite, and zeolite (2) iron oxyhydroxides (3) pyrite (4) various carbonates and (5) quartz. These minerals form rapidly, within 0.015 and 0.12 million years after creation of the oceanic crust at the MOR. During these alteration... 

For removing low levels of priority metal pollutants from wastewater, using ferric chloride has been shown to be an effective and economical method [41]. The ferric salt forms iron oxyhydroxide, an amorphous precipitate in the wastewater. Pollutants are adsorbed onto and trapped within this precipitate, which is then settled out, leaving a clear effluent. The equipment is identical to that for metal hydroxide precipitation. Trace elements such as arsenic, selenium, chromium, cadmium, and lead can be removed by this method at varying pH values. Alternative methods of metals removal include ion exchange, oxidation or reduction, reverse osmosis, and activated carbon. 

Amouric, M. Baronnet, A. Nahon, D. Didier, P. (1986) Electron microscopic investigations of iron oxyhydroxides and accompanying phases in lateritic iron-crust pisolites. Clays Clay Min. 34 45-52... 

Bau, M. Usui, A. Pracejus, B. Mita, N. Kanai, Y. Irber,W. Dulski, P. (1998) Geochemistry of low-temperature water-rock interaction evidence from natural waters, andesite, and iron-oxyhydroxide precipitates at Nishiki-numa iron-spring, Hokkaido,.Japan. Chem. Geol. 151 293-307... 

J. Colloid Interface Sci. 150 453—460 Belzde, N. Tessier, A. (1990) Interactions between arsenic and iron oxyhydroxides in lacustrine sediments. Geochim. Cosmochim. 

Benjamin, M.M. Leckie, J.O. (1981) Multiple-site adsorption of Cd, Cu, Zn, and Pb on amorphous iron oxyhydroxide. J. Colloid Interface Sci. 79 209-221 Benjamin, M.M. Leckie, J.O. (1981a) Competitive adsorption of Cd, Zn, Cu and Pb on amorphous iron oxyhydroxide. J. Colloid Interface Sci. 83 410-419 Benjamin, M.M. Leckie, J.O. (1982) Effects of complexation by Cl, SO4, and S2O3 on the adsorption behavior of cadmium on oxide surfaces. Environ. Sci. Tech. 16 162-170 Benjamin, M.M. (1978) Effects of competing metals and complexing ligands on trace metal adsorption. Ph.D. Thesis Benjamin, M.M. Hayes, K.E. Leckie, K.O. 

Duran, J.D.G. Gonzallez-Caballero, E. (2000) Stability of cobalt-ferrite colloidal particles. Effect of pH and applied magnetic field. Langmuir 16 7954-7961 De Vitre, R. Belzile, N. Tessier, A. (1991) Spe-ciation and adsorption of arsenic on diage-netic iron oxyhydroxides. Limnol. Oceanogr. 36 1480-1485... 

Fortin, D. Leppard, G.G. Tessier, A. (1993) Characteristics of lacustrine diagenetic iron oxyhydroxides. Geochim. Cosmochim. Acta 57 4391-4404... 

McGarrah, J.E. (1991) Neptunium adsorption on synthetic amorphous iron oxyhydroxide. 

Jambor, J.L. Dutrizac, J.E. (1998) Occurrence and constitution of natural and synthetic fer-rihydrite, a widespread iron oxyhydroxide. Chem. Rev. 98 2549-2585 James, R.O. ElealyT.W. (1972) Adsorption of hydrolyzable metal ions at the oxide-water interface. Ill A thermodynamic model of adsorption. J. Colloid Interface Sci. 40 65-81 James, R.O. Parks, G.A. (1982) Characterization of aqueous colloids by their electrical double layer and intrinsic surface chemical properties. Surface Colloid Sci. 12 119-126... 

Liaw, B.J. Cheng, D.S. Yang, B.L. (1989) Oxidative dehydrogenation of 1-butene on iron oxyhydroxides and hydrated iron oxides. J. Catalysis 118 312-326... 

M.C. (1991) Relationship between zinc and phosphate adsorption on montmorillonite and an iron oxyhydroxide. Aust. J. Soil Res. 29 239-247... 

Mavrocordatos, D. Perret, D. (1998) Quantitative and qualitative characterization of aquatic iron oxyhydroxide particles by EF-TEM. J. Microscopy 191 83-90... 

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