Fe oxyhydroxide

Western Woodlaik Basin Franklin Seamount (9°55 S, 151L50 W) 2143-2366 Westernmost propagating tip of spreading center. Basaltic andesite and inferred sodic rhyolite. Spires aud mounds of Fe-Mn-Si oxide up to several meters thick and 200 m in extent. Venting 20-30 C clear solution. Inactive barite silica chimneys contain up to 21 ppm Au. vSi-bearing Fe oxyhydroxide. 

Initial °Th and Pa are generally considered to be associated with a detrital component that becomes cemented, or occluded, within the speleothem. This component may be composed of clays, alumino-silicates or Fe-oxyhydroxides (Fig. 3) with strongly adsorbed and Pa. Th and Pa incorporated in speleothems and similar deposits may also have been transported in colloidal phases (Short et al. 1998 Dearlove et al. 1991), attached to organic molecules (Langmuir and Herman 1980 Gaffney et al. 1992) or as carbonate complexes in solution (Dervin and Faucherre 1973a, b Joao et al. 1987). 

Johnson, C. A., 1986, The regulation of trace element concentrations in river and estuarine waters with acid mine drainage, the adsorption of Cu and Zn on amorphous Fe oxyhydroxides. Geochimica et Cosmochimica Acta 50, 2433-2438. 

Figure 5 shows the analytical results for Fe, Mn, As and P along a transect across a nodule from LG1. This nodule is enriched in Fe, As and P at the centre. The As and P enrichment are spatially correlated with the Fe-rich areas of the nodule, indicating co-precipitation of these trace elements with the Fe oxyhydroxide minerals. This compositional variation isassumed to reflect changes in the groundwater chemistry over time, potentially since the lake formed. 

Observations of the same clay sample in a very finer scale (500 nm) by TEM, may help to identify the potential Fe-oxyhydroxide surfaces attached on a sediment grain (Fig.6). Moreover, abundances of wide spread oxides that may have formed oxide minerals after binding with other elements such as Si, Fe and Al can easily be recognized from the right part of the TEM image (Fig. 7). 

KEYWORDS Tailings, antimony, Fe-oxyhydroxides, oxidation, sorption... 

A series of laboratory experiments by Leuz et al. (2006), showed that the Fe oxyhydroxide, goethite, (FeOOH) is an important sorbent for Sb(lll) and Sb(V) species in the near-neutral pH range. 

The smithsonite ore type is usually composed of a mixed assemblage consisting of dolomite, Fe-oxyhydroxide, quartz clay (kaoline and montmorillonite), minor amount of... 

The presence of iron in nickel oxyhydroxide electrodes has been found to reduce considerably the overpotential for oxygen evolution in alkaline media associated with the otherwise iron free material.(10) An in situ Mossbauer study of a composite Ni/Fe oxyhydroxide was undertaken in order to gain insight into the nature of the species responsible for the electrocatalytic activity.(IT) This specific system appeared particularly interesting as it offered a unique opportunity for determining whether redox reactions involving the host lattice sites can alter the structural and/or electronic characteristics of other species present in the material. 

The in situ Mossbauer experiments were conducted with 90% - Fe enriched 9 1 Ni/Fe oxyhydroxide films which were deposited in the fashion described above onto a gold on Melinex support(12) in a conventional electrochemical cell. Prior to their transfer into the in situ Mossbauer cell, the electrodes were cycled twice between 0 and 0.6 V vs. Hg/HgO,OH" in 1 M KOH. Two such films were used in the actual Mossbauer measurements in order to reduce the counting time. The in situ Mossbauer cell involved in these experiments was previously described. 

Hydrogen oxidation Iron reduction H2 Organic acids N03- Fe - (oxyhydroxides) OO2 Organic acids Identified from molecular analyses Mesophilic bacteria and hyperthermophilic archaea... 

The major changes in the soil solid affecting exchangeable cations are reduction and dissolution of Fe oxyhydroxide coatings (cf. Equation 3.44) ... 

Reductive dissolution of Fe oxyhydroxides holding sorbed As appears to explain the very large concentrations of As in water from wells drilled into alluvial sediments of the Brahmaputra and Ganges Rivers in Bangladesh and West Begal (Nickson et al 1998, 2000). Dissolved As has accumulated from the reduction of As-rich Fe oxyhydroxides formed upstream of the contaminated areas by weathering of As-rich base metal sulfides. The reduction is driven by sedimentary organic matter in the deposits. Release of As from oxidation of pyrite in shallow wells contributes little to the water contamination because any As(IV) released would be re-sorbed on Fe oxides formed in pyrite oxidation. 

Manceau, A. Lanson, B. Schlegel, M.L. Harge, J.C. Musso, M. Eybert-Berard, L. Haze-marm, J.-L. Chateigner, D. Lamble, G.M. (2000) Quantitative Zn speciation in smelter-contaminated soils by EXAFS spectroscopy. Am. J. Sd. 300 289-343 Manceau, A. Nagy, K.L. Spadini, L. Ragnars-dottir, K.V. (2000 a) Influence of anionic layer structure of Fe-oxyhydroxides on the structure of Cd surface complexes. J. Colloid Interface Sd. 228 306-316... 

Marinates, S. Hirmer, M. (1959) Kreta und das mykenische Hellas. Hirmer, Miinchen Mark, A. Merrill, D.T. McLearn, M.E. Winston, S. Fames, J. Kobayashi, S. Martin, WJ. (1988) Trace elements including As, Be, Cd, Cr, Cu, Pb, Mo, Ni, and Zn, can be removed from coal-fired power plant waste-waters by Fe oxyhydroxide adsorption. 49 Proc. Int. Water Conf Eng. Soc. West Pa. 361-368... 

Studies of the sorption of natural radionuclides from groundwater have established that minor minerals, such as clays coating the fractures in crystalline rock and Fe- and Mn-oxyhydroxides, are important sinks for radionuclides. For example, investigations carried out at the Aspo facility (Smellie Karlsson 1999) showed qualitatively that rare earth elements (REEs), Sc, Th, U, Ra, and Ba have been scavenged by Fe-oxyhydroxide and calcite precipitates,... 

The Mina Fe deposit at Salamanca, Spain, presents an interesting potential analogue for waste package interactions with SNF. The oxidized zone has a large abundance of Fe(III) and Mn-Fe oxyhydroxides (Perez del Villar et al. 2002). 

U-bearing minerals and adsorption processes (Salah et al. 2000 Perez del Villar et al. 2000). The vertical and lateral flow of groundwater is responsible for the oxidation and dissolution of primary sulphides, leading to acidic solutions that facilitated the oxidation and dissolution of uraninite. The resulting uranyl cations migrated and precipitated as uranyl minerals, mainly phosphates, silicates, silico-phosphates. In certain local conditions, reduction of these uranyl cations allowed precipitation of coffinite with a high content of P and LREE. Adsorption of uranium, together with P, mainly occurs on Fe-oxyhydroxides, but this kind of uranium retention seems less efficient than the precipitation, at least in the close vicinity to the... 

In the context of use of mine water for space heating and cooling purposes, concern is often expressed as to the possibility of fouling of pipework and exchanger elements by precipitation of secondary minerals such as Fe-oxyhydroxides... 

Where open-loop systems are unavoidable, mine water should be circulated through heat pumps and exchangers in such a way as to minimize contact with atmospheric Oz, which promotes oxidation of Fe2+ to poorly soluble Fe3+. Also consideration should be given to pressurized systems, in which down-mine pressures are maintained as far as possible, to hinder degassing of, for example, C02. Such degassing may elevate pH and promote precipitation of Fe-oxyhydroxides or carbonate scales. 

Fusi, P, Ristori, G. G., and Calamai, L., Stotzky G. (1989). Adsorption and binding of protein on clean (homoionic) and dirty (coated with Fe oxyhydroxides) montmorillonite, iUite and kaolinite. Soil Biol. Biochem. 21, 911-920. 

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