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Showing 1 to 20 of 27 for “"Oxyhydroxides"”.
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Scavenging of particulate and dissolved lead compounds by coprecipitation with manganese oxyhydroxides
… of heavy metals. During precipitation, Mn oxyhydroxides scavenge many heavy metals, including Pb, in a variety of natural environments. Because of this phenomenon, the precipitation of Mn oxyhydroxides may provide a remediation technique for removing Pb from contaminated aqueous solutions. …
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An investigation into the precipitation of Fe(III) oxyhydroxides in lime neutralization processes
… comprised of minuscule particles of Fe(III) oxyhydroxides and gypsum. The sludge is characterized by poor dewatering behaviour and postneutralization instability which increases the risk of the adsorbed or encapsulated dissolved metals to re-leach from the disposal sites, thus lessening the …
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The Chemistry of Metal Oxyhydroxides and their 3D Porous Hybrid Materials for the Capture, Transport and Degradation of Toxic Chemicals
… active sites in UiO-67 MOFs are the metal nodes (oxyhydroxides) and developed a paradigm which correlates the activities of the MOFs, the metal oxyhydroxides and their precursors. This new understanding can help researchers choose the optimum metal for the intended applications by avoiding the …
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Understanding Formation and Transport of Amorphous Iron Oxyhydroxides in Porous Media using Microfluidic Flow Cells- a Novel Method to Study Freshwater Iron Cycling
<p>The ground water and surface water interface (GSI or Hyporheic zone) is a spatially- and temporally-fluctuating biogeochemical transition zone connecting these two distinct hydrological components. The mixing zone is characterized by a near neutral pH, ambient temperature and a sharp oxygen …
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Effect of Amines as Corrosion Inhibitors for a Low Carbon Steel in Power Industry
… layer. FTIR demonstrated that DMA formed more oxyhydroxides, whereas morpholine presented magnetite to hematite transformation as early as 2 hours. SEM revealed that control and DMA produced acicular particles characteristic of oxyhydroxides while morpholine and DBU presented more equiaxed …
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Environmental mineralogy of gold recovery from refractory gold-arsenic-bearing Bakyrchik concentrates
… containing up to 25% As, iron oxides and oxyhydroxides (with up to 2.5% As), haidingerite, and calcium arsenate in studied samples. Sequential extraction demonstrated that in soil and sediment samples As is associated mainly with Al and amorphous Fe oxyhydroxides. Results suggest that the …
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The Low Temperature Surface Geochemistry And Kinetics Of Pyrrhotite Weathering: Influences On Acid Mine Drainage (amd)
… of metal vacancies. At the surface, Fe(III)-oxyhydroxides form through reaction with adsorbed oxygen and hydroxyl species.;Pyrrhotite reacted in {dollar}rm Hsb2SOsb4{dollar} (pH 3.0) develops Fe(III)-oxyhydroxide coated surfaces. Desiccation results in Fe(III)-oxyhydroxide spalling and …
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Fossil preservation and the effects of groundwater leaching on fossils in the Yorktown Formation (Upper Pliocene), Virginia
… caused precipitation of fine-grained iron oxyhydroxides. All carbonate material in the vicinity of the paleochannel is completely dissolved away, although iron oxyhydroxide coatings of fossils remain. Away from the paleochannel Crepidula fornicata (gastropod; aragonite), Ostrea sp. …
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Isolation, Purification, and Chemical Characterization of the Dihydroxamate-Type Siderophore, "Schizokinen," Produced by <em>Rhizobium leguminosarum</em> IARI 917.
… pH, iron is primarily found as insoluble oxyhydroxides and is unavailable to microorganisms. Many bacteria have the ability to produce siderophores, low molecular weight compounds that have a high affinity for Fe<sup>3+</sup>. Siderophores are part of a multi-component system that actively …
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Mechanisms of metal release from contaminated coastal sediments
… metals. The trace metals are scavenged by iron oxyhydroxides and released to the porewaters when these oxides are reduced. At the strongly reducing site in Boston Harbor, there is seasonal transfer of trace metals from oxide phases in winter, to sulfides phase in summer. At the Massachusetts Bay …
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Remobilization Of Cobalt, Copper, Nickel, Lead, And Zinc In A Riparian Wetland Model
… conditions where the dissolution of Fe and Mn-oxyhydroxides would have favored the release of metals previously adsorbed to these phases.
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Kinetics of Arsenopyrite Oxidative Dissolution by Oxygen
… more slowly due to precipitation of iron oxyhydroxides. Our results suggest that the rate determining step in arsenopyrite oxidation is determined by the attachment of oxygen at the anodic site in the mineral, and not the transfer of electrons from the cathodic site to oxygen, as is …
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Sediment Phosphorus Cycling in a Managed System Irondequoit Bay, N.Y.
… form, most likely sorbed onto iron and manganese oxyhydroxides. Iron and manganese profiles from the water column indicated that manganese from the sediment was cycling with phosphorus into the overlying waters, while iron did not demonstrate evidence of cycling. Iron was kept out of solution by …
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Mechanisms of metal release from contaminated coastal sediments
… metals. The trace metals are scavenged by iron oxyhydroxides and released to the porewaters when these oxides are reduced. At the strongly reducing site in Boston Harbor, there is seasonal transfer of trace metals from oxide phases in winter, to sulfides phase in summer. At the Massachusetts Bay …
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Arsenic Stability In Fresh and Aged Amorphous Ferric Hydroxide Sludges Generated from Brine Treatment Processes
… arsenic brines by co-precipitation with iron oxyhydroxides is an established and effective remediation method for small quantities of highly concentrated liquid arsenic waste, such as brines derived from mine tailings, ion exchange resin regeneration, and reverse osmosis treatment of drinking …
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Characterization of Uranium and Rare Earth Element Mobility and Attenuation Downstream of Decommissioned Tailings Impoundments at the Bicroft Mine near Bancroft, Ontario
… and µXRD). The results show that Fe- and Mn-oxyhydroxides, goethite, and birnessite are the main mineral hosts for U and REEs in both the colloids and sediments. In addition, detrital grains of U- and REE-bearing minerals were found >200 m downstream in colloids and wetland sediments, showing …
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Modeling Groundwater Denitrification by Ferrous Iron Using PHREEQC
… to decipher due to the precipitation of Fe(III)-oxyhydroxides from the aqueous solution. 2) in the event when denitrification by both Fe(II) and organic carbon gave rise to precipitating reaction products, the role of Fe(II) is deceivably masked by that of the organic carbon. Thus far, little is …
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The Removal and Recovery of Oxo-Anions from Aqueous Systems using Nano-Porous Silica Polyamine Composites
… process (precipitation with iron (III) oxyhydroxides) is by far the most economical and effective of these technologies and has been widely employed on a large scale. However, it has the significant disadvantage of creating a large amount of sludge for ultimate disposal and leaching of …
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The Removal and Recovery of Oxo-Anions from Aqueous Systems using Nano-Porous Silica Polyamine Composites
… process (precipitation with iron (III) oxyhydroxides) is by far the most economical and effective of these technologies and has been widely employed on a large scale. However, it has the significant disadvantage of creating a large amount of sludge for ultimate disposal and leaching of …
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Passive detection of phosphorus in agricultural drainage waters using reactive hybrid anion exchange resins
… resins, layered double hydroxides, metal oxyhydroxides, zerovalent iron, and zirconium and lanthanum oxides) and evaluated for the use as a P sink. While the pure resins had a non-selective affinity for P, iron (hydr)oxide coated anion exchange resins (hybrid resins) were more selective …
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