Quantum chemical calculations were performed to estimate relative Gibbs free energies of sulfate adsorption on variably charged Al- and Fe-(hydr)oxide clusters. Innersphere bidentate bridging and monodentate adsorption were predicted to be exergonic on positively charged Al- and Fe-(hydr)oxides (ranging from -19 to -124 kJ mol-1). However, inner-sphere and H-bonded adsorption on neutral Al- and...

ÐSurface coatings (bio®lms and associated minerals) were collected on glass slides in the oxic surface waters of Cayuga Lake (New York State, U.S.A.) and were used to evaluate the relative contributions of Fe, Mn and Al oxides and organic material to total observed Pb and Cd adsorption by the surface coating materials. Several alternative selective extraction techniques were evaluated with resp...

Aluminum, one of the most abundant elements in soils and sediments, is commonly found co-precipitated with Fe in natural Fe(III) (hydr)oxides; yet, little is known about how Al substitution impacts bacterial Fe(III) reduction. Accordingly, we investigated the reduction of Al substituted (0–13 mol% Al) goethite, lepidocrocite, and ferrihydrite by the model dissimilatory Fe(III)-reducing bacteriu...

Mixed oxides with large surface area and high thermal stability can be obtained by thermal treatment of the layered double hydroxides (LDH). Mg–Al–Fe mixed oxide samples with varying Mg/Al ratio and 5 mol.% of Fe were prepared in this way and the iron oxidation state (Feox) in these compounds was studied by X-ray photoelectron spectroscopy (XPS), using a calibration based on the relation of Feo...

INTRODUCTION Cycling of redox-sensitive elements such as Fe is affected by not only ambient Eh-pH conditions, but also by a signifi cant biomass that may derive energy through changes in redox state (e. The evidence now seems overwhelming that biological processing of redox-sensitive metals is likely to be the rule in surface-and near-surface environments, rather than the exception. The Fe redo...

Alloys Fe-(0, 5, 10)Cr-10Al (all in at.%) were oxidized at 900 o C in 1 atm oxygen to study the effect of Cr additions on the oxidation behavior. The oxidation kinetics was recorded with a thermal microbalance. The morphologies and microstructures of the oxide scales were examined using SEM, EDS, and XRD. Fe-10Al developed an Al2O3-rich scale during the initial stage of oxidation, and a non-pro...

To study the photodegradation of organic pollutants at the interface of minerals and water in natural environment, three series of alumina-coupled iron oxides (Al(2)O(3)-Fe(2)O(3)-300, Al(2)O(3)-Fe(2)O(3)-420, and Al(2)O(3)-Fe(2)O(3)-550) with different alumina fraction were prepared and characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halender (BJH), and...

Molybdenum adsorption behavior was investigated on various crystalline and x-ray amorphous Al and Fe oxide minerals, clay minerals, CaC@, and arid-zone calcareous and noncalcareous s soils. Molybdenum adsorption on botb Al and Fe oxides exhibited a maximum at low pH extending to about pH 4 to 5. Above pH 5 adsorption decreased rapidly, with little adsorption occurring above pH 8. Molybdenum ads...

The association of free Fe oxides with soils and clays from two Enon sandy loam (Ultic Hapludalfs, fine, mixed, thermic) soil saprolite profiles was studied. Goethite was the dominant Fe oxide identified. Lepidocrocite was detected in trace amounts in some sam ples. Fe/clay ratios were highest in the epipedons of these soils suggesting the concentrating of Fe oxides as a result of alumino silic...

In water treatment, adsorption & ion exchange are usually used on the stage of deep purification when higher selectivity to toxic molecules and ions is needed. Inorganic ion exchangers are that class of the adsorptive materials which, if developed by the advanced synthesis approaches, are capable to lower the concentrations of target anions up to the level requesting by World Health Organizatio...